Differential Impact of Class I and Class II Panel Reactive Antibodies on Post-Heart Transplant Outcomes

ABSTRACT Background Sensitized patients awaiting heart transplantation spend a longer time on the waitlist and have higher mortality. We are now able to further characterize sensitization by discriminating antibodies against class I and II, but the differential impact of these has not been assessed systematically. Methods and Results Using United Network for Organ Sharing data (2004–2015), we analyzed 17,361 adult heart transplant patients whose class I and II panel reactive antibodies were reported. Patients were divided into 4 groups: class I and II ≤25% (group 1); class I ≤25% and class II ˃25% (group 2); class II ≤25% and class I >25% (group 3); and both class I and II >25% (group 4). Outcomes assessed were treated rejection at 1-year mortality, all-cause mortality, and rejection-related mortality. Compared with group 1, only group 4 was associated with a higher risk of treated rejection at 1 year (odds ratio 1.31, 95% confidence interval [CI] 1.05–1.64), all-cause mortality (hazard ratio 1.24, 95% CI 1.06–1.46), and mortality owing to rejection (subhazard ratio 1.84, 95% CI 1.18–2.85), whereas groups 2 and 3 were not (P > .05). Conclusions Combined elevation in class I and II panel reactive antibodies seem to increase the risk of treated rejection and all-cause mortality, whereas risk with isolated elevation is unclear.