Aims: QRS prolongation is a negative prognostic factor for the development of ventricular arrhythmia after repair of tetralogy of Fallot (TOF). In this MRI study, we performed a multivariate analysis to determine the influence of volumetric and functional parameters as well as time factors on QRS duration.
Methods and results: Sixty-seven patients after surgical repair of TOF were studied using a 1.5T MRI. Measurement of the ventricles was performed with a multislice-multiphase sequence. Left and right ventricular volumes, ejection fractions (EF) and myocardial masses were determined. Pulmonary regurgitant fraction (PRF) was quantified by velocity encoded flow measurement in the main pulmonary artery. Maximum QRS duration was taken from a 12-channel ECG. Mean maximum QRS duration was 132 ms (+/- 29 ms). Mean PRF was 29.2% (+/- 13.4%). QRS duration correlated significantly with PRF (r = 0.49; p < 0.01; n = 54) and with right ventricular enddiastolic volume index (RVEDVI) (r = 0.29; p < 0.05; n = 67). Multivariate analysis revealed that the combination of PRF, postoperative period, age at surgical repair, and left ventricular (LV) enddiastolic volume are correlated with QRS prolongation.
Conclusion: In patients after repair of TOF, pulmonary regurgitation is related to QRS prolongation. Furthermore, even LV size plays a role in the enlargement of the QRS complex.