The purpose of this study was to analyze the changes of the late potential of Signal-averaged electrocardiography (SAECG) and Electrocardiography (ECG) parameters during follow up of those who had taken surgical repair of Tetralogy of Fallot (TOF).

Nine patients who had taken surgical repair of TOF since 1985 checked SAECG and standard 12 leads ECG twice in 1999 and 2005 in Kyungpook national university hospital. We evaluated changes of QRS duration, QT interval and JT interval, QRS dispersion, QT dispersion and JT dispersion of standard 12 leads ECG and Filtered QRS (f-QRS), High frequency low amplitude potential (HFLA), Root mean square in terminal 40 ms (RMS) and Mean voltage in terminal 40 ms (MV) of SAECG between in 1999 and 2005.

There were significant decrease of JT dispersion (101.11±50.11 vs 71.11±22.61 ms, P <0.05) and significant increase of HFLA (24.67±13.19 vs 32.89±14.21 ms, P <0.05). But there were no significant changes in other parameters.

In repaired TOF patients, we evaluated ECG and SAECG to detect possible late complications such as tricuspid regurgitation, right ventricular enlargement, ventricualar arrythmia and sudden death. And there were significant changes of ECG and SAECG in some parameters (JT dispersion, HFLA). But to see the relationships between the changes of these parameters and the long term prognosis, we need to check more patients and longer follow-up.