Prognostic impact and clinical outcomes of coronary flow reserve and hyperaemic microvascular resistance
Takumi Toya, Michel Corban, Ji Young Park, Ali Ahmad, Ilke Ӧzcan, Faten Sebaali, Jaskanwal Deep Singh Sara, Rajiv Gulati, Lilach O. Lerman, Amir Lerman
Abstract
BACKGROUND: Most studies dichotomise indices of coronary microvascular function to assess their prognostic values. AIMS: We aimed to investigate whether coronary flow reserve (CFR) and hyperaemic microvascular resistance (HMR) as continua predict major adverse cardiovascular events (MACE), comprising all-cause death, myocardial infarction, revascularisation, and stroke in patients with ischaemia and non-obstructive coronary artery disease. METHODS: A total of 610 patients were included and followed up over a median of 8.0 years (199 individual MACE in 174 patients). RESULTS: Both CFR and HMR as continua predicted MACE with an odds ratio (OR) of 0.70 (per 1-unit increase, 95% confidence interval [CI]: 0.53, 0.92; p=0.01) and 1.63 (per 1 mmHg/cm/s, 95% CI: 1.20, 2.21; p=0.002), respectively. This relationship remained significant after adjustment for age and sex with an adjusted OR of 0.66 (per 1 unit increase, 95% CI: 0.49, 0.89; p=0.01) and 1.42 (per 1 mmHg/cm/s, 95% CI: 1.03, 1.94; p=0.03). HMR added prognostic value to CFR in predicting MACE (net reclassification index 0.17, 95% CI: 0.02, 0.31; p=0.03; integrated discrimination improvement 0.01, 95% CI: 0.0001, 0.02; p=0.046). CONCLUSIONS: Both CFR and HMR as continuous variables predict future risk of MACE.