Ablation Lessens Burden of Atrial Fib Along With Recurrence Risk: CABANA

June 24, 2020

A prespecified secondary analysis of the CABANA study has helped clarify how catheter ablation affects the risk and prevalence of any subsequent atrial fibrillation (AF) itself, not just the clinical end points that were the study's primary focus.

Catheter ablation in the randomized trial cut the risk for a first recurrence of AF, regardless of whether there were symptoms, by about half over 5 years, compared with antiarrhythmic drug (AAD) therapy, observes a new report.

Patients in the ablation group also benefited from more than a two-thirds decline in AF burden, compared with about a 40% decline for those in the AAD therapy group.

It may not be surprising that the overall burden drops after ablation of paroxysmal AF, which made up about 43% of the baseline arrhythmia in the analysis, "but it was also substantially reduced in the group with persistent AF," for whom good ablation results are sometimes elusive, Jeanne E. Poole, MD, University of Washington Medical Center, Seattle, told theheart.org | Medscape Cardiology.

"Regardless of the baseline pattern of atrial fibrillation, AF burden was significantly decreased in both. I think it's really important that, even for the persistent and longstanding-persistent AF patients, you may be able to significantly improve the overall frequency and duration of AF," said Poole, who is lead author on the analysis published June 22 in the Journal of the American College of Cardiology. "Presumably that would translate into feeling better, but we didn't look at that in this study."

The current analysis "confirms the clear benefit of catheter ablation versus pharmacological therapy in preventing recurrent AF in patients with symptomatic AF, and is important in being one the largest prospective studies to report on the benefit of catheter ablation on AF burden," observes an accompanying editorial.

"Clearly, a burden assessment should be part of the reporting standards for assessing efficacy of therapy in preventing AF recurrence," state the authors, led by Francis E. Marchlinski, MD, Hospital of the University of Pennsylvania, Philadelphia.

A focus on time to first recurrence may be clinically misleading. "The fact remains that most patients do not mind an infrequent, short-lived AF episode that does not require hospitalization or reinitiation of anticoagulation or antiarrhythmic drug therapy, or does not significantly limit their activity and quality of life," the group writes.

Ideally, the effect of therapy on AF burden would be assessed "only for the patients with AF recurrence, and compared with a baseline burden assessment for each individual patient." Inclusion of patients without recurrences would skew results for all patients, which "may actually obscure clinically meaningful burden differences in patients with definite AF recurrences," they argue.

In CABANA, researchers randomly assigned 2204 patients with symptomatic AF to undergo ablation or receive rate- or rhythm-control AAD therapy. Results showed a nonsignificant 14% relative reduction in the primary outcome of death, disabling stroke, serious bleeding, or cardiac arrest over an average of about 4 years by intention-to-treat. All-cause mortality also fell numerically with ablation, without reaching significance.

But ablation showed significant advantages in some secondary end points. In particular, as noted in the March 2019 primary CABANA report, there was a 48% reduction in AF recurrences at 48 months, compared with AAD therapy (< .001).

The current analysis — limited to the 1240 patients who used several prespecified types of monitors to document AF recurrence and burden, including ambulatory electrocardiography with transtelephonic monitoring and biannual Holter monitoring — expanded on that lone secondary finding.

Recurrence of AF in the 611 patients in the ablation group and 629 who were on AAD therapy, about a third of whom were women, was defined as AF of at least 30 seconds in duration after an initial 90-day blanking period.

Over a 60-month follow-up, the hazard ratio (HR) for a first recurrence in the ablation group vs those on AAD therapy was:

  • 0.52 (95% CI, 0.45 - 0.60; P < .001) for any symptomatic or asymptomatic AF

  • 0.49 (95% CI, 0.39 - 0.61; P < .001) for any symptomatic AF

  • 0.53 (95% CI, 0.46 - 0.62; P < .001) for the composite of AF, atrial flutter, or atrial tachycardia

The 48% AF burden at baseline Holter in both patient groups decreased significantly to reach:

  • 6.3% at 12 months and 14.7% at 5 years in the ablation group

  • 14.4% at 12 months and 20.8% at 5 years for those on AAD.

Differences in AF burden between the two groups were significant at P < .01 throughout the 5 years.

Because AF ablation is aimed at symptoms, "ideally, any burden assessment and defined reduction in burden would need to be accompanied by a report of symptom and quality-of-life improvement," the editorial states, "to help control for the marked intra-patient variability in the relationship between symptoms and AF burden."

Such data on symptoms were not provided but are expected in future reports, it continues. "We believe including this important information could have strengthened the presentation and emphasized its potential immediate clinical relevance."

CABANA was supported by St. Jude Medical, Biosense Webster, Medtronic, and Boston Scientific. Poole disclosed receiving research funding from ATriCure, Biotronik, Medtronic, and Kestra; serving on an advisory board for Boston Scientific; serving as a speaker for Boston Scientific, Medtronic, and MediaSphere Medical; and serving on a data and safety monitoring board for a study funded by EBR Systems. Disclosures for the other authors are in the report. Marchlinski discloses serving on an advisory board for Medtronic, Abbott, and Biosense Webster. Disclosures for the other editorialists are in the document.

J Am Coll Cardiol. Published June 22, 2020. Abstract, Editorial

HFA Discoveries 2020 from the Heart Failure Association (HFA) of the European Society of Cardiology.

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