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Aims Atrial fibrillation (AF) is a complex heritable disease whose genetic underpinnings remain largely unexplained, though recent work has suggested that the arrhythmia may develop secondary to an underlying atrial cardiomyopathy. We sought to evaluate for enrichment of loss-of-function (LOF) and copy number variants (CNVs) in genes implicated in ventricular cardiomyopathy in ‘lone’ AF. Methods and results Whole-exome sequencing was performed in 255 early onset ‘lone’ AF cases, defined as arrhythmia onset prior to 60 years of age in the absence of known clinical risk factors. Subsequent evaluations were restricted to 195 cases of European genetic ancestry, as defined by principal component analysis, and focused on a pre-defined set of 43 genes previously implicated in ventricular cardiomyopathy. Bioinformatic analysis identified 6 LOF variants (3.1%), including 3 within the TTN gene, among cases in comparison with 4 of 503 (0.80%) controls [odds ratio: 3.96; 95% confidence interval (CI): 1.11–14.2; P = 0.033]. Further, two AF cases possessed a novel heterozygous 8521 base pair TTN deletion, confirmed with Sanger sequencing and breakpoint validation, which was absent from 4958 controls (P = 0.0014). Subsequent cascade screening in two families revealed evidence of co-segregation of a LOF variant with ‘lone’ AF. Conclusion ‘Lone’ AF cases are enriched in rare LOF variants from cardiomyopathy genes, findings primarily driven by TTN, and a novel TTN deletion, providing additional evidence to implicate atrial cardiomyopathy as an AF genetic sub-phenotype. Our results also highlight that AF may develop in the context of these variants in the absence of a discernable ventricular cardiomyopathy.

Objectives This study sought to identify minimum threshold values below which conduction over the atrioventricular (AV) node would be unexpected. Background Para-Hisian pacing is used to evaluate for the presence of a septal accessory pathway (AP); however, threshold values to differentiate nodal from AP conduction are unknown. Methods The authors performed high- and low-output para-Hisian pacing during sinus rhythm to capture the His and para-Hisian ventricular myocardium (H+V) and para-Hisian ventricular myocardium (V) alone, respectively. The change in stimulation (stim)-to-atrial electrogram interval after loss of His bundle capture in patients with (AP+) and without (AP−) a septal AP was evaluated. Stim-to-proximal coronary sinus (PCS) and stim-to-high right atrium (HRA) intervals were measured and within-patient differences (△) for V and H+V capture were calculated. Results A total of 23 AP+ and 45 AP− patients were evaluated. The difference in stimulus to earliest atrial signal in the high right atrial catheter seen with the loss of His bundle capture (△-stim-HRA) (21 ms; interquartile range [IQR]: 3 to 43 ms vs. 64 ms; IQR: 56 to 73 ms; p Conclusions A △-stim-PCS 51 ms for △-stim-PCS or >75 ms for △-stim-HRA excluded it. Alternatively, the minimum △-stim-PCS with loss of His capture compatible with AV nodal conduction in isolation was 37 ms, and a △-stim-PCS >51 ms effectively ruled out the presence of a septal AP.

INTRODUCTION Septal accessory pathway (AP) ablation can be challenging due to the complex anatomy of the septal region. The decision to access the left atrium (LA) is often made after failure of ablation from the right. We sought to establish whether the difference between ventriculo-atrial (VA) time during right ventricular (RV) apical pacing versus the VA during tachycardia would help establish the successful site for ablation of septal APs. METHODS Intracardiac electrograms of patients with orthodromic reciprocating tachycardia (ORT) using a septal AP with successful catheter ablation were reviewed. The ∆VA was the difference between the VA interval during RV apical pacing and the VA interval during ORT. The difference in the VA interval during right ventricular entrainment and ORT (StimA-VA) was also measured. RESULTS The median ∆VA time was significantly less in patients with a septal AP ablated on the right side compared with patients with a septal AP ablated on the left side (12 ± 19 vs. 56 ± 10 ms, p

Aims Atrial fibrillation (AF) significantly impairs patients’ quality of life (QOL). We performed this study to investigate the effect of AF-ablation success and atrial fibrillation burden (AFB) on QOL measures. Methods and results Overall, 230 patients with paroxysmal AF refractory to antiarrhythmic drugs were enrolled and underwent ablation in a multicentre, prospective cohort. Electrocardiogram, 48-h Holter, Canadian Cardiovascular Society Severity of Atrial Fibrillation (CCS-SAF), short form-12 (SF-12), and Atrial Fibrillation Effect on Quality of life (AFEQT) scales were used to assess patients. Atrial fibrillation burden was defined as total duration of AF during the month prior to each visit (h/month). The change in AFB was calculated as the difference between the month prior to the 12-month post-ablation and the baseline pre-ablation. The Minimal Clinically Important Difference (MCID) was considered as a 19-point change for AFEQT and 3–5-point change for SF-12 scores. There was significant rise in the AFEQT and SF12 and decrease in CCS-SAF score post-AF ablation; however, the magnitude of these changes was greater in patients without AF recurrence (P 19 h/month had significantly greater change in QOL scores. Atrial fibrillation burden Conclusion Patients experience significant improvements in QOL post-ablation, which correlate with a decrease in AFB despite ongoing brief recurrences of AF. Clinical Trial Registration NCT01562912. https://www.clinicaltrials.gov/ct2/show/NCT01562912? term=capcost&rank=1

Use of intraprocedural observation and pharmacologic challenges have been proposed as means to differentiate permanent pulmonary vein (PV)-left atrial conduction block from inadequate ablation lesions.The purpose of this study was to determine the prevalence and clinical impact of spontaneous and adenosine-provoked reconnection using contemporary atrial fibrillation (AF) ablation technologies.The CIRCA-DOSE (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration) study enrolled 346 patients with paroxysmal AF and randomized them to contact force-guided radiofrequency ablation (CF-RF) or cryoballoon ablation. Patients underwent provocative testing with adenosine after a 20-minute observation period. All patients received an implantable cardiac monitor for arrhythmia monitoring.Spontaneous reconnection was observed in 5.4% of PVs (71/1318) during the 20-minute postprocedure observation period, and dormant conduction was elicited in 5.7% of PVs (75/1318). Both spontaneous reconnection and dormant conduction were more common after CF-RF compared to cryoballoon ablation (P = .03 and P.0001, respectively). Acute PV reconnection (spontaneous or adenosine-provoked) was associated with a significantly higher incidence of recurrent atrial tachyarrhythmia in the cryoballoon group (hazard ratio [HR] 2.39; 95% confidence interval [CI] 1.44-3.96; P = .0007) but not in the CF-RF group (HR 1.47; 95% CI 0.84-2.58; P = .16). In the absence of acute reconnection, the freedom from recurrent arrhythmia did not differ between groups (HR 0.95; 95% CI 0.6057-1.495; P = .83).Patients without spontaneous or adenosine-provoked reconnection had better outcomes compared to those with acute PV reconnection, suggesting that efforts should be directed toward ensuring an ideal ablation lesion at the first attempt in order to achieve durable PV isolation.

