Survival after Intervention for Single-Ventricle Heart Disease Over 15 Years at a Single Institution
Alexander Zhu, MD, James M. Meza, MD, MSc, Neel K. Prabhu, BS, Andrew W. McCrary, MD, MSc, Veerajalandhar Allareddy, MD, Joseph W. Turek, MD, PhD, and Nicholas D. Andersen, MD
Take Home Points:
- In children with single-ventricle (SV) heart disease, survival differences in outcomes might be related to fundamental morphologic differences, patient characteristics, or procedural pathways. This study showed that survival differences in patients with SV heart disease were related primarily to underlying cardiac anatomy, patient characteristics, and procedural complexity. Left ventricular dominance, more recent intervention, and attainment of a 2-ventricle circulation were associated with improved survival. Chromosomal/syndromic abnormality, lower weight, hybrid Norwood procedure, non-left ventricular dominance, and earlier year of operation were risk factors for death.
Commentary from Dr. Masamichi Ono (Munich, Germany), section editor of Congenital Heart Surgery Journal Watch
Single center retrospective study included 381 patients among 477 patients with functional single ventricle who underwent cardiac surgical interventions between 2005 and 2020. Patients who were born before 2005, or underwent initial palliation at another hospital, were excluded from the study.
Patients were divided into 8 diagnostic groups assigned at birth: aortic atresia or aortic stenosis (AA/AS), double inlet left ventricle (DILV), double outlet right ventricle (DORV), hypoplastic left heart syndrome (HLHS), pulmonary atresia with intact ventricular septum (PA/IVS), tricuspid atresia, unbalanced complete atrioventricular canal (uCAVC), and other. Patients were also divided into 11 procedural categories based on the initial interventional procedure, including aortic arch repair/pulmonary artery banding (Arch/PAB), biventricular repair, ductal stent, heart transplant, hybrid Norwood procedure, Norwood procedure, pulmonary artery banding (PAB), systemic-pulmonary shunt (shunt), total anomalous pulmonary venous return repair (TAPVR), none, and other.
Survival stratified by fundamental diagnosis demonstrated that patients with DILV experienced the best survival (10-year: 89% ± 7%), and patients with HLHS experienced the worst survival (10-year: 55% ± 5%). The remaining 10-year survival rates are listed in increasing order: AA/AS (55% ± 11%), uCAVC (61% ± 7%), DORV (69% ± 8%), tricuspid atresia (76% ± 11%), other (82% ± 12%), and PA/IVS (85% ± 6%). Survival rates of index procedures are listed in increasing order: TAPVR (33% ± 18%), other (33% ± 19%), hybrid Norwood (2-year: 39% ± 15%), primary heart transplant (5-year: 50% ± 18%), Norwood (59% ± 4%), shunt (73% ± 5%), Arch/PAB (83% ± 11%), none (85% ± 10%), primary biventricular repair (86% ± 7%), PAB (95% ± 5%), and ductal stent (100% ± 0%). SV patients with LV dominance had higher survival compared with patients with right ventricular (RV) dominance (10-year: 78% ± 5% vs 58% ± 4%, P = .002). Patients with balanced ventricles had a survival rate intermediate between LV-dominant and RV-dominant patients (10-year: 68% ± 10%). Overall survival of patients who were able to achieve a biventricular circulation was superior to patients who remained with SV physiology (10-year: 87% ± 5% vs 63% ± 3%, P = .04). Patients on the SV pathway had similar survival compared with those who received a heart transplant during the study period (10-year: 59% ± 11%). Era analysis revealed that birth in the second half of the study period was associated with improved survival (8-year survival: 60% ± 4% from 2005-2012 vs 74% ± 3% from 2013-2020, P =.04). As for risk factors for deaths, chromosomal/syndromic abnormality, lower weight at the stage 1 procedure, and hybrid Norwood procedure were risk factors for death during the early phase. Conversely, later year of operation and LV dominance were protective factors.
This retrospective study was done at Duke University Medical Center and provides a holistic overview of survival after intervention for SV heart disease after birth over a 15-year period at a single institution. The reported outcomes are very informative. Key observations included significant differences in survival based on fundamental cardiac morphology, index procedure, as well as other non-modifiable patient characteristics. These factors are not new; the factors identified in this study were reported in the previous studies.
Ventricular dominance: It is clear that patients with LV-dominant lesions such as DILV, PAIVS, and tricuspid atresia had better survival compared with patients with RV-dominant lesions. Presence of a morphologic systemic ventricle and mitral valve, less invasive index procedure in neonatal period, and less association of systemic outflow obstruction, might be main reasons for better outcomes.
Lower weight at the stage 1 procedure and chromosomal/syndromic abnormality: they are ubiquitous risk factors that have appeared in most prior studies of single ventricle survival. Low weight at initial palliation was also highly associated with chromosomal/syndromic abnormality, such as heterotaxy, trisomy 21, VACTERL, and others). These risk factors are largely non-modifiable. Our resent study demonstrated that extracardiac anomalies, especially renal anomalies are highly associated to the mortality during the staged reconstruction of single ventricle patients (Vodiskar, et, al. EACTS 2021, under review by The Annals of Thoracic Surgery). In our opinion, these patients with chromosomal/extra-cardiac anomalies had worse outcomes after cavopulmonary shunt procedure. We assume that pulmonary vascular reaction to this procedure might be different from that in patients with normal chromosome, and surgeons may plan to establish a separate strategy for these patients with chromosomal/syndromic abnormality, including timing of cavopulmonary shunt procedure, and indications such as pulmonary artery pressure.
Era effect is also the important issue. Improved outcomes in the later era is an encouraging finding, because of improvements in surgical and postoperative care as well as increased prenatal diagnosis. Ductal stenting is the emerging technique to reduce the mortality of newborns.
Hybrid Norwood procedure: this result is likely institution specific due to our preference for surgical Norwood reconstruction whenever possible and reservation of the hybrid Norwood procedure only in salvage situations when children are not considered candidates for cardiopulmonary bypass. This is also consistent to our results.
Biventricular repair: This study demonstrated 43 patients, born with a presumed SV diagnosis, selected for primary biventricular repair (24 patients) or biventricular conversion after initial SV palliation (19 patients). Despite undergoing potentially high-risk or multi-staged interventions to achieve a 2-ventricle circulation, long- term survival of biventricular repair patients significantly exceeded those who remained with SV physiology. These results suggested us for more efforts to achieve biventricular correction, if patients had borderline hypoplastic heart disease and had a possibility to get biventricular circulation.
Although the results were similar to those in previous studies, this study provided a holistic overview of survival after surgical intervention for single ventricle heart disease after birth over a 15-year period.