The association between subclinical atrial fibrillation (SCAF) and heart failure (HF) remains uncertain despite the established link between HF and clinical atrial fibrillation. A secondary analysis of the ARTESiA (Apixaban for the Reduction of Thromboembolism in Patients with Device-Detected Subclinical Atrial Fibrillation) trial evaluated HF event rates and their relationship with SCAF characteristics in patients with device-detected arrhythmia.

The study, published in the European Journal of Heart Failure, included 3,986 patients from ARTESiA, which compared apixaban with aspirin for stroke prevention in individuals with SCAF episodes lasting 24 hours or less. Baseline episode frequency and duration were examined in relation to HF hospitalization or HF-related death. Progression of SCAF was defined as the occurrence of episodes exceeding 24 hours or transition to clinical atrial fibrillation (AF). This progression variable was incorporated as a time-dependent factor in the analysis.

During a mean follow-up of 4.1 ± 1.7 years, SCAF progression occurred in 1,244 patients, representing 31% of the cohort. HF hospitalization or HF-related death was recorded in 515 patients, corresponding to 13% of the population and an incidence rate of 3.3 events per 100 person-years, with a 95% confidence interval (CI) of 3.1 to 3.6. Among these outcomes, 172 HF-related events occurred after documented progression of SCAF, with a rate of 7.2 events per 100 person-years (95% CI 6.2 to 8.3).

Progression of SCAF was identified as an independent risk factor for HF hospitalization or HF-related death, with a hazard ratio of 2.72 (95% CI 2.24 to 3.31). In contrast, episodes limited to 24 hours or less did not show an association with HF events.

HF-related outcomes were observed frequently during follow-up. Risk differed according to progression to longer SCAF episodes or clinical AF.