Prognostic Impact of Sinus Rhythm in Atrial Fibrillation Patients: Separating Rhythm Outcomes From Randomized Strategy Findings From the CABANA Trial.

BACKGROUND: Clinically detected atrial fibrillation (AF) is associated with a significant increase in mortality and other adverse cardiovascular events. Since the advent of effective methods for AF rhythm control, investigators have attempted to determine how much these adverse prognostic AF effects could be mitigated by the restoration of sinus rhythm (SR) and whether the method used mattered. METHODS: The CABANA trial (Catheter Ablation versus Antiarrhythmic Drug Therapy for Atrial Fibrillation) randomized 2204 AF patients to ablation versus drug therapy, of which 1240 patients were monitored in follow-up using the CABANA ECG rhythm monitoring system. To assess the prognostic benefits of SR, we performed a prespecified analysis using Cox survival modeling with heart rhythm as a time-dependent variable and randomized treatment group as a stratification factor. RESULTS: In the 1240 patient study cohort, 883 (71.2%) had documented AF at some point during their postblanking follow-up. Among the 883 patients, 671 (76.0%) experienced AF within the first year of postblanking follow-up, and 212 (24.0%) experienced their first AF after ≥1 year of postblanking follow-up. The primary CABANA end point (death, disabling stroke, serious bleeding, or cardiac arrest) occurred in 95 (10.8%) of the 883 patients with documented AF and in 29 (8.1%) of the 357 patients with no AF recorded during follow-up. In multivariable time-dependent analysis, the presence of SR (compared with non-SR) was associated with a significantly reduced risk of the primary end point (adjusted hazard ratio, 0.57 [95% CI, 0.38-0.85]; P=0.006; independent of treatment strategy [ablation versus drugs]). Corresponding results for all-cause mortality were adjusted hazard ratio of 0.59 [95% CI, 0.35-1.01]; P=0.053). CONCLUSIONS: In patients in the CABANA trial with detailed long-term rhythm follow-up, increased time in SR was associated with a clinically consequential decrease in mortality and other adverse prognostic events. The predictive value of SR was independent of the therapeutic approach responsible for reducing the burden of detectable AF. REGISTRATION: URL: https://clinicaltrials.gov; Unique Identifier: NCT00911508.

Regional differences in outcomes with ablation versus drug therapy for atrial fibrillation: Results from the CABANA trial.

BACKGROUND: The finding of unexpected variations in treatment benefits by geographic region in international clinical trials raises complex questions about the interpretation and generalizability of trial findings. We observed such geographical variations in outcome and in the effectiveness of atrial fibrillation (AF) ablation versus drug therapy in the Catheter Ablation vs Antiarrhythmic Drug Therapy for Atrial Fibrillation (CABANA) trial. This paper describes these differences and investigates potential causes. METHODS: The examination of treatment effects by geographic region was a prespecified analysis. CABANA enrolled patients from 10 countries, with 1,285 patients at 85 North American (NA) sites and 919 at 41 non-NA sites. The primary endpoint was a composite of death, disabling stroke, serious bleeding, or cardiac arrest. Death and first atrial fibrillation recurrence were secondary endpoints. RESULTS: At least 1 primary endpoint event occurred in 157 patients (12.2%) from NA and 33 (3.6%) from non-NA sites over a median 54.9 and 40.5 months of follow-up, respectively (NA/non-NA adjusted hazard ratio (HR) 2.18, 95% confidence interval (CI) 1.48-3.21, P < .001). In NA patients, 78 events occurred in the ablation and 79 in the drug arm, (HR 0.91, 95% CI 0.66, 1.24) while 11 and 22 events occurred in non-NA patients (HR 0.51, 95% CI 0.25,1.05, interaction P = .154). Death occurred in 53 ablation and 51 drug therapy patients in the NA group (HR 0.96, 95% CI 0.65,1.42) and in 5 ablation and 16 drug therapy patients in the non-NA group (HR 0.32, 95% CI 0.12,0.86, interaction P = .044). Adjusting for baseline regional differences or prognostic risk variables did not account for the regional differences in treatment effects. Atrial fibrillation recurrence was reduced by ablation in both regions (NA: HR 0.54, 95% CI 0.46, 0.63; non-NA: HR 0.44, 95% CI 0.30, 0.64, interaction P = .322). CONCLUSIONS: In CABANA, primary outcome events occurred significantly more often in the NA group but assignment to ablation significantly reduced all-cause mortality in the non-NA group only. These differences were not explained by regional variations in procedure effectiveness, safety, or patient characteristics. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0091150; https://clinicaltrials.gov/study/NCT00911508.

