Introduction: The prognostic value of electrophysiologic studies in individuals with the syndrome of right bundle branch block and ST segment elevation in precordial leads V1 to V3 (Brugada syndrome) remains controversial. Our previous data from 252 individuals with the syndrome suggested that programmed ventricular stimulation had a good overall accuracy to predict events. However, studies from independent investigators questioned our results. We report here the largest population with Brugada syndrome ever studied by programmed electrical stimulation of the heart.
Methods and results: Four hundred forty-three individuals with an ECG diagnostic of Brugada syndrome were studied by programmed electrical stimulation of the heart. The diagnosis was made because of the classic ECG showing a coved-type ST segment elevation in precordial leads V1 to V3. Of the 443 individuals, 180 had developed spontaneous symptoms (syncope or aborted sudden cardiac death) and 263 were asymptomatic at the time the diagnosis was made. The ventricular stimulation protocol included a minimum of two basic pacing cycle lengths with two ventricular premature beats from the right ventricular apex. A sustained ventricular arrhythmia was induced in 217 cases (49%). Symptomatic patients were more frequently inducible [126/180 (70%)] than asymptomatic individuals [91/263 (34%); P = 0.0001]. Males were more frequently inducible than females (54% vs 32%, P < 0.0001). Inducible individuals had a longer HV interval than noninducible patients (50 +/- 12 msec vs 46 +/- 10 msec, P < 0.002). HV interval and number of premature beats needed to induce VF were not related to outcome. Inducibility was statistically a powerful predictor of arrhythmic events during follow-up. Sixty of 217 inducible patients (28%) had spontaneous ventricular fibrillation compared with 5 of 221 noninducible patients (2%; P = 0.0001).
Conclusion: Inducibility of sustained ventricular arrhythmias during programmed ventricular stimulation of the heart is a good predictor of outcome in Brugada syndrome.