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Background Atrioventricular (AV) delay in cardiac resynchronisation therapy (CRT) recipients are typically optimised at rest. However, there are limited data on the impact of exercise-induced changes in heart rate on the optimal AV delay and left ventricular function. Methods and results The authors serially programmed AV delays in 41 CRT patients with intrinsic sinus rhythm at rest and during two stages of supine bicycle exercise with heart rates at 20 bpm (stage I) and 40 bpm (stage II) above baseline. The optimal AV delay during exercise was determined by the iterative method to maximise cardiac output using Doppler echocardiography. Results were compared to physiological change in PR intervals in 56 normal controls during treadmill exercise. The optimal AV delay was progressively shortened (p<0.05) with escalating exercise level (baseline: 123±26 ms vs stage I: 102±24 ms vs stage II: 70±22 ms, p<0.05). AV delay optimisation led to a significantly higher cardiac output than without optimisation did during stage I (6.2±1.2 l/min vs 5.2±1.2 l/min, p<0.001) and stage II (6.8±1.6 l/min vs 5.9±1.3 l/min, p<0.001) exercise. A linear inverse relationship existed between optimal AV delays and heart rates in CRT patients (AV delay=241-1.61xheart rate, R(2)=0.639, p<0.001) and healthy controls (R(2)=0.646, p<0.001), but the slope of regression was significantly steeper in CRT patients (p<0.001). Conclusions Haemodynamically optimal AV delay shortened progressively with increasing heart rate during exercise, which suggests the need for programming of rate-adaptive AV delay in CRT recipients. [ABSTRACT FROM AUTHOR]

This study assesses a technique for quantifying the frequency spectrum of atrial fibrillation (AF) using the surface electrocardiogram. Electrocardiograhic recordings were obtained in 61 patients during AF. After bandpass filtering, the QRST complexes were subtracted using a template-matching algorithm. The resulting fibrillatory baseline signal was subjected to Fourier transformation and displayed as a frequency power spectrum. These frequency spectra were compared to direct measurements from the right atrium and coronary sinus in 35 patients undergoing electrophysiologic study. The clinical use of this technique was explored by correlating fibrillatory frequency with the behavior of the arrhythmia in 26 patients referred for cardioversion. The electrocardiographic frequency spectrum during AF was characterized by a single peak that varied widely between patients (range 228 to 480 beats/min). There was a strong correlation between electrocardiographic peak frequency and that measured in the right atrium and coronary sinus (r = 0.79 to 0.98, p <0.0001). Episodes of AF that terminated in < 5 minutes had a lower frequency than those that persisted > 5 minutes (324 +/- 36 vs 402 +/- 78 beats/min, p = 0.001). Chronic AF (< 3 months in duration) had a lower frequency than chronic AF (present > 3 months) (336 +/- 48 vs 408 +/- 60 beats/ min, p = 0.012). Fibrillation frequency was an accurate predictor of conversion with ibutilide. Success rate was 100% in patients with peak frequency < 360 beats/min versus 29% in patients with frequencies > or = 360 beats/min (p = 0.003). Automatic analysis of the frequency content of the fibrillatory baseline on the surface electrocardiogram accurately reflects the average rate of AF. This measurement correlates with the clinical pattern of the arrhythmia and predicts the response to administration of ibutilide. [ABSTRACT FROM AUTHOR]

Background: Most studies of device-detected atrial fibrillation (AF) have recommended indefinite anticoagulation once a patient crosses a particular threshold for AF duration or burden. However, durations and burdens are known to fluctuate over time, but little is known about the magnitude of spontaneous fluctuations and the potential impact on anticoagulation decisions., Objective: To quantify spontaneous fluctuations in AF duration and burden in patients with implantable loop recorders (ILRs) METHODS: We reviewed all ILR interrogations for patients with non-permanent AF at our institution from 2018 to 2023. We excluded patients treated with rhythm control. The duration of longest AF episode at each interrogation was classified as < 6, 6-24, and > 24 h, and the AF burden reported at each interrogation was classified as < 2%, 2%-11.4%, and > 11.4%., Results: Out of 156 patients, the mean age at ILR implant was 70.9 ± 12.5 years, CHA 2 DS 2 -VASc score was 4.2 ± 1.8, duration of ILR follow-up was 23.4 ± 11.2 months, and number of ILR interrogations per patient was 18.0 ± 8.9. The duration of longest AF episode at any point during follow-up was < 6 , 6-24 , and > 24 h in 110, 30, and 16 patients, respectively. Among the 30 patients with a longest AF episode of 6-24 h at some point during follow-up, out of 594 total ILR interrogations, only 75 (12%) showed a longest episode of 6-24 h. In the remaining 519 interrogations, the longest episode was < 6 h. In patients with a longest episode of > 24 h at any point during follow-up (n = 16), only 47 out of 320 total ILR interrogations (15%) showed an episode of > 24 h. When evaluating AF burden, 96, 38, and 22 patients had maximum reported AF burdens of < 2%, 2%-11.4%, and > 11.4% at any point during ILR follow-up. Among those with a maximum burden of 2%-11.4% at some point during follow-up (n = 38), out of 707 ILR interrogations, only 76 (11%) showed a burden of 2%-11.4%. In the remaining 631 interrogations, the burden was < 2%. In the 22 patients with a burden > 11.4% at some point during follow-up, only 80 out of 480 interrogations (17%) showed a burden of > 11.4%. In 65% of interrogations, the burden was < 2%., Conclusion: Significant, spontaneous fluctuations in AF burden and duration are common in patients with ILRs. Even in patients with AF episodes of 6-24 h or > 24 h at some point during follow-up, the vast majority of interrogations show episodes of < 6 h. Similarly, in patients with burdens of 2%-11.4% or > 11.4% at some point during follow-up, the vast majority of interrogations show burdens of < 2%. More data are needed to determine whether crossing an AF burden or duration threshold once is sufficient to merit lifelong anticoagulation or whether spontaneous fluctuations in AF burden and duration should impact anticoagulation decisions., (© 2024 Wiley Periodicals LLC.)

