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.
M. Subramanian, Prabhu, M. A., Harikrishnan, M. S., Dr. Saritha Sekhar S., Pai, P. G., and Natarajan, K. Uma, “The Utility of Exercise Testing in Risk Stratification of Asymptomatic Patients with type 1 Brugada Pattern”, Journal of Cardiovascular Electrophysiology, vol. 28, no. 6, pp. 677-683, 2017.