Repeat catheter ablation for atrial fibrillation.

Catheter ablation of atrial fibrillation (AF) is an established therapy that reduces AF burden, improves quality of life, and reduces the risks of cardiovascular outcomes. Although there are clear guidelines for the application of de novo catheter ablation, there is less evidence to guide recommendations for repeat catheter ablation in patients who experience recurrent AF. In this review, we examine the rationale for repeat ablation, mechanisms of recurrence, patient selection, optimal timing, and procedural strategies. We discuss additional important considerations, including treatment of comorbidities and risk factors, risk of complications, and effectiveness. Mechanisms of recurrent AF are often due to non-pulmonary vein (non-PV) triggers; however, there is insufficient evidence supporting the routine use of empiric lesion sets during repeat ablation. The emergence of pulsed field ablation may alter the safety and effectiveness of de novo and repeat ablation. Extrapolation of data from randomized trials of de novo ablation does not optimally inform efficacy in cases of redo ablation. Additional large, randomized controlled trials are needed to address important clinical questions regarding procedural strategies and timing of repeat ablation.

Colchicine for the Prevention of Recurrent Arrhythmia After Catheter Ablation of Atrial Fibrillation: Results of a Single-Center, Retrospective Study.

BACKGROUND: There is evidence to suggest that colchicine reduces the risk of recurrent atrial fibrillation (AF) after catheter ablation; however, the tolerability and safety of colchicine in routine practice is unknown. METHODS: Patients undergoing catheter ablation for AF who received colchicine after ablation were matched 1:1 to patients who did not by age, sex, and renal function. Recurrent AF was compared between groups categorically at 12 months and via propensity weighted Cox proportional hazards models with and without a 3-month blanking period. RESULTS: Overall, 180 patients (n = 90 colchicine and n = 90 matched controls) were followed for a median (Q1, Q3) of 10.3 (7.0, 12.0) months. Mean age was 65.3 ± 9.1 years, 33.9% were women, mean CHA2DS2-VASc score was 2.9 ± 1.5, and 51.1% had persistent AF. Most patients (70%) received colchicine 0.6 mg daily for a median of 30 days. In the colchicine group, 55 patients (61.1%) were receiving at least one known interacting medication with colchicine. After ablation, one patient required colchicine dose reduction and four patients required discontinuation. After adjusting for covariate imbalance using propensity weighting, no significant association between colchicine use and AF recurrence was identified (adjusted hazard ratio 0.94, 95% confidence interval [CI] 0.48-1.85; p = 0.853). No significant association was found between colchicine use and all-cause hospitalizations (adjusted odds ratio 0.74, 95% CI 0.28-1.96; p = 0.548). CONCLUSION: Despite the frequent presence of drug-drug interactions, a 30-day course of colchicine is well-tolerated after AF ablation; however, we did not observe any association between colchicine and lower rates of AF recurrence or hospitalization.

Use of Ripple mapping to enhance localization and ablation of outflow tract premature ventricular contractions.

