Cardiac risk factors and myocardial perfusion reserve in women with microvascular coronary dysfunction

Women with myocardial ischemia without obstructive coronary artery disease (CAD) often have microvascular coronary dysfunction (MCD). Traditional cardiac risk factors (RFs) contribute modestly to MCD detected by invasive coronary reactivity testing (CRT). Cardiac magnetic resonance imaging (CMRI) is an emerging noninvasive technique used to evaluate MCD. We evaluated RFs related to CMRI myocardial perfusion in women with MCD. 53 women with CRT confirmed MCD underwent adenosine stress and rest CMRI (1.5 Tesla). The myocardial perfusion reserve index (MPRI) was calculated (Pie Medical) with lower MPRI meaning less perfusion reserve. Relationships between RFs and MPRI were examined. The mean age was 54±10 years with a mean body mass index (BMI) of 26.2±4.2. The mean MPRI was 1.63±0.39. Hypertension, dyslipidemia, elevated BMI, and post-menopausal status were inversely related to MPRI, while ever smoking, age, family history of CAD, history of irregular menses, and history of menopausal hormone therapy (MHT) or oral contraceptive (OC) use were not. Dyslipidemia and BMI remained significant independent predictors of MPRI. Regression modeling demonstrated that the RFs of dyslipidemia, obesity, hypertension, family history of CAD, and history of irregular menses explained 27% of the observed MCD variance.

In conclusion, impaired MPRI measured by CMRI is related to dyslipidemia and elevated BMI in women with MCD. These results suggest traditional RFs contribute modestly to MCD; a larger cohort of women with MCD should be examined to confirm and extend these observations. The impact of traditional CAD RF modification strategies, including optimal medical therapy, should be explored as MCD treatment targets.