ACCEL
Catheter Ablation for Atrial Fibrillation: Results of CABANA
April 01, 2019.David J. Wilber, MD, FACC, Maywood, IL
Educational Objectives
After completing the activity, the clinician will be better able to summarize the results of the CABANA trial comparing catheter ablation with antiarrhythmic drug therapy for atrial fibrillation, and state issues influencing the interpretation of the study results.
Summary
Interviewer: Spencer B. King III, MD, MACC
Take-home Messages:
- The CABANA trial compared catheter ablation with antiarrhythmic drug therapy for treating atrial fibrillation (AF).
- Ablation did not produce a significant reduction in the primary endpoint or in all-cause mortality, but the results were affected by crossovers (in both directions) and lower-than-expected event rates. Ablation did significantly reduce the combination of mortality or cardiovascular (CV) hospitalization compared to drug therapy.
- While there are concerns regarding the findings, the CABANA trial confirms that ablation is safe and effective across a broad range of patients and clinical presentations.
A recent consensus document on catheter and surgical ablation for atrial fibrillation offered several reasons AF has become a critical problem.1 In the United States alone, between 3 and 5 million people have AF, which increases risk of stroke by an average of 5-fold. In general, those strokes are more severe than those not related to AF. Plus, AF increases mortality and has been linked to an increased risk of sudden death.
As if that were not bad enough, AF increases the risk of heart failure, and recent studies have linked AF with the development of dementia.
Ablation
The goals of ablation have been to reduce or eliminate episodes of arrhythmia (fatigue and decreased exercise tolerance are common with persistent AF), improve quality of life (QOL), and reduce the incidence of all those long-term adverse events — not to mention all the hospitalizations and healthcare utilization attributed to treating patients with AF. And, perhaps, to retard or reverse progression.
When to ablate? Consensus is that the longer the delay to intervention, the more extensive (and repeated) the ablation, the poorer the outcomes, and the shorter the duration of postablation sinus rhythm.1 The best outcomes are associated with ablation within 3 months of developing continuous AF. Conversely, outcomes are very poor once continuous AF has gone on unimpeded for 3 to 5 years.
How can outcomes be improved? At the 2018 New York Cardiovascular Seminar, David Wilber, MD (Loyola University Medical Center), offered some suggestions. He noted that better pulmonary vein isolation helps — meaning wider extension, more durable lesions (through contact force and stability), the assessment of dormant/latent conduction, and enhanced tools to track lesion quality during energy delivery. Also, it is important to target AF drivers outside the pulmonary veins (fibrosis and scar, mapping during AF, using catecholamine to detect provocable triggers, or focus on the left atrial appendage).
Coping with CABANA
Given all this, there has been great interest in CABANA, the Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation trial.2
The December 2018 issue of ACCEL featured an interview with Jeanne Poole, MD, who presented initial CABANA results at ESC.18. The data have not been published yet, but presented data (including at the Heart Rhythm Society meeting in May 2018; Table) present a mixed message.
CABANA: Primary and Secondary Outcomes as Randomized (ITT)
|
| Ablation | Drug | Hazard Ratio | p Value |
| Primary Endpoint* | 8.0% | 9.2% | 0.86 | 0.30 |
| Secondary Outcomes | ||||
| All-cause mortality | 5.2% | 6.1% | 0.85 | 0.38 |
| Death or CV hospitalization | 51.7% | 58.1% | 0.83 | 0.002 |
*Composite of death, disabling stroke, major bleeding, cardiac arrest.
CI = confidence interval; CV = cardiovascular; ITT = intention to treat.
A total of 2,204 symptomatic patients with paroxysmal or persistent AF were randomized to percutaneous left atrial catheter ablation or state-of-the-art medical therapy. After a median follow-up of 48.5 months, ablation was associated with a nonsignificant 14% reduction (p = 0.30) in the primary endpoint (a composite of death, disabling stroke, serious bleeding, or cardiac arrest) using intention-to-treat analysis.
All-cause mortality was a secondary endpoint and, again, ablation was associated with a nonsignificant 15% reduction on an intention-to-treat basis (p = 0.377). However, when analyzed by treatment received and per protocol, there were significant benefits of ablation for both the primary endpoint and for mortality.
Ablation also produced a highly significant and sustained reduction in recurrent AF compared to drug therapy, as well as significant improvements in QOL.
However, in the December 2018 ACCEL, the essay accompanying the Poole interview included some reservations about the trial expressed by Milton Packer, MD (Baylor University Medical Center), who noted that the primary treatment effect in CABANA was affected by treatment crossovers and lower-than-expected event rates, which should be considered when interpreting the results.
Dr. Packer’s take-away: catheter ablation may be a reasonable choice for patients with distressing symptoms of AF, particularly of recent onset, or if patients have not responded to or would like to avoid antiarrhythmic therapy. Also, he added, “There is no clear or unbiased evidence that catheter ablation prevents any of the serious consequences of atrial fibrillation (death, stroke, or heart failure) in patients at high risk of cardiovascular events.”
Loyola was a top enrollment site for CABANA. According to Dr. Wilber, the study confirms that ablation is safe and effective across a broad range of patients and clinical presentations in providing sustained reductions in AF recurrences and improved QOL. And there is now evidence that ablation may favorably influence other long-term therapeutic goals, including cardiovascular hospitalizations and mortality.
Readings
1. Calkins H, Hindricks G, Cappato R, et al. 2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation. Heart Rhythm 2017;14:e275-e444.
2. Packer DL, Mark DB, Robb RA, et al. Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation (CABANA) Trial: Study Rationale and Design. Am Heart J 2018;199:192-9.
Disclosures
David J. Wilber, MD, FACC, Maywood, IL
Biosense Webster Inc (C); Medtronic (C); Thermedical Inc (D); Abbott (G); SentreHEART Inc (G)
Interviewer: Spencer B. King III, MD, MACC
Abbot (D); Baim (D); CeloNova VioSciences Inc (C); Capricor Therapeutics (D); Cardiovascular Research Foundation Duke University (D); International Society for Cardiovascular Translational Research (C); AtriCure Inc (C); Rockefeller Philanthropy Advisors (C); Harvard Clinical Research Institute – TRYTON Study (D); Merck & Co Inc (D); Mount Sinai School of Medicine (D); Stentys SA (D); Pfizer Inc (D)
Acknowledgements
CME/CE INFO
Accreditation:
The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.
The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.
Lecture ID:
AC510409
Expiration:
This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.
Instructions:
To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.
Estimated time to complete this CME/CE course:
Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.
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