INTRODUCTION: Accurate localization of septal outflow tract premature ventricular contractions (PVCs) is often difficult due to frequent mid-myocardial or protected origin. Compared with traditional activation mapping, CARTO Ripple mapping provides visualization of all captured electrogram data without assignment of a specific local activation time and thus may enhance PVC localization. METHODS: Electroanatomic maps for consecutive catheter ablation procedures for septal outflow tract PVCs (July 2018-December 2020) were analyzed. For each PVC, we identified the earliest local activation point (EA), defined by the point of maximal -dV/dt in a simultaneously recorded unipolar electrogram, and the earliest Ripple signal (ERS), defined as the earliest point at which three grouped simultaneous Ripple bars appeared in late diastole. Immediate success was defined as full suppression of the clinical PVC. RESULTS: Fifty-seven unique PVCs in 55 procedures were included. When ERS and EA were in the same chamber (RV, LV, or CS), the odds ratio for the successful procedure was 13.1 (95% confidence interval [CI] 2.2-79.9, p = .005). Discordance between sites was associated with a higher likelihood of needing multi-site ablation (odds ratio [OR] 7.9 [1.4-4.6; p = .020]). Median EA-ERS distance in successful versus unsuccessful cases was 4.6 mm (interquartile range 2.9-8.5) versus 12.5 mm (7.8-18.5); (p = .020). CONCLUSION: Greater EA-ERS concordance was associated with higher odds of single-site PVC suppression and successful septal outflow tract PVC ablation. Visualization of complex signals via automated Ripple mapping may offer rapid localization information complementary to local activation mapping for PVCs of mid-myocardial origin.

Effects of Ablation Versus Drug Therapy on Quality of Life by Sex in Atrial Fibrillation: Results From the CABANA Trial.

Background Women with atrial fibrillation (AF) demonstrate more AF-related symptoms and worse quality of life (QOL). Whether increased use of ablation in women reduces sex-related QOL differences is unknown. Sex-related outcomes for ablation versus drug therapy was a prespecified analysis in the CABANA (Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation) trial. Methods and Results Symptoms were assessed periodically over 60 months with the Mayo AF-Specific Symptom Inventory (MAFSI) frequency score, and QOL was assessed with the Atrial Fibrillation Effect on Quality of Life (AFEQT) summary and component scores. Women had lower baseline QOL scores than men (mean AFEQT scores 55.9 and 65.6, respectively). Ablation patients improved more than drug therapy patients with similar treatment effect by sex: AFEQT 12-month mean adjusted treatment difference in women 6.1 points (95% CI, 3.5-8.6) and men 4.9 points (95% CI, 3.0-6.9). Participants with baseline AFEQT summary scores <70 had greater QOL improvement, with a mean treatment difference at 12 months of 7.6 points for women (95% CI, 4.3-10.9) and 6.4 points for men (95% CI, 3.3-9.4). The mean adjusted difference in MAFSI frequency score between women randomized to ablation versus drug therapy at 12 months was -2.5 (95% CI, -3.4 to -1.6); for men, the difference was -1.3 (95% CI, -2.0 to -0.6). Conclusions Compared with drug therapy for AF, ablation resulted in more QOL improvement in both sexes, primarily driven by improvements in those with lower baseline QOL. Ablation did not eliminate the AF-related QOL gap between women and men. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00911508.

Cost-Effectiveness of Catheter Ablation Versus Antiarrhythmic Drug Therapy in Atrial Fibrillation: The CABANA Randomized Clinical Trial.

BACKGROUND: In the CABANA trial (Catheter Ablation vs Antiarrhythmic Drug Therapy for Atrial Fibrillation), catheter ablation did not significantly reduce the primary end point of death, disabling stroke, serious bleeding, or cardiac arrest compared with drug therapy by intention-to-treat, but did improve the quality of life and freedom from atrial fibrillation recurrence. In the heart failure subgroup, ablation improved both survival and quality of life. Cost-effectiveness was a prespecified CABANA secondary end point. METHODS: Medical resource use data were collected for all CABANA patients (N=2204). Costs for hospital-based care were assigned using prospectively collected bills from US patients (n=1171); physician and medication costs were assigned using the Medicare Fee Schedule and National Average Drug Acquisition Costs, respectively. Extrapolated life expectancies were estimated using age-based survival models. Quality-of-life adjustments were based on EQ-5D-based utilities measured during the trial. The primary outcome was the incremental cost-effectiveness ratio, comparing ablation with drug therapy on the basis of intention-to-treat, and assessed from the US health care sector perspective. RESULTS: Costs in the first 3 months averaged $20 794±SD 1069 higher with ablation compared with drug therapy. The cumulative within-trial 5-year cost difference was $19 245 (95% CI, $11 360-$27 170) and the lifetime mean cost difference was $15 516 (95% CI, -$2963 to $35,512) higher with ablation than with drug therapy. The drug therapy arm accrued an average of 12.5 life-years (LYs) and 10.7 quality-adjusted life-years (QALYs). For the ablation arm, the corresponding estimates were 12.6 LYs and 11.0 QALYs. The incremental cost-effectiveness ratio was $57 893 per QALY gained, with 75% of bootstrap replications yielding an incremental cost-effectiveness ratio <$100 000 per QALY gained. With no quality-of-life/utility adjustments, the incremental cost-effectiveness ratio was $183 318 per LY gained. CONCLUSIONS: Catheter ablation of atrial fibrillation was economically attractive compared with drug therapy in the CABANA Trial overall at present benchmarks for health care value in the United States on the basis of projected incremental QALYs but not LYs alone.

