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

OBJECTIVES

In pulmonary valve replacement (PVR) after tetralogy of Fallot (TOF) repair, the right ventricular end-diastolic and end-systolic volume index (RVEDVI and RVESVI) of cardiac magnetic resonance imaging (cMRI) are often used as indicators of the RV volume. We examined the utility of QRS duration, cardiothoracic ratio (CTR), and plasma brain natriuretic peptide (BNP) as indicators of the appropriate timing of cMRI to assess the RV volume and function before PVR.

METHODS

We assessed the correlation of QRS duration, CTR, and BNP with RVEDVI and RVESVI on cMRI in 26 patients after TOF repair. Fifteen underwent PVR (age, 45.2 ± 11.4 years). Twelve underwent post-PVR cMRI. The RV volume change from before to after PVR was investigated.

RESULTS

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 5 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 7 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.

CONCLUSIONS

A prolonged QRS duration is a useful marker of RVEDVI and RVESVI enlargement after TOF repair. We recommend performing cMRI before the QRS duration reaches 160 ms due to normalization of the RV volume after PVR.