Abstract P407: Sex Differences in Microvascular Response to Mental Stress and Adverse Cardiovascular Events Among Patients With Ischemic Heart Disease

Introduction: Microvascular dysfunction during acute mental stress may be an important determinant of major adverse cardiovascular outcomes (MACE) especially among middle-aged women survivors of an acute myocardial infarction (MI). Hypothesis: There are sex differences in the association between microvascular dysfunction and MACE. Methods: The Myocardial Infarction and Mental Stress Study 2 enrolled individuals who had been hospitalized for an MI in the past 8 months at the age of 60 years or younger, with an oversampling of women. Reactive hyperemia index (RHI) was used to measure digital microvascular function before and 30 minutes after a public-speaking mental stress task. This assessment was contrasted with macrovascular endothelial function at the brachial artery through flow-mediated dilation (FMD). Participants were followed for 5-years, and MACE was defined as a composite of cardiovascular death, first/recurring events for nonfatal MI, and hospitalizations for heart failure. Cox proportional hazards models were used to examine vascular response to stress (difference between post-stress and resting values) and MACE adjusting for demographics, clinical risk factors, medications, psychological factors, and mental stress ischemia. Lower RHI and FMD values are indicative of greater microvascular and endothelial dysfunction, respectively. Results: Of 263 participants, the mean age was 51 years and 48% were women. There were 64 patients with 141 adverse cardiovascular events (first and repeated). In the overall sample, there was no significant association between microvascular response to stress and MACE, but there was a significant interaction with sex (p = 0.03). Each standard deviation decrease in RHI response to stress was associated with 50% greater risk of MACE (HR: 1.50, 95% CI: 1.05, 2.13) among women only, while no association was observed in men (HR 0.93, 95% CI: 0.69, 1.26). Transient endothelial dysfunction in response to stress (for each standard deviation decrease in FMD) was associated with 35% greater risk of MACE (HR: 1.35; 95% CI: 1.07, 1.71), and was similar in women and men. Conclusions: Peripheral microvascular dysfunction with mental stress is associated with MACE among women but not among men. In contrast, brachial artery endothelial dysfunction is similarly related to MACE among both men and women. These results suggest that microvascular dysfunction is a female-specific mechanism linking psychological stress to adverse outcomes.