Prognostic value of coronary flow velocity reserve in obese patients with preserved ejection fraction and negative stress echocardiography

Background Obese patients often exhibit a clustering of cardiovascular risk factors and are frequently referred for noninvasive cardiac imaging. Coronary microvascular dysfunction (CMD) represents an early indicator of cardiovascular disease that can be noninvasively diagnosed using coronary flow velocity reserve (CFVR) measurements obtained during stress echocardiography (SE) in patients without evidence of obstructive coronary artery disease (CAD). Purpose This study aimed to evaluate the prognostic significance of CFVR in overweight and obese patients within a prospective multicenter cohort. Methods 2273 patients (mean age 65 ± 11 years; 51% women) classified as overweight or obese (for definition see Table) were included in 27 sites from 11 countries. All patients had normal left ventricular ejection fraction (EF ≥ 50%), no prior history of CAD, and underwent exercise or pharmacological SE, which was negative for inducible ischemia. CFVR of the left anterior descending coronary artery was assessed, with CMD defined as CFVR >2.0. Patients were divided into two groups based on the presence (Group 1) or absence (Group 2) of CMD. The primary endpoint was overall mortality. Results CMD was identified in 492 patients (22%), with a mean CFVR of 2.3 ± 0.5 across the study population. Group 1 patients (CMD) were older, with a greater prevalence of diabetes and metabolic syndrome compared to group 2 (no CMD) (Table). During a median follow-up period of 2.1 years (IQR: 1.2-3.7 years), 103 patients (5%) died. Patients with CMD had significantly worse late survival compared to those without CMD (3-year survival: 96 ± 1% vs. 96 ± 1%, p=ns; 6-year survival: 79 ± 4% vs. 93 ± 1%, p < 0.0001): see Figure. Multivariate analysis adjusting for age, sex, EF, body mass index, smoking habits, diabetes, dyslipidemia, arterial hypertension, and type of stress confirmed CMD as an independent predictor of mortality (hazard ratio: 1.8 [95% CI: 1.1–2.8], p = 0.01). Conclusions CMD, assessed via CFVR during SE, was a robust and independent prognostic marker of long-term mortality in obese patients with preserved EF and no evidence of inducible ischemia. These findings underscore the pivotal role of noninvasive assessment of CMD in refining risk stratification and guiding clinical decision-making in this high-risk population.