Results of a large multicentre study found a ventricular effective refractory period of <200 ms and QRS fragmentation to be significant and independent predictors of arrhythmias in Brugada syndrome. The PRELUDE registry, a late-breaking clinical trial presented at Heart Rhythm 2011, the Heart Rhythm Society’s 32nd Annual Scientific Sessions, adopted for the first time a standardised programmed electrical stimulation protocol to test ventricular tachycardia/ventricular fibrillation (VT/VF) inducibility accuracy, and other predictors of cardiac events in a prospective fashion. While the predictive accuracy of VT/VF inducibility in Brugada syndrome has been debated for several years, results of this study showed that VT/VF inducibility is not a predictor of arrhythmic events.
The prospective study included 308 individuals, enrolled in 41 electrophysiology centres in Italy, who had a type I electrocardiogram (ECG) and did not have a history of cardiac arrest. During an average follow-up of 34 months, 14 arrhythmic events (4.5%) occurred, with 13 patients experiencing appropriate shocks and one patient being resuscitated from sudden cardiac arrest. Traditionally, VT/VF inducibility is widely used to select patients with Brugada syndrome to receive a prophylactic implantable defibrillator. However, in the results of the PRELUDE registry nine of the 14 patients were non-inducible, revealing that VT/VF inducibility during programmed electrical stimulation is not predictive of cardiac events.
“Our study, which is the largest experience using a standardised inducibility protocol to date, aimed to assess the predictive accuracy of VT/VF inducibility and to identify additional predictors of arrhythmic events in Brugada syndrome,” said Carlo Napolitano, Fondazione Maugeri, Pavia, Italy and New York University School of Medicine. “While our observations show that VT/VF inducibility was not a predictor of arrhythmic events in this patient group, we provided demonstration that QRS fragmentation and a ventricular refractory period can be considered novel robust risk stratification metrics.”
A ventricular effective refractory period <200 ms and QRS fragmentation were identified as two new significant and independent predictors of arrhythmic events in Brugada syndrome within a large cohort of patients prospectively investigated. Furthermore, a multivariate survivorship analysis reconfirmed the prognostic value of current known markers, the presence of spontaneous type I ECG and a history of syncope, by showing an increased risk of arrhythmic events.
Correct classification of subjects at risk of life-threatening arrhythmias is extremely important in Brugada syndrome. No pharmacological therapy is available and individuals identified at “high-risk” should receive an ICD.