Pretransplant dobutamine stress echocardiography is useful and cost-effective in renal transplant candidates

Screening and risk stratification of coronary artery disease in end-stage renal disease

End-stage renal disease (ESRD) is a growing global health problem with major health and economic implications. Cardiovascular complication is the major cause of morbidity and mortality in this population. Clustering of traditional atherosclerotic risk factors, such as diabetes, systemic inflammation, and altered mineral metabolism, contributes to enhanced systemic atherosclerosis in patients with ESRD. Prevalence of obstructive coronary artery disease (CAD) on coronary angiography exceeds 50% in this population. Despite having extensive CAD and vascular disease, patients with ESRD often do not present with classic symptoms because of impaired exercise capacity and diabetes. Furthermore, clinical trial data are exceedingly lacking in this population, resulting in considerable clinical equipoise regarding the optimal approach to the identification and subsequent management of CAD in these patients. Traditional clinical screening tools, including conventional risk prediction models, are significantly limited in their predictive accuracy for cardiovascular events in patients with ESRD. Noninvasive cardiac stress imaging modalities, such as nuclear perfusion and echocardiography, have been shown to improve the traditional clinical model in identifying the presence of CAD. Furthermore, they add incremental prognostic information to angiographic data. Novel imaging techniques and biomarker assays hold significant promise in further improving the ability to identify and risk-stratify for CAD. This review focuses on the current understanding of the clinical risk profile of asymptomatic patients with ESRD with an emphasis on the strengths and limitations of various noninvasive cardiovascular imaging modalities, including the role of novel methods in refining risk prediction. In addition, issues and challenges pertaining to the optimal timing of initial risk assessment ("screening") and possible repeat screening ("surveillance") are addressed. We also summarize the current data on the approach to the patient with ESRD being evaluated for transplantation in the context of recent guidelines and position statements by various professional societies.

Prognostic value of cardiac tests in potential kidney transplant recipients: a systematic review

BACKGROUND

Whether abnormal myocardial perfusion scintigraphy (MPS), dobutamine stress echocardiography (DSE) or coronary angiography, performed during preoperative evaluation for potential kidney transplant recipients, predicts future cardiovascular morbidity is unclear. We assessed test performance for predicting all-cause mortality, cardiovascular mortality and major adverse cardiac events (MACE).

METHODS

We searched MEDLINE and EMBASE (to February 2014), appraised studies, and calculated risk differences and relative risk ratios (RRR) with 95% confidence intervals (95% CI) using random effects meta-analysis.

RESULTS

Fifty-two studies (7401 participants) contributed data to the meta-analysis. Among the different tests, similar numbers of patients experienced MACE after an abnormal test result compared with a normal result (risk difference: MPS 20 per 100 patients tested [95% CI, 0.11-0.29], DSE 24 [95% CI, 0.10-0.38], and coronary angiography 20 [95% CI, 0.08-0.32; P = 0.91]). Although there was some evidence that coronary angiography was better at predicting all-cause mortality than MPS (RRR, 0.69; 95% CI, 0.49-0.96; P = 0.03) and DSE (RRR, 0.72; 95% CI, 0.50-1.02; P = 0.06), noninvasive tests were as good as coronary angiography at predicting cardiovascular mortality (RRR, MPS, 0.89; 95% CI, 0.38-2.10; P = 0.78; DSE, 1.09; 95% CI, 0.12-10.05; P = 0.93), and MACE (RRR: MPS, 1.09; 95% CI, 0.64-1.86; P = 0.74; DSE, 1.56; 95% CI, 0.71-3.45; P = 0.25).

CONCLUSIONS

Noninvasive tests are as good as coronary angiography at predicting future adverse cardiovascular events in advanced chronic kidney disease. However, a substantial number of people with negative test results go on to experience adverse cardiac events.

Safety and feasibility of dobutamine stress cardiac magnetic resonance for cardiovascular assessment prior to renal transplantation

AIMS

Current guidelines recommend cardiovascular risk assessment prior to renal transplantation. There is currently no evidence for the role of cardiovascular magnetic resonance (CMR) in this population, despite an established evidence base in the non-chronic kidney disease (CKD) population. Our aim is to determine the feasibility and safety of dobutamine stress CMR (DSCMR) imaging in the risk stratification of CKD patients awaiting renal transplantation.

METHODS

CKD patients who were deemed at high risk for coronary artery disease (CAD) and awaiting renal transplantation underwent DSCMR.

RESULTS

Forty-one patients whose median age was 56 years (range 28–73 years) underwent DSCMR. Nineteen were undergoing haemodialysis, 10 peritoneal dialysis and 12 pre-dialysis. The aetiology of the renal failure was diabetes mellitus in 29%, glomerulonephritis in 24%, hypertension in 22% and autosomal dominant polycystic kidney disease in 10%. Thirty-eight patients (93%) achieved the end point, either positive for ischaemia or negative, achieving at least 85% of age-predicted heart rate. Two of them did not achieve target heart rate and one was discontinued because of severe headache. Of the 38 patients who achieved the end point, 35 (92%) were negative for inducible wall motion abnormalities and four (10%) were positive. There were no serious adverse effects.