Background: Early recurrence of atrial tachyarrhythmias (ERAT) within 3 months of thermal ablation for atrial fibrillation (AF) is common and often considered transient. Pulsed field ablation (PFA) is a nonthermal energy source in which ERAT is not well described., Objective: The purpose of this study was to analyze ERAT in patients with AF undergoing PFA in the Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF (PULSED AF) trial., Methods: This analysis included 154 (52.4%) paroxysmal AF and 140 (47.6%) persistent AF who had ≥10 rhythm assessments during the 90-day blanking period. ERAT was defined as any instance of ≥30 seconds of AF, atrial flutter, or atrial tachycardia on transtelephonic monitoring (weekly and symptomatic) or ≥10 seconds on electrocardiography (at 3 months), both within 90 days. Late recurrence of atrial tachyarrhythmias (LRAT) was defined as observed atrial tachyarrhythmias between 90 days and 12 months., Results: The overall prevalence of ERAT was 27.1% in patients with paroxysmal AF and 31.6% in patients with persistent AF. In patients with ERAT, 73% had ERAT onset within the first month of the procedure. The presence of ERAT was associated with LRAT in patients with paroxysmal AF (hazard ratio 6.4; 95% confidence interval 3.6-11.3) and patients with persistent AF (hazard ratio 3.8; 95% confidence interval 2.2-6.6). Yet, in 29.4% of patients with paroxysmal AF and 34.3% of patients with persistent AF with ERAT, LRAT was not observed. LRAT was positively correlated with the number of ERAT observations., Conclusion: ERAT after PFA predicted LRAT in patients with paroxysmal and persistent AF. However, the concept of a blanking period after PFA is still valid, as approximately one-third of patients with ERAT did not continue to have LRAT during follow-up and may not need reablation., Competing Interests: Disclosures Dr Tarakji, Mr Cerkvenik, and Dr van Bragt are employees and stockholders of Medtronic. Dr Boersma’s cardiology department receives consultation funds from Medtronic, Boston Scientific (BS), Abbott Medical (AM), Adagio Medical, and ZOLL. Dr Natale receives grants and/or consultation funds from Medtronic, Abbott, Biosense Webster (BW), Biotronik, BS, and iRhythm. Dr Haines receives grants and/or consultation funds from Medtronic. Dr DeLurgio receives grants, consultation funds, and/or honoraria funds from Medtronic, AtriCure, and BS. Dr Sood receives consultation or honoraria funds from Johnson & Johnson, Abbott, BS, AtriCure, Bristol Myers Squibb, and Pfizer. Dr Marchlinski receives grants, consultation funds, and/or honoraria funds from Medtronic, BW, AM, and Biotronik. Dr Calkins receives grants, consultation funds, and/or honoraria funds from Medtronic, BS, AM, AtriCure, and BW. Dr Hoyt receives grants and/or consultation funds from Medtronic and AM. Dr Sanders receives grants, consultation funds, and/or honoraria funds from Medtronic, BS, AM, Becton Dickinson, PaceMate, and CathRx. Dr Packer receives grants and/or consultation funds from Medtronic. Dr Mittal receives consultation funds from Medtronic and BS. Dr Di Biase is a consultant for BW, Stereotaxis, and iRhythm and has received speaker honoraria/travel from BW, AM, BS, Medtronic, Biotronik, AtriCure, Siemens, and ZOLL. Dr Tada receives honoraria and/or grants from Medtronic, Daiichi Sankyo, AM, Nippon Boehringer Ingelheim, Eli Lilly, Otsuka Pharmaceutical, Marubun Tsusyo, Biotronik, Bristol Myers Squibb, BS, and Novartis Pharma. Dr Tomita receives research funding from Boehringer Ingelheim, Bayer, Daiichi Sankyo, BS, AM, and Biotronik and speakers’ honorarium from Boehringer Ingelheim, Bayer, Daiichi Sankyo, and Bristol Myers Squibb. Dr Tomita is also a concurrent professor of an endowment department supported by Medtronic Japan, Japan Lifeline, and Fukuda Denshi Kitatohoku Hanbai. Dr Kuck receives grants and/or consultation funds from Medtronic and Cardiovalve. Dr Verma receives grants and/or consultation funds from Medtronic, BW, Bayer, MedLumics, Adagio Medical, and BS. The others have nothing to declare., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Early guidance recommended a bolus of intravenous heparin at the beginning of leadless pacemaker (LP) implantation procedures. However, due to concern about bleeding complications, more recent practice has tended toward omitting the bolus and only running a continuous heparin infusion through the introducer sheath. The impact of omitting the heparin bolus on procedural outcomes is not clear., Methods: We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. The decision to bolus with heparin was at operator discretion., Results: Among 621 LP implants, 326 received an intravenous heparin bolus, 243 did not, and 52 patients were excluded because heparin bolus status could not be confirmed. There was a trend toward more frequent omission of the heparin bolus with more recent implants. Median follow-up after LP implant was 14.3 (interquartile range [IQR]: 8.4-27.9) months. There was no difference between heparin bolus and no bolus groups in the number of device deployments/recaptures (1.42 ± 0.81 vs. 1.31 ± 0.66, p = .15). Implant-related adverse events were also similar between heparin bolus and no bolus groups: access-site hematoma requiring intervention (7 vs. 5, p = .99), pseudoaneurysm (1 vs. 1, p = .99), cardiac perforation (1 vs. 1, p = .99), intraprocedural device thrombus formation (2 vs. 4, p = .41), 30-day rehospitalization (21 vs. 15, p = .98), and 30-day all-cause mortality (16 vs. 14, p = .70). There was one additional nonfatal cardiac perforation in a patient who was excluded due to unknown heparin bolus status. Regarding device electrical parameters between heparin bolus and no bolus groups, there were no significant differences at the time of implant: pacing capture threshold 0.5 ± 0.4 vs. 0.5 ± 0.3, p = .10; pacing impedance 739.9 ± 226.4 vs. 719.1 ± 215.4, p = .52; R wave sensing 11.7 ± 5.7 vs. 12.0 ± 5.4, p = .34). Long-term device performance was also similar between groups., Conclusion: Omission of the systemic heparin bolus at the time of LP implantation appears safe in appropriately selected patients. Heparin bolus may still be considered in long cases requiring multiple device deployments or in patients at high risk for thrombotic complications., (© 2024 Wiley Periodicals LLC.)

