Prognostic value of electrophysiologic investigations in Brugada syndrome

The prognostic value of electrophysiologic investigations in individuals with Brugada syndrome is unclear. Previous studies failed to determine its value because of a limited number of patients or lack of events during follow-up. We present data on the prognostic value of electrophysiologic studies in the largest cohort ever collected of patients with Brugada syndrome.

Two hundred fifty-two individuals with an ECG diagnostic of Brugada syndrome were studied electrophysiologically. The diagnosis was made because of a classic ECG with a coved-type ST segment elevation in precordial leads V1 to V3. Of the 252 individuals, 116 had previously developed spontaneous symptoms (syncope or aborted sudden cardiac death) and 136 were asymptomatic at the time of diagnosis. A sustained ventricular arrhythmia was induced in 130 patients (51%). Symptomatic patients were more frequently inducible (73%) than asymptomatic individuals (33%) (P = 0.0001). Fifty-two individuals (21%) developed an arrhythmic event during a mean follow-up of 34 +/- 40 months. Inducibility was a powerful predictor of arrhythmic events during follow-up both in symptomatic and asymptomatic individuals. Overall accuracy of programmed ventricular stimulation to predict outcome was 67%. Overall accuracy in asymptomatic individuals was 70.5%, with a 99% negative predictive value. Overall accuracy in symptomatic patients was 62%, with only a 4.5% false-negative rate. No significant differences were found in the duration of the H-V interval during sinus rhythm between symptomatic or asymptomatic individuals. However, the H-V interval was significantly longer in the asymptomatic individuals who became symptomatic during follow-up compared with those who did not develop symptoms (59 +/- 8 msec vs 48 +/- 11 msec, respectively; P = 0.04).

Inducibility of sustained ventricular arrhythmias is a good predictor of outcome in Brugada syndrome. In asymptomatic individuals, a prolonged H-V interval during sinus rhythm is associated with a higher risk of developing arrhythmic events during follow-up. Symptomatic patients require protective treatment even when they are not inducible. Asymptomatic patients can be reassured if they are noninducible.