The Utility of Exercise Testing in Risk Stratification of Asymptomatic Patients With Type 1 Brugada Pattern.
BACKGROUND
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.


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, eight MAE occurred (five VF and three 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 >2 mm 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 increasing MAE in subjects with one, two, or three predictors, respectively (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.
Department of Cardiology at Amrita Institute of Medical Sciences, Amritha Vishhwavidhyapeetham, Ponekkara, Kochi, Kerala, India.
Muthiah
M
Subramanian
Department of Cardiology at Amrita Institute of Medical Sciences, Amritha Vishhwavidhyapeetham, Ponekkara, Kochi, Kerala, India.
Mukund A
MA
Prabhu
Department of Cardiology at Amrita Institute of Medical Sciences, Amritha Vishhwavidhyapeetham, Ponekkara, Kochi, Kerala, India.
Madhavankutty Santhakumari
MS
Harikrishnan
Department of Cardiology at Amrita Institute of Medical Sciences, Amritha Vishhwavidhyapeetham, Ponekkara, Kochi, Kerala, India.
Saritha S
SS
Shekhar
Department of Cardiology at Amrita Institute of Medical Sciences, Amritha Vishhwavidhyapeetham, Ponekkara, Kochi, Kerala, India.
Praveen G
PG
Pai
Department of Cardiology at Amrita Institute of Medical Sciences, Amritha Vishhwavidhyapeetham, Ponekkara, Kochi, Kerala, India.
Kumaraswamy
K
Natarajan
D000328:Adult; D019540:Area Under Curve; D058070:Asymptomatic Diseases; D053840:Brugada Syndrome / Q000150:complications / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D016022:Case-Control Studies; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D018572:Disease-Free Survival; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology
brugada syndrome; brugada type 1 pattern; exercise testing; risk stratification; sudden cardiac death