Background Neither the clinical characteristics nor risk stratification of symptomatic and asymptomatic patients with Brugada syndrome have been clearly determined. We compared clinical and ECG characteristics of symptomatic and asymptomatic patients with Brugada syndrome to identify new markers for distinguishing high- from low-risk patients.
Methods A total of 216 consecutive individuals with Brugada syndrome (mean age 52±14 years, 197 males) were enrolled in the Japan Idiopathic Ventricular Fibrillation Study (J-IVFS). Clinical and ECG characteristics were compared among 3 groups of patients: VF group; patients with aborted sudden death and documented VF (N=34), Syncope (Sy) group; patients with syncope without documented VF (N=70), and Asymptomatic (As) group; subjects without symptoms (N=112). Comparisons were made among the 3 groups as well as between the symptomatic (VF/Sy) and asymptomatic (As) groups. Short-term prognosis was also compared among the 3 groups, and between the VF/Sy and As groups.
Results 1) Clinical characteristics: incidence of past history of AF was significantly higher in the VF and Sy groups than in the AS group (26, 26, and 12 %, respectively; [p=0.04]), though no other clinical parameters differed among the groups. 2) On resting 12-lead ECG, r-J interval (interval from QRS onset to J point) in lead V2 and QRS duration in lead V6 were highest in the VF group (104, 98, and 92 msec in V2 [p<0.001]; 106, 103, and 94 msec in V6 [p<0.0001], respectively, VF vs. Sy vs. As). 3) Positive late potential and inducibility of VF by EPS did not differ in incidence among the 3 groups. 4) Clinical follow-up: during a mean follow-up of 36±16 months, incidence of cardiac events (sudden death and/or VF) was higher in the VF/Sy groups than in the As group (29, 8, and 0 %, respectively [p<0.001]). Multivariate analysis showed that the frequencies of r-J interval ≥ 90 msec in lead V2 and QRS duration ≥ 90 msec in lead V6 were significantly higher in patients with cardiac events (p=0.02, 0.02, respectively).
Conclusions In symptomatic patients, prolonged ventricular depolarization in precordial leads of the ECG was prominent in the VF group, and this sign can be used to distinguish high- from low-risk patients with Brugada syndrome.
Meta-Analysis of Risk Stratification of SCN5A With Brugada Syndrome: Is SCN5A Always a Marker of Low Risk?