Background: Atrial fibrillation (AF) and heart failure (HF) frequently coexist and can be challenging to treat. Pharmacologically based rhythm control of AF has not proven to be superior to rate control. Ablation-based rhythm control was compared with rate control to evaluate if clinical outcomes in patients with HF and AF could be improved. Methods: This was a multicenter, open-label trial with blinded outcome evaluation using a central adjudication committee. Patients with high-burden paroxysmal (>4 episodes in 6 months) or persistent (duration Results: From December 1, 2011, to January 20, 2018, 411 patients were randomly assigned to ablation-based rhythm control (n=214) or rate control (n=197). The primary outcome occurred in 50 (23.4%) patients in the ablation-based rhythm-control group and 64 (32.5%) patients in the rate-control group (hazard ratio, 0.71 [95% CI, 0.49–1.03]; P =0.066). Left ventricular ejection fraction increased in the ablation-based group (10.1±1.2% versus 3.8±1.2%, P =0.017), 6-minute walk distance improved (44.9±9.1 m versus 27.5±9.7 m, P =0.025), and NT-proBNP demonstrated a decrease (mean change –77.1% versus –39.2%, P P =0.0036), as did the AF Effect on Quality of Life score (least-squares mean difference of 6.2 [95% CI, 1.7–10.7]; P =0.0005). Serious adverse events were observed in 50% of patients in both treatment groups. Conclusions: In patients with high-burden AF and HF, there was no statistical difference in all-cause mortality or HF events with ablation-based rhythm control versus rate control; however, there was a nonsignificant trend for improved outcomes with ablation-based rhythm control over rate control. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01420393.

Patients with hemodynamically tolerated ventricular tachycardia (VT) and minimally reduced left ventricular ejection fraction (LVEF) remain a group that presents a prognostic and therapeutic dilemma.We studied patients from our implanted cardioverter-defibrillator (ICD) database who received ICDs for hemodynamically tolerated VT and mildly reduced LVEF (36%-49%) at time of implant between May 2015 and December 2019. Time to appropriate ICD therapy was assessed. Clinical features associated with recurrent VT/ventricular fibrillation (VF) with ICD therapies were explored using binary logistic regression.Among 2037 ICDs placed between May 2015 and December 2019, 64 subjects met the inclusion criteria. The mean age of the study group was 68 ± 12 years, and 58 (90.6%) subjects were male. Average ejection fraction was 40% ± 4.4 (range 36%-49%). Twenty-two (34%) subjects received antitachycardia pacing (ATP) for VT at 229 ± 265 days after ICD placement. Fifteen (23%) subjects received appropriate ICD shocks 305 ± 321 days after implant. The rate of recurrent VT/VF among the 37 patients with ICD therapy was 195 ± 39 beats per minute (bpm). This was significantly more rapid than initial presenting VT rates before ICD placement (183 ± 27 bpm) (P = 0.048). Multivariate analysis showed no factors independently associated with recurrent VT/VF.Patients with mildly impaired LV function and hemodynamically tolerated VT receive appropriate ICD therapies over the 3 years following implant. This patient group warrants further investigation, as their recurrent VT/VF rates can be much more rapid, and 23% go on to receive appropriate ICD shocks.

Key Points Question What proportion of patients with left ventricular dysfunction identified during hospitalization for acute myocardial infarction have follow-up assessment of left ventricular ejection fraction (LVEF)? Findings In this cohort study of 501 patients, 303 patients had undergone LVEF reassessment by 6 months, with significant variability according to patient-level and site-level characteristics. Meaning These findings suggest that programs to improve the quality of post–myocardial infarction care should include measures to ensure that indicated repeat cardiac imaging is performed., This cohort study assesses adherence with guideline-recommended left ventricular ejection fraction (LVEF) reassessment after myocardial infarction and studies the evolution of LVEF over 6 months of follow-up in the Acute Myocardial Infarction Quality Assurance (AMIQA) Canada study., Importance Persistently depressed left ventricular ejection fraction (LVEF) after myocardial infarction (MI) is associated with adverse prognosis and directs the use of evidence-based treatments to prevent sudden cardiac death and/or progressive heart failure. Objective To assess adherence with guideline-recommended LVEF reassessment and to study the evolution of LVEF over 6 months of follow-up. Design, Setting, and Participants This was a multicenter cohort study at Canadian academic and community hospitals with on-site cardiac catheterization services. Patients with type 1 acute MI and LVEF less than or equal to 45% during the index hospitalization were enrolled between January 2018 and August 2019 and were followed-up for 6 months. Data analysis was performed from May 2020 to September 2021. Exposures Baseline clinical factors, in-hospital care and LVEF, and site-specific features. Main Outcomes and Measures The main outcomes were receipt of repeat LVEF assessment by 6 months and the presence of a persistent LVEF reduction at 2 thresholds: LVEF less than or equal to 40%, prompting consideration of additional medical therapy for heart failure, or LVEF less than or equal to 35%, prompting referral for implanted cardioverter defibrillator in addition to medical therapy. Results This study included 501 patients (mean [SD] age, 63.3 [13.0] years; 113 women [22.6%]). Overall, 370 patients (73.4%) presented with STEMI, and 454 (90.6%) had in-hospital revascularization. The median (IQR) baseline LVEF was 40% (34%-43%). Of 458 patients (91.4%) who completed the 6-month follow-up, 303 (66.2%; 95% CI, 61.7%-70.5%) had LVEF reassessment, with a range of 46.7% to 90.0% across sites (χ213 = 19.6; P = .11). Participants from community hospitals were more likely than those from academic hospitals to undergo LVEF reassessment (73.6% vs 63.2%; χ21 = 4.50; P = .03), as were those with worse LVEF at baseline. Follow-up LVEF improved by an absolute median (IQR) of 8% (3%-15%). However, 103 patients (34.1%) met the definitions of clinically relevant LVEF reduction, including 52 patients (17.2%) with LVEF less than or equal to 35% and 51 patients (16.9%) with LVEF of 35.1% to 40.0%. Conclusions and Relevance In this cohort study, approximately 1 in 3 patients with at least mild LVEF reduction after acute MI did not undergo indicated LVEF reassessment within 6 months, suggesting that programs to improve the quality of post-MI care should include measures to ensure that indicated repeat cardiac imaging is performed. In those with follow-up imaging, clinically relevant persistent LVEF reduction was identified in more than one-third of patients.

