Marker of Sudden Death: S-Wave in Lead I in Brugada Syndrome

Study Questions:

Other than the classic Brugada pattern, are there any other electrocardiographic markers of sudden cardiac death (SCD) in patients with the Brugada Syndrome (BrS)?


The subjects of this retrospective study were 347 patients (mean age 45 years) with a type I BrS pattern on the electrocardiogram. The electrocardiograms recorded at the time of referral were analyzed. One hundred eighty-six patients underwent programmed ventricular stimulation and 12 patients underwent detailed voltage mapping.


During a mean follow-up of 45 months, 79.5% of patients were asymptomatic, 11.2% had syncope, and 9.2% had ventricular fibrillation (VF)/SCD. An S-wave was present in lead I in 56% of asymptomatic patients, 51% of patients with syncope, and 97% of patients with VF/SCD. An S-wave amplitude ≥0.1 mV, duration ≥40 ms, and area ≥1 mm2 had negative predictive values of 98.5-99.5% and positive predictive values between 19.6% and 23.2% for VF/SCD during follow-up. The strongest independent predictors of VF/SCD were an S-wave duration ≥40 ms in lead I (hazard ratio [HR], 38) and an S-wave area ≥1 mm2 in lead I (HR, 17.1). Endocardial activation times were significantly longer in the right ventricular outflow tract (RVOT) among patients with than without an S-wave in lead I.


A wide or large S-wave in lead I is a strong predictor of VF/SCD in patients with a type I BrS pattern.


The presence of an S-wave in lead I was not an accurate predictor of VF/SCD in this study. However, the results indicate that the absence of a prominent S-wave in lead I accurately identifies a very low-risk group of BrS patients that is unlikely to benefit from an implantable cardioverter-defibrillator.

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