Family history of premature myocardial infarction (FHMI) may be a useful marker of cardiovascular disease (CVD) risk in young subjects, but comparisons of its implications for CVD risk factor burden, prevalent atherosclerosis, and risk awareness between young men and women have not been reported.

We analyzed data from 2404 young subjects with ages 30 to 50 in the Dallas Heart Study, which is a population-based study. Family history of premature MI was defined as a first-degree relative with myocardial infarction (MI) before age 50 (men) or 55 (women). Coronary artery calcification was measured by computed tomography scan, and perceived lifetime risk of MI was assessed by questionnaire. Analyses were sex-stratified.

Women with versus without FHMI had an increased composite risk factor burden (≥2 CVD risk factors, 49.1% vs 39.1%; P < .001), an association not seen in men (P = .6). Family history of premature MI was independently associated with coronary artery calcification among women (adjusted odds ratio, 2.0; 95% confidence interval, 1.0-4.1) but not among men (adjusted odds ratio, 1.7; 95% confidence interval, 0.9-3.2). A higher proportion of subjects with FHMI versus no FHMI perceived their lifetime risk of MI to be at ≥ average in women (59.7% vs 47.4%; P < .001) and men (75.0% vs 48.3%; P = .004), with the increment greatest among men (P interaction = .02).

Despite a stronger association with CVD risk factors and atherosclerosis prevalence with FHMI among young women compared with men, young women with FHMI demonstrated less CVD risk awareness and worse lifestyle choices. Family history of premature MI may be an especially useful risk assessment tool in young women, and greater efforts are needed to promote CVD risk awareness among young women with FHMI.