Background <p>In about 8% of survivors of sudden cardiac death, no structural or electrical heart disease can be identified. Some of these patients with idiopathic ventricular fibrillation (IVF) present ECG markers of early repolarization (Early Repolarization Syndrome, ERS). The <i>T</i>_peak–<i>T</i>_end interval has been linked to increased arrhythmic risk in different clinical settings, such as Brugada syndrome or hypertrophic cardiomyopathy. As there is limited data about the relationship of <i>T</i>_peak–<i>T</i>_end and arrhythmogenesis in IVF, respectively, its significance in risk stratification in ERS, the aim of this study was to investigate a possible correlation between sustained ventricular arrhythmia (VA) recurrences in these patients and the <i>T</i>_peak–<i>T</i>_end interval.</p> Methods and results <p>We retrospectively investigated 56 consecutive IVF patients (64.3% male, mean age 37.8 ± 12.9 years) who received an implantable cardioverter–defibrillator for secondary prevention. Markers of early repolarization were present in 32.1% of cases. During a mean follow-up of 41.2 ± 35.8 months, 11 patients (19.6%) received in total 18 adequate ICD-therapies. Patients with VA recurrence showed longer <i>T</i>_peak–<i>T</i>_end compared to arrhythmia-free patients (105 ± 14 ms vs. 91 ± 14 ms, <i>p</i> = 0.03). The combination of prolonged <i>T</i>_peak–<i>T</i>_end (&gt; 90 ms) and an early repolarization pattern was associated with a 12-fold increased risk of recurrent VA (<i>p</i> = 0.002).</p> Conclusion <p>Prolonged <i>T</i>_peak–<i>T</i>_end was associated with VA recurrence in patients with survived IVF. This correlation was even more pronounced in IVF patients with early repolarization pattern. The <i>T</i>_peak–<i>T</i>_end interval might play a future role in risk stratification of patients with ERS.</p> Graphical abstract <p></p>