Background: The major limiting factor to successful heart transplantation in infants is the limited supply of donors. To examine the impact of donor limitations on survival after listing, a multiinstitutional study was designed to identify risk factors for death while waiting and for longer interval to transplantation.
Methods: Between January 1 and December 31, 1993, 118 infants 6 months of age or younger (86 younger than 29 days) were listed for heart transplantation from 21 institutions. The primary diagnosis was hypoplastic left-sided heart syndrome (HLHS) in 70 (59%), other congenital defects in 32 (27%), cardiomyopathy or myocarditis in 13 (11%), and other diagnoses in 3. Among the 48 patients without HLHS, 32 (67%) required inotropic, mechanical, or prostaglandin support, whereas 16 (33%) did not.
Results: At 6 months after listing, only 6% remained on the list awaiting transplantation, 59% underwent transplantation. 31% died while waiting, and 4% were removed from the list. The greatest mortality rate before transplantation was among patients with HLHS in whom the actuarial mortality rate if they were unable to receive a transplant was 77% at 6 months, compared with 52% in patients without HLHS and without inotropic or mechanical support (p = 0.05). By multivariable analysis, risk factors for death while waiting included inotropic support (p = 0.02), smaller size (p = 0.0007), and blood type O (p = 0.003). Surgical procedures before listing did not significantly influence pretransplantation mortality rates. The interval from listing to transplantation increased with young age (p = 0.01) in patients without HLHS and smaller size (p = 0.001) and blood group O (p = 0.0006) for patients with HLHS. The effect of blood type O on mortality rates and longer interval to transplantation was due to the distribution of type O donor hearts to non-type O recipients. Palliative operations after listing did not favorably influence survival; nine patients underwent first-stage Norwood while waiting, and six died before transplantation.
Conclusions: The mortality rate is unacceptably high among infants awaiting transplantation, particularly in patients with HLHS. Infants receiving intravenous inotropes or mechanical support at listing are at high risk of early death while waiting. The distribution of blood group O donors to non-blood group O recipients results in higher mortality rates among blood group O recipients. Greater emphasis should be placed on medical strategies to improve survival while waiting and on expanding existing graft resources.