Mortality associated with atrial fibrillation in patients with myocardial infarction: a systematic review and meta-analysis.

BACKGROUND: Atrial fibrillation (AF) is a common finding in patients with myocardial infarction (MI). Atrial fibrillation is not generally perceived by clinicians as a critical event during the acute phase of MI; however, its prognostic influence in MI remains controversial. Furthermore, contradictory data exist concerning the risk of death according to AF timing. This article, a systematic review and first meta-analysis, aims to quantify the mortality risk associated with AF in MI patients and its timing.

METHODS AND RESULTS: A comprehensive search of several electronic databases (1970 to 2010; adults, any language) identified MI studies that evaluated mortality related to AF. Evidence was reviewed by 2 blinded reviewers with a formal assessment of the methodological quality of the studies. Adjusted odds ratios were pooled across studies using the random-effects model. The I(2) statistic was used to assess heterogeneity. In the 43 included studies (278 854 subjects), the mortality odds ratio associated with AF was 1.46 (95% confidence interval, 1.35 to 1.58; I(2)=76%; 23 studies). This worse prognosis persisted regardless of the timing of AF; the odds ratio of mortality for new AF with no prior history of AF was 1.37 (95% confidence interval, 1.26 to 1.49), I(2)=28%, 9 studies), and for prior AF was 1.28 (95% confidence interval, 1.16 to 1.40; I(2)=24%; 4 studies). The sensitivity analysis of new AF studies adjusting for confounding factors did not show a decrease in risk of death.

CONCLUSIONS: Atrial fibrillation is associated with increased risk of mortality in MI patients. New AF with no history of AF before MI remained associated with an increased risk of mortality even after adjustment for several important AF risk factors. These subsequent increases in mortality suggest that AF can no longer be considered a nonsevere event during MI.