Catheter Ablation for atrial fibrillation (AF) is an is an established treatment strategy. Several studies have shown that catheter ablation has significant effects in restoring sinus rhythm in AF. The recently published randomized controlled CASTLE AF trial demonstrated that AF ablation in patients with symptomatic heart failure improves quality of life and functional status with a beneficial effect on overall mortality and heart failure associated hospitalization compared to medical therapy. Aim of the CABANA (Catheter Ablation vs. Antiarrhythmic Drug Therapy for Atrial Fibrillation) trial is to evaluate if catheter ablation has similar benefits in a general population suffering from symptomatic AF compared to medical therapy.
The CABANA trial is an investigator-led, prospective, multicenter, randomized, open-label clinical trial to evaluate the efficacy of catheter ablation in preventing or reducing the risks for disabling stroke, serious bleeding, or cardiac arrest (primary endpoint)in patients suffering from AF compared to medical therapy using antiarrhythmic drugs. It randomized 2204 patients with AF to either catheter ablation or medical therapy.
After a follow up of 12 months, patients in the catheter ablation group did not show a reduction for death, disabling stroke, serious bleeding, or cardiac arrest (primary endpoint) with 8.0% in the catheter ablation group versus 9.2% in the medical therapy group.
For secondary end-points, the outcome in patients that underwent ablation versus medical therapy was 5.2% vs. 6.1% for all-cause mortality (p = 0.38), 51.7% vs. 58.1% for a composite of death or cardiovascular hospitalization (p <0.01), which was mainly driven by reduction in cardiovascular hospitalizationand 49.9% vs. 69.5% for AF recurrence (p < 0.001).
Notably, more than a quarter of patients in the medical therapy group (301/1096 [27.5%])underwent ablation and about 9% (102/1108 [9.2%]) of patients randomized to the ablation group did not undergo ablation and only received medical therapy instead.
In a “treatment- received” analysis comparing results not “per-protocol” but “as treated”, ablation showed an advantage over medical therapy with a relative reduction for the primary outcome of 23% in patient undergoing ablation and a 32% relative reduction in overall mortality.
SOURCE:
Packer DL, Mark DB, Robb RA, et al. Effect of catheter ablation vs antiarrhythmic drug therapy on mortality, stroke, bleeding, and cardiac arrest among patients with atrial fibrillation: the CABANA randomized clinical trial. JAMA. 2019;Epub ahead of print.
Pro vs. Contra Discussion
Ablation of atrial fibrillation reduces mortality and morbidity!
COMPLIMENTS
CABANA is the first randomized trial comparing catheter ablation and medical therapy for the primary endpoints death, disabling stroke, serious bleeding, or cardiac arrest in a large cohort of patients suffering from atrial fibrillation. Without disregarding the results from the “per protocol” analysis ablation significantly reduced the composite endpoint of mortality or cardiovascular hospitalizations compared to medical therapy.
The above stated message is driven by the results of the as-treated analysis, demonstrating that when patients actually received ablation, there was a 33% reduction for the primary endpoint and a 40% mortality risk reduction compared to medical therapy.
CRITICISM
The use of catheter ablation showed no significant effect in preventing strokes, bleeding complications, cardiac arrests and mortality in patients with atrial fibrillation when compared to the use of antiarrhythmic drugs!
The estimated event rate for the primary endpoint prior to the trial with 10% in the ablation group and 15% in the medical therapy group were clearly overestimated in that specific study cohort (CABANA showed an event rate of 5.2% (ablation group) and 6.1% (medical therapy group)).An additional high cross-over rate between groups dumped the study`s statistical power. Furthermore an “as treated” analysis is not acceptable in arandomized, controlled trial, since it is inconsistent with randomization and violates the intention to treat principle and therefore can not be accepted as evidence for efficacy.
