Prognostic significance of a low T/R ratio in Brugada Syndrome

Abstract

Abnormalities of myocardial repolarization may play a key role in the initiation of ventricular fibrillation (VF) in Brugada syndrome (BrS). Recent studies have shown that the height of the T-waves and the T/R ratio are inversely proportional to the sudden cardiac arrest (SCA) risk in early repolarization syndrome and hypertrophic cardiomyopathy. To study the prognostic value of a low T/R ratio in patients (pts) with a spontaneous Brugada type 1 pattern (SBT1). In an international retrospective study, we reviewed 115 pts (mean age 45.1 ± 12.8 years, 91.3% males) with SBT1. Forty-five presented a documented VF and/or SCA at a mean age of 38.7 ± 11.5 years, 20 came from a review of published cases reports. Six ECG markers and the T/R ratio in leads V5 and II were studied. A low T/R ratio was defined by < 0.2. The T/R ratio was significantly lower in pts with VF/SCA (lead V5: 0.28 ± 0.15 vs. 0.36 ± 0.17, P = 0.008; lead II: 0.47 ± 0.33 vs. 0.61 ± 0.51, P = 0.04). A low T/R ratio in lead V5 or II was significantly associated with VF/SCA (respectively 44.4% vs. 14.3%, P < 0.001 and 22.2% vs. 7.1%, P = 0.02). In multivariate analysis by logistic regression, a low T/R ratio in lead V5 was an independent marker of a higher risk of VF/SCA with an OR of 4.11 ( P = 0.02). Brugada type 1 pattern in peripheral leads, wide QRS in lead V2 and early repolarization were other independent risk markers (see Fig. 1 ). A low T/R ratio in lead V5 is an independent marker for VF/SCA risk in patients with a SBT1.