Abstract / Summary
Background. Women with premature myocardial infarction (MI) have worse outcomes than similarly aged men despite less severe disease, and stress-related factors have been implicated. We examined sex differences in the association of mental stress-induced myocardial ischemia (MSIMI) with cardiovascular outcomes after premature MI and explored vascular and inflammatory mechanisms. Methods. We studied 602 individuals (mean age 51 years; 46% women) within 8 months of MI who underwent 99mTc-sestamibi myocardial perfusion imaging at rest and after mental stress. MSIMI was defined as a summed difference score [≥]3. We measured reactive hyperemia index (RHI) as peripheral microvascular reactivity to stress and interleukin-6 (IL-6) as inflammatory response to stress. The primary endpoint was cardiovascular death or nonfatal MI; the secondary endpoint added heart failure hospitalization. Cox proportional hazards models adjusted for sociodemographic factors, clinical, and psychiatric history. Results. MSIMI was more common in women than men (19.2% vs. 13.2%, p=0.04). Over a median follow-up of 34.2 months, 51 primary and 91 secondary endpoint events occurred. The hazard ratio (HR) of MSIMI for the primary endpoint was 3.2 (95% CI, 1.3, 7.6) in women and 1.9 (95% CI, 0.8, 4.5) in men (p for interaction=0.41), which remained similar after multivariable adjustment. The adjusted population attributable fraction was 27.6% (99% CI, 3.9%, 36.9%) in women and 11.1% (95% CI, ?5.8%, 18.4%) in men. In exploratory analyses, all MSIMI-related primary endpoint events among women occurred in Black women (HR, 4.3; 95% CI, 1.7?11.1). Associations with the secondary endpoint were weaker and attenuated after adjustment. IL-6 and RHI responses did not attenuate associations. Conclusions. Among women, MSIMI was associated with about threefold increased risk and over one quarter attributable fraction for cardiovascular death or nonfatal MI. Black women were at especially high risk. While larger studies are warranted to confirm sex differences and explore mechanisms, these data underscore the impact of emotional factors on morbidity and mortality in post-MI women.