Influence of atrial fibrillation type on outcomes of ablation vs. drug therapy: results from CABANA.

AIMS: Influence of atrial fibrillation (AF) type on outcomes seen with catheter ablation vs. drug therapy is incompletely understood. This study assesses the impact of AF type on treatment outcomes in the Catheter Ablation vs. Antiarrhythmic Drug Therapy for Atrial Fibrillation Trial (CABANA). METHODS AND RESULTS: CABANA randomized 2204 patients ≥65 years old or <65 with at least one risk factor for stroke to catheter ablation or drug therapy. Of these, 946 (42.9%) had paroxysmal AF (PAF), 1042 (47.3%) had persistent AF (PersAF), and 215 (9.8%) had long-standing persistent AF (LSPAF) at baseline. The primary endpoint was a composite of death, disabling stroke, serious bleeding, or cardiac arrest. Symptoms were measured with the Mayo AF-Specific Symptom Inventory (MAFSI), and quality of life was measured with the Atrial Fibrillation Effect on Quality of Life (AFEQT). Comparisons are reported by intention to treat. Compared with drug therapy alone, catheter ablation produced a 19% relative risk reduction in the primary endpoint for PAF {adjusted hazard ratio [aHR]: 0.81 [95% confidence interval (CI): 0.50, 1.30]}, and a 17% relative reduction for PersAF (aHR: 0.83, 95% CI: 0.56, 1.22). For LSPAF, the ablation relative effect was a 7% reduction (aHR: 0.93, 95% CI: 0.36, 2.44). Ablation was more effective than drug therapy at reducing first AF recurrence in all AF types: by 51% for PAF (aHR: 0.49, 95% CI: 0.39, 0.62), by 47% for PersAF (aHR: 0.53, 95% CI: 0.43,0.65), and by 36% for LSPAF (aHR 0.64, 95% CI 0.41,1.00). Ablation was associated with greater improvement in symptoms, with the mean difference between groups in the MAFSI frequency score favouring ablation over 5 years of follow-up in all subgroups: PAF had a clinically significant -1.9-point difference (95% CI: -1.2 to -2.6); PersAF a -0.9 difference (95% CI: -0.2 to -1.6); LSPAF a clinically significant difference of -1.6 points (95% CI: -0.1 to -3.1). Ablation was also associated with greater improvement in quality of life in all subgroups, with the AFEQT overall score in PAF patients showing a clinically significant 5.3-point improvement (95% CI: 3.3 to 7.3) over drug therapy alone over 5 years of follow-up, PersAF a 1.7-point difference (95% CI: 0.0 to 3.7), and LSPAF a 3.1-point difference (95% CI: -1.6 to 7.8). CONCLUSION: Prognostic treatment effects of catheter ablation compared with drug therapy on the primary and major secondary clinical endpoints did not differ consequentially by AF subtype. With regard to decreases in AF recurrence and improving quality of life, ablation was more effective than drug therapy in all three AF type subgroups. CLINICALTRIALS.GOV IDENTIFIER: NCT00911508.

Acute echocardiographic and hemodynamic response to his-bundle pacing in patients with first-degree atrioventricular block.

