Cardiac Imaging Before Kidney Transplantation | Journal Scan
What is the optimal test to evaluate for obstructive coronary artery disease (CAD) prior to kidney transplantation?
This study examined 138 patients evaluated for CAD as part of a workup for kidney transplant. Subjects underwent coronary artery calcium scoring (CACS), coronary computed tomography angiography (CCTA), single-photon emission computed tomography (SPECT), and invasive angiography. The accuracy of these tests to identify ≥50% stenosis on invasive angiography was compared.
Mean age was 54 years, and 68% were male. All patients had stage 5 chronic renal insufficiency, and 57% were not yet on dialysis. The prevalence of CAD with ≥50% stenosis on invasive angiography was 22%. In comparison to invasive angiography, the sensitivity and specificity of these tests to identify CAD with ≥50% stenosis was 67% and 77% for CACS (using a threshold of 400), 93% and 63% for CCTA, 53% and 82% for SPECT, 33% and 97% for hybrid CACS and SPECT, and 67% and 86% for CCTA/SPECT. During the follow-up period, 15% of patients (11/79) not on dialysis at the start of the study had dialysis initiated, although no cases were attributed to contrast-induced nephropathy.
The authors concluded that CCTA and CCTA/SPECT can be useful to identify patients with ≥50% coronary artery stenosis.
This study demonstrates that CCTA and SPECT can be useful in evaluating patients prior to renal transplant, but highlights the limitations of such study designs. CCTA has excellent sensitivity and SPECT has poor sensitivity if our question is: ‘Does this patient have a coronary stenosis ≥50%?’ The problem here is that many lesions with a stenosis ≥50% will not result in ischemia. Further, many lesions with anatomic stenosis and ischemia may not merit revascularization. These results don’t really answer our clinical question. The real question is: ‘Does this patient need revascularization prior to renal transplant?’ This study does not provide data on the accuracy of these tests to identify a stenosis ≥70% (or left main stenosis ≥50%), and more importantly, does not provide data on which of these tests was most likely to identify patients who merited consideration of revascularization. It is also notable that the majority of patients (57%) had stage 5 chronic renal insufficiency, but were not yet on dialysis. While the authors stated that acetylcysteine was administered to ‘prevent contrast-induced nephropathy,’ there are conflicting data on its effectiveness. Although the 11 patients started on dialysis after the CCTA or invasive angiography did not have this attributed to contrast-induced nephropathy, I cannot understand why we would ever use a nephrotoxic test in this population when tests that present no risk of accelerating a need for dialysis are available. While there appears to be a role for both CCTA and SPECT in this population, these results raise more questions than answers.
Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Nuclear Imaging
Keywords: Acetylcysteine, Angiography, Calcium, Constriction, Pathologic, Coronary Artery Disease, Coronary Stenosis, Diagnostic Imaging, Follow-Up Studies, Kidney Failure, Chronic, Kidney Transplantation, Prevalence, Renal Dialysis, Renal Insufficiency, Chronic, Tomography, Emission-Computed, Single-Photon, Vascular Calcification
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