New-onset versus chronic atrial fibrillation in acute myocardial infarction: differences in short- and long-term follow-up

Atrial fibrillation (AF) occurs commonly in patients with acute myocardial infarction (AMI) and has been established as a marker of adverse prognosis. There are only few clinical trials that investigate differences between new-onset and chronic AF in AMI. We hypothesize that chronic AF is associated with an increased rate of adverse short- and long-term outcomes.

In a single center study, over a period of 28 months, 375 consecutive patients with AMI were included [337 patients without AF (89.9%) and 38 with AF (10.1%)]. As much as 16 patients had new-onset AF (42.1%) and 22 had chronic AF (57.9%). Patients with severe coronary artery disease develop AF more often in AMI, and the existence of AF was associated with a poor prognosis. Compared to patients with new-onset AF, chronic AF was more frequently associated with advanced age (75 vs. 70 years, p not significant), reduced left ventricular ejection fraction (44.8 vs. 54.0%, p < 0.05) and NSTEMI (63.6 vs. 36.4%, p < 0.05). Only chronic AF resulted in increased in-hospital death (18.2 vs. 0.0%; p < 0.005) at the 2-year follow-up, 14 patients with AF died (63.6%), predominantly due to cardiovascular reasons.

Our results indicate that patients with chronic AF had a higher incidence of in-hospital death than those with new-onset AF or without. Chronic AF includes a group of older and sicker patients than their counterparts with new-onset AF. Understanding these findings may ultimately lead to better care of patients with this arrhythmia to prevent the development of the underlying atrial substrate in chronic AF patients and to improve their otherwise worse prognosis.