Ventricular repolarization heterogeneity on the admission electrocardiogram in acute coronary syndrome: relationship of the Tpeak–Tend interval and Tp-e/QTc ratio to angiographic complexity, clinical risk and six-month outcome

Background: Repolarization heterogeneity underlies malignant arrhythmia in acute coronary syndrome (ACS). We examined whether the admission Tpeak–Tend (Tp-e) interval and Tp-e/QTc ratio track angiographic complexity, clinical risk and six-month outcome. Methods: We prospectively enrolled 250 consecutive patients with ACS at a single tertiary centre. Hodges-corrected QT, Tp-e and Tp-e/QTc were measured in leads V4–V6 on the admission electrocardiogram, with echocardiography, angiography and SYNTAX/GRACE scoring. The composite outcome comprised ventricular arrhythmia, heart failure, cardiogenic shock and death. Results: Interobserver agreement was excellent (ICC 0.99–1.00). All three indices rose incrementally across SYNTAX and GRACE categories (P < 0.001). Tp-e correlated with SYNTAX (r = 0.786) and GRACE (r = 0.645), and both scores were independently associated with Tp-e/QTc (β = 0.616, P < 0.001 and β = 0.167, P = 0.008). Tp-e ≥ 125 ms identified a high SYNTAX (AUC 0.945) and a high GRACE (AUC 0.924) score. The composite outcome occurred in 48 patients (19.2%). Event-free survival was lower with QTc prolongation and an abnormal Tp-e/QTc (log-rank χ² 25.86 and 15.61; P < 0.001). On Cox regression, Tp-e/QTc (HR 1.111, 95% CI 1.017–1.213) and ejection fraction (HR 0.948, 95% CI 0.922–0.976) remained independent predictors (P = 0.019 and P < 0.001). Adding Tp-e to GRACE improved prediction (IDI 0.044, P = 0.027; continuous NRI 0.235, P = 0.020). Conclusions: In ACS, Tp-e and Tp-e/QTc increase with anatomical and clinical severity, and Tp-e/QTc independently predicts six-month events. By refining GRACE-derived prognostic information, these indices merit consideration in early risk stratification.