BACKGROUND: Atrial pacing and right ventricular (RV) pacing are both associated with adverse outcomes among patients with first-degree atrioventricular block (1°AVB). His-bundle pacing (HBP) provides physiological activation of the ventricle and may be able to improve both atrioventricular (AV) and inter-ventricular synchrony in 1°AVB patients. This study evaluates the acute echocardiographic and hemodynamic effects of atrial, atrial-His-bundle sequential (AH), and atrial-ventricular (AV) sequential pacing in 1°AVB patients. METHODS: Patients with 1°AVB undergoing atrial fibrillation ablation were included. Following left atrial (LA) catheterization, patients underwent atrial, AH- and AV-sequential pacing. LA/left ventricular (LV) pressure and echocardiographic measurements during the pacing protocols were compared. RESULTS: Thirteen patients with 1°AVB (mean PR 221 ± 26 ms) were included. The PR interval was prolonged with atrial pacing compared to baseline (275 ± 73 ms, p = .005). LV ejection fraction (LVEF) was highest during atrial pacing (62 ± 11%), intermediate with AH-sequential pacing (59 ± 7%), and lowest with AV-sequential pacing (57 ± 12%) though these differences were not statistically significant. No significant differences were found in LA or LV mean pressures or LV dP/dT. LA and LV volumes, isovolumetric times, electromechanical delays, and global longitudinal strains were similar across pacing protocols. CONCLUSION: Despite pronounced PR prolongation, the acute effects of atrial pacing were not significantly different than AH- or AV-sequential pacing. Normalizing atrioventricular and/or inter-ventricular dyssynchrony did not result in acute improvements in cardiac output or loading conditions.

Leadless pacemaker implantation after lead extraction for cardiac implanted electronic device infection.

BACKGROUND: Cardiac implanted electronic device (CIED) pocket and systemic infection remain common complications with traditional CIEDs and are associated with high morbidity and mortality. Leadless pacemakers may be an attractive pacing alternative for many patients following complete hardware removal for a CIED infection by eliminating surgical pocket-related complications as well as lower risk of recurrent complications. OBJECTIVE: To describe use and outcomes associated with leadless pacemaker implantation following extraction of a CIED system due to infection. METHODS: Patient characteristics and postprocedural outcomes were described in patients who underwent leadless pacemaker implantation at Duke University Hospital between November 11, 2014 and November 18, 2019, following CIED infection and device extraction. Outcomes of interest included procedural complications, pacemaker syndrome, need for system revision, and recurrent infection. RESULTS: Among 39 patients, the mean age was 71 ± 17 years, 31% were women, and the most frequent primary pacing indication was complete heart block (64.1%) with 9 (23.1%) patients being pacemaker dependent at the time of Micra implantation. The primary organism implicated in the CIED infection was Staphylococcus aureus (43.6%). Nine of the 39 patients had a leadless pacemaker implanted before or on the same day as their extraction procedure, and the remaining 30 patients had a leadless pacemaker implanted after their extraction procedure. During follow-up (mean 24.8 ± 14.7 months) after leadless pacemaker implantation, there were a total of 3 major complications: 1 groin hematoma, 1 femoral arteriovenous fistula, and 1 case of pacemaker syndrome. No patients had evidence of recurrent CIED infection after leadless pacemaker implantation. CONCLUSIONS: Despite a prior CIED infection and an elevated risk of recurrent infection, there was no evidence of CIED infection with a mean follow up of over 2 years following leadless pacemaker implantation at or after CIED system removal. Larger studies with longer follow-up are required to determine if there is a long-term advantage to implanting a leadless pacemaker versus a traditional pacemaker following temporary pacing when needed during the periextraction period in patients with a prior CIED infection.

Association Between Age and Outcomes of Catheter Ablation Versus Medical Therapy for Atrial Fibrillation: Results From the CABANA Trial.

