Association of C-reactive protein–triglyceride–glucose index with coronary microvascular dysfunction in patients without obstructive coronary artery disease

Background Patients with angina symptoms and no obstructive coronary lesions may have coronary microvascular dysfunction (CMD). The C–reactive protein–triglyceride–glucose index(CTI) is a novel metabolic-inflammatory marker, but its value in CMD remains unclear. This study aimed to evaluate the association of metabolic indices with CMD and determine the incremental value of CTI compared with other metabolic indices. Methods This retrospective cohort study included 129 patients without obstructive coronary artery disease who underwent stress echocardiography after coronary angiography. The associations of CTI, triglyceride–glucose (TyG) index, TyG–Body mass index (TyG–BMI), remnant cholesterol–inflammation index (RCII), and metabolic score for insulin resistance (METS–IR) with CMD were evaluated using correlation analyses and multivariable logistic regression models. ROC curve analysis and DeLong tests were performed to compare predictive performance among metabolic indices, while restricted cubic spline analyses and subgroup analyses were conducted to assess dose–response relationships and the robustness of the associations. Results Among 129 patients, 64 (49.6%) had CMD. CTI was negatively correlated with coronary flow reserve ( r = −0.490, P < 0.001) and remained independently associated with CMD after multivariable adjustment (OR: 2.472, 95% CI: 1.480–4.128). CTI showed the best predictive performance among the evaluated metabolic indices (AUC: 0.730, 95% CI: 0.644–0.817), with significant improvement in risk classification (NRI = 0.541, P = 0.010). Higher CTI levels were associated with increased CMD prevalence, and the association remained consistent across most subgroups. Conclusion CTI is strongly associated with CMD and provides incremental value for CMD risk stratification beyond conventional metabolic indices. CTI may serve as a promising metabolic-inflammatory biomarker for identifying individuals with CMD.