Meta-analysis finds sex differences in acute MI hard to track

We haven’t always spoken the same language in acute MI studies, researchers found when trying evaluate differences and changes to mortality in male and female patients using 46 years of data. The meta-analysis published online July 22 in Circulation found that study differences made comparisons difficult.

Emily M. Bucholz, MPH, of Yale University’s School of Medicine in New Haven, Conn., and colleagues used 39 studies pulled from Medline between 1966 and 2012. Due in part to heterogeneity in the variables studied, risks varied widely, with some studies reporting significant risk differences between the sexes, others reporting next to no differences in risk.

Age-unadjusted mortality was reported higher for women five to 10 years out from acute MI. Adjusting for age seemed to remove much of the sex differences actually seen. Bucholz et al found in this analysis that treatment greatly affected risks and outcomes for the sexes.

Notably, women made up less than one-third of the subjects in most studies reviewed by the research team.

C. Noel Bairy Merz, MD, of Cedars-Sinai Medical Center in Los Angeles, wrote an editorial on the problems Bucholz et al uncovered, commenting that part of the problem seems to stem from how women are diagnosed. While women are a third of patients diagnosed with coronary heart disease and MI, women comprise more than half of fatalities from ischemic heart disease.

“Established normative standard studies for CPK and troponin assays clearly demonstrate sex differences in reference thresholds for AMI [acute MI] diagnosis in women versus men; e.g. lower thresholds are appropriate for women, yet male-standard thresholds are used in practice, resulting in lower detection of AMI in women,” Bairy Merz wrote. “Indeed, an initial report suggests that the current high sensitivity troponin threshold failed to detect 20% of AMI in women. ECG abnormalities are less likely to be diagnostic for obstructive CAD in women than in men, but there is little work evaluating ECG AMI criteria stratified by sex.”

Bucholz et al stated differences in age, treatment utilization and clinical presentation impacted disparity in long-term prognosis after AMI. They asked that future studies focus on patient factors with the strongest impacts on sex differences in mortality, with the understanding that risk factors differ by sex. They also requested that researchers devise strategies to manage risk factors in women when symptoms begin and following hospitalization to further reduce mortality rates.