Predicting nonobstructive coronary artery disease in NSTEMI: a retrospective study and risk score model

Nonobstructive coronary artery disease (CAD) is increasingly recognized in patients presenting with non–ST-segment elevation myocardial infarction (NSTEMI). Early identification of such patients may help raise clinical suspicion for alternative mechanisms of myocardial injury and guide further diagnostic evaluation. To determine the prevalence of nonobstructive CAD in NSTEMI, identify associated clinical predictors, and develop a simple clinical risk score for its prediction. This retrospective observational study included patients with NSTEMI who underwent coronary angiography between January 2017 and December 2021. Nonobstructive CAD was defined as < 50% luminal stenosis in all major epicardial arteries. Clinical, electrocardiographic, echocardiographic, and laboratory variables were compared between patients with nonobstructive and obstructive CAD. Multivariable logistic regression was used to identify independent predictors and derive a clinical risk score. Model discrimination was evaluated using receiver operating characteristic curve (ROC) analysis, and calibration was assessed using calibration plots and the Brier score. A total of 522 patients were included, of whom 74 (14.2%) had nonobstructive CAD. Four independent predictors were identified: female sex, absence of dyslipidemia, absence of ST-segment deviation, and absence of regional wall motion abnormalities. The model demonstrated good discrimination with an area under the ROC curve (AUC) of 0.804 (95% CI 0.747–0.861). Bootstrap internal validation (1000 resamples) showed minimal optimism, with an optimism-corrected AUC of 0.79. A cut-off score ≥ 5 yielded a sensitivity of 72.1%, specificity of 72.3%, and a negative predictive value of 94.4%. Nonobstructive CAD was observed in a substantial proportion of patients presenting with NSTEMI. A simple bedside clinical score demonstrated good discrimination and a high negative predictive value at the proposed cut-off, suggesting that the score may help raise suspicion for alternative mechanisms of myocardial injury (including MINOCA phenotypes) rather than serving as a definitive rule-out tool. The score should complement clinical judgment and requires external prospective validation.