AF an independent risk factor for first-time MI

Atrial fibrillation (AF) is independently associated with a higher rate of first-time MI, especially in blacks and women, according to a study published online Nov. 4 in JAMA Internal Medicine.

The authors, led by Elsayed Z. Soliman, MD, MSc, of Wake Forest School of Medicine in Winston-Salem, N.C., used data from the REGARDS study (REasons for Geographic and Racial Differences in Stroke), a study designed to determine what factors could be behind geographic and racial differences in stroke mortality between blacks and whites. REGARDS investigators enrolled participants, particularly blacks and residents of the southeastern “stroke belt” region, between 2003 and 2007.

Soliman and colleagues assessed the relationship between AF and risk of incident MI in 23,928 REGARDS participants after 6.9 years of follow-up. There were 1,631 participants with AF. Over the study period, there were 648 first-time MIs. After adjusting for age, the incidence of MI in people with AF was twice as high as in people without AF. The risk remained significant after adjusting for other risk factors such as total cholesterol, body mass index, diabetes and smoking status.  

Further analysis found that MI risk associated with AF was significantly higher in women (hazard ratio [HR] 2.16) than in men (HR 1.39). Blacks were also at significantly higher risk when compared with whites (HR 2.53 vs. 1.26). Older age, however, was not a factor in the relationship between MI and AF.

The authors noted among limitations that their analysis may not have included paroxysmal and/or intermittent AF, which may have underestimated the number of participants with AF. Additionally, the study evaluated risk only in blacks and whites.

However, they argued that their findings have broad implications.

“These findings add to the growing concerns of the seriousness of AF as a public health burden: in addition to being a well-known risk factor for stroke, AF is also associated with increased risk of MI,” they wrote.