Catheter ablation superior to medical therapy for AF with heart failure

Catheter ablation of atrial fibrillation (AF) in patients with coexisting heart failure improves outcomes, including survival, compared with medical therapy of AF. The finding comes from a multicenter, open-label, randomized, controlled clinical trial known as Catheter Ablation versus Standard Conventional Therapy in Patients with Left Ventricular Dysfunction and Atrial Fibrillation (CASTLE-AF).

CASTLE-AF represents the first randomized controlled evidence that catheter ablation can improve hard endpoints such as survival and hospitalization for heart failure in patients with both AF and heart failure. Previous trials hinted at such an improvement through soft endpoints, such as left ventricular ejection fraction (LVEF) and maintenance of sinus rhythm.

In CASTLE-AF, 398 patients from 33 sites in Europe, Australia, and the United States were enrolled. Eligible patients were those with symptomatic paroxysmal or persistent AF who had not responded to antiarrhythmic drugs, had unacceptable side effects, or were unwilling to take those drugs.

All patients had New York Heart Association class II-IV heart failure, an LVEF of 35% or less, and an implanted defibrillator. In addition, all had an implantable defibrillator to facilitate detection of AF recurrence.

At the baseline evaluation, 363 patients remained in the trial and were randomized to undergo either catheter ablation (179 patients) or medical therapy for rate or rhythm control (184 patients). At enrollment, median age for both the ablation and medical therapy groups was 64 years; both groups were overwhelmingly male: 87% and 84%, respectively.

Ablation was performed to achieve isolation of all pulmonary veins and to restore sinus rhythm. Additional ablation lesions were made at the discretion of the experienced ablation operators, all of whom had performed at least 50 ablation procedures. After ablation, all patients received warfarin for at least 6 months; treatment thereafter was extended at the discretion of the treating physician.

Medical therapy for AF was administered in accordance with guidelines at the time of the trial. Efforts to maintain sinus rhythm were recommended. The aim of rate control treatment was a ventricular rate of 60 to 80 bpm at rest and 90 to 115 bpm during moderate exercise, which varied according to the patient’s age.

After a median follow-up of approximately 3 years, the composite primary endpoint—death from any cause or hospitalization for worsening heart failure—occurred in significantly fewer patients in the ablation group than in the medical-therapy group: 51 patients (28.5%) vs 82 patients (44.6%), corresponding to a hazard ratio of 0.62 (P=0.007). The number of patients who would need to be treated to prevent that primary endpoint at 36 months was 8.3.

The ablation group also experienced improvement in several secondary endpoints, including significant reductions in death from any cause (13.4% vs 25.0%; P=0.01); in cardiovascular death (11.2% vs 22.3%; P=0.009); in heart failure hospitalization (20.7% vs 35.9%; P=0.004); and in cardiovascular hospitalization (35.8% vs 48.4%; P=0.04).

Serious adverse events in the ablation group included three patients with pericardial effusion, one of whom required pericardiocentesis. Three patients had severe bleeding that required blood transfusion. Asymptomatic pulmonary vein stenosis was diagnosed in one patient at follow-up.

Review of the implanted devices showed that 63.1% of patients in the ablation arm and 21.7% randomized to medical therapy were in sinus rhythm at 60 months of follow-up (P < 0.001). Recurrence of AF in patients who had undergone the ablation procedure was 50.0% at 60 months, supporting a reduction in AF burden.

To read more about this study, click here.