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Background: The AV delay optimization of biventricular pacemakers (cardiac resynchronization therapy) may maximize hemodynamic benefit but consumes specialist time to conduct echocardiographically. Noninvasive BP monitoring is a potentially automatable alternative, but it is unknown whether it gives the same information and similar precision (signal/noise ratio). Moreover, the immediate BP increment on optimization has been reported to decay away: it is unclear whether this is the result of an (undesirable) decrease in stroke volume or a (desirable) compensatory relief of peripheral vasoconstriction.Methods and Results: To discriminate between these alternative mechanisms, we measured simultaneous beat-to-beat stroke volume (flow) using Doppler echocardiography, and BP using finger photoplethysmography, during and after AV delay changes from 40 to 120 ms in 19 subjects with cardiac pacemakers. BP and stroke volume both increased immediately (P<0.001, within 1 heartbeat). BP showed a clear decline a few seconds later (average rate, -0.65 mm Hg/beat; r=0.95 [95% CI, 0.86-0.98]); in contrast, stroke volume did not decline (P=0.87). The immediate BP increment correlated strongly with the stroke volume increment (r=0.74, P<0.001). The signal/noise ratio was 3-fold better for BP than stroke volume (6.8±3.5 versus 2.3±1.4; P<0.001).Conclusions: Improving AV delay immediately increases BP, but the effect begins to decay within a few seconds. Reassuringly, this is because of compensatory vasodilatation rather than reduction in cardiac function. Pacemaker optimization will never be reliable unless there is an adequate signal/noise ratio. Using BP rather than Doppler minimizes noise. The early phase (before vascular compensation) has the richest signal lode. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although higher blood pressures are generally recognised to be an adverse prognostic marker in risk assessment of cardiology patients, its relationship to risk in chronic heart failure (CHF) may be different. OBJECTIVE: To examine systematically published reports on the relationship between blood pressure and mortality in CHF. METHODS: Medline and Embase were used to identify studies that gave a hazard or relative risk ratio for systolic blood pressure in a stable population with CHF. Included studies were analysed to obtain a unified hazard ratio and quantify the degree of confidence. RESULTS: 10 studies met the inclusion criteria, giving a total population of 8088, with 29 222 person-years of follow-up. All studies showed that a higher systolic blood pressure (SBP) was a favourable prognostic marker in CHF, in contrast to the general population where it is an indicator of poorer prognosis. The decrease in mortality rates associated with a 10 mm Hg higher SBP was 13.0% (95% CI 10.6% to 15.4%) in the heart failure population. This was not related to aetiology, ACE inhibitor or beta blocker use. CONCLUSION: SBP is an easily measured, continuous variable that has a remarkably consistent relationship with mortality within the CHF population. The potential of this simple variable in outpatient assessment of patients with CHF should not be neglected. One possible application of this information is in the optimisation of cardiac resynchronisation devices. [ABSTRACT FROM AUTHOR]

Competing Interests: Disclosures The authors have no conflicts of interest to disclose.

Background: Inappropriate therapy (IAT) is an undesirable side effect of implantable cardiac defibrillator (ICD) therapy. Early studies with the subcutaneous ICD (S-ICD) showed relatively high inappropriate shock (IAS) rates. The PRAETORIAN (Prospective Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) trial demonstrated that the S-ICD is noninferior to the transvenous ICD (TV-ICD) with regard to the combined end point of IAS and complications. This secondary analyses evaluates all IAT in the PRAETORIAN trial., Methods: This international, multicenter trial randomized 849 patients with an indication for ICD therapy between S-ICD (n=426) and TV-ICD therapy (n=423). ICD programming was mandated by protocol. All analysis were performed in the modified intention-to-treat population., Results: In both groups 42 patients experienced IAT (48-month Kaplan-Meier estimated cumulative incidence, 9.9% and 10.1%, respectively; hazard ratio (HR), 0.99 [95% CI, 0.65-1.52]; P =0.97). There was no significant difference in patients experiencing IAS between both groups ( P =0.14). In the S-ICD group, 81 IAT episodes with 124 IAS and 1 inappropriate antitachycardia pacing occurred versus 89 IAT episodes with 130 IAS and 124 inappropriate antitachycardia pacing in the TV-ICD group. IAT episodes were most frequently caused by supraventricular tachycardias in the TV-ICD group (n=83/89) versus cardiac oversensing in the S-ICD group (n=40/81). In the TV-ICD group, a baseline heart rate >80 bpm (HR, 1.99 [95% CI, 1.05-3.76]; P =0.03), a history of atrial fibrillation (HR, 2.66 [95% CI, 1.41-5.02]; P =0.003), and smoking (HR, 2.46 [95% CI, 1.31-4.09]; P =0.005) were independent predictors for IAT. A QRS duration >120 ms was an independent predictor for IAT caused by cardiac oversensing in the S-ICD group (HR, 3.13 [95% CI, 1.34-7.31]; P =0.008). Post-IAS interventions significantly reduced IAS recurrence in both groups ( P =0.046)., Conclusions: There was no significant difference in IAT and IAS rates between the S-ICD and TV-ICD in a conventional ICD population, but causes and predictors for IAT differed between the devices. After the first IAS, an intervention significantly reduced the recurrence rate of IAS., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022., Competing Interests: Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cardiac, and has stock options from AtaCor Medical, Inc. Dr El Chami reports consultancy fees from Boston Scientific and Medtronic. Dr Mittal reports consultancy fees from Boston Scientific and Medtronic.Dr Neuzil reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. K.M. Kooiman reports consultancy fees from Boston Scientific. Dr Lambiase reports educational and research grants from and is in the research board of Boston Scientific, and reports research grants from Abbott. Dr Vernooy reports consultancy fees from Medtronic and Abbott. M.C. Burke is a consultant, receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. Dr Wright has consultancy arrangements with Boston Scientific and Medtronic and a research grant from Boston Scientific. Dr Nordbeck reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. Dr Miller reports consultancy fees from Boston Scientific. Dr Whinnett is an advisor for Boston Scientific, on the advisory board for Medtronic and Abbot, and reports speaker fees from Medtronic. The other authors report no conflicts.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to overcome the risk of lead-related complications associated with the transvenous implantable cardioverter-defibrillator (TV-ICD). In contrast to the TV-ICD, the S-ICD is a completely extrathoracic device. Subsequently, complications differ between these 2 implantable cardioverter-defibrillators, which might impact patient perceptions of the therapies. This prespecified secondary analysis of the PRAETORIAN trial evaluates differences in quality of life., Methods: The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) randomized patients with an implantable cardioverter-defibrillator indication, without the need for pacing to S-ICD or TV-ICD therapy. Two questionnaires were collected at baseline, discharge, 12 months, and 30 months. The Duke Activity Status Index measures cardiac-specific physical functioning, and the 36-Item Short Form Health Survey measures physical and mental well-being, with the subscales bodily pain and mental health being of interest in this analysis. Mann-Whitney U tests were used to compare study arms, and a mixed model was used to describe the questionnaire outcomes over time., Results: Patients were randomized to S-ICD (n=426) and TV-ICD (n=423). In the S-ICD group, 20% were women versus 19% in the TV-ICD group. The median age was 63 (interquartile range, 54-69) years in the S-ICD group versus 64 (interquartile range, 56-69) years in the TV-ICD group. There were no significant differences in the Duke Activity Status Index and 36-Item Short Form Health Survey subscales for bodily pain and mental health between the groups at any time point. Patients with a shock in the last 90 days had significantly lower scores for social functioning ( P =0.008) and role limitations due to emotional problems ( P =0.001) than patients without a shock, but this effect did not differ between treatment arms., Conclusions: In a large randomized cohort of patients with an S-ICD or TV-ICD, no difference in overall quality of life was observed. However, implantable cardioverter-defibrillator shocks resulted in a reduction in quality of life, regardless of the device type or appropriateness., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022., Competing Interests: Dr Knops reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac and has stock options from AtaCor Medical, Inc. Dr El Chami reports consultancy fees from Boston Scientific and Medtronic. Dr Mittal reports consultancy fees from Boston Scientific and Medtronic. K.M. Kooiman reports consultancy fees from Boston Scientific. Dr Lambiase reports educational and research grants from and is in the research board of Boston Scientific, and reports research grants from Abbott. Dr Vernooy reports consultancy fees from Medtronic and Abbott. M.C. Burke is a consultant and receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. Dr Wright has consultancy arrangements with Boston Scientific and Medtronic and iRhythm and a research grant from Boston Scientific. Dr Nordbeck reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. Dr Miller reports consultancy fees from Boston Scientific. Dr Whinnett is an advisor for Boston Scientific and is on the advisory board for Medtronic and Abbot and reports speaker fees from Medtronic. The other authors report no conflicts.

