Background: Atrial fibrillation (AF) or flutter occurring after myocardial infarction may occur alone or in association with other complications. Whether the arrhythmia portends a poor prognosis independent of other complications with contemporary therapy is unknown.
Methods and results: As part of the Global Use of Strategies To Open occluded coronary arteries (GUSTO-III) trial, we evaluated whether postinfarction complications were associated with the subsequent development of AF and whether AF independently predicted death over periods of 30 days and 1 year. Information including exact timing was collected on deaths and major in-hospital postinfarction complications up to 30 days. Of the 13,858 patients with sinus rhythm at enrollment, 906 later had AF or flutter and 12, 952 did not. We compared outcomes between these 2 groups, adjusting for differences in baseline characteristics and prefibrillation complications. Worsening heart failure, hypotension, third-degree heart block, and ventricular fibrillation were independent predictors of new-onset AF. The unadjusted odds ratio (OR) for death among patients with versus those without AF was 2.74 (95% confidence interval [95% CI], 2.56-3.34). After adjusting for baseline differences, the OR was reduced to 1.63 (95% CI, 1.31-2.02). Adjustment for other in-hospital complications before the onset of AF further reduced the OR to 1.49 (95% CI, 1.17-1.89).
Conclusions: Atrial fibrillation or flutter occurs secondary to other postinfarction complications but independently portends a worse prognosis. Prevention and management may improve outcome.