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Men have twice the risk of heart attack compared with women

Researchers estimated that men have nearly twice the risk of myocardial infarction when compared with women, according to findings published in JAMA Internal Medicine.

The difference in risk for myocardial infarction between men and women could not be explained by differences in previously identified risk factors.

Grethe Albrektsen, PhD, from the Norwegian University of Science and Technology, and colleagues reported a sex-specific age-incidence curve in their study, which demonstrated a low risk for MI in young and middle-aged women that was equivalent to men aged 10 to 15 years younger.

"Despite limited empirical evidence, several hypotheses on biological mechanisms have been proposed for explaining a potential sex difference in the risk of CHD," they wrote. "The low risk of CHD in premenopausal women is suggested to be related to a protective effect of endogenous female hormones, but this theory has been questioned. Sex heterogeneity in insulin resistance mechanisms, favorable [LDL] cholesterol characteristics in women, and differences in aging processes influencing arterial stiffness have also been hypothesized to be of importance. The increase in risk of CHD in postmenopausal women, possibly hormone related or due to age-related changes in risk factor levels, may lead to a diminishing sex contrast in risk of CHD with increasing age."

As part of the Tromsø Study, Albrektsen and colleagues conducted a population-based prospective study of 33,997 participants in Tromsø, Norway to quantify the risk differences between genders and assess the role of various risk factors.

They calculated incidence rates (IRs) and incidence rate ratios (IRRs) of MI after following the participants for a median of 17.6 years, during which 2,793 individuals, 886 of whom were women, received MI diagnoses.

The researchers reported that the overall IRR for men compared with women was 2.72 (95% CI, 2.5-2.96) after adjusting for age and birth cohort. In all age groups, men had a higher risk for MI, but Albrektsen and colleagues found that IRRs decreased with age, from 3.64 (95% CI, 2.85-4.65) in participants aged 35 to 54 years to 2 (95% CI, 1.76-2.28) in those aged 55 to 74 years to 1.66 (95% CI, 1.42-1.95) for those aged 75 to 94 years.

Adjusting for total cholesterol levels and HDL levels demonstrated the most influence on sex-based risk estimates, along with diastolic BP and smoking. The difference between sexes was still present after adjustment for these risk factors (IRR = 2.07; 95% CI, 1.89-2.26).

In addition, adjusting for physical activity, diabetes, BMI and systolic BP did not significantly impact the gap.

"Men have roughly twice the risk of MI compared with women, a contrast that cannot be explained by established CHD risk factors," Albrektsen and colleagues concluded. "The sex difference persists throughout life but declines with age. The minor changes in IRs when moving from premenopausal to postmenopausal age in women make it unlikely that changes in female hormone levels influence the risk of MI. A better understanding of the mechanisms behind the observed gender gap in risk of MI is important both for prevention and treatment of disease in women, as well as in men." – by Chelsea Frajerman Pardes

Disclosures: The researchers report no relevant financial disclosures.