gms | German Medical Science

The Brugada Syndrome is characterized by ST segment elevation in the right precordial leads (V1-V3) in ECG and development of ventricular fibrillation (VF) in apparently healthy individuals. Thus patients with the Brugada syndrome have a high risk for sudden cardiac death (SCD). While there are many individuals showing ST elevation in V1-V3 without developing VF, diagnostic criteria to identify the Brugada syndrome and to predict potential risk for SCD has not been established. ESC Working Group of Arrhythmia has presented two consensus reports proposing diagnostic criteria and risk stratification, but it is not certain whether the two proposed criteria can identify patients with the Brugada syndrome from those exhibiting Brugada-type ECG and predict high risk patients from those without history of developing VF. We conducted the group study in Japan to characterize potentially high risk patients among cases showing the Brugada-type ECG changes. Two-hundred and seventeen cases were enrolled, and were divided into 3 groups, documented VF Group (V), Syncope Group without documentation of VF (S) and Asymptomatic Group (A). Their clinical characteristics including ECG signs and electrophysiological evaluation were compared among 3 groups, and they were followed for a median of 33.5 months. Our results demonstrated that V and S groups had longer QRS intervals in V2 and V6 than those in A group, higher incidences in paroxysmal atrial fibrillation, but no differences in family history of SCD, positive VF induction by EPS and positive late potentials among 3 groups. Drug challenge was performed in 89 patients and 13 cases developed cardiac events (syncope 1, VT/VF 11 and SCD 1) during follow-up period. All the 13 cases belonged to symptomatic groups (V + S). Among 13 cases, conversion to Type 1 ECG by drug challenge was observed only in 3 and others did not exhibit Type 1 ECG changes. They were saddle-back type or undifferentiated type from the proposed criteria. Therefore, appearance of Type 1 ECG by drug challenge is not predictable for cardiac events in subjects with Brugada-type ECG and the association of clinical signs with documented VT/VF and syncope are important signs in risk stratification for cardiac events and SCD.