Impaired coronary flow reserve in patients with supra-normal left ventricular ejection fraction at rest

PURPOSE: Recently, a “U” hazard ratio curve between resting left ventricular ejection fraction (LVEF) and prognosis has been observed in patients referred for routine clinical echocardiograms. The present study sought to explore whether a similar “U” curve existed between resting LVEF and coronary flow reserve (CFR) in patients without severe cardiovascular disease (CVD) and whether impaired CFR played a role in the adverse outcome of patients with supra-normal LVEF (snLVEF, LVEF ≥ 65%). METHODS: Two hundred ten consecutive patients (mean age 52.3 ± 9.3 years, 104 women) without severe CVD underwent clinically indicated rest/dipyridamole stress electrocardiography (ECG)-gated (13) N-ammonia positron emission tomography/computed tomography (PET/CT). Major adverse cardiac events (MACE) were followed up for 27.3 ± 9.5 months, including heart failure, late revascularization, re-hospitalization, and re-coronary angiography for any cardiac reason. Clinical characteristics, corrected CFR (cCFR), and MACE were compared among the three groups categorized by resting LVEF detected by PET/CT. Dose–response analyses using restricted cubic spline (RCS) functions, multivariate logistic regression, and Kaplan–Meier survival analysis were conducted to evaluate the relationship between resting LVEF and CFR/outcome. RESULTS: An inverted “U” curve existed between resting LVEF and cCFR (p = 0.06). Both patients with snLVEF (n = 38) and with reduced LVEF (rLVEF, LVEF < 55%) (n = 66) displayed a higher incidence of reduced cCFR than those with normal LVEF (nLVEF, 55% ≤ LVEF < 65%) (n = 106) (57.9% vs 54.5% vs 34.3%, p < 0.01, respectively). Both snLVEF (p < 0.01) and rLVEF (p < 0.05) remained independent predictors for reduced cCFR after multivariable adjustment. Patients with snLVEF encountered more MACE than those with nLVEF (10.5% vs 0.9%, log-rank p = 0.01). CONCLUSIONS: Patients with snLVEF are prone to impaired cCFR, which may be related to the adverse prognosis. Further investigations are warranted to explore its underlying pathological mechanism and clinical significance. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00259-021-05566-y.