Acceptable short-term outcomes after open heart surgery in kidney transplant recipients: a case control study

Abstract

Background Cardiovascular disease is common in kidney transplant recipients. They are considered high risk surgery candidates due to comorbidity and immunosuppression. We assessed short-term results of open-heart surgery in kidney transplant recipients and matched controls between 1989 – 2016 at our center. Methods Ninety-five patients underwent open heart surgery (48 coronary artery bypass grafting, 27 valve replacements or repairs and 29 combined procedures) after kidney transplantation. Controls (n=95) were matched for age, sex, type and year of surgery. Mean follow-up was 5.6 (4.9) years. Independent two-sample t-test and chi-square test were used to compare continuous variables and frequencies, respectively. Logistic regression was used to identify preoperative risk factors for 30-day mortality. Results Included were 76 men and 19 women; mean age 60.3 (11.1) years, 7.1 (5.6) years after transplantation. Kidney transplants had lower renal function, more hypertension, but less pulmonary hypertension than matched controls. Intraoperative data was comparable between kidney transplants and controls. Kidney transplants experienced more frequent acute kidney injury (57% versus 21%, p<0.001), more bleeding (1288 (1081) mL versus 957 (548) mL, p=0.01) and more red cell transfusions (4.9 (5.6) versus 3.2 (5.4) units, p=0.04). Infections were borderline more frequent in kidney transplants (30% versus 20%, p=0.10). Thirty-day mortality was 6.3% in kidney transplants and 2.1% in controls (p=0.14). Independent risk factors for 30-day mortality were acute myocardial infarction last 90 days before surgery (OR 12.5, p=0.02) and current smoking (OR 17.3, p=0.02). Conclusions Kidney transplant recipients undergoing cardiac surgery have acceptable short-term results compared with matched controls; 30-day mortality rates were similar. Careful peri- and postoperative management is, however, warranted as kidney transplant recipients experience more bleeding and higher frequency of AKI.