Competing Interests: Declaration of Competing Interest The authors have no competing interests to declare.

Introduction: Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions., Methods: This retrospective study included patients who received a Micra VR (Micra TM MC1VR01) or Micra AV (Micra TM MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up., Results: A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 ± 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 ± 1.1 years: 1.6 ± 1.3 years for the Micra VR group and 0.8 ± 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% ± 37.2% postprocedure vs. 47.7% ± 40.6% at last follow-up, p < .001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% ± 10.6% vs. 51.5% ± 11.2% p < .001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% ± 11.9% vs. 48.8% ± 11.9%, p = .003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% ± 9.0% vs. 54.6% ± 9.7%, p = .06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction., Conclusion: Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort., (© 2023 Wiley Periodicals LLC.)

Background: The Vein of Marshall Ethanol for Untreated Persistent AF (VENUS) trial demonstrated that adding vein of Marshall (VOM) ethanol infusion to catheter ablation (CA) improves ablation outcomes in persistent atrial fibrillation (AF). There was significant heterogeneity in the impact of VOM ethanol infusion on rhythm control., Objective: The purpose of this study was to assess the association between outcomes and (1) achievement of bidirectional perimitral conduction block and (2) procedural volume., Methods: The VENUS trial randomized patients with persistent AF (N = 343) to CA combined with VOM ethanol or CA alone. The primary outcome (freedom from AF or atrial tachycardia [AT] lasting longer than 30 seconds after a single procedure) was analyzed by 2 categories: (1) successful vs no perimitral block and (2) high- (>20 patients enrolled) vs low-volume centers., Results: In patients with perimitral block, the primary outcome was reached 54.3% after VOM-CA and 37% after CA alone (P = .01). Among patients without perimitral block, freedom from AF/AT was 34.0% after VOM-CA and 37.0% after CA (P = .583). In high-volume centers, the primary outcome was reached in 56.4% after VOM-CA and 40.2% after CA (P = .01). In low-volume centers, freedom from AF/AT was 30.77% after VOM-CA and 32.61% after CA (P = .84). In patients with successful perimitral block from high-volume centers, the primary outcome was reached in 59% after VOM-CA and 39.1% after CA (P = .01). Tests for interaction were significant (P = .002 for perimitral block and P = .04 for center volume)., Conclusion: Adding VOM ethanol infusion to CA has a greater impact on outcomes when associated with perimitral block and performed in high-volume centers. Perimitral block should be part of the VOM procedure., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Manual compression (MC), historically the most common method to achieve hemostasis after percutaneous vascular procedures, is time consuming, requires prolonged bedrest, and is uncomfortable for patients and clinicians. Recent studies demonstrate the efficacy and safety of vascular closure devices and suggest shorter times to hemostasis and patient ambulation compared with MC. The current study evaluated the feasibility of the VASCADE® venous vascular closure system (VVCS) while allowing for urinary catheter (UC) elimination, and elimination of protamine and/or same calendar day discharge (SCDD)., Methods and Results: In this prospective, multicenter trial, patients were enrolled and assigned to the following groups: no UC, no protamine, and/or SCDD (no co-enrollment in no protamine and SCDD). After completing the catheter-based cardiac procedure, access sites were closed using the VVCS. Outcomes included final hemostasis (all sites) without major access site-related complications at 30 days, rates of access site closure-related complications, device success, and study group success. All 168 patients had hemostasis without major access site-related complications through 30 days. In the no UC group, 160 out of 164 (97.6%) patients did not receive a UC. Additionally, 39 out of 41 (95.1%) patients received heparin without protamine reversal and no access site bleeding-related ambulation delays, and 18 out of 18 (100%) patients were discharged on the same day. There were no major access site closure-related complications, few minor complications, and adverse events were generally mild and well managed., Conclusion: The VVCS was effective for achieving hemostasis following catheter-based procedures; access site closure-related complications and adverse events were well managed., (© 2020 Wiley Periodicals LLC.)

Importance: Catheter ablation of persistent atrial fibrillation (AF) has limited success. Procedural strategies beyond pulmonary vein isolation have failed to consistently improve results. The vein of Marshall contains innervation and AF triggers that can be ablated by retrograde ethanol infusion., Objective: To determine whether vein of Marshall ethanol infusion could improve ablation results in persistent AF when added to catheter ablation., Design, Setting, and Participants: The Vein of Marshall Ethanol for Untreated Persistent AF (VENUS) trial was an investigator-initiated, National Institutes of Health-funded, randomized, single-blinded trial conducted in 12 centers in the United States. Patients (N = 350) with persistent AF referred for first ablation were enrolled from October 2013 through June 2018. Follow-up concluded in June 2019., Interventions: Patients were randomly assigned to catheter ablation alone (n = 158) or catheter ablation combined with vein of Marshall ethanol infusion (n = 185) in a 1:1.15 ratio to accommodate for 15% technical vein of Marshall ethanol infusion failures., Main Outcomes and Measures: The primary outcome was freedom from AF or atrial tachycardia for longer than 30 seconds after a single procedure, without antiarrhythmic drugs, at both 6 and 12 months. Outcome assessment was blinded to randomization treatment. There were 12 secondary outcomes, including AF burden, freedom from AF after multiple procedures, perimitral block, and others., Results: Of the 343 randomized patients (mean [SD] age, 66.5 [9.7] years; 261 men), 316 (92.1%) completed the trial. Vein of Marshall ethanol was successfully delivered in 155 of 185 patients. At 6 and 12 months, the proportion of patients with freedom from AF/atrial tachycardia after a single procedure was 49.2% (91/185) in the catheter ablation combined with vein of Marshall ethanol infusion group compared with 38% (60/158) in the catheter ablation alone group (difference, 11.2% [95% CI, 0.8%-21.7%]; P = .04). Of the 12 secondary outcomes, 9 were not significantly different, but AF burden (zero burden in 78.3% vs 67.9%; difference, 10.4% [95% CI, 2.9%-17.9%]; P = .01), freedom from AF after multiple procedures (65.2% vs 53.8%; difference, 11.4% [95% CI, 0.6%-22.2%]; P = .04), and success achieving perimitral block (80.6% vs 51.3%; difference, 29.3% [95% CI, 19.3%-39.3%]; P < .001) were significantly improved in vein of Marshall-treated patients. Adverse events were similar between groups., Conclusions and Relevance: Among patients with persistent AF, addition of vein of Marshall ethanol infusion to catheter ablation, compared with catheter ablation alone, increased the likelihood of remaining free of AF or atrial tachycardia at 6 and 12 months. Further research is needed to assess longer-term efficacy., Trial Registration: ClinicalTrials.gov Identifier: NCT01898221.

