Optimal Use of Z-Scores to Preserve the Pulmonary Valve Annulus During Repair of Tetralogy of Fallot.

Abstract

The size of the pulmonary annulus measured as a z-score is often used to determine when to insert a transannular patch (TAP). Multiple "cutoffs" are quoted in the literature; this could lead to inappropriate insertion. We aimed to determine whether the use of z-scores derived from different populations may have contributed to the varied "cutoffs" quoted. PubMed was searched using the terms: "tetralogy," "Fallot," "transannular," "patch," "mortality," and "death." Studies published between January 1, 2005, and October 5, 2017, were included; studies without participants under the age of 18 years and studies that did not describe the operative procedure were excluded. Of 52 papers retrieved, 19 were included representing 2,500 repaired patients; 1,371 (54.8%) had a TAP. Five (26.3%) papers representing 638 patients (25.5%) quoted a z-score "cutoff" and what data set was used; "cutoffs" ranged from -2 to -4 and were derived from 2 different data sets. Three studies quoted a data set that has been shown in previous work to be problematic; the only quoted "cutoffs" of -4 were from two of these studies. Surprisingly few (26.3%) studies mention what pulmonary annulus size "cutoff" was used to decide when to insert a TAP. Z-scores derived from different populations were used by different studies and it is possible that this may have contributed to the varied "cutoffs' quoted. Recommendations to perform valve-sparing surgery in pulmonary annuli as small as -4 may not be warranted. Future papers should record "cutoffs" employing recommended z-score data set.