Significance of a positive family history for coronary heart disease in patients with a zero coronary artery calcium score (from the Multi-Ethnic Study of Atherosclerosis)

Abstract

Although a coronary artery calcium (CAC) score of 0 is associated with a very low 10-year risk for cardiac events, this risk is nonzero. Subjects with a family history of coronary heart disease (CHD) has been associated with more subclinical atherosclerosis than subjects without a family history of CHD. The purpose of this study was to assess the significance of a family history for CHD in subjects with a CAC score of 0. The Multi-Ethnic Study of Atherosclerosis cohort includes 6,814 participants free of clinical cardiovascular disease (CVD) at baseline. Positive family history was defined as reporting a parent, sibling, or child who had a heart attack. Time to incident CHD or CVD event was modeled using the multivariable Cox regression; 3,185 subjects were identified from the original Multi-Ethnic Study of Atherosclerosis cohort as having a baseline CAC score of 0 (mean age 58 years, 37% men). Over a median follow-up of 10 years, 101 participants (3.2%) had CVD events and 56 (1.8%) had CHD events. In age- and gender-adjusted analyses, a family history of CHD was associated with an ∼70% increase in CVD (hazard ratio 1.73, 95% confidence interval 1.17 to 2.56) and CHD (hazard ratio 1.72, 95% confidence interval 1.01 to 2.91) events. CVD events remained significant after further adjustment for ethnicity, risk factors, and baseline medication use. In conclusion, asymptomatic subjects with a 0 CAC score and a positive family history of CHD are at increased risk for CVD and CHD events compared with those without a family history of CHD, although absolute event rates remain low.