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BARCELONA -- Catheter ablation for atrial fibrillation (Afib) was better than drugs at protecting patients with heart failure from death and hospitalization, according to results of the CASTLE-AF trial presented here.

The trial randomized Afib patients with left ventricular (LV) ejection fractions at 35% or below to ablation (n=179) or conventional therapy (n=184), reported Nassir Marrouche, MD, of the University of Utah at Salt Lake City, and colleagues at the (ESC) meeting.

Combined mortality and worsening heart failure admissions rates favored the ablation group after 5 years (28.5% versus 44.6% for controls, HR 0.62, 95% CI 0.43-0.87). A significant difference between therapies was preserved when all-cause mortality (13.4% versus 25%, HR 0.53, 95% CI 0.32-0.86) and heart failure hospitalization (20.7% versus 35.9%, HR 0.56, 95% CI 0.37-0.83) were analyzed individually.

Marrouche's group included patients mostly intolerant to or unwilling to take anti-arrhythmic drugs, leaving just under one-third of their group on amiodarone (Cordarone) and the like. Both arms of the trial were largely on ACE inhibitors, beta blockers, diuretics, and/or anticoagulation on baseline.

Importantly, all participants also had an implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) already implanted. In a , Marrouche acknowledged that it was a limitation to CASTLE-AF that patients had to have these devices.

Another caveat: a run-in period with patients excluded before the final cohort was randomized. This can introduce bias, according to discussant Carina Blomström-Lundqvist, MD, PhD, of Uppsala University in Sweden, at the late-breaking trial ESC session.

She nevertheless called CASTLE-AF "highly relevant."

"It's time to offer Afib ablation procedures at an earlier stage in heart failure patients with Afib. But patient selection is important; that should reflect the populations included in this trial," Blomström-Lundqvist said. She described them as "healthier" patients -- being relatively young at a median age 64, over half in NYHA Class II, and a less than one-third having long-standing persistent Afib -- who are likely to tolerate catheter ablation.

The ablation group in the trial underwent with additional lesions made at the operator's discretion.

Effects of the procedure seemed long-lasting: Afib burden as captured by implanted device memory fell from 50% of the time to around 30% at 3 months post-ablation (though Afib burden crept up slightly again by the 5-year mark); and LV ejection fraction went up 8 absolute percentage points from baseline after ablation (versus 0 for the conventional therapy group, P=0.005).

On subgroup analysis, LV ejection fraction interacted with treatment type, giving patients with very low ejection fractions (under 25%) much better outcomes with ablation over conventional therapy (P=0.01).

"A significant number of patients undergoing the ablation treatment were still in normal rhythm at the end of the study," the investigators added. Blomström-Lundqvist said this was a notable surprise to her.

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