QRS–T Angle and High-Sensitivity Troponin in the Early Diagnosis of Non–ST Segment Elevation Myocardial Infarction in the Emergency Department

Background : Non-ST segment elevation myocardial infarction (NSTEMI) poses significant diagnostic challenges in the emergency department, primarily due to reliance on delayed high-sensitivity troponin results. The QRS–T angle, reflecting myocardial electrical heterogeneity, may serve as an early adjunctive marker to support clinical decision-making and facilitate timely identification of higher-risk patients Methods : In this prospective cohort, 604 patients presenting with suspected NSTEMI were evaluated. Demographic, clinical, and electrocardiographic parameters were documented at admission, and the frontal QRS–T angle was automatically derived from 12-lead ECGs. Serial high-sensitivity troponin T measurements and coronary angiography findings were recorded. The associations of the QRS–T angle with troponin-defined risk groups and angiographic involvement were systematically analyzed, providing an integrated assessment of its diagnostic value in the acute setting. Results : The QRS–T angle demonstrated a stepwise increase with angiographic severity: patients with single-vessel disease had a mean angle of 61.2°, whereas those with multivessel disease exhibited significantly higher values of 78.0° (p<0.001). QRS–T angle also correlated positively with serial high-sensitivity troponin T concentrations and stratified patients across troponin-based risk categories. A cutoff of 24.5° effectively identified moderate-to-high risk patients, with AUC values of 0.690 and 0.713 for the first and second troponin measurements, respectively. In patients with low initial troponin values (3–14 ng/L), QRS–T angles were significantly higher in those with angiographic involvement compared to those without lesions (59.3° vs. 31.0°, p=0.043) Conclusions The frontal QRS–T angle demonstrated significant associations with both troponin levels and angiographic severity in NSTEMI patients. Increasing QRS–T angles paralleled higher biomarker concentrations and more extensive coronary involvement. These findings suggest that the QRS–T angle may serve as a rapid and easily obtainable parameter of myocardial stress, complementing troponin testing and supporting early risk assessment in the emergency department.