Perioperative outcomes and readmissions following cardiac operations in kidney transplant recipients

Objective Although kidney transplant (KTx) recipients are at significant risk for cardiovascular disease, outcomes following cardiac operations have been examined in limited series. The present study thus aimed to assess the impact of KTx on in-hospital perioperative outcomes and readmissions in a nationally representative cohort. Methods All adults undergoing elective coronary artery bypass grafting, valve repair/replacement or a combination thereof were identified from the 2010-2018 Nationwide Readmissions Database. Patients were stratified by history of KTx. Transplant-capable centres were defined as hospitals performing at least one KTx annually. To perform risk-adjustment in assessing outcomes, multivariable regression models were developed. Results Of an estimated 1 407 351 patients included for analysis, 0.2% (n=2849) were KTx recipients. Compared with the general cardiac surgical population, patients with prior KTx experienced higher adjusted odds of in-hospital mortality (adjusted OR (AOR) 2.44, 95% CI 1.72 to 3.47, p<0.001) and perioperative complication (AOR 1.67, 95% CI 1.44 to 1.94, p<0.001). Additionally, KTx was independently associated with greater readmission rates within 30 days (AOR 1.96, 95% CI 1.65 to 2.34, p<0.001) with kidney injury contributing significantly to the burden of rehospitalisation (4.6 vs 1.8%, p=0.005). In a subpopulation comprised of only KTx recipients, treatment at a transplant-capable centre reduced odds of kidney injury with non-transplant hospitals as reference (AOR 0.65, 95% CI 0.43 to 0.98, p=0.037). Conclusions Kidney transplant recipients undergoing cardiac operations encounter significant risks compared with the general surgical population. Referral to transplant-capable centres should be explored to improve outcomes and to preserve allograft function in this population.