Background: Experience with retrieval of a Watchman left atrial (LA) appendage (LAA) closure device (WD) is limited. An embolized or grossly malpositioned WD warrants retrieval to minimize the risk of thromboembolic complications and vascular occlusion., Objective: The purpose of this study was to report approaches for percutaneous retrieval of a WD from multicenter experience., Methods: Data on successful WD retrievals were obtained from high-volume operators. Data included clinical characteristics; structural characteristics of the LA and LAA; and procedural details of the deployment and retrieval procedure, type of retrieval (immediate: during the same procedure; delayed: during a separate procedure after the successful deployment), equipment used, complications, and postretrieval management., Results: Ten successful percutaneous and 1 surgical retrievals comprised this study. Seven patients had immediate retrieval, while 4 had delayed retrieval. The median duration before delayed retrieval was 45 days (range 1-45 days). The median LAA diameter and size of a successfully deployed WD was 16 mm (range 14-24 mm) and 21 mm (range 21-30 mm), respectively. A WD was retrieved from the LA (n = 1), LAA (n = 2), left ventricle (n = 2), and aorta (n = 6). The reason for retrieval from the LAA was inadequate deployment, resulting in a significant peri-device leak. Retrieval from the LA or LAA was successfully performed using snares (n = 2) and a Raptor grasping device (n = 1). Retrieval from the left ventricle was achieved with a snare (n = 1) and surgery (n = 1). Retrieval from the aorta required snares (n = 5) and retrieval forceps (n = 1). Five patients were successfully reimplanted with a larger size WD. The only complication during percutaneous retrieval was a pseudoaneurysm., Conclusion: Retrieval of an embolized or malpositioned WD is feasible, and familiarity with snares and grasping tools can facilitate a successful removal., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

The treatment of AF has evolved over the past decade with increasing use of catheter ablation in patients refractory to medical therapy. While pulmonary vein isolation using endocardial catheter ablation has been successful in paroxysmal AF, the results have been more controversial in patients with long-standing persistent AF where extrapulmonary venous foci are increasingly recognised in the initiation and maintenance of AF. Hybrid ablation is the integration of minimally invasive epicardial ablation with endocardial catheter ablation, and has been increasingly used in this population with better results. The aim of this article was to analyse and discuss the evidence for the integration of catheter and minimally invasive surgical approaches to treat AF with specific focus on convergent ablation and exclusion of the left atrial appendage using a surgically applied clip., Competing Interests: Disclosure: AK, KM, NS, DD, YG and FY received consulting fees from Atricure. All other authors have no conflicts of interest to declare., (Copyright © 2020, Radcliffe Cardiology.)

Introduction: The VICTORY AF Study was designed to evaluate the risk of the procedure and/or device-related strokes in patients with PersAF on warfarin undergoing ablation with a phased radiofrequency (RF) system., Methods: The VICTORY AF trial was a prospective, multicenter, single-arm, investigational study. PersAF patients on vitamin K antagonism without major structural heart disease or history of stroke/transient ischemic attack undergoing phased RF ablation for atrial fibrillation (AF) were included. The primary outcome was the incidence of the procedure and/or device-related stroke within 30 days of the ablation by a board-certified neurologist's assessment. The secondary outcomes were an acute procedural success, 6 months effectiveness (defined as the reduction in AF/atrial flutter episodes lasting ≥10 minutes by 48-hour Holter 6 months postablation) and the number of patients with pulmonary vein (PV) stenosis., Results: A total of 129 (108 PersAF, 21 long-standing PersAF) patients were treated (mean age: 60.6 ± 7.7; 79.8% male, 54.3% CHA2Ds2-VASc score ≥ 2). Two nondisabling strokes were reported (1.6%); one before discharge and the second diagnosed at the 30-day visit. Due to slow enrollment, the study was terminated before reaching the 95% one-sided upper confidence boundary for stroke incidence. Acute procedural success was 93.8%, and at 6 months, 72.8% of patients demonstrated ≥90% reduction in AF burden, 78.9% were off all antiarrhythmic drugs. There were no patients with PV stenosis of greater than 70%., Conclusions: VICTORY AF demonstrated a 1.6% incidence of stroke in PersAF undergoing ablation with a phased RF system which did not meet statistical confidence due to poor enrollment. The secondary outcomes suggest comparable efficacy to phased RF in the tailored treatment of permanent AF trial. Rigorous clinical evaluation of the stroke risk of new AF ablation technologies as well as restriction to Vitamin K antagonist anticoagulation appears to be unachievable goals in a clinical multicenter IDE trial of AF ablation in the current era., (© 2020 Wiley Periodicals, Inc.)

