Determinants of QRS Duration in Patients with Tetralogy of Fallot After Pulmonary Valve Replacement

Background: Following the repair of TOF patients may be left with pulmonary regurgitation and a dilated right ventricle (RV), which in turn can lead to ventricular arrhythmias and sudden death. A prolonged QRS is a predictor of ventricular arrhythmias. However, whether subsequent pulmonary valve replacement (PVR) can reverse QRS-prolongation is controversial. We hypothesized that changes in QRS duration following PVR are determined by preoperative QRS-duration and RV volumes METHODS: A retrospective single-center cohort study was conducted on 142 post-TOF repair patients (mean age 25 ± 13 years) who underwent PVR between 1995 and 2019. Information on QRS duration and RV volumes measured by cardiac MRI (available in 83 patients) were collected. A linear mixed model was used to investigate the association between the preoperative QRS duration and RV volumes and the postoperative QRS duration.

Results: The QRS-duration following PVR continued to increase in all subjects with a prolonged preoperative QRS-duration(>160 ms, rate of increase of 0.87 msec ± 0.33 per year; p = .01), markedly raised RV end-diastolic volume (RVEDV; ≥166 ml/m2, rate of increase of 2.0 msec ± 0.37 per year; p < .01) or RV end-systolic volume (RVESV; ≥89 ml/m , rate of increase of 1.25 msec ± 0.43 per year; p = .01). In contrast, in patients with preoperative QRS-duration <160 msec (p = .16), RVEDV <166 ml/m (p = .14), or RVESV < 89 ml/m2 (p = .37), the QRS-duration did not change significantly when compared to preoperative values.

Conclusions: In subjects with shorter QRS and smaller RV volumes, QRS duration did not show further prolongation following PVR. While markedly prolonged QRS and increased RV volumes were associated with a small but constant increase in QRS duration despite PVR.