Background: Advanced generation ablation technologies have been developed to achieve more effective pulmonary vein isolation (PVI) and minimize arrhythmia recurrence after atrial fibrillation (AF) ablation. Methods: We randomly assigned 346 patients with drug-refractory paroxysmal AF to contact force–guided radiofrequency ablation (CF-RF; n=115), 4-minute cryoballoon ablation (Cryo-4; n=115), or 2-minute cryoballoon ablation (Cryo-2; n=116). Follow-up was 12 months. The primary outcome was time to first documented recurrence of symptomatic or asymptomatic atrial tachyarrhythmia (AF, atrial flutter, or atrial tachycardia) between days 91 and 365 after ablation or a repeat ablation procedure at any time. Secondary end points included freedom from symptomatic arrhythmia and AF burden. All patients received an implantable loop recorder. Results: One-year freedom from atrial tachyarrhythmia defined by continuous rhythm monitoring was 53.9%, 52.2%, and 51.7% with CF-RF, Cryo-4, and Cryo-2, respectively ( P =0.87). One-year freedom from symptomatic atrial tachyarrhythmia defined by continuous rhythm monitoring was 79.1%, 78.2%, and 73.3% with CF-RF, Cryo-4, and Cryo-2, respectively ( P =0.26). Compared with the monitoring period before ablation, AF burden was reduced by a median of 99.3% (interquartile range, 67.8%–100.0%) with CF-RF, 99.9% (interquartile range, 65.3%–100.0%) with Cryo-4, and 98.4% (interquartile range, 56.2%–100.0%) with Cryo-2 ( P =0.36). Serious adverse events occurred in 3 patients (2.6%) in the CF-RF group, 6 patients (5.3%) in the Cryo-4 group, and 7 patients (6.0%) in the Cryo-2 group, with no significant difference between groups ( P =0.24). The CF-RF group had a significantly longer procedure duration but significantly shorter fluoroscopy exposure ( P Conclusions: In this multicenter, randomized, single-blinded trial, CF-RF and 2 different regimens of cryoballoon ablation resulted in no difference in 1-year efficacy, which was 53% by time to first recurrence but >98% burden reduction as assessed by continuous cardiac rhythm monitoring. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01913522.

BACKGROUND Multipolar phased pulmonary vein ablation catheter (PVAC), specifically its second-generation (PVAC-Gold), has been associated with reduced procedural time for atrial fibrillation (AF) ablation compared to traditional catheters. We performed this study to compare the efficacy of PVAC with point-by-point radiofrequency (RF) ablation. METHODS This is a multicenter-cohort study (2012-2017), involving patients with symptomatic, paroxysmal AF refractory to at least one antiarrhythmic medication. Overall, 230 patients were enrolled to (A) PVAC and (B) control groups. Subanalyses were done for ablations performed with PVAC-Gold, and for ablations performed without left atrial (LA) ablation in addition to pulmonary vein isolation. Electrocardiogram and 48-h Holter monitoring were used to assess patients at 3, 6, 9, and 12 months postablation. Recurrence was defined as any atrial arrhythmia >30 s excluding an initial 3-month blanking period. RESULTS Freedom from any atrial arrhythmia at 12 months postablation was 35.70% and 52.80% in groups A and B, respectively (P = .01). Freedom from atrial arrhythmia was not significantly different when limiting the PVAC cohort to PVAC-Gold and excluding patients with additional LA ablation (A: 44.30%; B: 44.30%, P = .80). Procedural and ablation time was significantly lower in group A than B. Multivariate regression model showed female gender (odds ratio [OR] = 2.90) and recurrence during blanking period (OR = 6.60) as significant predictors of recurrence. CONCLUSION This study suggests that PVAC may achieve less freedom from AF than point-by-point RF; however, efficacy is similar when comparing PVAC-Gold and point-by-point stand-alone PV isolation. PVAC is associated with significantly reduced procedural times for AF ablation.

IMPORTANCE: Patients with atrial fibrillation (AF) have impaired health-related quality of life primarily owing to symptoms related to AF episodes; however, quality of life can be influenced by AF therapies, AF complications, the frequency of follow-up visits and hospitalizations, illness perceptions, and patient factors, such as anxiety or depression. OBJECTIVE: To determine the association between change in AF burden and quality of life in the year following ablation. DESIGN, SETTING, AND PARTICIPANTS: The current study is a secondary analysis of a prospective, parallel-group, multicenter, single-masked randomized clinical trial (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE] study), which took place at 8 Canadian centers. Between September 2014 and July 2017, 346 patients older than 18 years with symptomatic, primarily low-burden AF refractory to antiarrhythmic therapy referred for first catheter ablation were enrolled. All patients received an implantable cardiac monitor at least 30 days before ablation and were followed up with up to December 2018. Data were analyzed from April 2020 to June 2021. INTERVENTIONS: Patients were randomized 1:1:1 to contact force–guided radiofrequency ablation, 4-minute cryoballoon ablation, or 2-minute cryoballoon ablation. The exposure in the present analysis is the absolute difference in AF burden prior to ablation and 12 months following ablation, as evaluated by the Atrial Fibrillation Effect on Quality of Life (AFEQT) Score. MAIN OUTCOMES AND MEASURES: Absolute difference in quality of life from baseline to 12 months postablation. RESULTS: Of 346 included patients, 231 (66.7%) were male, and the median (interquartile range) age was 60 (52-66) years. A total of 328 patients (94.8%) had paroxysmal AF. The median (interquartile range) preablation AF burden was 2.0% (0.1-11.9), and the AF burden decreased to 0% at 12 months postablation. At 12 months, a 1-point improvement in AFEQT score was observed for every absolute reduction in daily AF burden of 15.8 minutes (95% CI, 7.2-24.4; P

Early recurrence of atrial tachyarrhythmia (ERAT) is common after pulmonary vein isolation (PVI) and has been associated with an increased risk of late atrial fibrillation (AF) recurrence.The purpose of this study was to determine the incidence and outcomes of patients experiencing ERAT after PVI using advanced-generation ablation technologies.This is a prespecified substudy of the CIRCA-DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double-Short vs Standard Exposure Duration) trial, a prospective, randomized, multicenter study comparing PVI with contact force-guided radiofrequency ablation to secondary-generation cryoballoon ablation for paroxysmal AF. All study patients received an implantable cardiac monitor to allow continuous rhythm monitoring. ERAT was defined as any recurrent atrial tachyarrhythmia within the first 90 days after AF ablation.ERAT occurred in 61% of the 346 patients at a median of 12 days (range 1-90 days) after ablation. ERAF was a significant predictor of late recurrence (60.1% with ER vs 25.9% without ER; P.001) and symptomatic atrial tachyarrhythmia (31.6% with ERAF vs 6.7% without ERAF; P.001). Receiver operating curve analyses revealed a strong correlation between ERAT timing and burden and late recurrence. Multivariate analysis identified ER timing (hazard ratio [HR] 2.90; 95% confidence interval [CI] 1.41-5.95; P = .004) and burden (HR 1.05 per 1% ER burden; 95% CI 1.04-1.07; P.001) as strong independent predictors of late recurrence. Incidence rate, timing, burden, and prognostic significance of ER did not differ between the study groups.ERAT remains common after PVI despite use of advanced-generation ablation technologies. Early AF recurrence beyond 3 weeks after ablation is associated with increased risk of late recurrence.

