Atrial Fibrillation and Incident Myocardial Infarction in the Elderly

BACKGROUND: Atrial fibrillation (AF) has been shown to be independently associated with an increased risk of myocardial infarction (MI) in a predominantly middle-aged population; however, this association has not been examined in older populations. HYPOTHESIS: AF is associated with MI in older adults. METHODS: A total of 4608 participants (85% white, 40% male) from the Cardiovascular Health Study without evidence of baseline coronary heart disease were included in this analysis. AF cases were identified during the yearly study electrocardiogram, a self-reported history of a physician diagnosis, or by hospitalization data. Incident MI was identified using medical records with local and central adjudication. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between AF and incident MI. RESULTS: A total of 434 (9.4%) participants had evidence of AF before incident MI. Over a median follow-up of 12.2 years, a total of 797 (17.3%) participants developed MI. In a multivariable Cox proportional hazards analysis adjusted for socio-demographics, cardiovascular risk factors, and potential confounders, AF was associated with an increased risk of MI (HR: 1.7, 95% CI: 1.4-2.2). A significant interaction was detected by race, with black (HR: 3.1, 95% CI: 1.7-5.6) AF participants having an increased risk of MI compared with whites (HR: 1.6, 95% CI: 1.2-2.1; P interaction = 0.030). CONCLUSIONS: AF is associated with an increased risk of MI in a population of older adults.