OBJECTIVES: The present study was designed to establish possible predictors of unfavorable outcome in infants with pulmonary valve stenosis. BACKGROUND: Balloon pulmonary valvuloplasty is the treatment of choice for typical pulmonary valve stenosis. Patients with dysplastic valves may be less suitable candidates for this procedure because they have morphologic abnormalities of the complex valve-anulus-trunk that cause the obstructive phenomenon. METHODS: Twenty-five children (mean age +/- SD 1.1 +/- 0.7 years) with normal anulus diameter underwent balloon pulmonary valvuloplasty using a balloon/anulus ratio of 1.2 +/- 0.11. From the lateral view of a right ventricular angiogram, the following variables were quantified and scored: A, supravalvular narrowing; B, texture of the valve surface; C, diastolic deformity of the Valsalva sinuses; D, trunk/anulus ratio; E, systolic valve motion; and F, presence of a contrast jet. Paired t test, stepwise multivariate correlation with "dummy" variable methods were applied for both hemodynamic and valve-anulus-trunk determinations. RESULTS: The right ventricular-pulmonary artery gradient decreased from 66 +/- 21 (range 40 to 120) to 24 +/- 11 (range 10 to 50) mm Hg (p less than 0.001), whereas the right ventricular systolic pressure decreased from 89 +/- 20 (range 60 to 130) to 48 +/- 15 (range 30 to 80) mm Hg (p less than 0.001). Only variables A, B and D had significant influence in a percent reduction in right ventricular pulmonary artery gradient (R2 0.94, SEE 5.7; p less than 0.001). A score greater than or equal to greater than 4 obtained by adding the values from these three variables was correlated with poor outcome. CONCLUSIONS: These data show that there is an adequate relation between scores and outcome. We conclude that children less than 2 years old with pulmonary valve stenosis and a score greater than or equal to 4 should not be candidates for balloon pulmonary valvuloplasty.