Background: There are limited data on cardiac implantable electronic device implantation (CIED) in patients with persistent left superior vena cava (PLSVC)., Objective: To describe the outcomes of implanting CIEDs with a focus on cardiac resynchronization therapy (CRT) in patients with PLSVC., Methods: We identified all patients with a PLSVC that underwent CIED implantation from December 2008 until February 2019 at our institution by querying the electronic medical record (n = 34). We then identified controls in a 3:1 fashion (n = 102) by matching on device type (CRT vs non-CRT). Procedure success, complications, fluoroscopy and procedural time were recorded. Outcomes were compared using a two-way analysis of variance test and conditional regression modeling for continuous and categorical variables, respectively., Results: A total of 34 patients with PLSVC underwent 38 procedures. Four patients underwent dual chamber system implantation followed by a subsequent upgrade to CRT. Thirteen patients underwent CRT implantation: one was implanted via the right subclavian while the rest were implanted via the PLSVC. Left ventricular (P = .06). Procedure and fluoroscopy times were significantly higher in the PLSVC as compared with the control group (97.7 vs 66.1 minute, P < .001 and 18.1 minute vs 8.7 minutes, P = .005, respectively)., Conclusion: CIED implant in patients with PLSVC is feasible but technically more challenging and appears to be associated with higher risk of right ventricular lead dislodgment., (© 2020 Wiley Periodicals, Inc.)

Background: The SanketLife is a low cost, portable, pocket sized 12 lead ECG mechanised by SanketLife app running on compatible iOS and Android phones that connect wirelessly via Bluetooth technology to the device., Objective: The current study was conducted to assess the diagnostic accuracy of SanketLife ECG in comparison to standard 12 lead ECG (GE-2000) in detection of cardiovascular diseases., Research Design and Methods: This was a prospective diagnostic test accuracy trial conducted in outpatient settings of a tertiary cardiac care centre in India. A total of 100 patients, attended cardiology OPD, were included in the study. Consecutive ECGs were taken by 12 lead standard ECG as well as by SanketLife ECG. Diagnostic accuracy variables such as sensitivity, specificity, negative and positive predictive value, negative and positive likelihood ratios were estimated. Ethical permission was taken from the Institutional ethical committee., Results & Conclusion: The analysis showed a high degree of agreement and accuracy of SanketLife in detecting major cardiovascular conditions (Major Minnesota codes) such as Left and right bundle branch block, ST-segment elevation and ST-segment depression, AV conduction block. SanketLife showed high sensitivity (98.15%) and specificity (100%) in diagnosing major cardiovascular conditions., Competing Interests: Declaration of competing interest None., (Copyright © 2019 Indian Heart Rhythm Society. All rights reserved.)

Background: Long-term data on the safety and efficacy of left atrial appendage closure (LAAC) for stroke prevention in patients with nonvalvular atrial fibrillation remain limited., Objectives: The purpose of this study was to evaluate 4.5- to 5-year data in 2 U.S. Food and Drug Association LAAC mandated registries (CAP [Continued Access to PROTECT-AF] and CAP2 [Continued Access to PREVAIL]) for safety and efficacy., Methods: Two registries of patients implanted with LAAC devices provide the largest source of follow-up data. Both accompanied their respective randomized clinical trials, PROTECT-AF (Watchman Left Atrial Appendage System for Embolic PROTECTion in Patients With Atrial Fibrillation) and PREVAIL (Prospective Randomized Evaluation of the WATCHMAN LAA Closure Device In Patients with Atrial Fibrillation versus Long Term Warfarin Therapy), which used the same endpoints (primary efficacy of composite of stroke, systemic embolism, cardiovascular/unexplained death, and safety)., Results: CAP included 566 patients with an average follow-up of 50.1 months (2,293 patient-years), and CAP2 included 578 patients with an average follow-up of 50.3 months (2,227 patient-years). CAP2 patients were significantly older and had higher CHA 2 DS 2 -VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke/transient ischemic attack, vascular disease, age 65 to 74 years, sex category) scores (4.51 vs. 3.88; p < 0.001). Procedural success was similar in both (94%). The primary composite endpoint occurred at a rate of 3.05 per 100 patient-years in CAP and 4.80 per 100 patient-years in CAP2; events contributing to this endpoint were most commonly cardiovascular/unexplained death (1.69 per 100 patient-years for CAP and 2.92 per 100 patient-years for CAP2). Hemorrhagic stroke was significantly less than ischemic stroke (0.17 per 100 patient-years in CAP and 0.09 per 100 patient-years in CAP2), and total stroke rates were significantly less than predicted by CHA 2 DS 2 -VASc score (78% reduction with CAP, 69% reduction with CAP2)., Conclusions: These registries, which contain the longest and largest follow-up data of patients with the Watchman device, support LAAC as a safe and effective therapy for long-term anticoagulation in patients with nonvalvular atrial fibrillation, and document the lowest rate of hemorrhagic stroke identified in this population., (Copyright © 2019. Published by Elsevier Inc.)

Background: The performance of Abbott/St. Jude Medical (Sylmar CA) Tendril pacing leads has not been well characterized., Objective: We sought to assess the performance of Tendril leads as compared with that of different pacing leads., Methods: We retrospectively identified patients implanted with the following leads: Tendril leads 1888 TC, 2088 TC, and 1688 TC, Medtronic (Fridely, MN) 4076 CapSureFix Novus, and Boston Scientific (Natick, MA) FINELINE II Sterox Pacing EZ leads (models 4469, 4470, and 4471). The primary end point was the incidence of lead malfunction assessed by Kaplan-Meier analysis., Results: During the study period, 9782 leads were implanted, including 8512 Tendril leads, 731 Medtronic 4076 CapSureFix Novus leads, and 539 FINELINE II leads. A total of 540 leads (5.5%) malfunctioned during a mean follow-up of 3.6 ± 2.9 years. Lead malfunction manifested predominantly as noise and/or low impedance (95%). Lead malfunction rates were significantly higher at 5 years for Tendril vs non-Tendril leads (7.0% vs 2.1%; P < .001). The highest rate of failure at 5 years was seen in the Tendril 1888 TC leads (9.9%), followed by Tendril 1688 (5.7%) and Tendril 2088 (5.2%) leads. In contrast, malfunction rates were significantly lower for the Medtronic 4076 (2.6%) and FINELINE II (1.7%) leads. During follow-up to 10 years, the incidence of lead malfunction for Optim-insulated Tendril leads (models 1888 TC and 2088 TC) was significantly higher than that for the non-Optim-insulated Tendril 1688 TC lead (24.5% vs 7.1%) (P = .008)., Conclusion: Tendril leads appear to have a higher rate of malfunction than do comparator leads. Optim insulation may partly explain the higher failure rate., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Although the subcutaneous ICD (S-ICD®) is an attractive alternative in patients with end-stage renal disease (ESRD), data on S-ICD outcomes in dialysis patients are lacking., Methods: Patients with cardiomyopathy undergoing S-ICD implantation in our center were stratified by need for chronic dialysis at the time of implant. The primary endpoint was incidence of death, heart failure hospitalization or appropriate S-ICD shocks, and secondary endpoints were incidence of inappropriate shocks or implant related complications requiring surgical re-intervention. Mean follow-up was longer in the nondialysis cohort (514 ± 495 vs. 227 ± 233 days, P = 0.006), so all endpoints were analyzed using time-dependent comparisons and reported as annual event rates., Results: Out of 79 S-ICD implants included in this analysis, 27 patients were on dialysis. Dialysis patients were older and more likely to be diabetic. Mean ejection fraction across the entire cohort was 26.9% without significant difference between dialysis and nondialysis groups. Although not significant, the incidence of the primary endpoint was higher in the dialysis cohort (23.8%/year vs. 10.9%/year, P = 0.317), driven primarily by a higher rate of appropriate shocks. The rate of inappropriate shocks was similar between groups (dialysis 6.0%/year vs. nondialysis 6.8%/year, P = 0.509). No patients in the dialysis cohort had complications requiring surgical re-intervention versus 6 patients in the nondialysis cohort (P = 0.086)., Conclusions: Our data suggest that S-ICD implantation in dialysis patients is not associated with an excess risk of implant related complications or inappropriate shocks., (© 2015 Wiley Periodicals, Inc.)

