Survival after heart transplant listing for infants on mechanical circulatory support

BACKGROUND: Infants with heart failure remain at significant risk for wait list mortality, despite mechanical circulatory support (MCS). It is unclear if the outcomes are influenced by modality of support or underlying diagnosis. We sought to compare the outcomes of infants <10 kg, focusing on modality of support and underlying diagnosis. METHODS AND RESULTS: Using the Pediatric Heart Transplant Society database, we evaluated survival following first MCS device in children <10 kg who were listed for heart transplant between 2010 and 2018. There were 2049 children <10 kg, with the predominant diagnosis being congenital heart disease (CHD) (59.8% [n=1226]) and 28.1% (n=577) requiring MCS. Extracorporeal membrane oxygenation (ECMO) was the most common form of MCS at listing, with ventricular assist device (VAD) more common after listing. There was no difference in the use of ECMO at or after listing for cardiomyopathy versus CHD (8.9% versus 7.2%; P=0.2; 5.4% versus 6.4%; P=0.4). However, there was a significant difference in the use of VAD both at listing (8% versus 2.4%; P<0.001) and after (22.8% versus 5.1%; P<0.001) between the 2 groups. When comparing these groups, patients with CHD were smaller and younger and had a higher proportion with previous cardiac surgery. Survival at 3 months demonstrated better survival for VAD therapy compared with ECMO (74.3% versus 48.6%; P<0.001). In patients <5 kg, survival did not differ between ECMO and VAD (P=0.01) for the CHD or the cardiomyopathy group (P=0.38), but patients with cardiomyopathy demonstrated better survival on both forms of support. CONCLUSIONS: Survival for patients <10 kg on ECMO is inferior compared with VAD. Patients with cardiomyopathy <5 kg had better survival with both modes of MCS compared with those with CHD. These findings support the need for small, durable devices for neonates and infants, with particular focus in patients with CHD.