Impact of new-onset atrial fibrillation in patients with ST-segment elevation myocardial infarction

New-onset atrial fibrillation (NOAF) complicating ST-segment elevation myocardial infarction (STEMI) remains clinically challenging. The aim of this study was to assess the incidence of NOAF, identify risk factors for the development of atrial fibrillation (AF), and analyze the impact on patient care, therapy, and outcomes during long-term follow-up.

This retrospective single-center study reviewed consecutive patients undergoing coronary angiography (CAG) for acute STEMI between May 2015 and September 2023. Patients were stratified in NOAF, defined as AF diagnosed during the index hospitalization or within 12 months of follow-up, AF prior to the hospitalization for STEMI, and patients with no AF.

We analyzed 1301 consecutive patients undergoing CAG for STEMI. NOAF was detected in 112 patients (9.8%), and 68 patients (5.2%) had prior AF. NOAF patients were 74% males, with a mean age of 69 ± 11 years. During a median follow-up of 683 days, the rates of stroke were 10% in patients with NOAF compared to 3.8% (p = 0.001) in patients without AF. Major bleeding occurred in 7% vs. 1.7%, p = 0.001, and death in 16% vs. 6.8%, p < 0.001 of patients with NOAF vs. no AF.

NOAF was detected in almost 1 out of 10 STEMI patients and was associated with a higher rate of stroke, major bleeding, and death as in patients with no AF and with similar rates compared with prior AF. Future studies assessing optimal anticoagulation therapy in this challenging patient population are warranted.