Background: Ventricular tachycardia (VT) reduces cardiac output through high heart rates, loss of atrioventricular synchrony, and loss of ventricular synchrony. We studied the contribution of each mechanism and explored the potential therapeutic utility of His bundle pacing to improve cardiac output during VT., Methods: Study 1 aimed to improve the understanding of mechanisms of harm during VT (using pacing simulated VT). In 23 patients with left ventricular impairment, we recorded continuous ECG and beat-by-beat blood pressure measurements. We assessed the hemodynamic impact of heart rate and restoration of atrial and biventricular synchrony. Study 2 investigated novel pacing interventions during clinical VT by evaluating the hemodynamic effects of His bundle pacing at 5 bpm above the VT rate in 10 patients., Results: In Study 1, at progressively higher rates of simulated VT, systolic blood pressure declined: at rates of 125, 160, and 190 bpm, -22.2%, -42.0%, and -58.7%, respectively (ANOVA p < 0.0001). Restoring atrial synchrony alone had only a modest beneficial effect on systolic blood pressure (+ 3.6% at 160 bpm, p = 0.2117), restoring biventricular synchrony alone had a greater effect (+ 9.1% at 160 bpm, p = 0.242), and simultaneously restoring both significantly increased systolic blood pressure (+ 31.6% at 160 bpm, p = 0.0003). In Study 2, the mean rate of clinical VT was 143 ± 21 bpm. His bundle pacing increased systolic blood pressure by + 14.2% (p = 0.0023). In 6 of 10 patients, VT terminated with His bundle pacing., Conclusions: Restoring atrial and biventricular synchrony improved hemodynamic function in simulated and clinical VT. Conduction system pacing could improve VT tolerability and treatment., (© 2024. The Author(s).)

Background: Conduction system pacing (CSP) by His bundle pacing or left bundle branch area pacing (LBBAP) is incorporated into Heart Rhythm Society guidelines for the management of bradycardia and cardiac resynchronization therapy. Despite increasing adoption with both lumenless leads and stylet-driven leads, concerns regarding the feasibility and safety of the extraction of CSP leads remain., Objective: The aim of the study was to report on the safety, feasibility, and clinical outcomes of the extraction of CSP leads., Methods: Patients undergoing the extraction of CSP leads from 10 international centers were enrolled in this retrospective study. Data regarding indications, lead location, lead type, extraction tools, procedural success, complications, and reimplantation in the conduction system were collected., Results: Overall, 341 patients (age 69 ± 15 years; female 117 (34%); cardiomyopathy 157 (46%); lead dwell time 22 ± 26 months) underwent the extraction of 224 His bundle pacing and 117 LBBAP leads (lumenless leads 321; stylet-driven leads 20). Complete procedural success was achieved in 338 (99%), while clinical success was 100% with retained distal fragments in 3 patients (1%). Among patients with a lead dwell time of >6 months (6-193 months; n = 226), manual extraction was successful in 198 (87%), mechanical tools in 22 (10%), and laser in 6 (3%). Femoral tools were necessary in 3 patients. Minor complications occurred in 7 patients (2.1%). Reimplantation in the conduction system was successful in 233 of 244 patients attempted (95%)., Conclusion: The overall success rates of the extraction of CSP leads were very high (although the LBBAP lead dwell time was <3 years), with a low need for extraction tools and minimal complication. Reimplantation in the conduction system is feasible and safe., Competing Interests: Disclosures Dr Vijayaraman has received honoraria and research support from and is a consultant and serves on the advisory board for Medtronic, serves on the advisory board of and is a consultant for Abbott, and has received honoraria from Biotronik and Boston Scientific. He owns a patent for His bundle pacing delivery tool. Dr Koneru has received honoraria from Medtronic and Biotronik and has received fellowship support from Boston Scientific, Biosense Webster, Medtronic, and Abbott Medical. Dr Sharma has received honoraria from Medtronic and is a consultant for Medtronic, Abbott, and Biotronik. Dr De Pooter has received speaker honoraria and consultancy fees from Medtronic, Biotronik, Abbott, and Boston Scientific. Dr Schaller has received honoraria from Medtronic, Cook Medical, and Phillips. Dr Cano has received honoraria from and is a consultant for Medtronic, Biotronik, and Boston Scientific. Dr Whinnett has received honoraria from Medtronic and Boston Scientific and is a consultant for Medtronic and Abbott. Dr Migliore is a consultant for and has received research support from Boston Scientific and Cook Medical. Dr Ponnusamy has received honoraria from Medtronic. Dr Zanon has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and MicroPort. Dr Heuverswyn has received honoraria from Abbott and Boston Scientific. Dr Ellenbogen is a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik and has received honoraria from Medtronic, Boston Scientific, and Biotronik. Dr Herweg is a speaker and consultant for Abbott and is a speaker for and has received fellowship support from Medtronic. The rest of the authors report no conflicts of interest., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Targeting maximal ventricular resynchronization, with the shortest QRS duration (QRSd), is commonly implemented after cardiac resynchronization therapy (CRT)., Objective: The purpose of this study was to compare optimization of ventricular resynchronization with optimization of left ventricular (LV) filling during CRT by measuring their acute hemodynamic effects., Methods: Patients with standard CRT indications, recruited from 2 centers, underwent biventricular pacing (BVP) and left bundle branch pacing (LBBP). We performed a within-patient comparison of acute hemodynamic response of systolic blood pressure (SBP) at the atrioventricular delay (AVD) with the shortest QRSd against the AVD with the most efficient LV filling. In a validation substudy, we also performed electrical assessment using QRS area (QRSa) and hemodynamic assessment with the maximum rate of LV pressure rise (dP/dt max )., Results: Thirty patients (age 65 ± 10 years; 53% male) were recruited. The AVD producing maximal ventricular resynchronization was associated with a significantly shorter QRSd (difference 15 ± 12 ms for BVP and 18 ± 13 ms for LBBP, both P <.01) and a significantly smaller improvement in SBP (difference -3 ± 4 mm Hg for BVP and -2 ± 2 mm Hg for LBBP, both P <.01) compared with the AVD that optimized filling. Similar findings were observed in the substudy, with a significantly smaller improvement in dP/dt max assessed with QRSd and QRSa (difference -9% ± 7% and -6% ± 4% during BVP, and -5% ± 6% and -3% ± 3% during LBBP, all P <.01)., Conclusion: Targeting the maximal ventricular resynchronization results in suboptimal acute hemodynamic performance with both BVP and LBBP as CRT. These findings support prioritizing LV filling when programming AVD for CRT., Competing Interests: Disclosures Dr Hongyang Lu is an employee of Medtronic. Dr Zachary I. Whinnett is on the advisory board of Medtronic, Abbot, and Boston Scientific, and receives speaker fees from Medtronic and Biotronik. All other authors have no conflicts to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Patients with hypertrophic cardiomyopathy (HCM) are at risk for lethal ventricular arrhythmia, but the electrophysiological substrate behind this is not well-understood. We used non-invasive electrocardiographic imaging to characterize patients with HCM, including cardiac arrest survivors. Methods: HCM patients surviving ventricular fibrillation or hemodynamically unstable ventricular tachycardia (n = 17) were compared to HCM patients without a personal history of potentially lethal arrhythmia (n = 20) and a pooled control group with structurally normal hearts. Subjects underwent exercise testing by non-invasive electrocardiographic imaging to estimate epicardial electrophysiology. Results: Visual inspection of reconstructed epicardial HCM maps revealed isolated patches of late activation time (AT), prolonged activation-recovery intervals (ARIs), as well as reversal of apico-basal trends in T-wave inversion and ARI compared to controls ( p < 0.005 for all). AT and ARI were compared between groups. The pooled HCM group had longer mean AT (60.1 ms vs. 52.2 ms, p < 0.001), activation dispersion (55.2 ms vs. 48.6 ms, p = 0.026), and mean ARI (227 ms vs. 217 ms, p = 0.016) than structurally normal heart controls. HCM ventricular arrhythmia survivors could be differentiated from HCM patients without a personal history of life-threatening arrhythmia by longer mean AT (63.2 ms vs. 57.4 ms, p = 0.007), steeper activation gradients (0.45 ms/mm vs. 0.36 ms/mm, p = 0.011), and longer mean ARI (234.0 ms vs. 221.4 ms, p = 0.026). A logistic regression model including whole heart mean activation time and activation recovery interval could identify ventricular arrhythmia survivors from the HCM cohort, producing a C statistic of 0.76 (95% confidence interval 0.72-0.81), with an optimal sensitivity of 78.6% and a specificity of 79.8%. Discussion: The HCM epicardial electrotype is characterized by delayed, dispersed conduction and prolonged, dispersed activation-recovery intervals. Combination of electrophysiologic measures with logistic regression can improve differentiation over single variables. Future studies could test such models prospectively for risk stratification of sudden death due to HCM., Competing Interests: Medtronic has not influenced or sponsored any of the research here but has provided speaker fees to PK for a topic unrelated to this work. Imperial Innovations holds the patent for the intellectual property of the Ventricular Conduction Stability algorithm on behalf of the authors MS-S, KL, FN, AV, DF, and PK. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Chow, Leong, Shun-Shin, Jones, Guttmann, Mohiddin, Lambiase, Elliott, Ormerod, Koa-Wing, Lefroy, Lim, Linton, Ng, Qureshi, Whinnett, Peters, Francis, Varnava and Kanagaratnam.)

