T Wave Inversion: A Screening Tool for Rapidly Differentiating Acute Coronary Syndrome and Pulmonary Embolism

Introduction Acute coronary syndrome (ACS) and acute pulmonary embolism (PE) are life-threatening conditions with similar clinical presentations. As current diagnostic tools, such as computed tomography pulmonary angiography, for distinguishing between these two conditions are time-consuming and may not be available in all settings, we tried in this study to devise a diagnostic tool based on electrocardiography to distinguish between ACS and acute PE based on T wave features. Methods Medical records of patients with diagnoses of ACS and acute PE, who were referred to three hospitals affiliated with Shiraz University of Medical Sciences, Shiraz, Iran, from March 2019 to March 2021, were evaluated. One expert cardiologist read patients' electrocardiograms (ECGs). All ECGs were recorded at the standard 25 mm/s and 10 mm/mV. The sum of T wave inversion or TWI (mV) in consecutive leads, including anterior leads (V1, V2, V3, and V4), inferior leads (II, III, aVF), and lateral leads (I, aVL, V5, and V6) were calculated to estimate the cut-off points used to differentiate ACS versus acute PE. The receiver operating characteristic (ROC) curve was used to estimate the diagnostic accuracy of T wave changes. The Youden index was used to calculate the optimum cut-offs for sensitivity and specificity. Results Of 151 patients with a mean age of 55.44±12.88 years, 74 were in the acute PE and 77 were in the ACS groups. The results showed that the TWI sum in anterior leads >1.2 mV (P<0.001), in lateral leads >0.9 mV (P<0.001), in anterior-to-inferior leads ratio >12 (P<0.001), and V₄/V₁ leads ratio >4 (P<0.001) rules out acute PE. Anterior-to-lateral TWI ratio (AUC=0.807, sensitivity=70.3%, specificity=10%) was significantly distinctive among ACS and acute PE patients. Conclusion TWI sum in anterior leads >1.2 mV, in lateral leads >0.9 mV, in anterior-to-inferior leads ratio >12, and in V₄/V₁ leads ratio >4 rules out acute PE. The anterior-to-lateral TWI ratio obtained from patients' ECG was significantly distinctive among the patients and can be used as a screening tool.