New-Onset Atrial Fibrillation During ST-Segment-Elevation Myocardial Infarction: Risk of Recurrence and Its Clinical Impact During 10 Years of Follow-Up.

Background: Atrial fibrillation (AF) often complicates ST-segment-elevation myocardial infarction (STEMI), but data on AF recurrence after first-ever AF during STEMI are scarce. We aimed at assessing the risk of AF recurrence after first-ever transient AF during admission for STEMI.

Methods: We performed a single-center, register-based cohort study. Patients with STEMI discharged alive after primary percutaneous coronary intervention during 2007 to 2010 were followed until 2018. Clinical characteristics, date of AF diagnosis, and mortality status were retrieved from Swedish national registries. All ECGs recorded before, during, or after STEMI were reviewed. The primary end point was the first documented AF episode after discharge, and the secondary end point was mortality. The risk of AF during follow-up was calculated using the Fine-Gray subdistributional hazard model for AF and total mortality, regressed on prespecified clinical and demographic covariates. In patients with first-ever transient AF during STEMI, we looked for the factors associated with AF recurrence.

Results: Of 2120 patients discharged alive, 127 (5.9%) had AF during admission for STEMI. Patients with AF during STEMI were more likely to develop AF during follow-up (hazard ratio [HR], 4.82 [95% CI, 3.86-6.02]; P<0.001), with 28% AF recurrence by 1 year. Compared with no AF, patients with AF during STEMI had a higher risk of death (HR, 1.17 [95% CI, 1.01-1.35]; P=0.033). No clinical or demographic characteristics predicted recurrent AF during follow-up. Low P-wave voltage in lead I at predischarge electrocardiography was independently associated with recurrent AF during follow-up (HR, 2.39 [95% CI, 1.23-4.62]; P=0.010).

Conclusions: Transient AF during STEMI is associated with an increased risk of AF after discharge and long-term mortality.