BACKGROUND: Observational data suggest that catheter ablation may be safe and effective to treat younger and older patients with atrial fibrillation. No large, randomized trial has examined this issue. This report describes outcomes according to age at entry in the CABANA trial (Catheter Ablation versus Antiarrhythmic Drug Therapy for Atrial Fibrillation). METHODS: Patients with atrial fibrillation ≥65 years of age, or <65 with ≥1 risk factor for stroke, were randomly assigned to catheter ablation versus drug therapy. The primary outcome was a composite of death, disabling stroke, serious bleeding, or cardiac arrest. Secondary outcomes included all-cause mortality, the composite of mortality or cardiovascular hospitalization, and recurrence of atrial fibrillation. Treatment effect estimates were adjusted for baseline covariables using proportional hazards regression models. RESULTS: Of 2204 patients randomly assigned in CABANA, 766 (34.8%) were <65 years of age, 1130 (51.3%) were 65 to 74 years of age, and 308 (14.0%) were ≥75 years of age. Catheter ablation was associated with a 43% reduction in the primary outcome for patients <65 years of age (adjusted hazard ratio [aHR], 0.57 [95% CI, 0.30-1.09]), a 21% reduction for 65 to 74 years of age (aHR, 0.79 [95% CI, 0.54-1.16]), and an indeterminate effect for age ≥75 years of age (aHR, 1.39 [95% CI, 0.75-2.58]). Four-year event rates for ablation versus drug therapy across age groups, respectively, were 3.2% versus 7.8%, 7.8% versus 9.6%, and 14.8% versus 9.0%. For every 10-year increase in age, the primary outcome aHR increased (ie, less favorable to ablation) an average of 27% (interaction P value=0.215). A similar pattern was seen with all-cause mortality: for every 10-year increase in age, the aHR increased an average of 46% (interaction P value=0.111). Atrial fibrillation recurrence rates were lower with ablation than with drug therapy across age subgroups (aHR 0.47, 0.58, and 0.49, respectively). Treatment-related complications were infrequent for both arms (<3%) regardless of age. CONCLUSIONS: We found age-based variations in clinical outcomes for catheter ablation compared with drug therapy, with the largest relative and absolute benefits of catheter ablation in younger patients. No prognostic benefits for ablation were seen in the oldest patients. No differences were found by age in treatment-related complications or in the relative effectiveness of catheter ablation in preventing recurrent atrial arrhythmias. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT00911508.

Safety of continuous left atrial phased-array intracardiac echocardiography during left atrial ablation for atrial fibrillation.

Background: Pulmonary vein (PV) isolation using radiofrequency ablation (RFA) to treat atrial fibrillation (AF) requires delivery of contiguous transmural lesions at the PV antra while avoiding injury to the esophagus. Continuous 2-dimensional phased-array intracardiac echocardiography (ICE) from within the left atrium (LA) can provide consistent high-resolution images of catheter tip contact and location during ablation. Objective: The purpose of this study was to compare near-term safety outcomes of therapeutic AF ablation with and without ICE imaging from within the LA. Methods: The study cohort included 590 consecutive patients undergoing RFA for AF including continuous ICE imaging during ablation from within either the right atrium (RA) or the LA. Subjects were followed prospectively, and periprocedural complications within 30 days were identified and recorded. Results: All subjects had RA ICE imaging to guide transseptal catheterization. Ultrasound imaging from both RA and LA was used in 243 (41.2%). Respectively, the LA vs RA only imaging cohorts were comparable with respect to age (median 64 [interquartile range 57.4-71.2] years vs 64 [56.2-70.6] years; P = .425); history of hypertension (64.0% vs 67.2%; P = .421); diabetes mellitus (23.1% vs 19.4%; P = .268); previous cerebrovascular accident/transient ischemic attack (10.8% vs 8.4%; P = .331); and AF type (P = .241). There were no significant differences in major complications within 30 days between the 2 cohorts (P = .649) and no identified cases of esophageal or phrenic nerve injury or PV stenosis. Conclusions: Routine continuous LA ICE imaging seems to be safe and holds potential to facilitate lesion delivery during RFA for AF.

Optimizing mechanically sensed atrial tracking in patients with atrioventricular-synchronous leadless pacemakers: A single-center experience.

