Abstract 11634: Risk Factors for Mortality in the Single Ventricle Reconstruction Trial: Beyond Shunt Type
Background. We sought to identify patient and pre-operative risk factors for death and cardiac transplantation in infants with single RV malformations undergoing the Norwood operation. We also examined whether any of these factors could facilitate the choice of a modified Blalock-Taussig shunt (MBTS) or a right ventricle-to-pulmonary artery shunt (RVPAS).
Methods. We used competing risks methodology to analyze three states: death without transplant, cardiac transplant, and survival without transplant. The mortality hazard was characterized by a two-phase model (early and constant). Parametric time-to-event modeling and bootstrapping to assess reliability were used to identify independent predictors in multivariable analysis. Preterm was defined as gestational age (GA) < 37 wk.
Results. Among 549 patients with mean follow-up of 33±11 months, there were 178 deaths and 19 transplants. Three-year event rates were 33% for mortality and 5% for transplant. Independent risk factors for death included lower socioeconomic status (SES; p=.01), presence of a genetic syndrome (p<.001), lower GA (p<.001), obstructed pulmonary venous return (p<.001), and smaller ascending aorta diameter (p=.02). Regarding cardiac anatomy (aortic stenosis, AS; aortic atresia, AA; mitral stenosis, MS; mitral atresia MA), patients with AS/MS had better survival than both those with AS/MA and those with a diagnosis other than hypoplastic left heart syndrome (p<.001). Patients with AA/MA had survival similar to those with AA/MS (p=.5). Shunt type impacted survival only in specific subgroups: term infants with AA (50% of cohort) had better survival with the RVPAS (hazard ratio [HR]=0.36, p<.001). The MBTS was associated with better survival in the 4% who were preterm and had a patent aortic valve (RVPAS vs. MBTS HR=3.0, p=.003).
Conclusions. Independent risk factors for mortality at a mean of 33 ±11 months post Norwood operation include; lower SES, anatomy, genetic syndrome, lower GA, and shunt type. The optimal shunt type depends on preterm status and aortic valve patency. For 46% of patients, our findings suggest that neither shunt may be superior. Risk stratification using this model may also identify which newborns will have a very poor prognosis.
- © 2011 by American Heart Association, Inc.