Background Patients with persistent atrial fibrillation (AF) undergoing catheter‐based AF ablation have lower success rates than those with paroxysmal AF. We compared healthcare use and clinical outcomes between patients according to their AF subtypes. Methods and Results Consecutive patients undergoing AF ablation were prospectively identified from a population‐based registry in Ontario, Canada. Via linkage with administrative databases, we performed a retrospective analysis comparing the following outcomes between patients with persistent and paroxysmal AF: healthcare use (defined as AF‐related hospitalizations/emergency room visits), periprocedural complications, and mortality. Multivariable Poisson modeling was performed to compare the rates of AF‐related and all‐cause hospitalizations/emergency room visits in the year before versus after ablation. Between April 2012 and March 2016, there were 3768 consecutive patients who underwent first‐time AF ablation, of whom 1040 (27.6%) had persistent AF. The mean follow‐up was 1329 days. Patients with persistent AF had higher risk of AF‐related hospitalization/emergency room visits (hazard ratio [HR], 1.21; 95% CI, 1.09–1.34), mortality (HR, 1.74; 95% CI, 1.15–2.63), and periprocedural complications (odds ratio, 1.36; 95% CI, 1.02–1.75) than those with paroxysmal AF. In the overall cohort, there was a 48% reduction in the rate of AF‐related hospitalization/emergency room visits in the year after versus before ablation (rate ratio [RR], 0.52; 95% CI, 0.48–0.56). This reduction was observed for patients with paroxysmal (RR, 0.45; 95% CI, 0.41–0.50) and persistent (RR, 0.74; 95% CI, 0.63–0.87) AF. Conclusions Although patients with persistent AF had higher risk of adverse outcomes than those with paroxysmal AF, ablation was associated with a favorable reduction in downstream AF‐related healthcare use, irrespective of AF type.

Introduction: Persistently reduced LVEF after acute MI predicts adverse prognosis and directs use of evidence-based treatments to prevent sudden death (SCD) and/or progressive heart failure. We conducted a multicentre, prospective, observational study to assess adherence with guideline recommendations to repeat imaging assessment post-MI in those with initially depressed LVEF. Methods: We enrolled 501 patients with type 1 acute MI and LVEF ≤45% during the index hospitalization, from 14 Canadian sites. Outcomes were the proportion having a repeat LVEF assessment by 6 months and the proportion with an actionable reduced LVEF in follow-up: Results: Mean age was 63.3 ± 13.0, and 113 (22.6%) were female. Overall, 370 (73.4%) presented with STEMI, and 454 (91.6%) had one or more in-hospital revascularization procedures. The mean baseline LVEF was 36.9% ± 6.7%. Over a median follow-up of 198 days, 18 (3.6%) patients died and 27 (5.3%) were lost to follow-up. Of 456 remaining patients, 303 (66.5%) had LVEF reassessment and significant variation was observed across sites (range 46.7-90.0%; p=0.035). Patients from community vs academic hospitals were more likely to undergo LVEF reassessment (73.6% vs. 63.2%, p=0.034), as were those with worse LVEF at baseline ( Figure, panel A ). In those with follow-up LVEF (n=302), 61.6% had an actionable persistent LVEF reduction: 13.9% had LVEF Figure, Panel B ). Conclusions: One in three patients with at least mild LVEF reduction after acute MI did not undergo indicated LVEF reassessment within 6 months. In those with follow-up imaging, clinically actionable persistent LVEF reduction was identified in over one quarter of patients.

Background Concerns remain regarding the effectiveness of PVI using the fixed diameter non-compliant cryoballoon in the presence of a left common pulmonary vein (LCPV). We sought to evaluate the effectiveness of PVI performed by contact-force guided radiofrequency (CF-RF) versus second-generation cryoballoon-based ablation in patients with LCPV. Methods and results We enrolled 346 patients with paroxysmal AF and randomized them to CF-RF or cryoballoon ablation. PV anatomy was not assessed prior to enrolment, and there were no exclusions based on PV anatomy. All patients received an implantable cardiac monitor. LCPV was observed in 13.6% of patients (47/346). Left atrial time and fluoroscopy time did not differ between those with and without LCPV (P=0.58 and P=0.06, respectively). Freedom from any atrial tachyarrhythmia at one year was observed in 46.8% with LCPV and 54.5% without LCPV (P=0.06). In those with LCPV the freedom from any atrial tachyarrhythmia did not differ between those randomized to CF-RF or cryoballoon ablation (HR for recurrence 1.19, 95% CI 0.53-2.65, P=0.69). In those with LCPV the AF burden was reduced to a similar extent with CF-RF and cryoballoon ablation (99.7% vs. 99.5%, respectively; P=0.97). Conclusions In this randomized clinical trial, the presence of a LCPV was associated with a trend towards higher rates of arrhythmia recurrence following PVI. No significant difference in arrhythmia recurrence was observed between patients with LCPV randomized to cryoballoon ablation or contact-force guided RF ablation, suggesting that either ablation modality is suitable in this population. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation [CIRCA-DOSE], NCT01913522) This article is protected by copyright. All rights reserved.

ObjectivesThe primary objective of this study was to ascertain the reasons for emergency department (ED) attendance among patients with a history of atrial fibrillation (AF).DesignAppropriate ED attendance was defined by the requirement for an electrical or chemical cardioversion and/or an attendance resulting in hospitalisation or administration of intravenous medications for ventricular rate control. Quantitative and qualitative responses were recorded and analysed using descriptive statistics and content analysis, respectively. Random effects logistic regression was performed to estimate the OR of inappropriate ED attendance based on clinically relevant patient characteristics.ParticipantsParticipants ≥18 years with a documented history of AF were approached in one of eight centres partaking in the study across Canada (Ontario, Nova Scotia, Alberta and British Columbia).ResultsOf the 356 patients enrolled (67±13, 45% female), the majority (271/356, 76%) had inappropriate reasons for presentation and did not require urgent ED treatment. Approximately 50% of patients(172/356, 48%) were driven to the ED due to symptoms, while the remainder presented on the basis of general fear or anxiety (67/356, 19%) or prior medical advice (117/356, 33%). Random effects logistic regression analysis showed that patients with a history of congestive heart failure were significantly more likely to seek urgent care for appropriate reasons (p=0.03). Likewise, symptom-related concerns for ED presentation were significantly less likely to result in inappropriate visitation (p=0.02). When patients were surveyed on alternatives to ED care, the highest proportion of responses among both groups was in favour of specialised rapid assessment outpatient clinics (186/356, 52%). Qualitative content analysis confirmed these results.ConclusionsImproved education focused on symptom management and alleviating disease-related anxiety as well as the institution of rapid access arrhythmias clinics may reduce the need for unnecessary healthcare utilisation in the ED and subsequent hospitalisation.Trial registration numberNCT03127085

