Abstract: Objective To investigate whether Tpeak-Tend interval (Tp-e) and Tp-e/QT ratio are associated with malignant ventricular arrhythmia in patients with implantable cardioverter-defibrillator (ICD) for primary prevention. Methods A cohort of 68 consecutive patients with chronic heart failure undergoing standard ICD for primary prevention indications (NYHA function class II-III, left ventricular ejection fraction ≤35% , systolic cardiomyopathy without prior malignant ventricular arrhythmia) were enrolled in this study. The patients were followed up for 18-48 months and were divided into high-risk group and low-risk group according to the occurrence of the endpoint events of sudden cardiac death (SCD), ventricular tachycardia (VT), or ventricular fibrillation (VF). Electrocardiographic and echocardiographic characteristics, Tp-e, and Tp-e/ QT ratio were analyzed in all cases before ICD implantation. Results During the follow-up, ICD shock for sustained ventricular tachycardia or ventricular fibrillation occurred in 11 patients; nonsustained ventricular tachycardia (NSVT) that did not require therapy was detected by ICD in 7 patients (high-risk group, 18 cases). ICD did not detect ventricular tachycardia or ventricular fibrillation in 50 patients (low-rsk group). Compared with the low-rsik group, the high-risk group had an increased Tp-e /QT ratio (0.27±0.04 vs 0.22±0.05 P<0.01) and an increased Tp-e (105±15 vs 90±17 ms P<0.01). ROC analysis revealed that a Tp-e/QT ratio ≥0.255 had a sensitivity of 72.2% and a specificity of 65.9%, and a Tp-e ≥103 ms had a sensitivity of 66.7% and a specificity of 67.9% for predicting VT and VF in these patients. Conclusion Increased Tp-e and Tp-e/QT ratio are associated with increased risks of ventricular arrhythmias in patients with ICD for primary prevention.