Sex differences in long-term mortality after myocardial infarction: a systematic review

Background: Studies of sex differences in long-term mortality after acute myocardial infarction have reported mixed results. A systematic review is needed to characterize what is known about sex differences in long-term outcomes and to define gaps in knowledge.

Methods and results: We searched the Medline database from 1966 to December 2012 to identify all studies that provided sex-based comparisons of mortality after acute myocardial infarction. Only studies with at least 5 years of follow-up were reviewed. Of the 1877 identified abstracts, 52 studies met the inclusion criteria, of which 39 were included in this review. Most studies included fewer than one-third women. There was significant heterogeneity across studies in patient populations, methodology, and risk adjustment, which produced substantial variability in risk estimates. In general, most studies reported higher unadjusted mortality for women compared with men at both 5 and 10 years after acute myocardial infarction; however, many of the differences in mortality became attenuated after adjustment for age. Multivariable models varied between studies; however, most reported a further reduction in sex differences after adjustment for covariates other than age. Few studies examined sex-by-age interactions; however, several studies reported interactions between sex and treatment whereby women have similar mortality risk as men after revascularization.

Conclusions: Sex differences in long-term mortality after acute myocardial infarction are largely explained by differences in age, comorbidities, and treatment use between women and men. Future research should aim to clarify how these differences in risk factors and presentation contribute to the sex gap in mortality.