The role of donor age and ischemic time on survival following orthotopic heart transplantation

Background: The advances in immunotherapy, along with a liberalization of e ligibility criteria have contributed significantly to the ever increasing d emand for donor organs. In an attempt to expand the donor pool, transplant programs are now accepting older donors as well as donors from more remote areas. The purpose of this study is to determine the effect of donor age an d organ ischemic time on survival following orthotopic heart transplantatio n (OHT). Methods: From April 1981 to December 1996 372 audit patients underwent OHT at the University of Western Ontario. Cox proportional hazards models were used to identify predictors of outcome. Variables affecting survival were t hen entered into a stepwise logistic regression model to develop probabilit y models for 30-day- and 1-year-mortality. Results: The mean age of the recipient population was 45.6 +/- 12.3 years ( range 18-64 years: 54 less than or equal to 30; 237 were 31-55; 91 > 56 yea rs). The majority (329 patients, 86.1%) were male and the most common indic ations for OH were ischemic (n = 180;) and idiopathic (n = 171) cardiomyopa thy. Total ischemic time (TIT) was 202.4 +/- 84.5 minutes (range 47-457 min utes). In 86 donors TIT was under 2 hours while it was between 2 and 4 hour s in 168, and more than 4 hours in 128 donors. Actuarial survival was 80%, 73%, and 55% at 1, 5, and 10 years respectively. By Cox proportional hazard s models, recipient status (Status I-II vs III-TV; risk ratio 1.75; p = 0.0 03) and donor age, examined as either a continuous or categorical variable ([age < 35 vs greater than or equal to 35; risk ratio 1.98; p < 0.001], [ag e < 50 vs greater than or equal to 50; risk ratio 2.20; p < 0.001], [age < 35 vs 35-49 versus greater than or equal to 50; risk ratio 1.83; p < 0.001] ), were the only predictors of operative mortality. In this analysis, total graft ischemic time had no effect on survival. However, using the Kaplan-M eier method followed by Mantel-Cox logrank analysis, ischemic time did have a significant effect on survival if donor age was >50 years (p = 0.009). B y stepwise logistic regression analysis, a probability model for survival w as then developed based on donor age, the interaction between donor age and ischemic time, and patient status. Conclusions: Improvements in myocardial preservation and peri-operative man agement may allow for the safe utilization of donor organs with prolonged i schemic times. Older donors are associated with decreased peri-operative an d long-term survival following OHT, particularly if graft ischemic time exc eeds 240 minutes and if these donor hearts are transplanted into urgent (St atus III-IV) recipients.