SPECT-MPI PREDICTS DEATH AND HOSPITALIZATION OUTCOMES AFTER RENAL TRANSPLANTATION

Abstract

BACKGROUND: Cardiovascular disease remains a major cause of morbidity and mortality among patients with end-stage renal disease. While renal transplantation is increasingly performed, there is a lack of data on screening strategies for coronary artery disease (CAD) in patients post-renal transplantation. Our objective was to determine the prognostic value of Single-Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging (MPI) in a large patient population post-renal transplantation. METHODS: We examined patients who underwent renal transplantation and post-transplant SPECT-MPI at a single university center over a 10-year period in Ontario, Canada (from 2003-2012). All-cause mortality was compared between patients who underwent post-transplant SPECT MPI vs those who did not undergo testing. Patients were identified from hospital discharge abstracts of the Canadian Institute of Health Information (CIHI). Secondary outcomes were a composite of myocardial infarction (MI) and cardiovascular hospitalization. Outcomes were stratified by standard MPI score categories. Morbidity outcomes were determined from the CIHI database, while mortality was determined from the vital statistics registry. RESULTS: Among the study cohort, 556 (median age 48 [40-58 yrs]) underwent SPECT MPI post-renal transplantation. Patients who underwent SPECT MPI had higher prevalence of hypertension (93% vs. 85%, p<0.001), diabetes (56% vs 31%, p0). The median left ventricular ejection fraction by SPECT was 67% (IQR: 59-76) at rest and 70% (IQR: 62-77) post-stress. After adjusting for age, sex, prior MI, cardiac risk factors, and Charlson comorbidity index, an abnormal SSS conferred progressively increased risks of death or hospitalization (Figure). In particular, SSS 7 conferred increased risk of death with adjusted hazard ratio [HR] 2.55 (95%CI; 1.086.02, p1⁄40.03), and secondary outcomes of MI (adjusted HR 7.60 [95% CI; 1.64-35.24], p1⁄40.01), or cardiovascular hospitalization (adjusted HR 2.89 [95% CI; 1.615.21], p<0.001). In a matched comparison of 218 pairs of renal transplant patients with or without imaging, all-cause death was significantly lower in patients who underwent SPECT MPI (adjusted HR 0.47 [95%CI; 0.32-0.69], p<0.001). CONCLUSION: In this large cohort of patients post-renal transplantation, SPECT MPI stratified the risk of a broad range of cardiovascular disease events. Patients undergoing SPECT MPI exhibited lower mortality risk than those who did not undergo the procedure.