Effects of Gender on Coronary Microvascular Dysfunction andCardiac Outcomes.

BACKGROUND: Coronary microvascular dysfunction (CMD) is a prevalent and prognostically important finding in patients with symptoms suggestive of coronary artery disease (CAD). The relative extent to which CMD affects both genders is largely unknown. METHODS AND RESULTS: We investigated 405 men and 813 women referred for evaluation of suspected CAD with no previous history of CAD and no visual evidence of CAD on rest/stress positron emission tomography (PET) myocardial perfusion imaging. Coronary flow reserve (CFR) was quantified and CFR<2.0 used to define the presence of CMD. Major adverse cardiac events (MACE), including cardiac death, non-fatal myocardial infarction, late revascularization and hospitalization for heart failure, were assessed in blinded fashion over a median follow-up of 1.3 years (IQR 0.5-2.3 years). CMD was highly prevalent both in men and women (51% and 54%, respectively; P(Fisher exact test)=0.39; P(equivalence)=0.0002). Regardless of gender, CFR was a powerful incremental predictor of MACE (hazard ratio 0.80 [95% CI 0.75-086] per 10% increase in CFR; P<0.0001) and resulted in favorable net reclassification improvement (NRI=0.280 [95% CI 0.049-0.512]), after adjustment for clinical risk and ventricular function. In a subgroup (N=404; 307 female/97 male) without evidence of coronary artery calcification (CAC) on gated CT imaging, CMD was common in both genders, despite normal stress perfusion imaging and zero CAC (44% of men versus 48% of women; P(Fisher exact test)=0.56; P(equivalence)=0.041). CONCLUSIONS: CMD is highly prevalent among at risk individuals and is associated with adverse outcomes regardless of gender. The high prevalence of CMD in both genders suggests that it may be a useful target for future therapeutic interventions.