Background: Neurocardiogenic syncope is a common condition with significant associated psychological and physical morbidity. The effectiveness of therapeutic options for neurocardiogenic syncope beyond placebo remains uncertain., Methods: The primary endpoint was the risk ratio (RR) of spontaneously recurring syncope following any therapeutic intervention. We also examined the effect of blinding on treatment efficacy. We identified all randomised trials which evaluated the effect of any pharmacological, device-based or supportive intervention on patients with a history of syncope. A systematic search was conducted on Medline, Embase, PubMed databases and Cochrane Central Register for Controlled Trials from 1950 to 25 April 2023. Event rates, their RRs and 95% CIs were calculated, and a random-effects meta-analysis was conducted for each intervention. Data analysis was performed in R using RStudio., Results: We identified 47 eligible trials randomising 3518 patients. Blinded trials assessing syncope recurrence were neutral for beta blockers, fludrocortisone and conventional dual-chamber pacing but were favourable for selective serotonin reuptake inhibitors (SSRIs) (RR 0.40, 95% CI 0.26 to 0.63, p<0.001), midodrine (RR 0.70, 95% CI 0.53 to 0.94, p=0.016) and closed-loop stimulation (CLS) pacing (RR 0.15, 95% CI 0.07 to 0.35, p<0.001). Unblinded trials reported significant benefits for all therapy categories other than beta blockers and consistently showed larger benefits than blinded trials., Conclusions: Under blinded conditions, SSRIs, midodrine and CLS pacing significantly reduced syncope recurrence. Future trials for syncope should be blinded to avoid overestimating treatment effects., Prospero Registration Number: CRD42022330148., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Implantable cardioverter defibrillators (ICDs) have a long history and have progressed significantly since the 1980s. They have become an essential part of the prevention of sudden cardiac death, with a proven survival benefit in selected patient groups. However, with more recent trials and with the introduction of contemporary heart failure therapy, there is a renewed interest and new questions regarding the role of a primary prevention ICD, especially in patients with heart failure of non-ischaemic aetiology. This review looks at the history and evolution of ICDs, appraises the traditional evidence for ICDs and looks at issues relating to patient selection, risk stratification, competing risk, future directions and a proposed contemporary ICD decision framework.

Background: Left bundle branch area pacing (LBBAP) may be associated with greater improvement in left ventricular ejection fraction and reduction in death or heart failure hospitalization compared with biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy. We sought to compare the occurrence of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and new-onset atrial fibrillation (AF) in patients undergoing BVP and LBBAP., Methods: The I-CLAS study (International Collaborative LBBAP Study) included patients with left ventricular ejection fraction ≤35% who underwent BVP or LBBAP for cardiac resynchronization therapy between January 2018 and June 2022 at 15 centers. We performed propensity score-matched analysis of LBBAP and BVP in a 1:1 ratio. We assessed the incidence of VT/VF and new-onset AF among patients with no history of AF. Time to sustained VT/VF and time to new-onset AF was analyzed using the Cox proportional hazards survival model., Results: Among 1778 patients undergoing cardiac resynchronization therapy (BVP, 981; LBBAP, 797), there were 1414 propensity score-matched patients (propensity score-matched BVP, 707; propensity score-matched LBBAP, 707). The occurrence of VT/VF was significantly lower with LBBAP compared with BVP (4.2% versus 9.3%; hazard ratio, 0.46 [95% CI, 0.29-0.74]; P <0.001). The incidence of VT storm (>3 episodes in 24 hours) was also significantly lower with LBBAP compared with BVP (0.8% versus 2.5%; P =0.013). Among 299 patients with cardiac resynchronization therapy pacemakers (BVP, 111; LBBAP, 188), VT/VF occurred in 8 patients in the BVP group versus none in the LBBAP group (7.2% versus 0%; P <0.001). In 1194 patients with no history of VT/VF or antiarrhythmic therapy (BVP, 591; LBBAP, 603), the occurrence of VT/VF was significantly lower with LBBAP than with BVP (3.2% versus 7.3%; hazard ratio, 0.46 [95% CI, 0.26-0.81]; P =0.007). Among patients with no history of AF (n=890), the occurrence of new-onset AF >30 s was significantly lower with LBBAP than with BVP (2.8% versus 6.6%; hazard ratio, 0.34 [95% CI, 0.16-0.73]; P =0.008). The incidence of AF lasting >24 hours was also significantly lower with LBBAP than with BVP (0.7% versus 2.9%; P =0.015)., Conclusions: LBBAP was associated with a lower incidence of sustained VT/VF and new-onset AF compared with BVP. This difference remained significant after adjustment for differences in baseline characteristics between patients with BVP and LBBAP. Physiological resynchronization by LBBAP may be associated with lower risk of arrhythmias compared with BVP., Competing Interests: Disclosures Dr Herweg is a speaker and consultant for Abbott; is a speaker and receives fellowship support from Medtronic. Dr Sharma has received honoraria from Medtronic and Biotronik, and is a consultant for Medtronic, Abbott, and Biotronik. Dr Cano has received honoraria from and is a consultant for Medtronic, Biotronik, and Boston Scientific. Dr Ponnusamy has received honoraria from Medtronic. Dr Zanon has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Jastrzebski has received honoraria and is a consultant for Medtronic and Abbott. Dr Chelu has received research support from Patient-Centered Outcomes Research Institute (PCORI), National Institutes of Health (NIH), Abbott, Impulse Dynamics, and an honorarium from Impulse Dynamics. Dr Vernooy has been a consultant for Biosense Webster, Philips, Medtronic, Abbott, and Boston Scientific; his institution has received research and educational grants from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic and Boston Scientific and is a consultant for Medtronic and Abbott. Dr Nair has received grants in aid from Biosense Webster, Medtronic Inc., CIHR, and Heart and Stroke Foundation of Canada, and honoraria and consulting fees from Medtronic, Biosense Webster, and Boston Scientific. Dr Curila is a consultant for and has received honoraria from Medtronic, Biotronik, and Abbott. Dr Subzposh has received honoraria from Medtronic. Dr Ellenbogen is a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik, and has received honoraria from Medtronic, Boston Scientific, and Biotronik. Dr Vijayaraman has received honoraria and consultant, research, and fellowship support from Medtronic; he is a consultant for Abbott, Eaglepoint LLC, and has received honoraria from Boston Scientific, Biotronik, and holds a patent for a His bundle pacing delivery tool. The remaining authors report no conflicts of interest.

