Prognostic Significance of New-Onset Atrial Fibrillation Burden in Acute Myocardial Infarction Patients: A Comparison...

Acute myocardial infarction (AMI) with reduced or preserved left ventricular ejection fraction (LVEF) is associated with distinct prognoses and differing risk factor profiles. However, the use of new-onset atrial fibrillation (NOAF) burden in risk stratification of AMI patients, particularly across LVEF subgroups, remains unclear. We analyzed consecutive AMI patients without prior AF who developed their first in-hospital AF episode between 2014 and 2022. The patients were stratified by LVEF (AMIrEF: <40%; AMIpEF: ≥40%) and AF burden (>10.87% vs. ≤10.87%). The primary endpoint was a major adverse cardiovascular event (MACE), including cardiovascular death and heart failure hospitalization. Among 644 patients with LVEF data, 178 (27.6%) were AMIrEF and 466 (72.4%) were AMIpEF; 248 (38.5%) had a high AF burden. Over a median follow-up time of 4.2 years, the MACE incidence was 18.9 and 23.0 per 100 person-years in low- and high-burden AMIrEF patients, and 7.2 and 17.5 in AMIpEF patients, respectively. After multivariable adjustment, a high NOAF burden was significantly associated with increased MACE in AMIpEF patients [hazard ratio (HR): 2.63, 95% confidence interval (CI): 1.82-3.79], but not in AMIrEF patients [HR: 1.29, 95% CI: 0.79-2.10]. Propensity-matched analysis yielded concordant results [AMIrEF: 1.15 (0.69-1.90); AMIpEF: 2.45 (1.75-3.45)]. In conclusion, a high NOAF burden is strongly associated with adverse long-term cardiovascular outcomes in AMIpEF patients, highlighting its potential utility for risk stratification in this population.