There is a lack of consensus regarding the preoperative pulmonary valve (PV) Z-score "cut-off" in tetralogy of Fallot (ToF) patients to attempt a successful valve sparing surgery (VSS). Therefore, the aim of this study was to review the available evidence regarding the association between preoperative PV Z-score and rate of re-intervention for residual right ventricular outflow tract (RVOT) obstruction, i.e. successful valve sparing surgery. A systematic search of studies reporting outcomes of VSS for ToF was performed utilizing PubMed, EMBASE, and Scopus databases. Patients with ToF variants such as pulmonary atresia, major aortopulmonary collaterals, absent pulmonary valve, associated atrioventricular septal defect, and discontinuous pulmonary arteries were excluded. Out of 712 screened publications, 15 studies met inclusion criteria. A total of 1091 patients had surgery at a median age and weight of 6.9 months and 7.2 kg, respectively. VSS was performed on the basis of intraoperative PV assessment in 14 out of 15 studies. The median preoperative PV Z-score was -1.7 (0 to -4.9) with a median re-intervention rate of 4.7% (0-36.8%) during a median follow-up of 2.83 years (1.4-15.8 years). Quantitatively, there was no correlation between decreasing preoperative PV Z-scores and increasing RVOT re-intervention rates with a correlation coefficient of -0.03 and an associated p-value of 0.91. In observational studies, VSS for ToF repair was based on intraoperative evaluation and sizing of the PV following complete relief of all levels of obstruction of the RVOT, rather than pre-operative echocardiography derived PV Z-scores.
Keywords: pulmonary stenosis; pulmonary valve Z-score; right ventricular outflow tract obstruction; tetralogy of Fallot; valve sparing surgery.