Background: Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has been associated with greater clinical improvement in women than men. Recently, left bundle branch area pacing (LBBAP) has been shown to be an alternative form of CRT., Objectives: The purpose of this study was to investigate sex-specific outcomes for death and heart failure events in a large, international, multicenter, cohort of patients undergoing CRT with BVP or LBBAP., Methods: In this international study of 1,778 patients (575 female and 1203 male), sex-specific survival analysis was performed to compare the effect of LBBAP-CRT relative to BVP-CRT on the combined endpoint of death or heart failure hospitalization (HFH), and secondary endpoints of HFH only, and death alone., Results: Female patients were more likely to have nonischemic cardiomyopathy and left bundle branch block (LBBB) and less likely to have hypertension, diabetes, or coronary artery disease than were male patients. Overall, female patients had a better result with LBBAP compared with BVP than did male patients, with a significant 36% reduction in death or HFH (HR: 0.64; 95% CI: 0.43 to 0.97; P = 0.03) and a significant 60% reduction in HFH alone (HR: 0.4; 95% CI: 0.24 to 0.69, P < 0.01). Women had a greater reduction in death or HFH among those with nonischemic cardiomyopathy (HR: 0.45 95% CI: 0.26 to 0.79; P < 0.01) and LBBB (HR: 0.49; 95% CI: 0.27 to 0.87; P < 0.01). Sex-specific echocardiographic outcomes were better in women than in men., Conclusions: Women obtained significantly greater reductions in the combined endpoint of death or HFH (primarily driven by reduction in HFH) with LBBAP compared with BVP among patients requiring CRT than did men., Competing Interests: Funding Support and Author Disclosures Dr Subzposh has received honoraria from Medtronic. Dr Sharma has received honoraria from Medtronic; and has served as a consultant for Medtronic, Abbott, and Biotronik. Dr Cano has received honoraria from, and has served as a consultant for, Medtronic, Biotronik, and Boston Scientific. Dr Ponnusamy has received honoraria from Medtronic. Dr Herweg has served as a speaker and a consultant for Abbott; and has been a speaker for, and recipient of fellowship support from, Medtronic. Dr Zanon has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Jastrzebski has received honoraria from, and served as a consultant for, Medtronic and Abbott. Dr Chelu has received research support from PCORI, NIH, Abbott, Impulse Dynamics; and has received an honorarium from Impulse Dynamics. Dr Vernooy has served as a consultant for Biosense Webster, Philips, Medtronic, Abbott, and Boston Scientific; and his institution has received research and educational grants from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic, and Boston Scientific; and has served as a consultant for Medtronic and Abbott. Dr Nair has received a grant-in-aid from Biosense Webster and Medtronic Inc, CIHR, and Heart and Stroke Foundation of Canada; and has received honoraria and consulting fees from Medtronic, Biosense Webster, and Boston Scientific. Dr Curila has served as a consultant for, and has received honoraria from, Medtronic, Biotronik, and Abbott. Dr Ellenbogen has served as a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik; and has received honoraria from Medtronic, Boston Scientific, and Biotronik. Dr Vijayaraman has received honoraria and research and fellowship support from, and has served as a consultant for, Medtronic; has served as a consultant for Abbott and Eaglepoint LLC; has received honoraria from Boston Scientific and Biotronik; and holds a patent for HBP delivery tool. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Conduction system pacing (CSP), including both left bundle branch area pacing (LBBAP) and His-bundle pacing (HBP) has been proposed as an alternative therapy option for patients with indication for cardiac pacing to treat bradycardia or heart failure., Objective: The purpose of this study was to evaluate implant success, safety, and electrical performances of HBP and LBBAP in the multinational Physiological Pacing Registry., Methods: The international prospective observational registry included 44 sites from 16 countries globally between November 2018 and May 2021., Results: Of 870 subjects enrolled, CSP lead implantation was attempted in 849 patients. Subjects with successful CSP lead implantation were followed for 6 months (5 ± 2 months). CSP lead implantation was successful in 768 patients (90.4%). Implant success was 95.2% (239/251) for LBBAP and 88.5% (529/598) for HBP (P = .002). Procedural duration and fluoroscopy duration were comparable between LBBAP and HBP (P = .537). Capture threshold at implant was 0.69 ± 0.39 V at 0.46 ± 0.15 ms in LBBAP and 1.44 ± 1.03 V at 0.71 ± 0.33 ms in HBP (P <.001). Capture threshold at 6 months was 0.79 ± 0.33 V at 0.44 ± 0.13 ms in LBBAP and 1.59 ± 0.97 V at 0.67 ± 0.31 ms in HBP (P <.001). Pacing threshold rise ≥1 V was observed at 6 months in 3 of 208 (1.4%) of LBBAP and 55 of 418 (13.2%) of HBP (P <.001). Serious adverse events related to implant procedure or CSP lead occurred in 5 of 251 (2.0%) with LBBAP and 25 of 598 (4.2%) with HBP (P = .115)., Conclusion: This large prospective multicenter study demonstrates that CSP is technically feasible in most patients with relatively higher implant success and suggests that, with current technology, LBBAP may have better pacing parameters than HBP., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The prognostic impact of ventricular tachycardia (VT) catheter ablation is an important outstanding research question. We undertook a reconstructed individual patient data meta-analysis of randomised controlled trials comparing ablation to medical therapy in patients developing VT after MI., Methods: We systematically identified all trials comparing catheter ablation to medical therapy in patients with VT and prior MI. The prespecified primary endpoint was reconstructed individual patient assessment of all-cause mortality. Prespecified secondary endpoints included trial-level assessment of all-cause mortality, VT recurrence or defibrillator shocks and all-cause hospitalisations. Prespecified subgroup analysis was performed for ablation approaches involving only substrate modification without VT activation mapping. Sensitivity analyses were performed depending on the proportion of patients with prior MI included., Results: Eight trials, recruiting a total of 874 patients, were included. Of these 874 patients, 430 were randomised to catheter ablation and 444 were randomised to medical therapy. Catheter ablation reduced all-cause mortality compared with medical therapy when synthesising individual patient data (HR 0.63; 95% CI [0.41-0.96]; p=0.03), but not in trial-level analysis (RR 0.91; 95% CI [0.67-1.23]; p=0.53; I 2 =0%). Catheter ablation significantly reduced VT recurrence, defibrillator shocks and hospitalisations compared with medical therapy. Sensitivity analyses were consistent with the primary analyses., Conclusion: In patients with postinfarct VT, catheter ablation reduces mortality., Competing Interests: Disclosures: PK is on the editorial board of Arrhythmia & Electrophysiology Review; this did not influence peer review. All other authors have no conflicts of interest to declare. Author contributions: Conceptualisation: RKR, JPH, ADA, ZIW; data curation: FAS, AAM, AN, JWS, JSM, NK, BP, DK, NWFL; formal analysis: RKR, JPH, MJSS; funding acquisition: ADA; investigation: RKR, JPH, YA, MJSS, DPF, ZIW, VL, PK, ADA; methodology: RKR, JPH, YA, MJSS, ADA; project administration: RKR, ADA; resources: FAS, AAM, AN, JWS, JSM, NK, BP, DK, NWFL; software: RKR, JPH, MJSS; supervision: ADA, PK, VL, ZIW, DPF, NWFL, DK, BP; validation: ADA; visualisation: RKR, JPH, MJSS; writing – original draft preparation: RKR, ADA; writing – review and editing: JPH, YA, MJSS, FAS, AAM, KS, AN, JWS, JSM, NK, BP, DK, NWFL, DPF, ZIW, ZL, PK., (Copyright © The Author(s), 2023. Published by Radcliffe Group Ltd.)