BACKGROUND: Atrioventricular (AV)-synchronous single-chamber leadless pacing using a mechanical atrial sensing algorithm produced high AV synchrony in clinical trials, but clinical practice experience with these devices has not yet been described. OBJECTIVE: To describe pacing outcomes and programming changes with AV-synchronous leadless pacemakers in clinical practice. METHODS: Consecutive patients without persistent atrial fibrillation who received an AV-synchronous leadless pacemaker and completed follow-up between February 2020 and April 2021 were included. We evaluated tracking index (atrial mechanical sense followed by ventricular pace [AM-VP] divided by total VP), total AV synchrony (sum of AM-ventricular sense [AM-VS], AM-VP, and AV conduction mode switch), use of programming optimization, and improvement in AV synchrony after optimization. RESULTS: Fifty patients met the inclusion criteria. Mean age was 69 ± 16.8 years, 24 (48%) were women, 24 (48%) had complete heart block, and 17 (34%) required ≥50% pacing. Mean tracking index was 41% ± 34%. Thirty-five patients (70%) received ≥1 programming change. In 36 patients with 2 follow-up visits, tracking improved by +9% ± 28% (P value for improvement = .09) and +18% ± 19% (P = .02) among 15 patients with complete heart block. Average total AV synchrony increased from 89% [67%, 99%] to 93% [78%, 100%] in all patients (P = .22), from 86% [52%, 98%] to 97% [82%, 99%] in those with complete heart block (P = .04), and from 73% [52%, 80%] to 78% [70%, 85%] in those with ≥50% pacing (P = .09). CONCLUSION: In patients with AV-synchronous leadless pacemakers, programming changes are frequent and are associated with increased atrial tracking and increased AV synchrony in patients with complete heart block.

Ablation Versus Drug Therapy for Atrial Fibrillation in Racial and Ethnic Minorities.

BACKGROUND: Rhythm control strategies for atrial fibrillation (AF), including catheter ablation, are substantially underused in racial/ethnic minorities in North America. OBJECTIVES: This study sought to describe outcomes in the CABANA trial as a function of race/ethnicity. METHODS: CABANA randomized 2,204 symptomatic participants with AF to ablation or drug therapy including rate and/or rhythm control drugs. Only participants in North America were included in the present analysis, and participants were subgrouped as racial/ethnic minority or nonminority with the use of National Institutes of Health definitions. The primary endpoint was a composite of death, disabling stroke, serious bleeding, or cardiac arrest. RESULTS: Of 1,280 participants enrolled in CABANA in North America, 127 (9.9%) were racial and ethnic minorities. Compared with nonminorities, racial and ethnic minorities were younger with median age 65.6 versus 68.5 years, respectively, and had more symptomatic heart failure (37.0% vs 22.0%), hypertension (92.1% vs 76.8%, respectively), and ejection fraction <40% (20.8% vs 7.1%). Racial/ethnic minorities treated with ablation had a 68% relative reduction in the primary endpoint (adjusted hazard ratio [aHR]: 0.32; 95% confidence interval [CI]: 0.13-0.78) and a 72% relative reduction in all-cause mortality (aHR: 0.28; 95% CI: 0.10-0.79). Primary event rates in racial/ethnic minority and nonminority participants were similar in the ablation arm (4-year Kaplan-Meier event rates 12.3% vs 9.9%); however, racial and ethnic minorities randomized to drug therapy had a much higher event rate than nonminority participants (27.4% vs. 9.4%). CONCLUSION: Among racial or ethnic minorities enrolled in the North American CABANA cohort, catheter ablation significantly improved major clinical outcomes compared with drug therapy. These benefits, which were not seen in nonminority participants, appear to be due to worse outcomes with drug therapy. (Catheter Ablation vs Anti-arrhythmic Drug Therapy for Atrial Fibrillation Trial [CABANA]; NCT00911508).

High-Resolution Measurement of Local Activation Time Differences From Bipolar Electrogram Amplitude.

