Impact of age and sex in coronary microvascular function in patients with angina and nonobstructive coronary arteries

Abstract Background Angina and nonobstructive coronary arteries (ANOCA) is increasingly recognized and encompasses vasomotor disorders such as coronary microvascular dysfunction (CMD) and vasospastic angina (VA). (1,2) Purpose To evaluate the effect of age and sex on coronary microvascular function in patients with ANOCA. Methods We included 206 patients (72.3% female) with ANOCA who underwent invasive coronary function testing including vasoreactivity testing with acetylcholine provocation, guidewire-based assessment of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and fractional flow reserve (FFR). Results Mean age was 57.1 ± 11.2 years with a range from 27 to 81 years and 149 (72.3%) were women. Baseline mean transit times (Tmn) were similar among the three age groups but women had lower values compared to men (0.99 ± 0.43 vs. 1.27 ± 0.49; p=0.001). Hyperemic Tmn were higher in older patients, and lower in women (0.33 ± 0.19 vs. 0.41 ± 0.22; p=0.031). Women had lower IMR (24.5 ± 13.5 vs. 30.2 ± 18.1; p=0.038), but similar CFR (3.43 ± 1.59 vs. 3.73 ± 1.94; p=0.315). On multivariable regression model, female sex was only associated with lower hyperemic Tmn (β=-0.52, p=0.037), but not with baseline Tmn, CFR, or IMR. Increasing age was associated with progressive decrease in CFR (β=-0.05, 95% CI: -0.08 to -0.02; p=0.001) and increase in IMR (β=0.63, 95% CI: 0.38 to 0.87; p0.001) (Figure 1). Older patients had higher rates of CMD, but lower rates of VA and symptomatic myocardial bridging (Figure 2). Conclusions Older age, but not sex, was associated with a decrease in coronary microvascular function and increase in microcirculatory resistance, represented by decreased CFR and increased IMR. As invasive assessment of microvascular function is increasingly utilized in clinical practice, thresholds for abnormal CFR and IMR should be interpreted in the context of patient age and sex.Figure 1 Figure 2