Patients with heart failure (HF) and high atrial fibrillation (AF) burden at 6 months were associated with hard clinical outcomes. These findings, from a subanalysis, were published in the Journal of the American College of Cardiologists: Clinical Electrophysiology.

The Catheter Ablation vs Standard Conventional Treatment in Patients With LV Dysfunction and AF (CASTLE-AF) study was of a multicenter prospective controlled design. Patients (N=280) with HF, AF, and a Biotronik implantable cardioverter-defibrillator device were randomized to receive pulmonary vein ablation (n=128) or pharmacotherapy (n=152). Follow-up occurred at 3 and 6 months, then yearly up to 5 years for arrhythmia, HF hospitalization, and mortality.

Patients who received ablation or pharmacotherapy were aged median 63 (interquartile range [IQR], 55-69) and 65 (IQR, 57-74) years (P =.028), 88% and 85% were men, 51.6% and 47.3% had an AF burden of <50%, 34% and 54% had ischemic HF (P =.001), 23% and 36% had a history of myocardial infarction (P =.021), and 19% and 29% were taking digitalis (P =.047), respectively.

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Recurrence of AF at 30 seconds was not associated with treatment (ablation: hazard ratio [HR], 1.82; 95% CI, 0.73-4.50; P =.196; pharmacotherapy: HR, 1.34; 95% CI, 0.76-2.37; P =.306). After first AF recurrence, no association with mortality was observed (ablation: HR, 7.76; 95% CI, 0.86-8.783; P =.086; pharmacotherapy: HR, 1.49; 95% CI, 0.73-3.02; P =.271).

Among all patients, AF burden had a bimodal distribution, with peaks near 0% and 100%. Baseline AF burden <50% did not associate with arrhythmia (HR, 1.16; 95% CI, 0.76-1.76; P =.473), mortality (HR, 1.26; 95% CI, 0.69-2.29; P =.446), or HF hospitalization (HR, 1.02; 95% CI, 0.65-1.61; P =.932).

At 6 months, patients who received ablation had less AF burden (mean, 52.4%±7.4% vs 15.7%±5.4%; P <.001), which corresponded with a decreased burden of -32.5% (95% CI, -40.8% to -24.3%; P <.001) at 6 months among the ablation cohort. In contrast, the change in HF burden was 0.3% (95% CI, -4.6% to 5.2%; P =.913) among the pharmacotherapy recipients.

Among patients who had AF burden of <50% at 6 months, they had lower risk for arrhythmia (HR, 0.33; 95% CI, 0.15-0.71; P =.014) and all-cause mortality (HR, 0.23; 95% CI, 0.07-0.71; P =.031).

This study was biased by its skewed baseline cohort differences and had limited power as its purpose was exploratory and hypothesis-generating.

These data indicated 30-second AF recurrence was not a clinically relevant predictor. AF burden at 6 months was associated with mortality and arrhythmia risk.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of authors’ disclosures.


Brachmann J, Sohns C, Andresen D, et al. Atrial fibrillation burden and clinical outcomes in heart failure: the CASTLE-AF trial. JACC Clin Electrophysiol. 2021;S2405-500X(20)31208-1. doi:10.1016/j.jacep.2020.11.021.