Introduction: In about 8% of people who survived sudden cardiac death no structural or electrical heart disease can be identified. Early repolarization pattern (ERP) has been associated with idiopathic ventricular fibrillation (IVF) and with cardiovascular mortality in the general population. As there is limited data about medium and long- term outcome of IVF, the aim of our single-center study was to observe sustained ventricular arrhythmia (VA) recurrences in these patients and to identify a possible correlation of VA with ECG markers of early repolarization. 

Methods: In this study, we retrospectively investigated 56 consecutive IVF patients (64.3% male; mean age 37.6 years) who received an implantable cardioverter-defibrillator (53.8% S-ICD) for secondary prevention. All patients received coronary angiography and cardiac magnetic resonance imaging without evidence of underlying structural heart disease. Besides, LQT, SQT and Brugada syndrome, as well as CPVT were excluded.  In accordance with previous studies ERP was defined as J-point elevation ≥ 0.1 mV in two or more contiguous inferior or lateral leads and divided into QRS slurring or notching.

Results: Markers of early repolarization were present in 32.1% of cases with a preponderance of QRS slurring (77.8%) compared to QRS-notching (22.2 %). During a mean follow-up of 41.2 months 11 patients (19.6%) received in total 18 adequate ICD-therapies. VF was most the common cause for ICD-therapy (61.1%) but monomorphic or polymorphic VT also occurred in four, respectively one patient. Presence of ERP was associated with a significant trend towards higher arrhythmia recurrences. 7 of 18 patients with ERP (38.9%) received 12 ICD-therapies over a mean follow-up of 38.9 month (1.7 therapies /100 patient years) whereas only 4 of 38 patients (10.5%) without ERP had arrhythmia recurrence (0.38 therapies/100 patient years) (p= 0.011). No difference between specific pattern of ERP (QRS-slurring vs. QRS-notching) with regard to arrhythmic burden was observed. In total, 8 inappropriate ICD-therapies occurred in 7 patients (12.5%) with a non-significant trend towards a higher incidence of inappropriate ICD-therapies in patients with a transvenous ICD (p=0.19).

Conclusion: Early repolarization pattern occurs frequently in patients with idiopathic ventricular fibrillation. Overall, the recurrence rate of VT/VF seems to be low compared to other secondary-prevention ICD populations. However, a significant correlation between ERP and ventricular arrhythmia recurrences could be observed in this cohort. Interestingly, fast monomorphic VA might also play a role in the studied IVF-population, but nevertheless our data support the use of the subcutaneous ICD in this collective.