This study sought to identify minimum threshold values below which conduction over the atrioventricular (AV) node would be unexpected.Para-Hisian pacing is used to evaluate for the presence of a septal accessory pathway (AP); however, threshold values to differentiate nodal from AP conduction are unknown.The authors performed high- and low-output para-Hisian pacing during sinus rhythm to capture the His and para-Hisian ventricular myocardium (H+V) and para-Hisian ventricular myocardium (V) alone, respectively. The change in stimulation (stim)-to-atrial electrogram interval after loss of His bundle capture in patients with (AP+) and without (AP-) a septal AP was evaluated. Stim-to-proximal coronary sinus (PCS) and stim-to-high right atrium (HRA) intervals were measured and within-patient differences (△) for V and H+V capture were calculated.A total of 23 AP+ and 45 AP- patients were evaluated. The difference in stimulus to earliest atrial signal in the high right atrial catheter seen with the loss of His bundle capture (△-stim-HRA) (21 ms; interquartile range [IQR]: 3 to 43 ms vs. 64 ms; IQR: 56 to 73 ms; p 0.001) and difference in stimulus to earliest atrial signal in the proximal coronary sinus catheter seen with the loss of His Bundle capture (△-stim-PCS) (11 ms; IQR: 0 to 30 ms vs. 61 ms; IQR: 52 to 72 ms; p 0.001) were shorter in AP+ patients. The shortest △-stim-PCS and △-stim-HRA in AP- patients were 37 ms and 32 ms, respectively, whereas the longest corresponding intervals in AP+ patients were 51 ms and 75 ms, respectively.A △-stim-PCS 37 ms or △-stim-HRA 32 ms confirmed the presence of a septal AP, whereas a value51 ms for △-stim-PCS or75 ms for △-stim-HRA excluded it. Alternatively, the minimum △-stim-PCS with loss of His capture compatible with AV nodal conduction in isolation was 37 ms, and a △-stim-PCS51 ms effectively ruled out the presence of a septal AP.

Femoral venous access is required for most electrophysiology procedures. Limited data are available regarding post-procedure venous thromboembolism (VTE), specifically deep vein thrombosis (DVT) and pulmonary embolism (PE). Potential preventative strategies are unclear. We aimed to survey Canadian centers regarding incidence of VTE and strategies for prevention of VTE after procedures that do not require post-procedure anticoagulation. An online survey was distributed to electrophysiologists representing major Canadian EP centers. Participants responded regarding procedural volume, incidence of VTE post-procedure, and their practice regarding pharmacological and non-pharmacological peri-procedural VTE prophylaxis. The survey included 17 centers that performed a total of 6062 procedures in 2016. Ten patients (0.16%) had VTE (including 9 DVTs and 6 PEs) after diagnostic electrophysiology studies and right-sided ablation procedures excluding atrial flutter. Five centers (41.6%) administered systemic intravenous heparin during both diagnostic electrophysiology studies and right-sided ablation procedures. For patients taking oral anticoagulants, 10 centers (58.8%) suspend therapy prior to the procedure. Two centers (11.8%) routinely prescribed post-procedure pharmacologic prophylaxis for VTE. Four centers (23.5%) used compression dressings post-procedure and all prescribed bed rest for a maximum of 6 h. Of the variables collected in the survey, none were found to be predictive of VTE. VTE is not a common complication of EP procedures. There is significant variability in the strategies used to prevent VTE events. Future research is required to evaluate strategies to reduce the risk of VTE that may be incorporated into EP practice guidelines.

Aims Cardiac resynchronization therapy (CRT) has been shown to reduce mortality and heart failure (HF) hospitalization but its effects on the rate of ventricular arrhythmias (VAs) appears to be neutral. We hypothesize that CRT with LV epicardial stimulation is inherently pro-arrhythmic and increases VA rates in the absence of reverse ventricular remodelling while conferring an anti-arrhythmic effect in mechanical responders. Methods and results In this systematic review and meta-analysis, we considered retrospective cohort, prospective cohort, and randomized controlled trials comparing VA rates between cardiac resynchronization therapy-defibrillator (CRT-D) non-responders, CRT-D responders and those with implantable cardioverter-defibrillator (ICD) only. Studies were eligible if they defined CRT-D responders using a discrete left ventricular volumetric value as assessed by any imaging modality. Studies were identified through searching electronic databases from their inception to July 2017. We identified 2579 citations, of which 23 full-text articles were eligible for final analysis. Our results demonstrated that CRT-D responders were less likely to experience VA than CRT-D non-responders, relative risk (RR) 0.49 [95% confidence interval (CI) 0.41-0.58, P

Background The risk of stroke from atrial flutter and its relationship with progression to atrial fibrillation (AF) is unclear. This study describes the incidence of AF and stroke in patients with atrial flutter, and whether atrial flutter ablation attenuates the incidence of AF and stroke. Methods We performed a population-based retrospective cohort study of adults with typical atrial flutter with no AF history. Using linked health administrative databases we defined 3 cohorts: (1) adult patients diagnosed with new isolated atrial flutter; (2) a contemporary, 1-to-1 matched cohort from the Ontario population; and (3) patients with isolated atrial flutter who underwent atrial flutter ablation. Results A total of 9339 new typical atrial flutter patients were identified and 7248 were matched to general population subjects. Over the 3-year follow-up, AF occurred in 40.4% of patients with atrial flutter, and 3.3% of the matched general population (rate ratio, 12.2; P P Conclusions Patients with isolated atrial flutter develop AF and stroke at a higher rate than the general population. Catheter ablation reduces but does not eliminate future AF incidence and stroke risk and continued anticoagulation after successful atrial flutter ablation might therefore be warranted.

