Low T/R ratio in inferolateral leads: A new ECG marker of sudden cardiac arrest in patients with a spontaneous type 1 Brugada pattern

Abstract

Prediction of the individual risk of sudden cardiac arrest (SCA) remains the main challenge in Brugada syndrome. Several studies have shown that the surface electrocardiogram (ECG) can provide useful information that allows to estimate the risk of SCA. The T-wave amplitude is inversely correlated with the risk of ventricular fibrillation (VF) & SCA in several heart diseases. The purpose of this study was to evaluate the prognostic value of a low T/R ratio in patients with a spontaneous type-1 Brugada pattern (SBT1). In a multicenter study, we retrospectively reviewed 115 pts (105 males, 91.3%) with a SBT1. 45 had VF and/or SCA (38.7 ± 11.5 years old, all males), while 70 (49.3 ± 12.0 years, 10 women) remained free of ventricular arrhythmia. 6 ECG markers plus the lowest T/R ratio among leads V5 & II were studied. The lowest T/R ratio among leads II & V5 was significantly smaller in the VF/SCA group (0.26 ± 0.15 vs. 0.35 ± 0.16; P = 0.006). The optimized cut-off value was ≤ 0.17 by the receiver operating characteristic curve method. 44.4% of pts in the VF/SCA group had a lowest T/R ratio among leads II & V5 ≤ 0.17 compared to 11.4% in the non-VF/SCA group ( P < 0.001). In multivariate analysis, a lowest T/R ratio among leads II & V5 ≤ 0.17 was independently associated with VF/SCA (OR 6.10, 95% CI 1.92-19.40; P = 0.002). Type-1 Brugada pattern in a peripheral lead (OR 10.78) and early repolarization (OR 3.60) were the other independent ECG markers of VF/SCA ( Fig. 1 ). A low T/R ratio among leads II & V5 is independently and strongly related to the risk of VF/SCA in patients with a spontaneous type-1 Brugada pattern.