AF confers excess risk for death after myocardial infarction
MedWire News: Atrial fibrillation (AF) is an independent risk factor for death in patients with myocardial infarction (MI), study findings indicate.
The risk was greatest in patients who developed AF more than 30 days post-MI, highlighting the need for continued follow-up after the index event, say Véronique Roger (Mayo Clinic, Rochester, Minnesota, USA) and co-authors in the journal Circulation.
The team used data from the Rochester Epidemiology Project to identify 3220 adults hospitalized for a first-ever MI between 1983 and 2007.
At the time of MI, 304 patients had a prior diagnosis of AF while 729 developed AF during a mean follow-up of 6.6 years. In the latter group, 218 cases were classified as "early" (occurring ≤2 days post-MI), 119 as "intermediate" (3-30 days) and 392 as "late" (>30 days).
The cumulative incidence of AF at 5 years post-MI was 19%, and the risk for AF did not change over the study period.
Roger and co-authors found that, after adjusting for clinical characteristics and heart failure, the presence of AF was associated with a large increase in overall mortality (hazard ratio [HR]=3.77).
Importantly, the excess risk for death differed markedly according to the timing of AF onset, with adjusted HRs of 1.46, 1.63, 1.81, and 2.58 for prior, early, intermediate, and late AF, respectively.
AF was also associated with an increased risk for cardiovascular death, with adjusted HRs of 1.55, 1.72, 1.94, and 2.70 for prior, early, intermediate, and late AF, respectively.
"AF after MI is associated with a large excess risk of death," write Roger et al. They add: "It has been suggested that the timing of AF onset may represent different mechanisms and, accordingly, may differentially influence outcomes."
In an accompanying editorial, Emelia Benjamin (Framingham Heart Study, Massachusetts, USA) and co-authors noted that the timeframes used to classify AF onset are "somewhat arbitrary" and also highlight the potential for residual confounding.
Nevertheless they said the study "serves as a reminder of the potential adverse consequences of AF in the setting of MI," and add: "Both clinicians and patients would be well-served by attempts to systematically assess the safety and effectiveness of strategies to prevent and manage AF in specific disease subsets."
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By Joanna Lyford