Background Subcutaneous implantable cardioverter-defibrillators provide an alternative to transvenous defibrillation but require higher shock outputs and offer no antitachycardia pacing. The Substernal Pacing Acute Clinical Evaluation (SPACE) study evaluated the feasibility of pacing from an extravascular substernal location. Objectives The primary purpose of the SPACE study was to characterize pacing from the substernal space. Secondary objectives included evaluating extracardiac stimulation and recording electrograms. Methods The SPACE study prospectively evaluated the feasibility of pacing with a commercially available electrophysiology catheter acutely implanted in the substernal space via minimally invasive subxiphoid access. Pacing data were collected in ≥7 vectors using constant current stimulation up to 20 mA and pulse width up to 10 ms. Results Catheter placement was successful in all 26 patients who underwent the procedure, with a mean placement time of 11.7 ± 10.1 minutes. Eighteen patients (69%) had successful ventricular capture in ≥1 tested vector. The mean pacing threshold at a pulse width of 10 ms was 7.3 ± 4.2 mA across all vectors (5.8 ± 4.4 V). Failed capture was generally associated with suboptimal catheter placement or presumed air ingression. A low level of extracardiac stimulation was observed in 1 patient. The mean R-wave amplitude ranged from 2.98 to 4.11 mV in the unipolar configuration and from 0.83 to 3.95 mV in the bipolar configuration. Conclusion The data from the SPACE study demonstrate that pacing is feasible from the extravascular substernal location. A substernal electrode configuration has the potential to provide pacing in a future extravascular device without need for intracardiac hardware placement.

Introduction In patients with ischemic heart disease and ventricular tachycardia (VT) refractory to high dose amiodarone, the two most common therapeutic options are adjunctive mexiletine therapy or catheter ablation. There are little existing data on the efficacy of these strategies. We examined the relative efficacy of adjunctive mexiletine and catheter ablation among patients enrolled in the VANISH trial. Methods All subjects enrolled in the VANISH trial who had VT refractory to high dose (≥ 300 mg daily) amiodarone at baseline were included. Per protocol, subjects randomized to escalated drug therapy received adjunctive mexiletine. Results Nineteen of the 259 patients were receiving high-dose amiodarone at baseline and 11 were randomized to escalated therapy with mexiletine and 8 to ablation. The adjunctive mexiletine group had a higher rate of the primary composite outcome (death, VT storm, or appropriate shock) in comparison to catheter ablation (HR 6.87 [2.08-22.8]). Over 90% of the patients in the adjunctive mexiletine/group experienced a primary endpoint during a median 9.2 months' follow-up. There was no difference in the rate of adverse events between the two groups. Conclusions Mexiletine has limited efficacy in the treatment of recurrent VT despite high-dose amiodarone therapy, in patients with ischemic heart disease. Catheter ablation is a superior strategy in this population.

Background/objective We compared health-related quality of life (HRQoL) in patients randomized to escalated therapy and those randomized to ablation for ventricular tachycardia in the VANISH trial. Methods HRQoL was assessed among VANISH patients at baseline and 3-, 6-, and 12-month follow-up visits. Four validated instruments were used: the SF-36, the implanted cardioverter defibrillator (ICD) Concerns questionnaire (ICDC), the Hospital Anxiety and Depression Scale (HADS), and the EuroQol five dimensions questionnaire (EQ-5D). Linear mixed-effects modeling was used for repeated measures with SF-36, HADS, ICDC, and EQ-5D as dependent variables. In a second model, treatment was subdivided by amiodarone use prior to enrollment. Results HRQoL did not differ significantly between those randomized to ablation or escalated therapy. On subgroup analysis, improvement in SF-36 measures was seen at 6 months in the ablation group for social functioning (63.5-69.3, P = 0.03) and energy/fatigue (43.0-47.9, P = 0.01). ICDC measures showed a reduction in ICD concern in the ablation group at 6 months (10.4-8.7, P = 0.01) and a reduction in ICD concern in the escalated therapy group at 6 months (10.9-9.4, P = 0.04). EQ-5D measures showed a significant improvement in overall health in ablation patients at 6 months (63.4-67.3, P = 0.04). Conclusion Patients in the VANISH study randomized to ablation did not have a significant change in quality of life outcomes compared to those randomized to escalated therapy. Some subgroup findings were significant, as those randomized to ablation showed persistent improvement in SF-36 energy/fatigue and ICD concern, and transient improvement in SF-36 social functioning and EQ-5D overall health.

© 2017, Springer Science+Business Media Dordrecht. Cardiac Resynchronization Therapy (CRT) fails to provide benefit in up to one-third of patients. Maximizing the geographic separation of right and left ventricular pacing lead sites has been suggested as one way to improve response. Cardiac CT provides an opportunity to explore 3-dimensional inter-lead distance (ILD) measures for the prediction of CRT response. The objective of this study was to investigate associations between standardized measures of ILD by cardiac CT and echocardiographic response to CRT. Forty-two consecutive patients undergoing CRT had serial clinical and echocardiographic evaluations performed in addition to a post-procedural cardiac-gated CT with blinded measurement of direct and circumferential (via the myocardium) ILD measures. Clinical response to CRT, the primary clinical outcome, was defined as a ≥15% reduction in LVESV using echocardiography at 6-months. The mean age and ejection fraction was 63.6 ± 8.9 years and 25.2 ± 7.8%, respectively. The primary outcome occurred in 35 of 42 patients (83%). Both direct and circumferential CT-based ILD measures were associated with the primary outcome by univariate analysis. Receiver Operator Characteristic analysis identified Circumferential ILD to have the strongest predictive accuracy (AUC 0.78). Inter- and intra-observer reproducibility of CT-derived ILD measures was excellent. Circumferential ILD measures on cardiac CT are predictive of clinical response to CRT. Incorporation of these measures into the selection of optimal pacing targets, particularly from pre-procedural CT coronary vein imaging may be of therapeutic benefit and warrants further investigation.

This study evaluated the impact of contact force-guided radiofrequency ablation versus cryoballoon ablation on quality of life and health care utilization.Traditional outcome parameters, such as arrhythmia-free survival, are insufficient to evaluate the clinical impact of atrial fibrillation (AF), as it fails to the capture patient- and health system-level differences in treatment approaches.The CIRCA-DOSE (Cryoballoon Vs. Contact-Force Atrial Fibrillation Ablation) study randomly assigned 346 patients with drug-refractory paroxysmal AF to contact force-guided radiofrequency or cryoballoon ablation. Health-related quality-of-life (HRQOL) was assessed at baseline, and at 6 and 12 months post-ablation using a disease-specific and generic HRQOL instruments. Health care utilization (hospitalization, emergency department visits, and cardioversion) and antiarrhythmic drug use for the 12 months preceding ablation was compared with the 12 months following ablation.Disease-specific and generic HRQOL was moderately to severely impaired at baseline and improved significantly at 6 and 12 months of follow-up (median improvement in AFEQT [Atrial Fibrillation Effect on QualiTy of Life] score 32.4 [interquartile range: 17.7 to 48.9]). When compared with the 12 months pre-ablation, the proportion and absolute number of cardioversions decreased significantly (41.1% vs. 10.1% of patients, 137 vs. 35 events; p 0.0001). Similar significant reductions in emergency department visits (66.7% vs. 25.1% of patients, 224 vs. 87 events; p 0.0001), and hospitalizations (25.5% vs. 14.5% of patients, 86 vs. 50 events; p 0.001) were observed. There were no significant differences between randomized groups.In this multicenter randomized trial, catheter ablation with advanced-generation technologies resulted in a significant improvement in HRQOL and a significant reduction in health care utilization in the year following AF ablation. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation [CIRCA-DOSE]; NCT01913522).

