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Comparing Management Strategies for Infants with Critical Left Heart Obstruction

Each year, 3 out of 10,000 babies will be born with critical left heart obstruction (CLHO). Most infants born with severe left-sided cardiac defects, such as CLHO, require at least three major open-heart surgeries before the age of 5. The first operation is especially high risk because it typically occurs about 7 days of age. To address the high risk associated with this operation, a temporizing procedure known as “hybrid palliation” (bilateral pulmonary artery banding [bPAB] with or without ductal stent palliation) was implemented. Hybrid palliation is quicker, less technically demanding, and allows surgeons to postpone the complex operation by a couple months to allow a baby to grow.

Previous research, however, has had conflicting results and has not demonstrated which pathway leads to better outcomes. The studies have been limited to single centers with small sample size and short-term follow-up.

Madison Argo, MD, and colleagues at more than 20 institutions sought to compare infant characteristics and survival between the two groups. From 2005 to 2019, 1,045 infants from 28 Congenital Heart Surgeons’ Society institutions underwent hybrid palliation (214 infants) or non-hybrid management (831 infants). One challenge in comparing these two pathways is that babies who receive hybrid palliation tend to be sicker, have lower birth weight, and more severe left-sided cardiac anatomy than babies who receive non-hybrid management.

To navigate the analytic challenge of comparing the two dissimilar groups and making a more even comparison, the researchers balanced the groups to account for the differences in severity of illness. The 12-year survival after hybrid palliation versus non-hybrid management did not significantly differ (58% versus 63%, respectively), even for lower birth weight babies who are among the highest risk groups. Regardless of pathway, mortality for infants born with CLHO is high, and hybrid palliation confers no survival advantage.

The researchers observed two surprising results. First, early post-operative mortality was similar after hybrid palliation versus non-hybrid management, despite hybrid palliation being considered a relatively quicker and less technically demanding operation. This led them to infer that post-hybrid palliation physiology may still have a degree of instability and thus require close monitoring.

The second surprising result was that overall survival was similar after hybrid palliation versus non-hybrid management for babies born weighing <2.5 kg. Hybrid palliation is commonly used when infants born with CLHO have low birth weight, these findings challenge this.

Dr. Argo writes, “Our study compares two groups, and the results yield an average treatment effect; but they do not focus on the individual treatment effect. Therefore, the next step is to identify the optimal surgical pathway for specific individual patient characteristics and circumstances.”

Dr. Argo will present the results of this study during the Presidential Plenary Session, Monday, May 8, at the American Association for Thoracic Surgery (AATS) 103rd Annual Meeting in Los Angeles.