Long-term impact of the burden of new-onset atrial fibrillation in patients with acute myocardial infarction: results from the NOAFCAMI-SH registry.

AIMS  We aimed to investigate the prognostic impact of the burden of new-onset atrial fibrillation (NOAF) on long-term cardiovascular outcomes in patients with acute myocardial infarction (AMI). METHODS AND RESULTS  This retrospective analysis consecutively included patients without a documented atrial fibrillation (AF) history who admitted for AMI at Shanghai Tenth People's Hospital between February 2014 and March 2018. Atrial fibrillation burden was measured as the percentage of time spent in AF, and its optimal cut-off value of 10.87% was identified by X-tile software. Of 2399 patients (mean age: 65.8 years, 76.6% of men), 278 (11.6%) developed NOAF during hospitalization. During a median follow-up of 2.7 years, the incidence of all-cause death was 3.19, 9.00, and 17.41 per 100 person-years in the sinus rhythm (SR), low-burden (AF burden ≤ 10.87%), and high-burden (AF burden > 10.87%) groups, respectively. After adjustment for confounders, it was the high-burden NOAF [hazard ratio (HR): 1.94, 95% confidence interval (CI): 1.28-2.95] rather than the low-burden one (HR: 1.47, 95% CI: 0.97-2.21) that was significantly associated with increased mortality compared with SR. Concordant results were obtained in our propensity score-matched analyses [2.55 (1.57-4.16) and 1.32 (0.85-2.05) for high- and low-burden NOAF, respectively). In addition, post-myocardial infarction NOAF was associated with an increased risk of heart failure irrespective of its burden. Only those high-burden individuals were at heightened risk of ischaemic stroke. The restricted cubic spline curves illustrated a dose-response relationship of NOAF burden with outcomes. CONCLUSION In patients with NOAF complicating AMI, high AF burden was strongly associated with long-term outcomes.