Assessment of Microvolt T Wave Alternans in Children with Repaired Tetralogy of Fallot during 24-Hour Holter Electrocardiography.

Background We aimed to examine microvolt T wave alternans (MTWA) in 24-hour Holter electrocardiography (ECG) of children with repaired tetralogy of Fallot (TOF) to assess associations of MTWA with ventricular arrhythmias, ECG parameters, and echocardiographic findings. Methods Holter ECG records and archive files of 56 repaired TOF patients (62.5% male) who were analyzed retrospectively. Subjects’ ECG parameters and MTWA values were compared with age–sex-matched control group. T wave changes were analyzed by time-domain-modified moving average method from the three channels of 24-hour Holter ECG. Results Mean age was 123.4 ± 48.3 months. Median MTWA value was 55.5 μV in the control group, whereas 95.5 μV in patients group (P < 0.001). A significant weak positive correlation was found between the presence of ventricular extrasystoles and tricuspid regurgitation. There was no correlation between ECG parameters, echocardiographic findings, and MTWA. Conclusions MTWA was increased in children with repaired TOF as reported before. To our knowledge, this is the first study analyzing MTWA with 24-hour Holter ECG in repaired TOF patients.