Impact of kidney transplant on post-operative morbidity and mortality in patients with pre-operative cardiac dysfunction.

Background: Several studies show an increase in complications, both cardiac and non-cardiac, and a higher mortality in patients with preexisting cardiac disease when they undergo elective surgery. Due to the high incidence of cardiac dysfunction in patients with concomitant chronic kidney disease, we wanted to determine if the same negative impact is demonstrated in patients undergoing kidney transplantation.

Methods: A retrospective analysis was done on 582 patients who underwent kidney transplant from a single transplant center between 2014 and 2019. Participants for this study were divided into two groups based on cardiac ejection fraction: normal EF (≥40%) (n = 540) and low EF (<40%) (n = 33); exclusion criteria included patients undergoing multi-organ transplants (n = 9). Characteristics and outcomes of patients were compared before and after transplant using chi-square tests for categorical measures, and either Kruskal-Wallis or paired Student's t tests for continuous measures. Overall survival (OS) between groups was assessed using the Kaplan-Meier test. We compared outcomes between the normal EF and low EF groups using logistic regression in raw data, and propensity score matched sample and inverse-probability-weighting to mitigate selection bias.

Results: There was no significant difference in survival between patients in the low EF and normal EF groups (p = .33). Among patients with low EF, mean EF after transplant significantly improved (mean: 55.83% ± 5.75%) compared to mean EF before transplant (38.28% ± 7.35%), (p = < .0001). Of the patients with a low EF before transplant, 1 in 5 had a history of CAD, compared to only 1 in 10 among those patients with a normal EF, p = .0657. Post-transplant complications were comparable between the groups.

Conclusion: Patients undergoing kidney transplantation with a low ejection fraction do not demonstrate an increased incidence of morbidity or mortality in the peri- and post-transplant follow-up compared with patients with a normal ejection fraction. Cardiac events post-transplantation is also comparable between the two groups. Of note, patients with a low EF have a significantly improved EF after kidney transplant which is likely a function of improvement in their physiologic state after the kidney transplant.