Pulmonary Valve Replacement-Related Change in Biventricular Global Function Index in Repaired Tetralogy of Fallot

BACKGROUND: Reduced biventricular global function index (BVGFI) is associated with adverse outcomes in repaired tetralogy of Fallot (rTOF). The change in BVGFI associated with pulmonary valve replacement (PVR) is unknown. OBJECTIVES: To characterize BVGFI following PVR in rTOF and identify pre-PVR factors associated with severely depressed post-PVR BVGFI. METHODS: Single-center retrospective cohort study of rTOF patients with a cardiac magnetic resonance (CMR) examination within 1 year before and 2 years after their first PVR and no interval cardiac procedures (n=133). CMR parameters between rTOF and normal controls (n=136) were compared. BVGFI was categorized as normal (≥46.2), mild-moderately depressed (40.0-46.1), or severely depressed (<40.0). Pre- vs. post-PVR changes and pre-PVR correlates of severely depressed post-PVR BVGFI were explored. RESULTS: When adjusted for age and sex, pre-PVR BVGFI was lower in patients with rTOF compared to controls (47.7±0.6 vs. 56.0±0.5, p<0.001), with 48% of rTOF patients having subnormal pre-PVR BVGFI. Overall, compared with pre-PVR values, mean BVGFI did not change after PVR (46.6±7.7 vs. 45.6±6.7, p=0.28), while RVGFI declined from 49.6±10.2 pre-PVR to 46.1±9.0 post-PVR (p=0.003). Among patients with normal pre-PVR BVGFI (n=69), 64% remained normal, whereas 36% declined. Of those with severely depressed pre-PVR BVGFI (n=24), 50% remained severely depressed, and only 4% achieved normalization of BVGFI after PVR. Factors independently associated with severely depressed post-PVR BVGFI were lower pre-PVR BVGFI, male sex, moderate or severe pulmonary regurgitation (PR), and higher left ventricular end-systolic volume index (LVESVi). Type of pre-PVR hemodynamic load was not associated with the odds of severely depressed BVGFI post-PVR. CONCLUSIONS: BVGFI is depressed in about half of rTOF patients pre-PVR and did not significantly change post-PVR remaining stable in most patients. Lower pre-PVR BVGFI, male sex, moderate or severe PR, and higher LVESVi are independently associated with severely depressed post-PVR BVGFI.