Background: Insight into type 5 long QT syndrome (LQT5) has been limited to case reports and small family series. Improved understanding of the clinical phenotype and genetic features associated with rare KCNE1 variants implicated in LQT5 was sought through an international multicenter collaboration. Methods: Patients with either presumed autosomal dominant LQT5 (N = 229) or the recessive Type 2 Jervell and Lange-Nielsen syndrome (N = 19) were enrolled from 22 genetic arrhythmia clinics and 4 registries from 9 countries. KCNE1 variants were evaluated for ECG penetrance (defined as QTc >460 ms on presenting ECG) and genotype-phenotype segregation. Multivariable Cox regression was used to compare the associations between clinical and genetic variables with a composite primary outcome of definite arrhythmic events, including appropriate implantable cardioverter-defibrillator shocks, aborted cardiac arrest, and sudden cardiac death. Results: A total of 32 distinct KCNE1 rare variants were identified in 89 probands and 140 genotype positive family members with presumed LQT5 and an additional 19 Type 2 Jervell and Lange-Nielsen syndrome patients. Among presumed LQT5 patients, the mean QTc on presenting ECG was significantly longer in probands (476.9±38.6 ms) compared with genotype positive family members (441.8±30.9 ms, P P =0.001). Event incidence did not differ significantly for Type 2 Jervell and Lange-Nielsen syndrome patients relative to the overall heterozygous cohort (10.5% [2/19]; HR 1.7 [95% CI, 0.3–10.8], P =0.590). The cumulative prevalence of the 32 KCNE1 variants in the Genome Aggregation Database, which is a human database of exome and genome sequencing data from now over 140 000 individuals, was 238-fold greater than the anticipated prevalence of all LQT5 combined (0.238% vs 0.001%). Conclusions: The present study suggests that putative/confirmed loss-of-function KCNE1 variants predispose to QT prolongation, however, the low ECG penetrance observed suggests they do not manifest clinically in the majority of individuals, aligning with the mild phenotype observed for Type 2 Jervell and Lange-Nielsen syndrome patients.

Introduction Anticoagulation guidelines for patients with atrial fibrillation (AF) disregard AF burden. A strategy of targeted anticoagulation with novel oral anticoagulants (NOACs) based on continuous rhythm assessment with an implantable cardiac monitor (ICM) has recently been explored. We evaluated the potential cost-effectiveness of this strategy versus projected outcomes with continuous anticoagulation. Methods and Results We developed a Markov model using data from the Rhythm Evaluation for AntiCoagulaTion With COntinuous Monitoring (REACT.COM) pilot study (N = 59) and prior NOAC trials to calculate the costs and quality-adjusted life years (QALYs) associated with ICM-guided intermittent anticoagulation for AF vs. standard care over a 3-year time horizon. Health state utilities were estimated from the pilot study population using the SF-12. Costs were based on current Medicare reimbursement. Over 14±4 months of follow-up 18 of 59 patients had 35 AF episodes. The ICM-guided strategy resulted in a 94% reduction in anticoagulant use relative to continuous treatment. There were no strokes, 3 (5.1%) TIAs, 2 major bleeding events (on aspirin) and 3 minor bleeding events with the ICM-guided strategy. The projected total 3-year costs were $12,535 for the ICM-guided strategy vs. $13,340 for continuous anticoagulation. Projected QALYs were 2.45 for both groups. Conclusion Based on a pilot study, a strategy of ICM-guided anticoagulation with NOACs may be cost-saving relative to expected outcomes with continuous anticoagulation, with similar quality-adjusted survival. This strategy could be attractive from a health economic perspective if shown to be safe and effective in a rigorous clinical trial. This article is protected by copyright. All rights reserved

Background Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive disease characterized by replacement of normal myocardium by fibrofatty tissue. The right ventricular (RV) apex is the typical target for implantable cardioverter-defibrillator (ICD) lead placement, raising concerns for suboptimal lead performance in medium- to long-term follow-up. Objective The purpose of this study was to determine whether placement of ICD leads at the RV apex was associated with performance deterioration of medium-term leads in ARVC patients compared to non-ARVC patients. Methods In this multicenter, retrospective, case-control study, ICD lead performance measures of R-wave, impedance, and pacing thresholds were compared at baseline and between 1-year and 5-year postimplantation follow-up using mixed-effect models adjusted for age and sex. Results One hundred one ARVC patients (49 women, age 50.6 ± 14.5 years) were compared to 56 control patients (37 women, age 48.2 ± 14.2 years). The mean difference in R wave between years 1 and 2 was –0.85 mV ( P = .16) compared to a mean difference at years 5 and 6 of –1.85 mV ( P = .02). There was no difference in impedance or pacing threshold or in lead lifetime between the 2 groups over 6-year follow-up (5.91 ± 3.89 years vs 5.48 ± 3.70 years, P = .239). Conclusion In ARVC patients with ICD leads implanted in the RV apex, ventricular sensing deteriorates significantly during medium-term follow-up. Septal RV lead placement should be explored as the first choice at implantation.

Sustained monomorphic ventricular tachycardia or repetitive premature ventricular complexes can be seen in patients with structurally normal hearts. Among these types of patients, the prognosis is predominantly benign and the treatment mostly focused on elimination of symptoms rather than improving survival or reduction of mortality. This article focuses on the pharmacologic options for management and compares them with invasive options. Based on the current literature, we demonstrate that medical therapies should be used as first-line management and favored over invasive therapies. Understanding the arrhythmia mechanism is critical in choosing the appropriate medication among the wide variety of antiarrhythmic drugs available.

Recurrent ventricular tachycardia among survivors of myocardial infarction with an implantable cardioverter-defibrillator (ICD) is frequent despite antiarrhythmic drug therapy. The most effective approach to management of this problem is uncertain.We conducted a multicenter, randomized, controlled trial involving patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite the use of antiarrhythmic drugs. Patients were randomly assigned to receive either catheter ablation (ablation group) with continuation of baseline antiarrhythmic medications or escalated antiarrhythmic drug therapy (escalated-therapy group). In the escalated-therapy group, amiodarone was initiated if another agent had been used previously. The dose of amiodarone was increased if it had been less than 300 mg per day or mexiletine was added if the dose was already at least 300 mg per day. The primary outcome was a composite of death, three or more documented episodes of ventricular tachycardia within 24 hours (ventricular tachycardia storm), or appropriate ICD shock.Of the 259 patients who were enrolled, 132 were assigned to the ablation group and 127 to the escalated-therapy group. During a mean (±SD) of 27.9±17.1 months of follow-up, the primary outcome occurred in 59.1% of patients in the ablation group and 68.5% of those in the escalated-therapy group (hazard ratio in the ablation group, 0.72; 95% confidence interval, 0.53 to 0.98; P=0.04). There was no significant between-group difference in mortality. There were two cardiac perforations and three cases of major bleeding in the ablation group and two deaths from pulmonary toxic effects and one from hepatic dysfunction in the escalated-therapy group.In patients with ischemic cardiomyopathy and an ICD who had ventricular tachycardia despite antiarrhythmic drug therapy, there was a significantly lower rate of the composite primary outcome of death, ventricular tachycardia storm, or appropriate ICD shock among patients undergoing catheter ablation than among those receiving an escalation in antiarrhythmic drug therapy. (Funded by the Canadian Institutes of Health Research and others; VANISH ClinicalTrials.gov number, NCT00905853.).

