Atrial Fibrillation and Risk of ST-Segment-Elevation Versus Non-ST-Segment-Elevation Myocardial Infarction: The Atherosclerosis Risk in Communities (ARIC) Study

Abstract

Background: It has recently been reported that atrial fibrillation (AF) is associated with an increased risk of myocardial infarction (MI). However, the mechanism underlying this association is currently unknown. Further study of the relationship of AF with the type of MI (ST-segment-elevation MI [STEMI] versus non-ST-segment-elevation MI [NSTEMI]) might shed light on the potential mechanisms.

Methods and results: We examined the association between AF and incident MI in 14 462 participants (mean age, 54 years; 56% women; 26% blacks) from the Atherosclerosis Risk in Communities (ARIC) study who were free of coronary heart disease at baseline (1987-1989) with follow-up through December 31, 2010. AF cases were identified from study visit ECGs and by review of hospital discharge records. Incident MI and its types were ascertained by an independent adjudication committee. Over a median follow-up of 21.6 years, 1374 MI events occurred (829 NSTEMIs, 249 STEMIs, 296 unclassifiable MIs). In a multivariable-adjusted model, AF (n=1545) as a time-varying variable was associated with a 63% increased risk of MI (hazard ratio,1.63; 95% confidence interval, 1.32-2.02). However, AF was associated with NSTEMI (hazard ratio, 1.80; 95% confidence interval, 1.39-2.31) but not STEMI (hazard ratio, 0.49; 95% confidence interval, 0.18-1.34; P for hazard ratio comparison=0.004). Combining the unclassifiable MI group with either STEMI or NSTEMI did not change this conclusion. The association between AF and MI, total and NSTEMI, was stronger in women than in men (P for interaction <0.01 for both).

Conclusions: AF is associated with an increased risk of incident MI, especially in women. However, this association is limited to NSTEMI.

Keywords: atrial fibrillation; electrocardiography; epidemiology; myocardial infarction.

© 2015 American Heart Association, Inc.

Figures

Figure 1

Unadjusted Kaplan Meier myocardial infarction free survival curves by atrial fibrillation status. *Time to event in the AF group is the time from detection of AF not the cohort inception.

Figure 2

Sex and race stratified age-adjusted incidence rates and incidence rate ratios of MI by AF status. MI= Myocardial infarction, AF= Atrial fibrillation. *Age-adjusted incidence rate ratio and incidence rates were based on the average age of the cohort (54 years). †Time to event in the AF group is the time from detection of AF not the cohort inception.