CONCLUSION

DSCMR is a well tolerated and viable investigation for the cardiovascular risk stratification of high-risk CKD patients prior to renal transplantation. DSCMR already has an established evidence base in the non-CKD population with superiority over other noninvasive techniques. Larger studies with outcome data are now required to define its true utility in the CKD population.

Cardiac testing for coronary artery disease in potential kidney transplant recipients

BACKGROUND

Patients with chronic kidney disease (CKD) are at increased risk of coronary artery disease (CAD) and adverse cardiac events. Screening for CAD is therefore an important part of preoperative evaluation for kidney transplant candidates. There is significant interest in the role of non-invasive cardiac investigations and their ability to identify patients at high risk of CAD. 

OBJECTIVES

We investigated the accuracy of non-invasive cardiac screening tests compared with coronary angiography to detect CAD in patients who are potential kidney transplant recipients.

SEARCH METHODS

MEDLINE and EMBASE searches (inception to November 2010) were performed to identify studies that assessed the diagnostic accuracy of non-invasive screening tests, using coronary angiography as the reference standard. We also conducted citation tracking via Web of Science and handsearched reference lists of identified primary studies and review articles.  

SELECTION CRITERIA

We included in this review all diagnostic cross sectional, cohort and randomised studies of test accuracy that compared the results of any cardiac test with coronary angiography (the reference standard) relating to patients considered as potential candidates for kidney transplantation or kidney-pancreas transplantation at the time diagnostic tests were performed. 

DATA COLLECTION AND ANALYSIS

We used a hierarchical modelling strategy to produce summary receiver operating characteristic (SROC) curves, and pooled estimates of sensitivity and specificity. Sensitivity analyses to determine test accuracy were performed if only studies that had full verification or applied a threshold of ≥ 70% stenosis on coronary angiography for the diagnosis of significant CAD were included.

MAIN RESULTS

The following screening investigations included in the meta-analysis were: dobutamine stress echocardiography (DSE) (13 studies), myocardial perfusion scintigraphy (MPS) (nine studies), echocardiography (three studies), exercise stress electrocardiography (two studies), resting electrocardiography (three studies), and one study each of electron beam computed tomography (EBCT), exercise ventriculography, carotid intimal media thickness (CIMT) and digital subtraction fluorography (DSF). Sufficient studies were present to allow hierarchical summary receiver operating characteristic (HSROC) analysis for DSE and MPS. When including all available studies, both DSE and MPS had moderate sensitivity and specificity in detecting coronary artery stenosis in patients who are kidney transplant candidates [DSE (13 studies) - pooled sensitivity 0.79 (95% CI 0.67 to 0.88), pooled specificity 0.89 (95% CI 0.81 to 0.94); MPS (nine studies) - pooled sensitivity 0.74 (95% CI 0.54 to 0.87), pooled specificity 0.70 (95% CI 0.51 to 0.84)]. When limiting to studies which defined coronary artery stenosis using a reference threshold of ≥ 70% stenosis on coronary angiography, there was little change in these pooled estimates of accuracy [DSE (9 studies) - pooled sensitivity 0.76 (95% CI 0.60 to 0.87), specificity 0.88 (95% CI 0.78 to 0.94); MPS (7 studies) - pooled sensitivity 0.67 (95% CI 0.48 to 0.82), pooled specificity 0.77 (95% CI 0.61 to 0.88)]. There was evidence that DSE had improved accuracy over MPS (P = 0.02) when all studies were included in the analysis, but this was not significant when we excluded studies which did not avoid partial verification or use a reference standard threshold of ≥70% stenosis (P = 0.09).  

AUTHORS' CONCLUSIONS

DSE may perform better than MPS but additional studies directly comparing these cardiac screening tests are needed. Absence of significant CAD may not necessarily correlate with cardiac-event free survival following transplantation. Further research should focus on assessing the ability of functional tests to predict postoperative outcome.

Should we screen for coronary artery disease in asymptomatic chronic dialysis patients?

The hemodialysis population is characterized by a high prevalence of 'asymptomatic' coronary artery disease (CAD), which should be interpreted differently from asymptomatic disease in the general population. A hemodynamically significant stenosis may not become clinically apparent owing to impaired exercise tolerance and autonomic neuropathy. The continuous presence of silent ischemia may cause heart failure, arrhythmias, and sudden death. Whether revascularization of an asymptomatic dialysis patient improves outcome remains a moot point, although several observational studies and one small RCT suggest a benefit. It can therefore be defended to screen asymptomatic dialysis patients for CAD. A number of noninvasive screening tests are available, but none has proved equally practical and reliable in the dialysis population as in the general population. Myocardial perfusion scintigraphy (MPS) before and after a pharmacological stress such as dipyridamole can reveal both ischemia and myocardial scarring. When compared with coronary angiography, low sensitivities were reported and attributed to impaired vasodilation to dipyridamole in dialysis patients. A more likely explanation is that not every anatomical stenosis will lead to impaired coronary blood flow on MPS. Numerous studies have shown an incremental prognostic value of dipyridamole-MPS over clinical data for prediction of adverse cardiac events, in some studies even over coronary angiography. Pending the availability of high-quality evidence, in our opinion asymptomatic dialysis patients could undergo dipyridamole-MPS, followed by coronary angiography in case of an abnormal scan. This combined physiological and anatomical evaluation of the coronary circulation allows us to determine which coronary stenosis is clinically relevant and therefore should be revascularized.

