ObjectiveTo investigate if the ratio of pulmonary valve annulus, which is the proportion of pulmonary valvular annulus size to total size of aortic valvular annulus and pulmonary valvular annulus, can better guide the choice of surgical approach than the value of z.MethodsA retrospective analysis was made for 254 patients who underwent total correction of tetralogy of Fallot in Guangdong General Hospital between January 2016 and January 2018. There were 154 males and 100 females with an average age of 14.60±18.76 years. The patients were categorized into two groups, a transannular patch group (TAP, n=164) and a non-TAP group (n=90). The sizes of pulmonary and aortic valvular annulus were evaluated in each group, and the cutoff value of proportion of pulmonary valvular annulus for TAP was calculated.ResultsBoth proportion of pulmonary valvular annulus and z-scores were smaller in the TAP group than those in the non-TAP group (0.29±0.06 vs. 0.36±0.06, P<0.001; –4.04±2.13 vs. –2.06±1.84, P<0.001, respectively). In receiver operating characteristics analyses, proportion of pulmonary valvular annulus and the z-score cutoff values were 0.353 (area under the curve 0.781, 95%CI 0.725–0.831) and –2.13 (area under the curve 0.766, 95%CI 0.709–0.817), respectively, demonstrating that the proportion of pulmonary valvular annulus was a more powerful diagnostic tool as a predictor of TAP.ConclusionOur results suggest that the proportion of pulmonary valvular annulus is an effective predictor for TAP and can be easily applied to clinical practice.