Title:
Durability of pulmonary homografts for reconstruction of the right ventricular outflow tract: how relevant are donor-related factors?

Abstract:
Our goal was to evaluate the influence of donor-related factors on the durability of pulmonary homografts (PHGs) for right ventricular outflow tract reconstruction of congenital heart defects.
Between 1990 and 2016, 223 PHGs were used in 197 patients for right ventricular outflow tract reconstruction. Long-term durability was investigated in relation to patient- and disease-specific as well as to donor-related factors, based on the PHG replacement rate. To minimize the effect of outgrowth, a subgroup analysis was performed on patients with PHG size >22 mm, as the discriminant cut-off identified by the classification tree method.
During a median follow-up of 8.5 years [interquartile range (IQR) 12.3], 47 (21%) PHGs were explanted within a mean interval of 9.5 ± 5.3 years, resulting in a freedom from PHG replacement of 82 ± 6% at 10 years. The risk factors for PHG explantation determined by univariable analysis were predominantly patient-related, including younger age (P = 0.003), extra-anatomic implantation (P = 0.006), bicuspidalization (P = 0.002) and younger donor age (P = 0.032). PHG size [hazard ratio (HR) 0.80, 95% confidence interval 0.73-0.88; P < 0.001] was the only independent determinant in multivariable analysis. The subgroup analysis comprised 119 PHG >22 mm, implanted at a median age of 15 years (IQR 7). A significant beneficial effect of ABO matching on the explantation rate was only identified with univariable analysis (HR 0.24, 95% confidence interval 0.12-4.68; P = 0.010).
Cryopreserved PHGs provide a durable substitute for right ventricular outflow tract reconstruction in congenital heart disease. PHG size at the time of implantation remains the principal determinant of PHG explantation during late follow-up. However, once an adult-sized homograft is required, matching for ABO blood group compatibility between host and donor might help to improve homograft durability.