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Arrhythmia2018New England Journal of Medicine

CASTLE-AF

Catheter Ablation versus Standard Conventional Therapy in Patients with Left Ventricular Dysfunction and Atrial Fibrillation

Sample Size
363
Study Design
Multicenter, randomized, controlled, open-label trial
Year Published
2018
Category
Arrhythmia

Clinical Question

Does catheter ablation for atrial fibrillation reduce mortality and heart failure hospitalizations compared to conventional medical therapy in patients with heart failure and reduced ejection fraction?

Population

Patients with symptomatic paroxysmal or persistent atrial fibrillation, NYHA class II-IV heart failure, LVEF ≤35%, and an implanted ICD or CRT-D device.

Intervention

Catheter ablation for atrial fibrillation (pulmonary vein isolation with additional lesions as needed)

Control

Conventional medical therapy (rate or rhythm control with antiarrhythmic drugs)

Primary Endpoint

Composite of all-cause mortality or worsening heart failure hospitalization

Key Findings

1

The primary composite endpoint occurred in 28.5% of ablation patients vs 44.6% of medical therapy patients (HR 0.62; 95% CI, 0.43-0.87; p=0.007).

2

All-cause mortality was 13.4% with ablation vs 25.0% with medical therapy (HR 0.53; 95% CI, 0.32-0.86; p=0.01).

3

Heart failure hospitalization was 20.7% with ablation vs 35.9% with medical therapy (HR 0.56; 95% CI, 0.37-0.83; p=0.004).

4

LVEF improved significantly more in the ablation group (+8.0% vs +0.2%; p=0.005).

5

Sinus rhythm maintenance at 60 months was 63.1% in the ablation group vs 21.7% in the medical therapy group.

Impact on Clinical Practice

CASTLE-AF was the first randomized trial to demonstrate a mortality benefit of catheter ablation for atrial fibrillation in any patient population. The 47% relative reduction in all-cause mortality was striking and exceeded expectations, establishing AF ablation as more than a symptomatic therapy. The trial provided compelling evidence that atrial fibrillation is not merely a bystander in heart failure but a driver of disease progression. By restoring sinus rhythm through ablation, patients experienced meaningful improvements in left ventricular function, fewer hospitalizations, and better survival. CASTLE-AF shifted the paradigm for AF management in heart failure patients from rate control (accepting the arrhythmia) to rhythm control through ablation. It provided the foundation for a proactive, intervention-oriented approach to AF in the heart failure population, where the consequences of ongoing arrhythmia are most severe.

Guideline Impact

CASTLE-AF contributed to the 2019 AHA/ACC/HRS Focused Update recommending catheter ablation for AF in patients with heart failure (Class IIb upgraded toward Class IIa). The 2020 ESC AF guidelines gave catheter ablation a Class IIa recommendation for patients with HFrEF to improve survival and reduce HF hospitalization.

Limitations

Relatively small sample size (363 patients) raises concerns about generalizability and the possibility of overestimating treatment effects.

Open-label design introduces potential bias in event detection and management decisions.

All patients had ICDs/CRT-Ds, which may limit applicability to the broader heart failure population without devices.

Callistus Ditah, MD
Reviewed by Callistus Ditah, MD
Surgery of the Aorta & Great Vessels

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