Association between the number of altered late potential criteria and increased arrhythmic risk in Brugada syndrome patients.

BACKGROUND: Brugada syndrome (BrS) is associated with abnormal electrophysiological properties at right ventricular epicardium, consisting of fragmented electrograms extending well beyond QRS termination. We aimed to evaluate the utility of signal-averaged electrocardiogram (SA-ECG) for the noninvasive assessment of late potentials (LP) and risk stratification of BrS patients. METHODS: A prospective, observational, single-center study of BrS patients is submitted to SA-ECG with the determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40 ms terminal portion of the QRS (RMS40), and duration of the low-amplitude electric potential component of the terminal portion of the QRS (LAS40). LP were considered positive when above standard cut-offs: fQRS > 114 ms, RMS40 < 20 µV, and LAS40 > 38 ms. The rates of malignant arrhythmic events (MAEs), defined as sudden death or appropriate shocks, were compared in relation to clinical characteristics and SA-ECG findings. RESULTS: A total of 106 BrS patients (mean age, 48 ± 12 years, 67.9% male) were studied, 49% with type-1 spontaneous pattern and 81% asymptomatic. During a median follow up of 4.7 years, 10 patients (7.1%) suffered MAEs, including 4 sudden deaths. The presence of LP was significantly associated with the arrhythmic risk, which increased with the number of altered LP criteria. In comparison to the patients who had none or 1 altered LP criterium, MAE risk was 4.7 times higher in those with 2 altered criteria and 9.4 times higher in those with 3 altered LP criteria. CONCLUSIONS: SA-ECG may be a useful tool for risk stratification in BrS. The presence of 2 or 3 abnormal LP criteria could identify a subset of asymptomatic patients at high risk of arrhythmic events.