Localized changes in myocardial conduction velocity (CV) are pro-arrhythmic, but high-resolution mapping of local CV is not yet possible during clinical electrophysiology procedures. This is in part because measurement of local CV at small spatial scales (1 mm) requires accurate annotation of local activation time (LAT) differences with very high temporal resolution (≤1 ms), beyond that of standard clinical methods. We sought to develop a method for high-resolution measurement of LAT differences and validate against existing techniques. First, we use a simplified theoretical model to identify a quantitative relationship between the LAT difference of a pair of electrodes and the peak amplitude of the bipolar EGM measured between them. This allows LAT differences to be calculated from bipolar EGM peak amplitude, by a novel "Determination of EGM Latencies by Transformation of Amplitude" (DELTA) method. Next, we use simulated EGMs from a computational model to validate this method. With 1 kHz sampling, LAT differences less than 4 ms were more accurately measured with DELTA than by standard LAT annotation (mean error 3.8% vs. 22.9%). In a 1-dimensional and a 2-dimension model, CV calculations were more accurate using LAT differences found by the DELTA method than by standard LAT annotation (by unipolar dV/dt timing). DELTA-derived LAT differences were more accurate than standard LAT annotation in simulated complex fractionated EGMs from a model incorporating fibrosis. Finally, we validated the DELTA method in vivo using 18,740 bipolar EGMs recorded from the left atrium of 10 atrial fibrillation patients undergoing catheter ablation. Using clinical EGMs, there was agreement in LAT differences found by DELTA, standard LAT annotation, and unipolar waveform cross-correlation. These results demonstrate an underlying relationship between a bipolar EGM's peak amplitude and the activation time difference between its two electrodes. Our computational modeling and clinical results suggest this relationship can be leveraged clinically to improve measurement accuracy for small LAT differences, which may improve CV measurement at small spatial scales.

Treatment-Related Changes in Left Atrial Structure in Atrial Fibrillation: Findings From the CABANA Imaging Substudy.

[Figure: see text].

Ablation Versus Drug Therapy for Atrial Fibrillation in Heart Failure: Results From the CABANA Trial.

BACKGROUND: In patients with heart failure and atrial fibrillation (AF), several clinical trials have reported improved outcomes, including freedom from AF recurrence, quality of life, and survival, with catheter ablation. This article describes the treatment-related outcomes of the AF patients with heart failure enrolled in the CABANA trial (Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation). METHODS: The CABANA trial randomized 2204 patients with AF who were ≥65 years old or <65 years old with ≥1 risk factor for stroke at 126 sites to ablation with pulmonary vein isolation or drug therapy including rate or rhythm control drugs. Of these, 778 (35%) had New York Heart Association class >II at baseline and form the subject of this article. The CABANA trial's primary end point was a composite of death, disabling stroke, serious bleeding, or cardiac arrest. RESULTS: Of the 778 patients with heart failure enrolled in CABANA, 378 were assigned to ablation and 400 to drug therapy. Ejection fraction at baseline was available for 571 patients (73.0%), and 9.3% of these had an ejection fraction <40%, whereas 11.7% had ejection fractions between 40% and 50%. In the intention-to-treat analysis, the ablation arm had a 36% relative reduction in the primary composite end point (hazard ratio, 0.64 [95% CI, 0.41-0.99]) and a 43% relative reduction in all-cause mortality (hazard ratio, 0.57 [95% CI, 0.33-0.96]) compared with drug therapy alone over a median follow-up of 48.5 months. AF recurrence was decreased with ablation (hazard ratio, 0.56 [95% CI, 0.42-0.74]). The adjusted mean difference for the AFEQT (Atrial Fibrillation Effect on Quality of Life) summary score averaged over the entire 60-month follow-up was 5.0 points, favoring the ablation arm (95% CI, 2.5-7.4 points), and the MAFSI (Mayo Atrial Fibrillation-Specific Symptom Inventory) frequency score difference was -2.0 points, favoring ablation (95% CI, -2.9 to -1.2). CONCLUSIONS: In patients with AF enrolled in the CABANA trial who had clinically diagnosed stable heart failure at trial entry, catheter ablation produced clinically important improvements in survival, freedom from AF recurrence, and quality of life relative to drug therapy. These results, obtained in a cohort most of whom had preserved left ventricular function, require independent trial verification. Registration: URL: https://www.clinicaltrials.gov/ct2/show/NCT00911508; Unique identifier: NCT0091150.