Prevalence of microvascular dysfunction in obese women undergoing stress cardiovascular magnetic resonance with quantitative perfusion

Aims To explore the frequency of coronary microvascular dysfunction (CMD) in obese women (obesity defined as a body mass index (BMI) greater than 30 kg/m²) undergoing stress cardiovascular magnetic resonance (CMR) using quantitative myocardial perfusion analysis. Methods and results Fifty-six women (with median age 64 ±10), 18 obese patients (32.1%) and 38 non-obese patients (67.9%), who underwent clinically indicated Stress Cardiovascular Magnetic Resonance (CMR) for clinical indication from 2022 to 2025 at our hospital were included and analysed retrospectively. Clinical parameters and CMR measurements were collected. Myocardial perfusion was assessed using two approaches: a qualitative method, which involved comparing stress and rest images and evaluating the presence of a significant circumferential subendocardial perfusion defect in first-pass stress perfusion (indicative of microvascular dysfunction); and the quantitative method, which involves calculating the endocardial-to-epicardial ratio under stress; and defining CMD when the a value is less than 1. Obese and non-obese groups were comparable in terms of demographics and clinical characteristics with the exception of dyslipidemia that was more frequent in the obese group compared to the non-obese group (61.1% vs 28.9%, respectively; P=0.021). The median value of stress endocardial-to-epicardial ratio was 1.108 (1.071-1.144), in obese patients was 1.066 (1.013-1.119), and in non-obese 1.127(1.080-1.175) with P=0.219. When myocardial perfusion was assessed qualitatively analysis, as 7 (12.5%) patients demonstrated values consistent with Microvascular Dysfunction, of whom CMD was observed in 4 obese patients (22.22%) were obese and 3 non-obese patients (7.9%) with P= 0.195 (figure 1). When myocardial perfusion was assessed quantitatively, CMD was more frequently observed among obese patients as compared to the non-obese group but it did not reach statistical significance (27.8% vs. 15.8% respectively with P=0.296). Among 11 patients with CMD based on qualitative assessment, only 1 had CMD based on quantitative perfusion. Among 7 patients with CMD based on quantitative analysis, only 1 had CMD on qualitative analysis. The number of obese patients with discordant results was 7 versus 9 of non-obese. Conclusions The frequency of CMD among obese patients is slightly higher as compared to non-obese patients. Quantative analysis does not identify obese patients with CMD who do not show on qualitative assessment.