QRS duration after pulmonary valve replacement in adults with repaired Tetralogy of Fallot: Prediction of ventricular arrhythmia and correlation with right ventricular size

Objectives The aim of this study is to analyze the relationship between QRS duration after pulmonary valve replacement (PVR) and ventricular arrhythmias (VA) in patients with repaired tetralogy of Fallot (ToF). Background ToF patients may face complications such as heart failure and VA after primary repair, often mitigated by PVR. Prior studies have shown a decrease in QRS duration and right ventricular (RV) size following PVR. It remains unclear whether a lack of QRS duration reduction identifies patients at risk of VA. Methods We retrospectively identified adult patients with repaired ToF who underwent surgical or transcatheter PVR. EKG data (pre-PVR, 30 days to 1-year post-PVR, and closest to CMR) was collected. The primary endpoint was sustained ventricular tachycardia (VT), ICD shock for sustained VT, or inducible VT on EP study. Results 85 patients were included (median follow-up 3.6 years; median age 34 years; 51% females). The primary outcome was noted in 8 patients. Mean QRS duration decreased by 5ms following PVR (p = 0.0001). Increased age at PVR, QRS ≥ 180ms post-PVR, no reduction in QRS after PVR, and a history of VT were associated with higher risk of the primary endpoint. The change in QRS was linearly correlated with the change in RVEDVi (R = 0.66). Conclusions Adults with repaired ToF experience a reduction in QRS duration post-PVR that correlates with the change of the RV size. Patients with QRS ≥ 180ms post-PVR, no reduction in QRS, increased age at repair, and a history of VT are at risk for recurrent VT and warrant closer monitoring/ICD consideration.