Atrial Fibrillation Burden at 6 Months Better Predictor Than 30-Second Atrial Fibrillation Recurrence

Stethoscope on an electrocardiogram, very shallow depth of field. Doctor and patient in the background
The study authors analyzed the association of atrial fibrillation recurrence with heart failure, atrial fibrillation burden, and clinical outcomes in HF patients with AF.

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.

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.