Coronary artery microvascular dysfunction: Role of sex and arterial load

BACKGROUND: The prognosis of cardiovascular disease is worse in women than men, and coronary microvascular dysfunction explains the excess cardiovascular risk in women. In addition, age-related increases in pulsatile arterial load are greater in women than men; and lower arterial compliance has been shown to independently predict cardiovascular events. However, whether arterial load differentially affects the coronary microvasculature in men and women remains unknown. We hypothesized that lower arterial compliance would be associated with coronary artery microvascular dysfunction in women. METHODS AND RESULTS: 285 subjects (60% women, age: 61.2 ± 11.0 yrs) undergoing cardiac ⁸²Rb positron-emission tomography between 2010 and 2013, with ejection fraction ≥50%, no heart failure, dyspnea, coronary artery disease or regional perfusion defects were included. Left ventricular microvascular function was assessed by myocardial flow reserve (MFR). Pulsatile arterial load was estimated by indexed arterial compliance [ACi: (stroke volume/pulse pressure)/BSA]. Multivariable linear regression evaluated associations of arterial compliance with myocardial flow reserve after adjustment for confounders. ACi was lower in women than men [0.39 ± 0.15 vs. 0.52 ± 0.28 (mL/mm Hg)/m², P < 0.0001]. We found that the effect of ACi on MFR differs by sex: lower ACi was associated with lower MFR in women (β ± SE: 0.20 ± 0.07, P = 0.004) but not in men (0.03 ± 0.11, P = 0.75). CONCLUSIONS: Lower ACi was associated with altered coronary microvascular function in women, but not in men. Our findings highlight low arterial compliance as a potential link between hypertension, coronary microvascular dysfunction and adverse cardiovascular events in women.