Identification of electrocardiographic risk markers for the initial and recurrent episodes of ventricular fibrillation in patients with Brugada syndrome

Introduction: New onset of ventricular fibrillation (VF) in asymptomatic patients with Brugada-type ECG is not frequent, but it cannot be negligible. Risk markers for predicting VF are usually based on results of analysis in symptomatic patients, and they have not been determined for asymptomatic patients. We analyzed ECG markers in patients with Brugada syndrome to differentiate the risk factors for VF in both symptomatic and asymptomatic patients. Methods: The subjects were 471 patients with Brugada syndrome and we divided the subjects into two groups: Asymptomatic group (n = 326) and Symptomatic group (syncope: n = 122, VF: n = 23). We analyzed the following ECG markers: RR, PQ, QRS, QT and Tpeak-Tend (Tpe) intervals, ST level, atrial fibrillation (AF), atrioventricular block, spontaneous type 1 ECG, early repolarization (ER) and fragmented QRS (fQRS). Results: During follow-up (91 ± 64 months), 41 patients experienced VF (Asymptomatic: n = 10, Symptomatic: n = 31). Univariable analysis showed that spontaneous type 1 ECG, Tpe interval (≥95 milliseconds), high ST level (≥0.52 mV) and fQRS were common predictors for VF in both the Asymptomatic and Symptomatic groups. In addition to the common risk factors, wide QRS (≥107 milliseconds), long QT interval (≥420 milliseconds), ER and AF were predictors for VF in Symptomatic group. Multivariable analysis of the Symptomatic group showed fQRS, Tpe and ER were independent predictors of prognosis. Conclusions: fQRS and Tpe interval are common risk factors for VF in both asymptomatic and symptomatic patients, whereas ER is a predictor for recurrent VF.