Aims: Homografts are frequently implanted in patients with tetralogy of Fallot (TOF). However, the lifespan of homografts is shorter than that of graft recipients, thus making surgical re-intervention unavoidable. Therefore, to determine variables that could influence their survival, we retrospectively studied the survival pattern of homografts used to treat TOF.
Methods and results: Sixty-eight TOF patients, >14 years of age (mean age: 34 +/- 11; 71% male), were selected from our database of congenital cardiology cases. These patients underwent their first homograft implantation at a median age of 24 years (range: 14-49). The primary endpoint, homograft failure, was defined as homograft replacement or percutaneous balloon dilatation when the echocardiographic gradient reached more than 50 mmHg. Kaplan-Meier analysis revealed that the mean event-free survival time of first homografts was 14.6 years (CI, 12.9-16.2 years). The median increase in the homograft gradient was 1.1 mmHg/year (range: 0.0-22.1) for a median follow-up time of 8.4 years (range: 1.3-17.9). Stepwise regression analysis identified the homograft gradient at 1 month after surgery to be prognostic for homograft degeneration (R(2) = 0.23, beta = 0.26, P = 0.001). Immunological variables, gender, and post-operative inflammatory indicators were unrelated to the degree of homograft gradient increase. Finally, patient age at the time of first homograft implantation and previous palliative surgery was significantly associated with the gradient at 1 month (Spearman's rho = -0.41 and -0.29, respectively; P = 0.004 and 0.048, respectively).
Conclusion: Homograft survival in patients with TOF repair is quite good. However, some patients develop accelerated homograft degeneration. We found that the gradient of the homograft 1 month after surgery is most indicative of accelerated homograft degeneration. We hypothesize that mechanical, not immunological, factors play an important role in homograft degeneration.