Introduction: The prognostic value of electrophysiologic investigations in
individuals with Brugada syndrome is unclear. Previous studies failed to de
termine its value because of a limited number of patients or lack of events
during follow-up. We present data on the prognostic value of electrophysio
logic studies in the largest cohort ever collected of patients with Brugada
syndrome.
Methods and Results: Two hundred fifty-two individuals with an ECG diagnost
ic of Brugada syndrome were studied electrophysiologically. The diagnosis w
as made because of a classic ECG with a roved-type ST segment elevation in
precordial leads V-1 to V-3. Of the 252 individuals, 116 had previously dev
eloped spontaneous symptoms (syncope or aborted sudden cardiac death) and 1
36 were asymptomatic at the time of diagnosis. A sustained ventricular arrh
ythmia was induced in 130 patients (51%). Symptomatic patients were more fr
equently inducible (73%) than asymptomatic individuals (33%) (P=0.0001). Fi
fty-two individuals (21%) developed an arrhythmic event during a mean follo
w-up of 34 +/- 40 months. Inducibility was a powerful predictor of arrhythm
ic 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 6
2%, with only a 4.5% false-negative rate. No significant differences were f
ound in the duration of the H-V interval during sinus rhythm between sympto
matic or asymptomatic individuals. However, the H-V interval was significan
tly longer in the asymptomatic individuals who became symptomatic during fo
llow-up compared with those who did not develop symptoms (59 +/-8 msec vs 4
8 +/- 11 msec, respectively; P=0.04).
Conclusion: Inducibility of sustained ventricular arrhythmias is a good pre
dictor of outcome in Brugada syndrome. In asymptomatic individuals, a prolo
nged H-V interval during sinus rhythm is associated with a higher risk of d
eveloping arrhythmic events during follow-up. Symptomatic patients require
protective treatment even when they are not inducible. Asymptomatic patient
s can be reassured if they are noninducible.