EXERCISE STRESS TESTS ARE NOT USEFUL FOR NONINVASIVE CARDIOVASCULAR EVALUATION OF RENAL TRANSPLANT CANDIDATES – RESULTS FROM A LARGE PATIENT COHORT

EXERCISE STRESS TESTS ARE NOT USEFUL FOR NONINVASIVE CARDIOVASCULAR EVALUATION OF RENAL TRANSPLANT CANDIDATES – RESULTS FROM A LARGE PATIENT COHORT

Pretransplant cardiovascular screening is widely recommended in kidney transplant candidates in order to facilitate eventfree postransplant patient and graft outcomes. Noninvasive tests are often advocated despite unclear test performances and predictive values in renal patients. We aimed to study the cardiovascular evaluation strategy in a big transplant center and the predictive potency of differing examinations.

In a retrospective analysis we investigated the results of pretransplant cardiovascular screening tests in 1319 kidney transplant recipients at the Medical University of Vienna. The results of exercise stress tests (EST), myocardial perfusion scans (MPS) coronary CT scans (CCT) and coronary angiographies (CA) were recorded. In a subsequent evaluation the value of exercise stress test results in patients were compared to those of healty potential kidney donors.

453 ESTs, 528 MPSs, 39 CCTs and 649 CAs were performed in 1319 patients. 310 patients (23.5%) did not undergo one of the respective tests. Diabetic patients were less frequently referred for EST or MPS than non-diabetics (P-value <0.01). A potential bias in the selection of the performed tests could not be analyzed due to the retrospective study design. In 53.8% (n=21) of patients tested by CCT, an Agatston-Score of zero excluded coronary artery disease (CAD). 72 MPS tests (13.6%) indicated CAD. In candidates screened by CA, 394 (60.7%) had evidence of CAD, leading to revascularization in 58 patients (8.9%). With regard to the expected informative value, EST performed poorly, as 77.0% of transplant candidates did not achieve target watt levels requested for a reliable test interpretation. In comparison 59.1% of the control group of healthy kidney donors demonstrated a sufficient performance (P-value <0.01). Using maximum heart rate as indicator for adequate performance, 37.9% of the ESTs in transplant candidates were sufficent for analysis, compared to 82.1% of ESTs in healthy individuals (P-value <0.01).

In the majority of kidney transplant candidates an exercise stress test as noninvasive examination does not fulfill the predictive power to test for coronary disease. Thus EST as a time consuming and cost generating pre-transplant evaluation test can be ommitted. In candidates with a high pre-test probability for coronary artery disease, early referal to coronary angiography seems to be more appropriate and succesful to detect CAD, than a non-invasive test strategy. Prospective controlled studies are urgently needed to develop an optimal strategy for cardiovascular evaluation before kidney transplantation.