Aims: Left bundle branch pacing (LBBP) can deliver physiological left ventricular activation, but typically at the cost of delayed right ventricular (RV) activation. Right ventricular activation can be advanced through anodal capture, but there is uncertainty regarding the mechanism by which this is achieved, and it is not known whether this produces haemodynamic benefit., Methods and Results: We recruited patients with LBBP leads in whom anodal capture eliminated the terminal R-wave in lead V1. Ventricular activation pattern, timing, and high-precision acute haemodynamic response were studied during LBBP with and without anodal capture. We recruited 21 patients with a mean age of 67 years, of whom 14 were males. We measured electrocardiogram timings and haemodynamics in all patients, and in 16, we also performed non-invasive mapping. Ventricular epicardial propagation maps demonstrated that RV septal myocardial capture, rather than right bundle capture, was the mechanism for earlier RV activation. With anodal capture, QRS duration and total ventricular activation times were shorter (116 ± 12 vs. 129 ± 14 ms, P < 0.01 and 83 ± 18 vs. 90 ± 15 ms, P = 0.01). This required higher outputs (3.6 ± 1.9 vs. 0.6 ± 0.2 V, P < 0.01) but without additional haemodynamic benefit (mean difference -0.2 ± 3.8 mmHg compared with pacing without anodal capture, P = 0.2)., Conclusion: Left bundle branch pacing with anodal capture advances RV activation by stimulating the RV septal myocardium. However, this requires higher outputs and does not improve acute haemodynamics. Aiming for anodal capture may therefore not be necessary., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: The use of left bundle branch area pacing (LBBAP) for bradycardia pacing and cardiac resynchronization is increasing, but implants are not always successful. We prospectively studied consecutive patients to determine whether septal scar contributes to implant failure., Methods: Patients scheduled for bradycardia pacing or cardiac resynchronization therapy were prospectively enrolled. Recruited patients underwent preprocedural scar assessment by cardiac MRI with late gadolinium enhancement imaging. LBBAP was attempted using a lumenless lead (Medtronic 3830) via a transeptal approach., Results: Thirty-five patients were recruited: 29 male, mean age 68 years, 10 ischemic, and 16 non-ischemic cardiomyopathy. Pacing indication was bradycardia in 26% and cardiac resynchronization in 74%. The lead was successfully deployed to the left ventricular septum in 30/35 (86%) and unsuccessful in the remaining 5/35 (14%). Septal late gadolinium enhancement was significantly less extensive in patients where left septal lead deployment was successful, compared those where it was unsuccessful (median 8%, IQR 2%-18% vs. median 54%, IQR 53%-57%, p < .001)., Conclusions: The presence of septal scar appears to make it more challenging to deploy a lead to the left ventricular septum via the transeptal route. Additional implant tools or alternative approaches may be required in patients with extensive septal scar., (© 2023 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Background: Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well established therapy in patients with reduced left ventricular ejection fraction (LVEF), heart failure, and wide QRS or expected frequent ventricular pacing. Left bundle branch area pacing (LBBAP) has recently been shown to be a safe alternative to BVP., Objectives: The aim of this study was to compare the clinical outcomes between BVP and LBBAP among patients undergoing CRT., Methods: This observational study included patients with LVEF ≤35% who underwent BVP or LBBAP for the first time for Class I or II indications for CRT from January 2018 to June 2022 at 15 international centers. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included endpoints of death, HFH, and echocardiographic changes., Results: A total of 1,778 patients met inclusion criteria: 981 BVP, 797 LBBAP. The mean age was 69 ± 12 years, 32% were female, 48% had coronary artery disease, and mean LVEF was 27% ± 6%. Paced QRS duration in LBBAP was significantly narrower than baseline (128 ± 19 ms vs 161 ± 28 ms; P < 0.001) and significantly narrower compared to BVP (144 ± 23 ms; P < 0.001). Following CRT, LVEF improved from 27% ± 6% to 41% ± 13% (P < 0.001) with LBBAP compared with an increase from 27% ± 7% to 37% ± 12% (P < 0.001) with BVP, with significantly greater change from baseline with LBBAP (13% ± 12% vs 10% ± 12%; P < 0.001). On multivariable regression analysis, the primary outcome was significantly reduced with LBBAP compared with BVP (20.8% vs 28%; HR: 1.495; 95% CI: 1.213-1.842; P < 0.001)., Conclusions: LBBAP improved clinical outcomes compared with BVP in patients with CRT indications and may be a reasonable alternative to BVP., Competing Interests: Funding Support and Author Disclosures Dr Vijayaraman has received honoraria and consultancy, research, and fellowship support from Medtronic; has served as a consultant for Abbott and Eaglepoint; has received honoraria from Boston Scientific and Biotronik; and has a patent for a His bundle pacing delivery tool. Dr Sharma has received honoraria from Medtronic; and has served as a consultant for Medtronic, Abbott, and Biotronik. Dr Cano has received honoraria from and served as a consultant for Medtronic, Biotronik, and Boston Scientific. Dr Ponnusamy has received honoraria from Medtronic. Dr Herweg has served as a speaker and consultant for Abbott; and has received speaking and fellowship support from Medtronic. Dr Jastrzebski has received honoraria from and served as a consultant for Medtronic and Abbott. Dr Zou has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Chelu has received research support from Patient-Centered Outcomes Research Institute, National Institutes of Health, Abbott, and Impulse Dynamics; and has received honorarium from Impulse Dynamics. Dr Vernooy has served as a consultant for Biosense Webster, Philips, Medtronic, Abbott, and Boston Scientific; and has received research and educational grants to his institution from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic and Boston Scientific; and has served as a consultant for Medtronic and Abbott. Dr Nair has received grants-in-aid from Biosense Webster, Medtronic, Canadian Institutes of Health Research, and Heart and Stroke Foundation of Canada; and has received honoraria and consulting fees from Medtronic, Biosense Webster, and Boston Scientific. Dr Curila has served as a consultant for and received honoraria from Medtronic, Biotronik, and Abbott. Dr Ellenbogen has served as a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik; and has received honoraria from Medtronic, Boston Scientific, and Biotronik. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aims: In heart failure (HF), implantable haemodynamic monitoring devices have been shown to optimize therapy, anticipating clinical decompensation and preventing hospitalization. Direct left-sided haemodynamic sensors offer theoretical benefits beyond pulmonary artery pressure monitoring systems. We evaluated the safety, usability, and performance of a novel left atrial pressure (LAP) monitoring system in HF patients., Methods and Results: The VECTOR-HF study (NCT03775161) was a first-in-human, prospective, multicentre, single-arm, clinical trial enrolling 30 patients with HF. The device consisted of an interatrial positioned leadless sensor, able to transmit LAP data wirelessly. After 3 months, a right heart catheterization was performed to correlate mean pulmonary capillary wedge pressure (PCWP) with simultaneous mean LAP obtained from the device. Remote LAP measurements were then used to guide patient management. The miniaturized device was successfully implanted in all 30 patients, without acute major adverse cardiac and neurological events (MACNE). At 3 months, freedom from short-term MACNE was 97%. Agreement between sensor-calculated LAP and PCWP was consistent, with a mean difference of -0.22 ± 4.92 mmHg, the correlation coefficient and the Lin's concordance correlation coefficient values were equal to 0.79 (p < 0.0001) and 0.776 (95% confidence interval 0.582-0.886), respectively. Preliminary experience with V-LAP-based HF management was associated with significant improvements in New York Heart Association (NYHA) functional class (32% of patients reached NYHA class II at 6 months, p < 0.005; 60% of patients at 12 months, p < 0.005) and 6-min walk test distance (from 244.59 ± 119.59 m at baseline to 311.78 ± 129.88 m after 6 months, p < 0.05, and 343.95 ± 146.15 m after 12 months, p < 0.05)., Conclusion: The V-LAP™ monitoring system proved to be generally safe and provided a good correlation with invasive PCWP. Initial evidence also suggests possible improvement in HF clinical symptoms., (© 2023 The Authors. European Journal of Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Introduction: It is not known whether the optimal atrioventricular (AV opt ) delay varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration., Methods: We assessed the hemodynamic AV opt in