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Outcomes at 6 Years in the SVR Trial
Study Questions:
What is the transplant-free survival at 6 years for patients enrolled in the SVR (Single Ventricle Reconstruction) trial?
Methods:
The SVR trial randomized patients with hypoplastic left heart syndrome (HLHS) to a Norwood procedure with either a modified Blalock-Taussig shunt (MBTS) or a right ventricle-to-pulmonary artery shunt (RVPAS). The initial cohort included 549 patients randomized and treated in the SVR trial. The present study made use of medical history collected annually using medical record review, telephone interviews, and the death index.
Results:
There was no difference in transplant-free survival between patients receiving a RVPAS as compared with a MBTS (64% vs. 59%, p = 0.25). The hazard ratio (HR) for death or transplant favored the RVPAS prior to Stage II surgery (HR, 0.66; 95% confidence interval [CI], 0.48-0.92). The effect of shunt type of death or transplant was not statistically significant between Stage II and Fontan surgery (HR, 1.36; 95% CI, 0.86-2.17; p = 0.17) or after the Fontan procedure (HR, 0.76; 95% CI, 0.33-1.74; p = 0.52). By 6 years, RVPAS had a higher incidence of catheter interventions (0.38 vs. 0.23 per patient-year; p < 0.001), which was mostly due to a higher rate of catheter interventions between the Stage II and Fontan procedures. By age 6 years, approximately one in five patients had had a thrombotic event and one in six had had seizures, with no differences in the shunt types. In terms of functional status at 6 years, 71% of patients were New York Heart Association (NYHA) class I, 21% were class II, 4% were class III, and 5% were class IV.
Conclusions:
By 6 years, children in the RVPAS had a 5% higher transplant-free survival, although the difference did not reach statistical significance. Significant morbidity and mortality have been seen in both treatment groups.
Perspective:
This study investigated outcomes at 6 years for patients enrolled in the SVR trial, which randomized patients to a Norwood procedure with a MBTS or a RVPAS. Relative benefits of the shunt types have seemed to swing back and forth at the predetermined time points for analysis. This study showed no clear survival benefit of one shunt type over the other. Most importantly, the SVR trial has provided an important data set for studying the mid- and long-term outcomes of patients with palliated single-ventricle heart disease. The results are sobering, with 61% overall survival at 6 months and relatively high rates of seizures and thrombotic events. The survival may currently be somewhat better with the wider use of interstage monitoring programs since the original study. These data can be helpful in counseling families regarding mid-term outcomes for patients with HLHS.
Keywords: Blalock-Taussig Procedure, Cardiac Surgical Procedures, Fontan Procedure, Heart Defects, Congenital, Heart Failure, Heart Transplantation, Heart Ventricles, Hypoplastic Left Heart Syndrome, Morbidity, Norwood Procedures, Seizures, Survival, Thrombosis
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