Background: The Sprint Fidelis (SF) and the Riata (RT) implantable cardioverter-defibrillator leads have been recalled for premature failure., Objective: Data on SF and RT extractions are limited; therefore, we performed a pooled analysis to compare the safety and efficacy of lead extraction for the SF and RT lead families., Methods: We retrospectively reviewed consecutive patients undergoing transvenous extraction of SF and RT leads at Emory University and the University of Pittsburgh Medical Center from January 2007 to October 2013. Patients were placed into 2 groups based on the presence of an SF or RT lead. The primary endpoint was a major procedural complication, defined as death, need for urgent cardiac surgery, and hemopericardium or hemothorax that required an intervention., Results: A total of 462 patients underwent extraction of recalled leads (SF, n = 360; RT, n = 102). The mean number of leads extracted in the RT group was higher than in the SF group (1.8 ± 0.9 vs 1.3 ± 0.7, P < .001), and there was a longer implantation time in the RT group (5.5 ± 2.5 vs 4.3 ± 2.0 years, P < .001). Complete procedural success was higher in the SF group (99.4% vs 96.1%, P =.024). Clinical success was similar (SF 99.4% vs RT 97.1%, P = .075). There were 6 major procedural complications in the entire cohort (1.3%). The rate of major complications was not different between the SF and RT groups (SF 1.1% vs RT 2.0%, P = .618). Total mortality was 0.65%, with no difference between the groups, Conclusion: Our data from 2 high-volume centers suggest that extraction of SF and RT leads is associated with excellent clinical success and a similar rate of major procedural complications., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Persistent and long-standing persistent atrial fibrillation (AF) often requires extensive and/or repeat radiofrequency (RF) ablation procedures., Objective: The Tailored Treatment of Persistent Atrial Fibrillation (TTOP-AF) study assessed the effectiveness and safety of the phased RF system in a randomized controlled comparison of medical therapy against phased RF ablation for the management of persistent and long-standing persistent AF., Methods: Patients who had failed at least 1 antiarrhythmic drug (AAD) were randomized (2:1) to ablation management (AM) or medical management (MM). AM patients were allowed up to 2 ablations. Index and retreatment procedures consisted of pulmonary vein isolation and ablation of complex fractionated atrial electrograms. MM patients received AAD changes and/or cardioversion. The primary end points of the TTOP-AF study included chronic effectiveness and safety at 6 months and acute safety within 7 days of ablation., Results: At 6 months, a greater proportion of AM patients achieved effectiveness off AAD (77 of 138 [55.8%]) compared to MM patients (19 of 72 [26.4%]) (P < .0001). Acutely, 92.8% (128/138) of the procedures were successful while 12.3% (17/138) experienced a serious procedure and/or device-related adverse event. The predefined acute safety end point was not met. The proportion of patients with chronic safety events did not differ significantly between groups., Conclusions: Catheter ablation of persistent/long-standing persistent AF with the phased RF ablation system is effective with greater reduction of AF compared with MM. More intense anticoagulation strategies, careful attention to catheter placement relative to the pulmonary vein ostia, and elimination of electrode interaction are expected to reduce the risk of stroke, pulmonary vein stenosis, and asymptomatic cerebral emboli., (© 2014 Heart Rhythm Society Published by Heart Rhythm Society All rights reserved.)