patients with chronic heart failure undergoing endocardial LV lead implantation. AV opt was assessed during atrio-BiVP with a "roving LV lead." Up to four locations were studied: mid-lateral wall, mid-septum (or a close alternative), site of greatest hemodynamic improvement, and LV lead implant site. The AV opt was compared to a fixed AV delay of 180 ms., Results: Seventeen patients were included (12 male, aged 66.5 ± 12.8 years, ejection fraction 26 ± 7%, 16 left bundle branch block or high percentage of right ventricular pacing [RVP], QRS duration 167 ± 27 ms). In most locations (62/63), AV opt increased systolic blood pressure during BiVP compared with RVP (relative improvement 6 mmHg, interquartile range [IQR] 4-9 mmHg). Compared to a fixed AV delay, the hemodynamic improvement at AV opt was higher (1 mmHg, IQR 0.2-2.6 mmHg, p < .001). Within most patients (16/17), we observed a difference in AV opt between pacing sites (median paced AV opt 209 ms, IQR 117-250). Within this range, the hemodynamic impact of these differences was small (median loss 0.6 mmHg, IQR 0.1-2.6 mmHg)., Conclusion: Within a patient, different endocardial LV lead locations have slightly different hemodynamic AV opt which are superior to a fixed AV delay. The hemodynamic consequence of applying an optimum from a different lead location is small., (© 2023 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Background Idiopathic ventricular fibrillation (VF) is a diagnosis of exclusion following normal cardiac investigations. We sought to determine if exercise-induced changes in electrical substrate could distinguish patient groups with various ventricular arrhythmic pathophysiological conditions and identify patients susceptible to VF. Methods and Results Computed tomography and exercise testing in patients wearing a 252-electrode vest were combined to determine ventricular conduction stability between rest and peak exercise, as previously described. Using ventricular conduction stability, conduction heterogeneity in idiopathic VF survivors (n=14) was compared with those surviving VF during acute ischemia with preserved ventricular function following full revascularization (n=10), patients with benign ventricular ectopy (n=11), and patients with normal hearts, no arrhythmic history, and negative Ajmaline challenge during Brugada family screening (Brugada syndrome relatives; n=11). Activation patterns in normal subjects (Brugada syndrome relatives) are preserved following exercise, with mean ventricular conduction stability of 99.2±0.9%. Increased heterogeneity of activation occurred in the idiopathic VF survivors (ventricular conduction stability: 96.9±2.3%) compared with the other groups combined (versus 98.8±1.6%; P =0.001). All groups demonstrated periodic variation in activation heterogeneity (frequency, 0.3-1 Hz), but magnitude was greater in idiopathic VF survivors than Brugada syndrome relatives or patients with ventricular ectopy (7.6±4.1%, 2.9±2.9%, and 2.8±1.2%, respectively). The cause of this periodicity is unknown and was not replicable by introducing exercise-induced noise at comparable frequencies. Conclusions In normal subjects, ventricular activation patterns change little with exercise. In contrast, patients with susceptibility to VF experience activation heterogeneity following exercise that requires further investigation as a testable manifestation of underlying myocardial abnormalities otherwise silent during routine testing.

Aims: Left bundle branch area pacing (LBBAP) is a promising method for delivering cardiac resynchronization therapy (CRT), but its relative physiological effectiveness compared with His bundle pacing (HBP) is unknown. We conducted a within-patient comparison of HBP, LBBAP, and biventricular pacing (BVP)., Methods and Results: Patients referred for CRT were recruited. We assessed electrical response using non-invasive mapping, and acute haemodynamic response using a high-precision haemodynamic protocol. Nineteen patients were recruited: 14 male, mean LVEF of 30%. Twelve had time for BVP measurements. All three modalities reduced total ventricular activation time (TVAT), (ΔTVATHBP -43 ± 14 ms and ΔTVATLBBAP -35 ± 20 ms vs. ΔTVATBVP -19 ± 30 ms, P = 0.03 and P = 0.1, respectively). HBP produced a significantly greater reduction in TVAT compared with LBBAP in all 19 patients (-46 ± 15 ms, -36 ± 17 ms, P = 0.03). His bundle pacing and LBBAP reduced left ventricular activation time (LVAT) more than BVP (ΔLVATHBP -43 ± 16 ms, P < 0.01 vs. BVP, ΔLVATLBBAP -45 ± 17 ms, P < 0.01 vs. BVP, ΔLVATBVP -13 ± 36 ms), with no difference between HBP and LBBAP (P = 0.65). Acute systolic blood pressure was increased by all three modalities. In the 12 with BVP, greater improvement was seen with HBP and LBBAP (6.4 ± 3.8 mmHg BVP, 8.1 ± 3.8 mmHg HBP, P = 0.02 vs. BVP and 8.4 ± 8.2 mmHg for LBBAP, P = 0.3 vs. BVP), with no difference between HBP and LBBAP (P = 0.8)., Conclusion: HBP delivered better ventricular resynchronization than LBBAP because right ventricular activation was slower during LBBAP. But LBBAP was not inferior to HBP with respect to LV electrical resynchronization and acute haemodynamic response., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Guidelines recommend patients undergoing a first pacemaker implant who have even mild left ventricular (LV) impairment should receive biventricular or conduction system pacing (CSP). There is no corresponding recommendation for patients who already have a pacemaker. We conducted a meta-analysis of randomized controlled trials (RCTs) and observational studies assessing device upgrades. The primary outcome was the echocardiographic change in LV ejection fraction (LVEF). Six RCTs (randomizing 161 patients) and 47 observational studies (2644 patients) assessing the efficacy of upgrade to biventricular pacing were eligible for analysis. Eight observational studies recruiting 217 patients of CSP upgrade were also eligible. Fourteen additional studies contributed data on complications (25 412 patients). Randomized controlled trials of biventricular pacing upgrade showed LVEF improvement of +8.4% from 35.5% and observational studies: +8.4% from 25.7%. Observational studies of left bundle branch area pacing upgrade showed +11.1% improvement from 39.0% and observational studies of His bundle pacing upgrade showed +12.7% improvement from 36.0%. New York Heart Association class decreased by -0.4, -0.8, -1.0, and -1.2, respectively. Randomized controlled trials of biventricular upgrade found improvement in Minnesota Heart Failure Score (-6.9 points) and peak oxygen uptake (+1.1 mL/kg/min). This was also seen in observational studies of biventricular upgrades (-19.67 points and +2.63 mL/kg/min, respectively). In studies of the biventricular upgrade, complication rates averaged 2% for pneumothorax, 1.4% for tamponade, and 3.7% for infection over 24 months of mean follow-up. Lead-related complications occurred in 3.3% of biventricular upgrades and 1.8% of CSP upgrades. Randomized controlled trials show significant physiological and symptomatic benefits of upgrading pacemakers to biventricular pacing. Observational studies show similar effects between biventricular pacing upgrade and CSP upgrade., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Ablation of autonomic ectopy-triggering ganglionated plexuses (ET-GP) has been used to treat paroxysmal atrial fibrillation (AF). It is not known if ET-GP localisation is reproducible between different stimulators or whether ET-GP can be mapped and ablated in persistent AF. We tested the reproducibility of the left atrial ET-GP location using different high-frequency high-output stimulators in AF. In addition, we tested the feasibility of identifying ET-GP locations in persistent atrial fibrillation., Methods: Nine patients undergoing clinically-indicated paroxysmal AF ablation received pacing-synchronised high-frequency stimulation (HFS), delivered in SR during the left atrial refractory period, to compare ET-GP localisation between a custom-built current-controlled stimulator (Tau20) and a voltage-controlled stimulator (Grass S88, SIU5). Two patients with persistent AF underwent cardioversion, left atrial ET-GP mapping with the Tau20 and ablation (Precision™, Tacticath™ [n = 1] or Carto™, SmartTouch™ [n = 1]). Pulmonary vein isolation (PVI) was not performed. Efficacy of ablation at ET-GP sites alone without PVI was assessed at 1 year., Results: The mean output to identify ET-GP was 34 mA (n = 5). Reproducibility of response to synchronised HFS was 100% (Tau20 vs Grass S88; [n = 16] [kappa = 1, SE = 0.00, 95% CI 1 to 1)][Tau20 v Tau20; [n = 13] [kappa = 1, SE = 0, 95% CI 1 to 1]). Two patients with persistent AF had 10 and 7 ET-GP sites identified requiring 6 and 3 min of radiofrequency ablation respectively to abolish ET-GP response. Both patients were free from AF for > 365 days without anti-arrhythmics., Conclusions: ET-GP sites are identified at the same location by different stimulators. ET-GP ablation alone was able to prevent AF recurrence in persistent AF, and further studies would be warranted., (© 2023. The Author(s).)

