Impact of Age and Sex on Coronary Flow Reserve and Microvascular Function in Patients With Angina and Nonobstructive...

Angina and nonobstructive coronary arteries is increasingly recognized, but the impact of age and sex on coronary microvascular function in this population has received limited study.

In 206 consecutive patients with angina and nonobstructive coronary arteries, invasive coronary function testing was performed including vasoreactivity testing with acetylcholine provocation, guidewire-based assessment of coronary flow reserve (CFR) with bolus thermodilution, and index of microcirculatory resistance (IMR). Multivariable regression models assessed associations of age and sex with coronary physiologic indices, and subgroup analyses were conducted to examine age-related trends in microvascular function separately in men and women.

Mean age was 57.1 ± 11.2 years (range, 27-81 years), and 149 (72.3%) were women. Increasing age was associated with progressive decrease in CFR (β = -0.05; P = .001) and increase in hyperemic mean transit time (Tmn; β = 0.009; P < .001) and IMR (β = 0.63; P < .001). Baseline Tmn was similar among the 3 age groups. Women had lower IMR (24.5 ± 13.5 vs 30.2 ± 18.1; P = .038), and shorter baseline and hyperemic Tmn, but similar CFR (3.43 ± 1.59 vs 3.73 ± 1.94; P = .315) compared with men. In sex-stratified analysis, age was associated with higher IMR in women (β = 0.51; P < .001), but not in men (β = 0.29; P = .154). CFR declined significantly with increasing age in both sexes, with a stronger association in women (β = -0.04; P < .001) than in men (β = -0.06; P = .011).

Increasing age was associated with a decrease in coronary microvascular function and increase in microcirculatory resistance, which was pronounced in women but not in men. There was no association of baseline Tmn with age, suggesting that age-related impairment in CFR was primarily driven by reduced hyperemic flow.