Optimal Use of Z-Scores to Preserve the Pulmonary Valve Annulus During Repair of Tetralogy of Fallot [1]
Awori and colleagues reviewed 19 published studies on repair of tetralogy of Fallot (TOF), representing 2,500 patients of which 54.8% had a transannular patch (TAP) inserted to relieve right ventricular outflow tract obstruction. The measured pulmonary annulus size, expressed as a z-score, is often used to determine when to insert a TAP, however similar z-scores derived via different methods can represent different annulus sizes and flow rates. Multiple suggested z-score “cut-offs” are quoted in the literature, and the authors wanted to know whether differences in z-score calculation methods were related to these different cut-off values. Surprisingly few studies (26.3%) mention what pulmonary annulus size “cut-off” was used, but the authors conclude that derivation of z-scores from different data sets may contribute to different cut-off values.