Aims: The effect of atrial fibrillation catheter ablation on cardiovascular outcomes in heart failure is an important outstanding research question. We undertook a meta-analysis of randomized controlled trials comparing ablation to medical therapy in patients with AF and heart failure., Methods and Results: We systematically identified all trials comparing catheter ablation to medical therapy in patients with heart failure and atrial fibrillation. The pre-specified primary endpoint was all-cause mortality in trials with at least 2 years of follow-up. The secondary endpoint was heart failure hospitalization. Sensitivity analyses were performed for trials with any follow-up and trials deemed at low risk of bias. Eight trials (1390 patients) were included. Seven hundred and seven patients were randomized to catheter ablation and 683 to medical therapy. In the primary analysis (three trials, n = 977), catheter ablation reduced mortality compared with medical therapy [relative risk (RR): 0.61, 95% confidence interval (CI): 0.44 to 0.84, P = 0.003]. Catheter ablation also reduced heart failure hospitalizations compared with medical therapy (RR: 0.60, 95% CI: 0.49-0.74, P < 0.001). The effect on stroke was not statistically significant (RR: 0.62, 95% CI: 0.28-1.37, P = 0.237). There was low heterogeneity between studies. Sensitivity analyses were consistent with the primary analyses., Conclusion: In patients with atrial fibrillation and heart failure, catheter ablation reduces mortality and the occurrence of heart failure hospitalizations., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Excessive prolongation of PR interval impairs coupling of atrio-ventricular (AV) contraction, which reduces left ventricular pre-load and stroke volume, and worsens symptoms. His bundle pacing allows AV delay shortening while maintaining normal ventricular activation. HOPE-HF evaluated whether AV optimized His pacing is preferable to no-pacing, in a double-blind cross-over fashion, in patients with heart failure, left ventricular ejection fraction (LVEF) ≤40%, PR interval ≥200 ms and either QRS ≤140 ms or right bundle branch block., Methods and Results: Patients had atrial and His bundle leads implanted (and an implantable cardioverter-defibrillator lead if clinically indicated) and were randomized to 6 months of pacing and 6 months of no-pacing utilizing a cross-over design. The primary outcome was peak oxygen uptake during symptom-limited exercise. Quality of life, LVEF and patients' holistic symptomatic preference between arms were secondary outcomes. Overall, 167 patients were randomized: 90% men, 69 ± 10 years, QRS duration 124 ± 26 ms, PR interval 249 ± 59 ms, LVEF 33 ± 9%. Neither peak oxygen uptake (+0.25 ml/kg/min, 95% confidence interval [CI] -0.23 to +0.73, p = 0.3) nor LVEF (+0.5%, 95% CI -0.7 to 1.6, p = 0.4) changed with pacing but Minnesota Living with Heart Failure quality of life improved significantly (-3.7, 95% CI -7.1 to -0.3, p = 0.03). Seventy-six percent of patients preferred His bundle pacing-on and 24% pacing-off (p < 0.0001)., Conclusion: His bundle pacing did not increase peak oxygen uptake but, under double-blind conditions, significantly improved quality of life and was symptomatically preferred by the clear majority of patients. Ventricular pacing delivered via the His bundle did not adversely impact ventricular function during the 6 months., (© 2022 The Authors. European Journal of Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Background: Accurately determining arrhythmia mechanism from a 12-lead electrocardiogram (ECG) of supraventricular tachycardia can be challenging. We hypothesized a convolutional neural network (CNN) can be trained to classify atrioventricular re-entrant tachycardia (AVRT) vs atrioventricular nodal re-entrant tachycardia (AVNRT) from the 12-lead ECG, when using findings from the invasive electrophysiology (EP) study as the gold standard., Methods: We trained a CNN on data from 124 patients undergoing EP studies with a final diagnosis of AVRT or AVNRT. A total of 4962 5-second 12-lead ECG segments were used for training. Each case was labeled AVRT or AVNRT based on the findings of the EP study. The model performance was evaluated against a hold-out test set of 31 patients and compared to an existing manual algorithm., Results: The model had an accuracy of 77.4% in distinguishing between AVRT and AVNRT. The area under the receiver operating characteristic curve was 0.80. In comparison, the existing manual algorithm achieved an accuracy of 67.7% on the same test set. Saliency mapping demonstrated the network used the expected sections of the ECGs for diagnoses; these were the QRS complexes that may contain retrograde P waves., Conclusion: We describe the first neural network trained to differentiate AVRT from AVNRT. Accurate diagnosis of arrhythmia mechanism from a 12-lead ECG could aid preprocedural counseling, consent, and procedure planning. The current accuracy from our neural network is modest but may be improved with a larger training dataset., (© 2023 Heart.)

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial., Methods and Results: The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047)., Conclusion: This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice., Competing Interests: Conflict of interest: R.E.K reports consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac and has stock options from AtaCor Medical Inc. S.M. reports consultancy fees from Boston Scientific. K.V. reports consultancy fees from Medtronic and Abbott. M.C.B. is a consultant and receives honoraria, as well as research grants from Boston Scientific and has equity in and is chief medical officer for AtaCor Medical, Inc. D.J.W. has consultancy arrangements with Boston Scientific and Medtronic and a research grant from Boston Scientific. P.N. reports modest speaker honoraria from Biotronik, Boston Scientific, and Medtronic. M.A.M. reports consultancy fees from Boston Scientific. Z.I.W. is an advisor for Boston Scientific and on the advisory board for Medtronic and Abbot and reports speaker fees from Medtronic. The other authors report no conflicts., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.)

Background: Atrioventricular nodal ablation (AVNA) combined with biventricular pacing (BVP) improves outcomes in patients with persistent atrial fibrillation (AF), adequate rate control, and reduced left ventricular ejection fraction (LVEF). His-bundle pacing (HBP) delivers physiological ventricular activation and is a promising alternative to BVP., Objective: The purpose of this trial was to compare HBP with BVP following AVNA., Methods: In this multicenter, prospective, randomized crossover trial, we recruited patients with persistent AF and reduced LVEF (≤40%). All patients underwent AVNA and received both HBP and BVP. Patients were randomized to either HBP or BVP for 9 months (phase 1), then were switched to the alternative pacing modality for the next 9 months (phase 2). The primary endpoint was change in LVEF., Results: Fifty patients (age 64.3 ± 10.3 years; ventricular rate 93.1 ± 19.9 bpm; 72% male) were enrolled. Thirty-eight patients completed the 2 phases and were included in the crossover analysis. A significant improvement in LVEF was observed with HBP compared to BVP (phase 1: ΔLVEF HBP 21.3% and ΔLVEF BVP 16.7%; phase 2: ΔLVEF HBP 3.5% and ΔLVEF BVP -2.4%; P generalized additive model = 0.015). Significant improvements in left ventricular end-diastolic diameter, New York Heart Association functional class, and B-type natriuretic peptide level were observed with both pacing modalities compared with baseline, whereas no significant differences were observed between HBP and BVP., Conclusion: HBP delivers a modest but significant improvement in LVEF in patients with persistent AF, impaired ventricular function, and narrow QRS duration post-AVNA compared with BVP. Larger long-term trials are required to confirm the additional improvements in function with HBP., (Copyright © 2022. Published by Elsevier Inc.)

