Dr. Natarajan K. U.

INTRODUCTION: Risk stratification of asymptomatic patients with a Brugada type 1 ECG pattern remains an unresolved clinical conundrum. In contrast to provocative pharmacological testing in Brugada syndrome, there is limited data on the role of exercise stress testing as a risk stratification modality. The objective of this study was to evaluate the utility of exercise testing in asymptomatic patients with type 1 Brugada pattern to prognosticate major arrhythmic events(MAE) during follow-up.

METHODS AND RESULTS: Treadmill exercise testing was conducted for 75 asymptomatic patients with type 1 Brugada pattern and for 88 healthy control subjects. The clinical end point of MAE was defined as the occurrence of sudden cardiac death(SCD) or resuscitated ventricular fibrillation(VF). During a follow-up of 77.9±28.9 months, 8 MAE occurred(5 VF and 3 SCD). Multivariate Cox regression analysis showed that the following were independent predictors of MAE in asymptomatic patients with a type 1 Brugada pattern: increase in S wave upslope duration ratio >30% at peak exercise(HR 1.35, 95% CI 1.08-10.97,p = 0.023),augmentation of J point elevation in lead aVR> 2mm in late recovery(HR 1.88, 95% 1.21 - 15.67,p = 0.011) and delayed HR recovery(HR 1.14, 95% CI 1.06-18.22,p = 0.042). A high risk cohort was identified by the final step wise regression model with good accuracy (specificity = 98.4%,sensitivity = 62.5%) and discriminative power(AUC = 0.93,95%CI 0.89-0.96,p = 0.002). Kaplan Meier analysis revealed that there increasing MAE in subjects with one, two,or three predictors(log rank p<0.001).

CONCLUSIONS: Exercise testing in asymptomatic patients with Type 1 Brugada pattern aids in identification of high risk patients and provides a unique window of opportunity for early intervention. This article is protected by copyright. All rights reserved.