Background: The Medtronic Sprint Fidelis defibrillator lead is at an increased risk for failure and was recalled in October 2007. Approximately 268,000 leads were implanted, and more than 100,000 patients still have active Fidelis leads. A number of studies have examined the rate and clinical predictors of lead failure, but none has addressed the effect of an implantable cardioverter-defibrillator generator exchange on subsequent lead failure. Although the manufacturer asserts that "Sprint Fidelis performance after device change-out is similar to lead performance without device change-out," published data are lacking., Objective: To assess the effect of implantable cardioverter-defibrillator generator exchange on the rate of Fidelis lead failure., Methods: A chart review was conducted in patients who underwent implantation of a Fidelis lead. Patients with a functioning Fidelis lead at generator exchange were compared with controls with leads implanted for a comparable amount of time not undergoing ICD replacement., Results: A total of 1366 patients received a Fidelis lead prior to the recall, of which 479 were still actively followed. Seventy-two patients with a functioning lead underwent generator exchange without lead replacement. Following generator replacement, 15 leads failed. Sixty percent of the Fidelis leads failed within 3 months. Generator exchange increased the rate of lead failure compared with matched controls (20.8% vs 2.54%; P < .001)., Conclusions: Generator exchange is associated with a higher than expected rate of Fidelis lead failure, often within 3 months. The risk-benefit ratio of Fidelis lead replacement at the time of generator exchange may be greater than appreciated., (Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Pacemakers and implanted cardioverter defibrillator (ICD) infection rates are rising. Renal insufficiency impairs immune function and is known to increase the risk of infection following implantation of orthopedic hardware. The purpose of the current study is to characterize the risk factors for pacemaker and ICD infection and to evaluate the role of renal insufficiency in this complication., Methods and Results: A large (n = 4,856) single center experience with pacemaker and ICD procedures was reviewed. Of these, 141 were extractions of infected devices and 76 of these patients had been implanted in the Emory system and had preimplant creatinine information available for analysis. These cases were compared to 76 control patients undergoing device implantation matched by date of implant who had no infective complications. Demographic and clinical data from both groups were compared using both univariate and multivariate analysis. The overall rate of infection was 1.5%. Patients with device infection were more likely to have congestive heart failure (CHF), be diabetic, have generator exchanges, and to take warfarin than controls. There was no difference in the prevalence of coronary disease, atrial fibrillation, steroid use, or malignancy between the two groups. Elevated creatinine (Cr > or = 1.5 mg/dL) was much more frequent in patients with infection than in controls (38% vs 12%, odds ratio 4.6, P < 0.001). Moderate to severe renal disease (GFR < or = 60 cc/min/1.73 m2) was the most potent risk factor for infection, with a prevalence of 42% in infected patients versus 13% in controls (odds ratio of 4.8)., Conclusions: Renal insufficiency dramatically increases the risk of infection complicating pacemaker or ICD surgery. This association should be part of the risk-benefit consideration prior to device implantation. Additional study of more extensive perioperative antibiotic therapy in this subset of patients is warranted.

Pacing of the RV and LV is a promising technique for treating patients with dilated cardiomyopathy and bundle branch block. The salutary effects of biventricular pacing may be due to resynchronization of LV activation. Currently, available biventricular pacemakers and implanted defibrillators produce simultaneous ventricular output pulses. The purpose of the current study was to assess the effects of variation in the timing of RV and LV activation, using the paced QRS duration as a marker of resynchronization. Twenty-six patients undergoing transvenous biventricular pacemaker implantation were studied. After stable lead positions were achieved, activation of the LV and RV was varied over a range of +/- 50 ms and the QRS duration measured on a 12-lead ECG. Only 6 (23%) of the 26 patients had maximal shortening of the paced QRS with simultaneous activation of the LV and RV. The shortest paced QRS duration was most often produced by an LV to RV interval of -30 ms (LV activation preceding RV activation). Optimization of LV to RV interval resulted in an additional 13% shortening of the paced QRS compared to simultaneous activation (P < 0.0001). Patients with leads located on the lateral or anterolateral walls of the LV were more likely to benefit from preexcitation of the LV than did patients with leads in the posterior position. Results of this study suggest that the ability to program the LV to RV interval may be useful to optimize the benefit of biventricular pacing.

Pacemaker dependent patients exhibit interventricular conduction delay due to right ventricular lead placement. The addition of a transvenous coronary sinus lead for biventricular pacing has been shown to be effective. Venous stenosis and thrombosis postpacemaker implantation can occur in up to 35% of patients. This report describes a patient with a preexisting left-sided dual chamber pacemaker and chronic left subclavian vein occlusion that was upgraded to a biventricular system byplacing a coronary sinus lead and single chamber ventricular triggered pacemaker on the opposite side.

Lead failure places patients with implantable cardioverter defibrillators (ICD) at risk for sudden cardiac death or results in delivery of inappropriate shocks. This study describes a mechanism of lead malfunction occurring at the junction of the terminal ring with the conductor coil of the rate sensing terminal connector in one specific model of a transvenous ICD lead. We detected the problem in a population of 179 patients with a mean age of 61 +/- 10 years and a mean lead implant duration of 16 +/- 11 months. All patients underwent pectoral ICD implantation using a submuscular approach. The implanting physician chose to place the ICD on the left side in 155 patients (87%) and on the right side in 24 patients (13%). Cephalic vein cutdown provided central venous access in 147 patients (82%), and subclavian vein puncture provided access in 32 patients (18%). Follow-up examination detected lead failure in six patients (3.5% over 31 months) due to insulation damage with or without conductor coil fracture at the junction of the terminal ring and conductor coil of the IS-1 rate sense terminal. We detected lead disruption 17 +/- 9 months (range 5-31 months) after implantation. Multiple nonsustained arrhythmia episodes exhibiting nonphysiologic intervals associated with noisy rate sensing electrograms during pocket manipulation led to discovery in three patients. The other three patients presented with inappropriate device discharges confirmed by stored high-energy lead electrograms showing normal rhythm. Pacing lead impedance abnormally dropped in two patients. Impedance remained stable in the other four patients. In conclusion, the generator pocket represents an important site of ICD transvenous lead vulnerability. Lead failure may result from conductor coil and/or insulation disruption at the interface with the rate sensing terminal connector.

This study compares LV performance during high right ventricular septal (RVS) and apical (RVA) pacing in patients with LV dysfunction who underwent His-bundle ablation for chronic AF. We inserted a passive fixation pacing electrode into the RVA and an active fixation electrode in the RVS. A dual chamber, rate responsive pulse generator stimulated the RVA through the ventricular port and the RVS via the atrial port. Patients were randomized to initial RVA (VVIR) or RVS (AAIR) pacing for 2 months. The pacing site was reversed during the next 2 months. At the 2 and 4 month follow-up visit, each patient underwent a transthoracic echocardiographical study and a rest/exercise first pass radionuclide ventriculogram. We studied nine men and three women (mean age of 68 +/- 7 years) with congestive heart failure functional Class (NYHA Classification): I (3 patients), II (7 patients), and III (2 patients). The QRS duration was shorter during RVS stimulation (158 +/- 10 vs 170 +/- 11 ms, P < 0.001). Chronic capture threshold and lead impedance did not significantly differ. LV fractional shortening improved during RVS pacing (0.31 +/- 0.05 vs 0.26 +/- 0.07, P < 0.01). RVS activation increased the resting first pass LV ejection fraction (0.51 +/- 0.14 vs 0.43 +/- 0.10, P < 0.01). No significant difference was observed during RVS and RVA pacing in the exercise time (5.6 +/- 3.2 vs 5.4 +/- 3.1, P = 0.6) or the exercise first pass LV ejection fraction (0.58 +/- 0.15 vs 0.55 +/- 0.16, P = 0.2). The relative changes in QRS duration and LV ejection fraction at both pacing sites showed a significant correlation (P < 0.01). We conclude that RVS pacing produces shorter QRS duration and better chronic LV function than RVA pacing in patients with mild to moderate LV dysfunction and chronic AF after His-bundle ablation.