Aims: Permanent transseptal left bundle branch area pacing (LBBAP) is a promising new pacing method for both bradyarrhythmia and heart failure indications. However, data regarding safety, feasibility and capture type are limited to relatively small, usually single centre studies. In this large multicentre international collaboration, outcomes of LBBAP were evaluated., Methods and Results: This is a registry-based observational study that included patients in whom LBBAP device implantation was attempted at 14 European centres, for any indication. The study comprised 2533 patients (mean age 73.9 years, female 57.6%, heart failure 27.5%). LBBAP lead implantation success rate for bradyarrhythmia and heart failure indications was 92.4% and 82.2%, respectively. The learning curve was steepest for the initial 110 cases and plateaued after 250 cases. Independent predictors of LBBAP lead implantation failure were heart failure, broad baseline QRS and left ventricular end-diastolic diameter. The predominant LBBAP capture type was left bundle fascicular capture (69.5%), followed by left ventricular septal capture (21.5%) and proximal left bundle branch capture (9%). Capture threshold (0.77 V) and sensing (10.6 mV) were stable during mean follow-up of 6.4 months. The complication rate was 11.7%. Complications specific to the ventricular transseptal route of the pacing lead occurred in 209 patients (8.3%)., Conclusions: LBBAP is feasible as a primary pacing technique for both bradyarrhythmia and heart failure indications. Success rate in heart failure patients and safety need to be improved. For wider use of LBBAP, randomized trials are necessary to assess clinical outcomes., Competing Interests: Conflict of interest: G.K., N.R., A.E, P.S.. L.H, M.C. and D.G—nothing to declare; M.J., P.M., W.H. and S.T. report speaker and consultancy fees from Medtronic; K.V. reports consultancy for Biosense Webster, Philips, Medtronic, Abbott, reports speaker fees from Microport and K.V.'s institution has received research and educational grants from Philips, Abbott, Medtronic, Biosense Webster; O.C. reports consulting fees from Biotronik, Medtronic and Boston Scientific and speaker’s fees from Medtronic and Boston Scientific; F.Z. reported speaker fees from Abbott, Biotronik, Boston Scientific, Medtronic and Microport; A.E.’s institution received speaker and advisory fees from Boston Scientific and Medtronic; H.B. reports speaker and/or consultancy fees (minor) from Abbott, Biotronik, Boston Scientific, Medtronic and Microport; Z.W. reports advisor and speaker fees from Medtronic, Boston Scientific advisor and Abbott Advisory board member; J. De P. reports speaker fees and honoraria from Medtronic, Boston Scientific and Biotronik. K.C. reports speaker and consultant fees for Medtronic and Biotronik., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Left bundle branch pacing (LBBP) has emerged as a promising pacing modality to preserve physiological left ventricular activation; however, prospective data evaluating its long-term safety and efficacy in pacemaker-dependent patients following atrioventricular junction (AVJ) ablation are lacking. This study aimed to examine the feasibility, safety, and efficacy of LBBP in patients with atrial fibrillation and heart failure (HF) after AVJ ablation and compare LBBP with His bundle pacing (HBP) through a propensity score (PS) matching analysis., Methods: We prospectively enrolled patients with atrial fibrillation and HF referred for AVJ ablation and LBBP between July 2017 and December 2019. The control group was patients selected from HBP implants performed from 2012 to 2019 using PS matching with a 1:1 ratio., Results: A total of 99 patients were enrolled in the study. The LBBP implant success rate was 100%. Left ventricular ejection fraction improved from baseline 30.3±4.9 to 1-year 47.3±14.5 in HF patients with reduced ejection fraction and from baseline 56.3±12.1 to 1-year 62.3±9.1 in HF patients with preserved ejection fraction (both P <0.001), and left ventricular ejection fraction in both groups remained stable for up to 3 years of follow-up. A threshold increase >2 V at 0.5 ms occurred in only one patient. Of 176 (81.9%) of 215 patients who received permanent HBP post-AVJ ablation, 86 were matched to the LBBP group by 1:1 PS (propensity score matched His bundle pacing, N=86; propensity score matched left bundle branch pacing, N=86). No significant differences in echocardiographic or clinical outcomes were observed between the 2 groups ( P >0.05), whereas lower thresholds, greater sensed R-wave amplitudes, and fewer complications were observed in the propensity score matched left bundle branch pacing group ( P <0.05)., Conclusions: LBBP is feasible, safe, and effective in patients with atrial fibrillation and HF post-AVJ ablation and has similar clinical benefits, a higher implant success rate, better pacing parameters, and fewer complications compared with HBP.

Aims: Accurately determining atrial arrhythmia mechanisms from a 12-lead electrocardiogram (ECG) can be challenging. Given the high success rate of cavotricuspid isthmus (CTI) ablation, identification of CTI-dependent typical atrial flutter (AFL) is important for treatment decisions and procedure planning. We sought to train a convolutional neural network (CNN) to classify CTI-dependent AFL vs. non-CTI dependent atrial tachycardia (AT), using data from the invasive electrophysiology (EP) study as the gold standard., Methods and Results: We trained a CNN on data from 231 patients undergoing EP studies for atrial tachyarrhythmia. A total of 13 500 five-second 12-lead ECG segments were used for training. Each case was labelled CTI-dependent AFL or non-CTI-dependent AT based on the findings of the EP study. The model performance was evaluated against a test set of 57 patients. A survey of electrophysiologists in Europe was undertaken on the same 57 ECGs. The model had an accuracy of 86% (95% CI 0.77-0.95) compared to median expert electrophysiologist accuracy of 79% (range 70-84%). In the two thirds of test set cases (38/57) where both the model and electrophysiologist consensus were in agreement, the prediction accuracy was 100%. Saliency mapping demonstrated atrial activation was the most important segment of the ECG for determining model output., Conclusion: We describe the first CNN trained to differentiate CTI-dependent AFL from other AT using the ECG. Our model matched and complemented expert electrophysiologist performance. Automated artificial intelligence-enhanced ECG analysis could help guide treatment decisions and plan ablation procedures for patients with organized atrial arrhythmias., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Pacing therapy aims to improve overall cardiac function by normalizing cardiac electrical activation. Although hemodynamic measurements allow the impact of cardiac pacing on cardiac function to be quantified, the protocol is crucial to minimize the effect of noise and achieve greater precision. Multiple steps can be undertaken to optimize accuracy of hemodynamic measurements. These include comparing with a reference state, using an average of a set number of beats, making repeated measurements, ensuring all beats are included, and pacing at faster heart rates. These measurements can aid comparison between different pacing modalities and guide optimal programming., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Conduction system pacing avoids the potential deleterious effects of right ventricular pacing in patients with bradycardia and provides an alternative approach to cardiac resynchronization therapy. We focus on the available observational and randomized evidence and review studies supporting the safety, feasibility, and physiologic promise of conduction system approaches. We evaluate the randomized data generated from the available clinical trials of conduction system pacing, which have led to the recent inclusion of CSP in international guidelines. The scope for future randomized trials will building on the physiologic promise of conduction system approaches and offering information on clinical end points is explored., Competing Interests: Disclosure D. Keene and Z.I. Whinnett receive honorarium from Medtronic for teaching., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Patients with heart failure (HF) are at an increased risk of hospital admissions. The aim of this report is to describe the feasibility, safety and accuracy of a novel wireless left atrial pressure (LAP) monitoring system in patients with HF., Methods: The V-LAP Left Atrium Monitoring systEm for Patients With Chronic sysTOlic & Diastolic Congestive heart Failure (VECTOR-HF) study is a prospective, multicenter, single-arm, open-label, first-in human clinical trial to assess the safety, performance and usability of the V-LAP system (Vectorious Medical Technologies) in patients with New York Heart Association class III HF. The device was implanted in the interatrial septum via a percutaneous, trans-septal approach guided by fluoroscopy and echocardiography. Primary endpoints included the successful deployment of the implant, the ability to perform initial pressure measurements and safety outcomes., Results: To date, 24 patients have received implants of the LAP-monitoring device. No device-related complications have occurred. LAP was reported accurately, agreeing well with wedge pressure at 3 months (Lin concordance correlation coefficient = 0.850). After 6 months, New York Heart Association class improved in 40% of the patients (95% CI = 16.4%-63.5%), while the 6-minute walk test distance had not changed significantly (313.9 ± 144.9 vs 232.5 ± 129.9 meters; P = 0.076)., Conclusion: The V-LAP left atrium monitoring system appears to be safe and accurate., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)