Validation of a clinical pathway to assess asymptomatic renal transplant candidates using myocardial perfusion imaging

Abstract

An AHA/ACCF scientific statement proposed 8 risk factors to assess the need for noninvasive coronary artery disease (CAD) surveillance in asymptomatic patients undergoing evaluation for kidney transplantation. The clinical application of these risk factors and the role of noninvasive testing in this context have not been defined. We retrospectively followed a cohort of 581 consecutive kidney transplant recipients of whom 401 had pre-transplant radionuclide myocardial perfusion imaging (MPI) and 90 had pre-transplant coronary angiography. The sum of pre-transplant AHA/ACCF risk factors (age >60 years, hypertension, diabetes, cardiovascular disease, dyslipidemia, smoking, dialysis >1 year, left ventricular hypertrophy) was calculated. MPI scans were analyzed by a "blinded" reader. Patients were followed for a mean of 3.7±2.3 years post-transplant for major adverse cardiac events (MACE), defined as cardiac death or non-fatal myocardial infarction. The sum of risk factors was associated with modest discriminatory capacity for obstructive angiographic CAD (area under the curve [AUC], 0.70; P=0.004), 30-day post-operative MACE (AUC, 0.60; P=0.036), and long-term MACE (AUC, 0.63; P<0.001). A threshold of ≥3 risk factors was optimal for identifying patients at risk. MPI provided incremental predictive value for obstructive CAD (P=0.02) and long-term MACE (P=0.04) but not post-operative MACE (P=0.56). MPI was best predictive of long-term MACE in intermediate risk (3-4 risk factors) patients. Asymptomatic kidney transplant candidates with ≥3 AHA/ACCF risk factors are at increased cardiac risk, and should be considered for noninvasive CAD surveillance. Intermediate risk patients (3-4 factors) benefit the most from pre-transplant MPI to define long-term MACE risk.