Abstract 10441: Sex-Specific Decline in Coronary Flow Reserve with Aging

Introduction: Coronary vasomotor response is different between males and females. Overall, females have lower coronary flow reserve (CFR) than males due to higher baseline coronary flow than males. Hypothesis: Sex has an essential role in the interaction between age and CFR. Methods: We included 668 patients with nonobstructive coronary artery disease who underwent invasive coronary vasoreactivity testing using intracoronary incremental doses of adenosine (18-72 μg). Changes in CFR (hyperemic flow velocity/baseline flow velocity) with aging were separately analyzed between males (N=207, mean age 53±13 years) and females (N=461, mean age 54±12 years). We further divided patients by age of 53 which is average age of menopause. Results: In males, CFR decreased with aging in younger patients <53 years and tended to decrease in older male patients (all ages [N=207]: r=-0.33, P <0.0001; <53 years [N=99]: r=-0.27, P =0.01; ≥53 years [N=108]: r=-0.17, P =0.07) ( Figure A ). In contrast, CFR did not decrease with aging in younger females <53 years, whereas there was a significant negative correlation between CFR and age in older females ≥53 years (all ages [N=461]: r=-0.15, P =0.001; <53 years [N=211]: r=-0.006, P =0.39; ≥53 years [N=250]: r=-0.25, P <0.0001) ( Figure B ). Baseline microvascular resistance (BMR) was similar between younger and older males ( P =0.30), whereas older females had higher baseline BMR than younger females ( P <0.0001) ( Figure C ). Conclusions: CFR decreased with aging in males and older females, but not in younger females, potentially highlighting the role of protective hormonal differences in maintaining low baseline coronary tone in younger females.