Programmed Ventricular Stimulation in Brugada Syndrome
What is the utility of programmed ventricular stimulation (PVS) in risk stratification of patients with Brugada syndrome?
This was a systematic review and pooled analysis of eight prospective observational studies of Brugada syndrome patients without a history of sudden cardiac arrest who underwent PVS.
A total of 1,312 patients experienced 65 cardiac events (median follow-up of 38 months). A total of 527 patients were induced into arrhythmias with up to triple extrastimuli. Induction was associated with cardiac events during follow-up (hazard ratio, 2.66), with the greatest risk observed among those induced with single or double extrastimuli. Annual event rates varied substantially by syncope history, presence of spontaneous type 1 electrocardiographic (ECG) pattern, and arrhythmia induction. The lowest risk occurred in individuals without syncope and with drug-induced type 1 patterns (0.23% [no induced arrhythmia with up to double extrastimuli]); and the highest risk occurred in individuals with syncope and spontaneous type 1 patterns (2.55% [no induced arrhythmia]; 5.60%, [induced arrhythmia]).
In Brugada syndrome patients, arrhythmias induced with PVS are associated with future ventricular arrhythmia risk. Induction with fewer extrastimuli is associated with higher risk. However, clinical risk factors are important determinants of arrhythmia risk, and lack of induction does not necessarily portend low ventricular arrhythmia risk, particularly in patients with high-risk clinical features.
Apart from patients with a history of cardiac arrest, risk stratification in patients with Brugada syndrome is challenging. All data come from observational registries. Some studies suggest an association between induced ventricular tachycardia or ventricular fibrillation and subsequent cardiac events, whereas others do not. There are many reasons for this dichotomy. The inclusion criteria have varied a great deal (e.g., inclusion of survivors of cardiac arrest or not, drug-induced vs. spontaneous type 1 ECG pattern, varying sizes of the cohorts, and varied length of follow-up). The present study excluded patients who met the secondary prevention criteria for implantable cardioverter-defibrillator. Consistent with prior reports, the highest incidence of events occurred in patients with syncope and spontaneous type 1 ECG pattern; the lowest risk was found in asymptomatic patients with drug-induced type 1 ECG patterns. Programmed ventricular stimulation appeared to be helpful when limited to protocols, including up to double extrastimuli in the intermediate-risk group based on clinical factors.
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