Integration of BNP and blood glucose for identifying coronary flow reserve impairment: A cardiovascular–kidney–metabolic perspective

Cardiovascular-kidney-metabolic (CKM) syndrome may predispose patients to coronary microvascular dysfunction (CMD) through systemic microvascular injury. We investigated the association between CKM risk factors and CMD, focusing on the diagnostic performance of accessible biomarkers. In this exploratory analysis, we retrospectively analyzed 65 patients who underwent invasive coronary physiological assessment with thermodilution-derived coronary flow reserve (CFR) and index of microcirculatory resistance (IMR). Clinical variables included casual blood glucose, B-type natriuretic peptide (BNP), and the urine albumin-to-creatinine ratio (ACR), along with echocardiographic indices of diastolic function. Among the 65 patients, 20 (31 %) had impaired CFR. BNP (AUC = 0.74; 95 % confidence interval, CI, 0.60-0.88) and casual blood glucose (area under the curve, AUC = 0.64; 95 % CI, 0.49-0.80) showed diagnostic accuracy for impaired CFR of <2.0, while ACR improved model performance when combined with BNP or E/e'. The combination of BNP and casual glucose significantly improved diagnostic performance compared with either marker alone (AUC = 0.83 vs. 0.75; 95 % CI, 0.73-0.93; <i>p</i> = 0.03). The elevated BNP (AUC = 0.77, 95 % CI: 0.59-0.95) and higher ACR (AUC = 0.71, 95 % CI: 0.52-0.90) were significantly associated with structural CMD defined as CFR < 2.0 and IMR ≥ 25, whereas casual blood glucose was not. From a CKM perspective, BNP and casual blood glucose were associated with impairment of CFR and may serve as simple, accessible biomarkers for its early detection and risk stratification.