Is the QRS duration useful for determining the optimal timing of pulmonary valve replacement after tetralogy of Fallot repair?

In pulmonary valve replacement (PVR) after tetralogy of Fallot (TOF) repair, it is recommended that PVR be performed before the right ventricular end-diastolic volume index (RVEDVI) reaches 170 ml/m 2 on cardiac magnetic resonance imaging (cMRI) to normalize the RV volume after PVR. We examined the utility of QRS duration, cardiothoracic ratio (CTR), and plasma brain natriuretic peptide (BNP) as markers of an enlarged RV volume to perform PVR at the optimal timing. We assessed the correlation of QRS duration, CTR, and BNP with RVEDVI and RVESVI on cMRI in 26 patients after TOF repair. Fifteen patients underwent PVR (age, 45.2 ± 11.4 years). The RV volume changes from before to after PVR were investigated. Twelve patients underwent post-PVR cMRI. QRS duration, BNP, and CTR were positively correlated with RVEDVI and RVESVI after TOF repair. The post-PVR QRS duration was also positively correlated with post-PVR RVEDVI (p = 0.017) and RVESVI (p = 0.001). From before to after PVR, in cases with QRS duration ≤ 160 ms, the QRS duration decreased from 110.4 ± 28.9 to 101.8 ± 30.5 ms (p = 0.063). Both RVEDVI and RVESVI decreased to the normal range in 4 of 5 cases. In contrast, in cases with QRS duration > 160 ms, the QRS duration decreased from 183.0 ± 17.4 to 160.3 ± 23.8 ms (p = 0.013); however, RVESVI did not normalize in 6 of 7 cases. A prolonged QRS duration is a useful marker of RVEDVI and RVESVI enlargement after TOF repair. A QRS duration of 160 ms is a sensitive cutoff value for predicting RV volume normalization after PVR.