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)?

Methods:

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.

Results:

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.

Conclusions:

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

Perspective:

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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