Background: The miniaturization of implantable cardioverter defibrillators (ICDs) has made pectoral implantation possible. However, postoperative pain following the procedure has not been systematically studied. The aim of the current study was to prospectively assess patient discomfort and identify factors influencing pain perception during follow-up., Methods: Pain related to device implantation was quantified in 21 consecutive patients (age, 61 +/- 11 years; 17 men and 21 women; 16 of 21 had coronary artery disease; left ventricular ejection fraction, 32% +/- 15%) undergoing pectoral ICD implantation with conscious sedation (fentanyl 118 +/- 72 micrograms midazolam 14 +/- 9 mg). Patients completed the Visual Analogue Scale (VAS, 0-100) and the McGill Pain Questionnaire 24 hours and 1 month postoperatively. Regression analysis was used to define clinical and procedure related variables affecting patient discomfort and frequency of postoperative analgesic use., Results: The mean VAS score was 34 +/- 20 24 hours postoperatively. A single (4.8%) patient described postoperative pain as severe. Pain was reported to be moderate by 10 (47.6%) patients and mild by 10 (47.6%) patients. Intraoperative fentanyl requirement was a predictor of postoperative pain (R = 0.51, P = 0.036), and procedural duration was a strong predictor of postoperative analgesic use (R = 0.75, P < 0.001). Pain at 1 month decreased to a VAS score of 19 +/- 18 (P = 0.002 vs 24 hours) and was rated to be severe, moderate, and mild by 1, 3, and 17 patients, respectively. Late pain was related to a VAS score at 24 hours (R = 0.67, P = 0.004)., Conclusions: (1) Pectoral ICD implantation using conscious sedation is well tolerated. (2) Postoperative discomfort correlates with longer procedural times and larger intraoperative narcotic requirements.

Recent technological advances in implantable defibrillator systems (ICD) have changed implantation approaches. The aim of this study was to investigate the influence of these improvements on procedure times, implant-related charges, patient recovery, and morbidity. Ninety-six consecutive patients undergoing implantation of a nonthoracotomy ICD were studied. Implantation was performed under general anesthesia with the generator placed abdominally in 22 patients (group I) and pectorally in 40 patients (group II). Thirty-four patients underwent pectoral implantation using conscious sedation (group III). Groups were comparable with respect to clinical variables. Implantation duration and total procedure duration were shorter in group III (67 +/- 21 minutes and 117 +/- 30 minutes) when compared with group I (100 +/- 25 minutes and 157 +/- 39 minutes) and group II (86 +/- 24 minutes and 153 +/- 34 minutes, P < 0.05). Patients in group III did not require admission to the Post-Anesthesia Care Unit. In contrast, patients in groups I and II spent 92 +/- 28 minutes and 91 +/- 31 minutes in the Post-Anesthesia Care Unit. Implantation-related charges were reduced in patients having pectoral implantation using conscious sedation ($1451 +/- 217 vs. $2354 +/- 550 and $2796 +/- 384, P < 0.05). Patients in group III had a lower frequency of postoperative oral analgesic use (3.2 +/- 2.7 doses, P < 0.05) and a shortened post-operative length of stay (1.9 +/- 1.6 days, P < 0.05) when compared with groups I (5.7 +/- 4.0 doses and 3.3 +/- 1.4 days) and II (5.2 +/- 3.5 doses and 2.6 +/- 1.1 days). The overall complication rate was low (6.3%), with no differences between groups. Advances in ICD technology have simplified implantation, leading to shorter, less painful, and less expensive procedures.

Intracardiac echocardiography was used to evaluate posteroseptal space anatomy in patients with atrioventricular nodal reentrant tachycardia compared with patients with other mechanisms of tachycardia. The posteroseptal space was found to be significantly wider in patients with atrioventricular nodal reentry, suggesting an anatomic basis for dual atrioventricular nodal physiology.

The objective of this study was to assess the operative risk and efficacy of implantable defibrillators for preventing sudden death in patients with heart failure awaiting transplantation. The average waiting time for elective cardiac transplantation is 6 months to 1 year. Sudden cardiac death is the major source of mortality in outpatients in stable condition awaiting cardiac transplantation. The efficacy of implantable defibrillator therapy in this population is not established. We analyzed the operative risk, time to appropriate shock, and sudden death in 15 patients determined to be at high risk of sudden death who were accepted onto the outpatient cardiac transplant waiting list. Nonfatal postoperative complications occurred in two (13%) subjects with epicardial defibrillating lead systems and in none with transvenous lead systems. Defibrillation energies were 16 +/- 2 J versus 24 +/- 2 J with epicardial and transvenous lead systems, respectively. Sudden death free survival until transplantation was 93%. Most of the patients (60%) had an appropriate shock during a mean follow-up of 11 +/- 12 months. The mean time to an appropriate shock was 3 +/- 3 months. Hospital readmission was required in three (20%) subjects to await transplantation on an urgent basis. However, two of these subjects had received appropriate shocks before readmission. In selected patients at high risk for sudden death while on the outpatient cardiac transplant waiting list, the operative risk is low and adequate defibrillation energies can be obtained to allow implantable defibrillator placement. Most subjects will have an appropriate shock as outpatients before transplantation, and sudden death free survival is excellent.(ABSTRACT TRUNCATED AT 250 WORDS)