Association Between Stress Hyperglycemia Ratio and Coronary Slow Flow Phenomenon in Patients with MINOCA

Background: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous clinical entity in which coronary microvascular dysfunction plays a central pathophysiological role. The coronary slow flow phenomenon (CSFP) represents an angiographic manifestation of microvascular dysfunction; however, reliable and practical biomarkers for its identification remain limited. The stress hyperglycemia ratio (SHR) reflects acute metabolic stress beyond chronic glycemic status. This study aimed to investigate the association between SHR and CSFP in patients with MINOCA. Methods: In this single-center retrospective cohort study, 2073 patients undergoing coronary angiography for suspected myocardial infarction between 1 January 2020 and 1 December 2025 were screened. 354 patients with MINOCA were included. Patients with CSFP were matched 1:2 with controls according to age and sex using exact matching. SHR and other laboratory parameters were assessed. Logistic regression and receiver operating characteristic (ROC) analyses were performed to identify independent predictors of CSFP. Results: Among the study population, 118 patients (33.3%) had CSFP. Patients with CSFP had significantly higher SHR levels, along with increased C-reactive protein, triglycerides, low-density lipoprotein cholesterol, and uric acid, whereas HbA1c and serum albumin levels were lower (all p < 0.05). In multivariable logistic regression analysis, SHR emerged as the strongest independent predictor of CSFP (OR: 1.48, 95% CI: 1.30– 1.69; p < 0.001). In ROC analysis, SHR demonstrated the highest discriminative performance for CSFP (AUC: 0.74), with an optimal cut-off value of 0.998, yielding a sensitivity of 66.1% and a specificity of 64.3%. Conclusion: SHR is independently associated with CSFP in patients with MINOCA, suggesting that acute metabolic stress plays a key role in coronary microvascular dysfunction. SHR may serve as a simple and readily available marker for identifying high-risk microvascular phenotypes in MINOCA patients. Keywords: myocardial infarction with non-obstructive coronary arteries, coronary slow flow phenomenon, stress hyperglycemia ratio, coronary microvascular dysfunction