Prevalence and Clinical Outcomes of Subclinical Atrial Fibrillation After Heart Failure Hospitalization.

BACKGROUND: Subclinical atrial fibrillation (SCAF) is common in older adults, but its clinical significance in heart failure (HF) patients remains unclear. We evaluated the prevalence of SCAF in patients hospitalized with HF without prior atrial fibrillation (AF) and examined its association with HF-related outcomes. METHODS: Hospitalized patients with a primary diagnosis of HF exacerbation without prior AF were prospectively recruited across 5 sites in Ontario, Canada. Participants were discharged home with 28-day continuous electrocardiogram monitoring to detect SCAF. The association between SCAF and HF readmission, cardiovascular death, and other HF-related outcomes at 1-year follow-up was determined using logistic regression models. RESULTS: Among 242 participants, the mean age was 70.9 ± 13.3 years; 51% were male; the mean body mass index was 31.6 ± 10.8 kg/m2; and the mean left ventricular ejection fraction was 42.3% ± 17.1%. SCAF was detected in 17 patients (7.1%), comprising 31 episodes with a median duration of 6.3 hours (interquartile range: 0.21-32.5). SCAF was associated with cardiovascular death (6 vs 28 events; adjusted odds ratio (aOR) 4.22 [95% confidence interval {CI}, 1.34-12.8]; P = 0.014) and progression to clinical AF (5 vs 14 events; aOR 8.26, [95% CI, 2.33-28.2]; P = 0.001), whereas a significant association was not observed with HF rehospitalization (4 vs 54 events; aOR 1.12 [95% CI, 0.32-3.31]; P = 0.85). CONCLUSIONS: In patients hospitalized with HF and no prior AF, SCAF was detected in approximately 1 in 14 individuals early after discharge and was associated with higher cardiovascular mortality and progression to clinical AF. No association with HF rehospitalization was observed, although the study may have been underpowered for this outcome. CLINICAL TRIAL REGISTRATION: NCT03541616.