Electrocardiographic findings in children with different degrees of pulmonary regurgitation following surgical correction of tetralogy of Fallot

Background and aim: To analyse selected electrocardiographic (ECG) parameters in children after correction of tetralogy of Fallot (TOF). Methods: The study group consisted of 65 patients with surgically corrected TOF aged 6 to 18 years, and the time since surgical correction ranged from 6 to 18 years. The patients were divided into two groups based on the degree of pulmonary regurgitation (PR) in ECHO-2D. Group I consisted of patients with mild/moderate PR, and Group II of patients with severe PR. The QT dispersion in standard resting ECG, QRS complex width and QT interval duration at rest and at the maximal exertion during a treadmill test were compared between the two groups. Results: Group I included 52 patients and Group II included 13 patients. Mean QT dispersion was 67 +/- 27 ms in Group I vs 91 +/- 37 ms in Group II (p < 0.05). During the treadmill test, mean QRS duration at rest and at peak exertion in Group I was 128 +/- 27 ms and 119 +/- 27 ms, respectively, and 149 +/- 10 ms and 165 +/- 11 ms, respectively, in Group II (p < 0.003 and p < 0.001). Differences between QRS complex duration at peak exertion and at rest (Delta QRS) in Groups I and II were -9 +/- 12 ms and +14 +/- 7 ms (p < 0.001). During the treadmill test, mean QT interval at rest and at peak exertion in Group I was 392 +/- 52 ms and 328 63 ms, respectively, and 367 +/- 25 ms and 370 +/- 35 ms, respectively, in Group II (NS and p < 0.08). Differences between QT interval at peak exertion and at rest (Delta QT) in Groups I and II were -60 +/- 56 ms and +2 +/- 21 ms, respectively (p < 0.001). Conclusions: In children with severe PR after TOF correction, no physiological shortening of QRS duration and QT interval during exertion is seen. The QT dispersion in resting ECG is higher in children with severe PR than in children with mild/moderate PR.