Page 30 - Cardiac testing for coronary artery disease in potential kidney transplant recipients

DSE and MPS are not perfect triage tests and a significant num-
ber of patients will either have their significant CAD missed (false significant CAD in kidney transplant candidates imposes further
negatives) or be referred unnecessarily for coronary angiography implications on patient management. These include consideration
(false positives). Furthermore, the imprecision of the likelihood of need for perioperative beta blockade, antiplatelet agents and an-
ratios resulting from significant between-study heterogeneity pro- ticoagulation. A recent registry study (De Lima 2010) confirmed
duces significant uncertainty in the post-test probabilities for both that in patients with CKD and significant CAD, medical therapy
positive and negative tests. A negative DSE test would still, in a results in adequate long-term event-free survival. However, in this
low risk population, yield a post-test probability of 10% to 27%. study, a greater cardiac event rate occurred in patients who ful-
However, both the desire to avoid complications arising from rou- filled criteria for revascularisation but declined intervention. Nev-
tine referral of such patients to an invasive gold standard investiga- ertheless, the lack of RCTs specifically addressing this question in
tions, and the lack of a more accurate alternative method of screen- kidney transplant settings means that uncertainty remains about
ing may or may not convince clinicians to consider such posterior if failure to perform coronary intervention when necessary results
test probabilities to be sufficiently low to excuse an asymptomatic in an accentuated increased risk of adverse events and death.
individual from having further invasive investigation.
Our results need to be considered together with the real world
limitations of practising medicine. Despite the apparent superi-
ority of DSE over MPS to detect severe CAD, the interaction of A U T H O R S ’ C O N C L U S I O N S
many clinical factors often result in different transplant centres Implications for practice
preferring one screening test over another. These factors may be
Of the non-invasive screening tests available to detect CAD in
institutional, arising from practicalities such as availability and or
potential kidney transplant candidates, MPS and DSE have been
expertise of one screening modality, but not both, in a transplant
studied in detail. Both tests, especially DSE, have roles as triage
centre; or patient-related issues such as lack of cardiorespiratory
tests for transplant candidates with intermediate of CAD. Nega-
fitness or mobility for exercise stress testing. DSE requires IV in-
tive DSE results preclude need for further evaluation using coro-
fusion and is not available in all cardiology departments. Many
nary angiography, avoiding unnecessary risk to patients and po-
cardiology practices offer exercise stress echocardiography, but we
tentially reducing healthcare costs. Given the wide heterogeneity
were unable to identify any studies of exercise stress echocardio-
in the estimates for both DSE and MPS, considerable uncertainty
graphy in potential kidney transplant recipients. The diagnostic
remains concerning the true post-test probabilities of each test.
accuracy of exercise stress echocardiography is likely to be sim-
Current evidence suggests that where feasible DSE should be used
ilar to DSE, although there is a higher chance of submaximal,
as the screening investigation of choice.
and therefore uninterpretable, stress test results in patients who
undergo this test. The patient factors that affect physician choice Implications for research
of screening test are less likely to be an issue in a population of
potential kidney transplant recipients compared with people who The ability to identify patients at high risk of CAD may not nec-
essarily enable clinicians to predict cardiac event-free survival fol-
are not transplantation candidates, given that transplantation can-
didates represent a selected healthier subpopulation of those with lowing transplantation. In the postoperative period, other factors
such as inflammation, sympathetic nervous system activation, hy-
CKD. MPS requires the presence of a nuclear medicine depart-
ment. Although these departments are found in tertiary referral percoagulability and hypoxia contribute to increased cardiac mor-
bidity and mortality (Yao 2004). Patients with kidney disease have
hospitals, they may not be present in smaller hospitals or resource-
poor settings. abnormal coronary microcirculation and reduced coronary flow
reserve, which may result in cardiac ischaemic events, even in the
For this review, we defined coronary artery stenosis as ≥ 50%
stenosis, and severe coronary artery stenosis as ≥ 70% steno- absence of macrovascular stenoses (Caliskan 2008; Niizuma 2008;
Sezer 2007). Future research examining the ability of functional
sis. Although asymptomatic patients with certain high risk coro-
nary lesions (e.g. left main or equivalent disease, and triple vessel tests to predict postoperative outcome is urgently needed.
CAD, particularly with left ventricular dysfunction) benefit from
revascularisation regardless of symptoms (Eagle 2004), the bene-
fit of preoperative revascularisation before transplant surgery re-
mains questionable. Two RCTs (CARP (McFalls 2004) and DE- A C K N O W L E D G E M E N T S
CREASE-V (Poldermans 2007)) did not demonstrate any revas- The authors would especially like to thank Petra Macaskill for
cularisation benefit in asymptomatic CAD before major vascu- her assistance in designing the statistical methodology for this re-
lar surgery. Nevertheless, the diagnosis of angiographically-proven view and providing invaluable statistical support. We also thank

Cardiac testing for coronary artery disease in potential kidney transplant recipients (Review) 28
Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.