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Transplantation-Free Survival and Interventions at 3 Years in the Single Ventricle Reconstruction Trial
Study Questions:
What are the 3-year outcomes for patients undergoing the Norwood procedure with right ventricle to pulmonary artery shunt (RVPAS) as compared with modified Blalock-Taussig shunt (MBTS) enrolled in the SVR (Single Ventricle Reconstruction) trial?
Methods:
In the original SVR trial, 549 patients were randomized to the Norwood procedure with either RVPAS or MBTS. For the current study, vital status and medical history were determined from annual medical records, death indexes, and phone interviews. Outcomes of interest included transplant-free survival, right ventricular ejection fraction (RVEF), and need for unplanned interventions.
Results:
By 3 years, no transplant-free survival benefit was seen in patients undergoing the Norwood procedure with RVPAS as compared with MBTS (67% vs. 61%, p = 0.15). Subjects undergoing the Norwood procedure with RVPAS showed slightly lower EF (41.7 ± 5.1% vs. 44.7%, p = 0.007) and increased frequency of catheter interventions (hazard ratio at >1 year, 2.48; 95% confidence interval, 1.28-4.80).
Conclusions:
By 3 years, the Norwood Procedure with RVPAS no longer conferred improved transplant survival as compared with the Norwood procedure with MBTS. Subjects undergoing Norwood with RVPAS showed lower RVEF and a greater need for catheter intervention over time.
Perspective:
The SVR trial demonstrated improved survival at 12 months for patients undergoing the Norwood procedure with RVPA shunt as compared with MTBS, but suggested convergence in survival rates over time. This extension study confirms the convergence of outcomes of the differing early management strategies by 3 years post-enrollment. The early postoperative and interstage stability seen in patients randomized to RVPA shunt is not without cost in terms of RV function and the need for catheter-based interventions. It will be important to understand the even longer-term impact of the right ventriculotomy on RV function and outcomes. This cohort of patients is an important source of data on outcomes for patients with hypoplastic left heart syndrome, but substudies should be interrupted with caution, taking into account the fact that the primary study was powered for the primary endpoints of rate of death or cardiac transplantation at 12 months.
Keywords: Norwood Procedures, Ventricular Function, Right, Survival Rate, Blalock-Taussig Procedure, Hypoplastic Left Heart Syndrome, Stroke Volume, Postoperative Period, Heart Transplantation
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