Ventricular Late Potential in Patients with Apparently Normal Electrocardiogram; Predictor of Brugada Syndrome

Backgrounds: Brugada syndrome can be overlooked due to its dynamic change in its electrocardiogram (ECG) manifestation. We hypothesized that positive ventricular late potential (VLP) in patients with nonspecific ECG would predict the inducible coved ST elevation (type-1 Brugada ECG) and the patients at high risk. Methods: Thirty-four patients of nonspecific ECG without structural heart disease were eligible for this study. All patients were referred for evaluation of syncopal episodes and/or cardiac arrest and/or frequent episodes of ventricular premature contractions. We assessed the correlation between baseline VLP and the alteration to a drug-induced type-1 Brugada ECG, and also evaluated the diagnostic accuracy of positive VLP in normal ECG subjects for the appearance of a drug-induced type-1 Brugada ECG. Results: Twenty-one patients presented positive VLP and 13 patients showed negative VLP. Parameters of VLP (fQRSd, RMS(40), LAS(40)) presented significant correlation with the alteration to a type-1 ECG by pilsicainide. VLP demonstrated high sensitivity and negative predictive value for the prediction of type-1 Brugada ECG. Furthermore, in their follow-up, at least two cases of ventricular fibrillation were recognized in 21 of positive VLP patients with apparently normal ECGs. Conclusions: VLP in apparently normal ECG can predict the alteration to a drug-induced type-1 Brugada ECG and unmask the patients at risk. (PACE 2010; 33:266-273)