Dynamic changes in ventricular depolarization during exercise in patients with Brugada syndrome

Area of Science:

• Cardiology
• Electrophysiology
• Medical Diagnostics

Background:

• Brugada syndrome (BS) is a genetic disorder linked to sudden cardiac death (SCD).
• Ventricular depolarization abnormalities are implicated in SCD risk for BS patients.
• Differentiating symptomatic and asymptomatic BS patients is crucial for risk stratification.

Purpose of the Study:

• To analyze dynamic changes in ventricular depolarization during exercise in symptomatic and asymptomatic BS patients.
• To identify electrophysiological markers that distinguish between symptomatic and asymptomatic BS populations.
• To develop a predictive model for risk stratification in BS patients.

Main Methods:

• 110 BS patients (25 symptomatic) underwent standardized exercise stress tests with 12-lead ECG.
• Ventricular depolarization features, including QRS duration and wave slopes, were automatically extracted.
• Logistic regression analysis was used to identify discriminating features and build a predictive model.

Main Results:

• Asymptomatic patients exhibited greater changes in the latter half of the QRS complex, particularly during recovery.
• An initial multivariate model identified QRS up-stroke slope in lead V2, sex, and heart rate recovery as significant predictors.
• An adjusted model, focusing on the QRS up-stroke slope in lead V2, achieved high discrimination (84% sensitivity, 100% specificity, AUC 94%).

Conclusions:

• Physical exercise testing effectively reveals distinct depolarization dynamics between symptomatic and asymptomatic BS patients.
• The QRS up-stroke slope in lead V2 during exercise stress testing is a key indicator for risk stratification in BS.
• This analysis and model may aid in identifying asymptomatic BS patients at high risk for cardiac events, warranting further validation.