Noninvasive cardiac testing in the end-stage renal disease patient

Relationship between elevated serum troponin values in end-stage renal disease patients and abnormal isotopic cardiac scans following stress

One hundred asymptomatic high-risk renal transplant candidates were screened for asymptomatic coronary artery disease using stress cardiac isotopic imaging. The cardiac markers, serum cTnT, cTnI, and CKMB, were collected pre and post stress testing. Of the 99 patients whose cardiac scans were technically satisfactory, 32 were normal, 49 had a definite imaging abnormality and the scan was indeterminate in the remaining 18 patients. Based on these results, patients were stratified into either normal, indeterminate or abnormal scan groups. They then were analyzed to detect any correlations between cardiac perfusion defects and either elevated pre-stress cardiac markers or consistent changes 24h after stress testing. While the mean pre-stress serum values for both cardiac troponin T (0.117 +/- 0.12 microgram/L) and cardiac troponin I (0.235 +/- 0.89 microgram/L) were increased in the abnormal cardiac scan group, only the cTnT value proved to differ significantly from the normal group (p < 0.01). For the indeterminate group neither marker was different from the normal scan group. Only an elevated serum cTnT > 0.1 microgram/L (OR 3.042, p = 0.030) proved to discriminate an abnormal scan in this population. It is concluded that the increase in pre-stress serum cTnT encountered in patients with chronic renal failure, with or without evidence of overt, symptomatic coronary artery disease, may represent a combination of subclinical myocardial damage and a prolonged half-life of the marker in the serum. Because of the frequency of elevated serum concentrations of cTnT and, to a lesser degree cTnI, the physician should exercise caution when interpreting a single elevated Troponin value during the evaluation of chest pain in patients with end-stage renal disease. A cTnT > 0.1 microgram/L increases the likelihood of finding significant coronary artery disease three fold in high-risk ESRD patients being evaluated for renal transplantation.

Current status of renal transplantation. Patient evaluations and outcomes

A systematic team approach to the assessment of renal transplant candidates is one of several factors that have resulted in improved kidney transplant and recipient survival rates, rates that were only imagined 4 decades ago.

Pre-transplant cardiac testing for kidney-pancreas transplant candidates and association with cardiac outcomes

BACKGROUND

Coronary artery disease is a major cause of mortality following renal transplantation, especially in those patients with diabetes. The accurate prediction of cardiac risk is therefore a major focus of the pre-transplant evaluation. The objective of this study was to retrospectively evaluate the ability of non-invasive cardiac testing (standard echocardiography, stress echocardiography, exercise tolerance testing, and nuclear myocardial perfusion) performed within 1 yr of kidney-pancreas transplant to predict post-transplant myocardial infarction.

METHODS

Clinical history and pre-transplant cardiac testing performed within 1 yr prior to transplantation were reviewed in a non-blinded fashion for 165 kidney-pancreas transplantation patients receiving allografts between June 1990 and May 1998. The predictive values of clinical symptoms and cardiac testing for cardiac events (fatal and non-fatal myocardial infarctions) up to 1 yr post-transplant were calculated.

RESULTS

Clinical history had a negative predictive value of 98% for cardiac events occurring within 1 yr following testing and 97% within 1 yr post-transplant. Collectively, non-invasive testing had a negative predictive value of 97% for 1 yr post-testing and 1 yr post-transplant.

CONCLUSION

Clinical history alone is highly suggestive but not sufficient for the prediction of post-kidney-pancreas transplant myocardial infarction. Although a useful supplement, cardiac testing does not predict all cardiac events out to 1 yr post-testing. In this high-risk patient population with diabetes and renal failure, other methods of risk assessment are needed to more accurately predict long-term cardiac outcome for patients awaiting transplantation.