Myocardial ischemia by radionuclide imaging and long-term outcomes after kidney transplantation

Purpose We examined the incidence of myocardial ischemia (MI) in kidney transplant recipients (KTR) using myocardial perfusion imaging (MPI), and its association with long-term outcomes after transplantation. Methods A retrospective observational study was conducted of asymptomatic KTRs who underwent post-transplant MPI screening for MI, as defined by moderate to severe myocardial perfusion defects, post-stress myocardial stunning or balanced ischemia. A composite outcome of all-cause mortality, graft loss, and major adverse cardiovascular events (MACE) was examined over minimum 5 years. Results We studied 135 KTRs who underwent 226 MPIs, with follow-up duration of 10 (7-13) years. 110 (81%) patients had normal MPIs, 11 (8%) had mild perfusion defects, and 14 (10%) had MI. Correspondingly, composite outcome developed in 6%, 27%, and 43% (p = 0.04), and MACE occurred in 7%, 0%, and 21% (p = 0.11), of the respective subgroups. Twenty-six patients developed the composite outcome after 5 (3-7) years post-transplantation, including 11 patients with MACE. On multivariate analysis, MI, higher low-density lipoprotein levels, and proteinuria > 0.3 g/day independently predicted the composite outcome; only MI predicted MACE (allp < 0.05). Ninety-one patients had two serial MPIs, which increased the positive predictive value for MACE from 17 to 25%. Absence of MI had negative predictive value of 83% for MACE and 93% for the composite outcome. Conclusion MI that is detected early post-kidney transplantation predicts long-term mortality, graft loss, and MACE in KTRs, with excellent negative but poor positive predictive values.