Comparison of long-term follow-up of electrocardiographic features in Brugada syndrome between the SCN5A-positive probands and the SCN5A-negative probands.

To investigate changes of electrocardiographic parameters with aging and their relation to the presence of SCN5A mutation in probands with Brugada syndrome (BS), we measured several electrocardiographic parameters prospectively during long-term follow-up (10 +/- 5 years) in 8 BS probands with SCN5A mutation (SCN5A-positive group, all men; age 46 +/- 10 years) and 36 BS probands without SCN5A mutation (SCN5A-negative group, all men; age 46 +/- 13 years). Throughout the follow-up period, depolarization parameters, such as P-wave (lead II), QRS (leads II, V(2), V(5)), S-wave durations (leads II, V(5)), and PQ interval (leads II) were all significantly longer and S-wave amplitude (II, V(5)) was significantly deeper in the SCN5A-positive group than in the SCN5A-negative group. The SCN5A-positive group showed a significantly longer corrected QT interval (lead V(2)) and higher ST amplitude (lead V(2)) than those in the SCN5A-negative group. The depolarization parameters increased with aging during the follow-up period in both groups; however, the PQ interval (lead II) and QRS duration (lead V(2)) were prolonged more prominently and the QRS axis deviated more to the left with aging in the SCN5A-positive group than in the SCN5A-negative group. In conclusion, conduction slowing was more marked and more progressively accentuated in Brugada probands with SCN5A mutation than in those without SCN5A mutation.