Sex-specific differences in coronary blood flow and flow velocity reserve in symptomatic patients with non-obstructive disease.

Abstract

Reduced coronary flow velocity reserve (CFVR) is associated with adverse cardiovascular outcomes. Whether CFVR and coronary blood flow (CBF) are similar in men and women with chest pain and non-obstructive CAD remains unknown. We hypothesised sex differences in CFVR and CBF. A total of 1,683 patients with signs/symptoms of ischaemia and angiographically unobstructed coronary arteries (<40% angiographic stenosis) underwent coronary vasomotion evaluation. CFVR was measured as hyperaemic/resting average velocity in the LAD. Mid-LAD diameter was measured with quantitative angiography and CBF calculated at rest (rCBF) and hyperaemia (hCBF). Resting microvascular resistance (rMR) was calculated as mean arterial pressure/rCBF. Of the total number of patients, 1,096 (65%) were women, median age 51 [42, 59] years. Compared to men, women had lower median CFVR (2.7 [2.4, 3.2] vs 3.1 [2.7, 3.6], p<0.001), higher rCBF (49.7 [34.0, 71.1] vs 45.9 [31.8, 68.7] ml/min, p=0.04), lower hCBF (139.5 [93.0, 195.2] vs 147.1 [95.7, 218.6] ml/min, p=0.02), but similar rMR (p=0.82). Female sex was an independent predictor of lower CFVR, higher rCBF, and lower hCBF. Compared to men, women with signs/symptoms of ischaemia and non-obstructive CAD have lower CFVR, higher rCBF, and lower hCBF. Female sex is a predictor of these sex-specific differences. The clinical diagnostic and prognostic implications of sex differences in coronary physiology need further evaluation.