Background The BRUISE CONTROL trial (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial) demonstrated that a strategy of continued warfarin during cardiac implantable electronic device surgery was safe and reduced the incidence of clinically significant pocket hematoma (CSH). CSH was defined as a post-procedure hematoma requiring further surgery and/or resulting in prolongation of hospitalization of at least 24 h, and/or requiring interruption of anticoagulation. Previous studies have inconsistently associated hematoma with the subsequent development of device infection; reasons include the retrospective nature of many studies, lack of endpoint adjudication, and differing subjective definitions of hematoma. Objectives The BRUISE CONTROL INFECTION (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial Extended Follow-Up for Infection) prospectively examined the association between CSH and subsequent device infection. Methods The study included 659 patients with a primary outcome of device-related infection requiring hospitalization, defined as 1 or more of the following: pocket infection; endocarditis; and bloodstream infection. Outcomes were verified by a blinded adjudication committee. Multivariable analysis was performed to identify predictors of infection. Results The overall 1-year device-related infection rate was 2.4% (16 of 659). Infection occurred in 11% of patients (7 of 66) with previous CSH and in 1.5% (9 of 593) without CSH. CSH was the only independent predictor and was associated with a >7-fold increased risk of infection (hazard ratio: 7.7; 95% confidence interval: 2.9 to 20.5; p Conclusions CSH is associated with a significantly increased risk of infection requiring hospitalization within 1 year following cardiac implantable electronic device surgery. Strategies aimed at reducing hematomas may decrease the long-term risk of infection. (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial [BRUISE CONTROL]; NCT00800137 )

Key Points Question What is the association between preablation atrial fibrillation (AF) episode duration and arrhythmia recurrence outcomes following AF ablation? Findings In this prespecified subanalysis of a randomized clinical trial of 346 patients with symptomatic AF undergoing catheter ablation, patients with AF episodes limited to less than 24 continuous hours had a significantly lower rate of recurrence following an ablation procedure. Arrhythmia recurrence and AF burden after ablation did not differ between patients with persistent AF (episodes lasting >7 days) and those with paroxysmal AF (episodes lasting 24 to 48 hours or 2 to 7 days). Meaning The findings of this study suggest that the contemporary definition of paroxysmal AF does not reflect post-AF ablation arrhythmia outcomes., This secondary analysis of a randomized clinical trial evaluates the association of baseline atrial fibrillation episode duration with post–atrial fibrillation ablation arrhythmia outcomes., Importance Contemporary guidelines recommend that atrial fibrillation (AF) be classified based on episode duration, with these categories forming the basis of therapeutic recommendations. While pragmatic, these classifications are not based on pathophysiologic processes and may not reflect clinical outcomes. Objective To evaluate the association of baseline AF episode duration with post-AF ablation arrhythmia outcomes. Design, Setting, and Participants The current study is a secondary analysis of a prospective, parallel-group, multicenter, single-masked randomized clinical trial (the Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE] study), which took place at 8 Canadian centers. Between September 2014 and July 2017, 346 patients older than 18 years with symptomatic AF referred for first catheter ablation were enrolled. All patients received an implantable cardiac monitor at least 30 days before ablation. Data analysis was performed in September 2019. Exposure Before ablation, patients were classified based on their longest AF episode. Ablation consisted of circumferential pulmonary vein isolation using standard techniques. Main Outcomes and Measures Time to first recurrence of symptomatic or asymptomatic atrial tachyarrhythmia (AF, atrial flutter, or atrial tachycardia) following ablation and AF burden (percentage of time in AF) on preablation and postablation continuous rhythm monitoring. Results The study included 346 patients (mean [SD] age, 59 [10] years; 231 [67.7%] men). Overall, 263 patients (76.0%) had AF episode duration of less than 24 hours; 25 (7.2%), 24 to 48 hours; 40 (11.7%), 2 to 7 days; and 18 (5.2%), more than 7 days. Documented recurrence of any atrial tachyarrhythmia following ablation was significantly lower in patients with baseline AF episode duration of less than 24 continuous hours compared with those with longer AF episodes (24 hours vs 24-48 hours: hazard ratio [HR], 0.41; 95% CI, 0.21-0.80; P = .009; 24 hours vs 2-7 days: HR, 0.25; 95% CI, 0.14-0.45; P 7 days: HR, 0.23; 95% CI, 0.09-0.55; P

Introduction Chronic anticoagulation is recommended for patients with AF and additional stroke risk factors, even during long periods of sinus rhythm. Continuous rhythm assessment with an insertable cardiac monitor (ICM) and use of rapid onset novel oral anticoagulants (NOACs) allow for targeted anticoagulation only around an AF episode, potentially reducing bleeding complications without compromising stroke risk. Methods This multicenter, single-arm study enrolled patients on NOAC with nonpermanent AF and CHADS2 score 1 or 2. After a 60-day run-in with no AF episodes ≥ 1 hour, NOACs were discontinued but reinitiated for 30 days following any AF episode ≥ 1 hour diagnosed through daily ICM transmissions. Major endpoints included time on NOAC, stroke, and bleeding. Results Among 59 enrollees, 75% were male, age 67 ± 8 years, 76% paroxysmal AF, 69% had prior AF ablation, and mean CHADS2 score 1.3 ± 0.5. Over 466 ± 131 mean days of follow-up there were 24,004 ICM transmissions with a compliance rate of 98.7%. A total of 35 AF episodes ≥ 1 hour occurred in 18 (31%) patients, resulting in a total time on NOAC of 1,472 days. This represents a 94% reduction in the time on NOAC compared to chronic anticoagulation. There were three traumatic bleeds (all on aspirin), three potential transient ischemic attacks (all on aspirin with CHADS2 score of 1), and no strokes or deaths. Conclusions A targeted strategy of ICM-guided intermittent NOAC administration is feasible. A large-scale trial is necessary to evaluate the safety of this approach.