Dipyridamole stress echocardiography in diagnosis and prognosis of hemodialysis patients with asymptomatic coronary disease

The prevalence of coronary artery disease (CAD) is high in hemodialysis (HD) patients. The aim of the study was to assess the diagnostic and prognostic value of dipyridamole stress echocardiography (DSE) in nondiabetic HD patients without signs or symptoms of CAD. In 51 out of 158 evaluated HD patients (21 females, age 67 [33-85] years, HD duration 38 [9-271] months), resting echocardiography and DSE were performed. Exclusion criteria were known CAD, diabetes mellitus, and pulmonary and oncologic pathologies. Logistic regression analysis was carried out to identify predictors of abnormal DSE response, while Cox regression analysis was performed to determine variables associated with total and cardiovascular mortality, after 43.3 (11-60) months of follow-up. Seven patients (14%) showed a positive response to DSE (DSE+). In 5/7, CAD was documented by angiography: All of them underwent coronary revascularization. DSE+ patients had significantly smaller body mass index than patients with a negative response (DSE-): 21.7 ± 1.9 vs. 25.1 ± 3.4 kg/m(2) (p = 0.018). During follow-up, 16 (31%) patients died. Older age hazard ratio [HR = 1.07; confidence interval (CI) = 1.01-1.12; p = 0.02] and higher plasma phosphate levels (HR = 10.41; CI = 2.30-47.17; p < 0.01) were predictors of total mortality. Male gender (HR = 22.7; CI = 1.45-354.4; p = 0.03), older age (HR = 1.24; CI = 1.03-1.50; p = 0.02), longer HD duration (HR = 1.13; CI = 1.01-1.26; p = 0.04), and positive response to DSE (HR = 5.82; CI = 1.04-32.65; p = 0.04) were associated with cardiovascular mortality. Ten percent of asymptomatic HD patients had significant CAD, but timely diagnosis did not seem to improve their prognosis. Total survival was associated with age and higher levels of plasma phosphate, while male gender, older age, longer HD duration, and DSE+ were predictors of cardiovascular mortality.

Cardiac testing for coronary artery disease in potential kidney transplant recipients: a systematic review of test accuracy studies

BACKGROUND

Cardiovascular disease is the leading cause of death after kidney transplant. Screening for coronary artery disease is integral to pretransplant evaluation, although the relative performance of different tests is uncertain.

STUDY DESIGN

Systematic review of diagnostic test accuracy studies using hierarchical summary receiver operating characteristic analysis.

SETTING & POPULATION

Kidney transplant candidates undergoing pretransplant assessment. SELECTION CRITERIA OF STUDIES: Studies evaluating the accuracy of screening tests for detecting coronary artery disease.

INDEX TESTS

Any non- or minimally invasive test used to diagnose coronary artery disease.

REFERENCE TEST

Coronary angiography.

RESULTS

11 studies (690 participants) evaluated dobutamine stress echocardiography; 7 (317 participants), myocardial perfusion scintigraphy; 2 (129 participants), exercise stress electrocardiography; and 2 (121 participants), other tests. Dobutamine stress echocardiography had pooled sensitivity of 0.80 (95% CI, 0.64-0.90) and specificity of 0.89 (95% CI, 0.79-0.94). Myocardial perfusion scintigraphy had pooled sensitivity of 0.69 (95% CI, 0.48-0.85) and specificity of 0.77 (95% CI, 0.59-0.89). Head-to-head comparison of dobutamine stress echocardiography and myocardial perfusion scintigraphy (2 studies; 116 participants) showed that dobutamine stress echocardiography had higher specificity and at least equivalent or higher sensitivity. Indirect comparison suggested dobutamine stress echocardiography may have improved accuracy over myocardial perfusion scintigraphy (P = 0.07).

LIMITATIONS

Power to detect differences in accuracy between tests is limited due to sparse data. Absence of significant coronary artery disease may not necessarily correlate with cardiac event-free survival after transplant.

CONCLUSIONS

Dobutamine stress echocardiography may perform better than myocardial perfusion scintigraphy; however, additional studies directly comparing dobutamine stress echocardiography and myocardial perfusion scintigraphy are needed. Further research should focus on assessing the ability of functional tests to predict postoperative outcome.

A preoperative echocardiographic predictive model for assessment of cardiovascular outcome after renal transplantation

OBJECTIVE

Major adverse cardiac events (MACE) frequently determine the outcome of renal transplantation (RT). Stress testing is advocated for preoperative risk assessment, but limited information is available on the prognostic value of these tests. We aimed to retrospectively assess the value of preoperative dobutamine stress echocardiography (DSE) in predicting MACE in patients undergoing RT.

METHODS

A total of 185 patients (age 56 +/- 11 years, 64% were men, creatinine level of 7.3 +/- 2.9 mg/d, 27% were smokers, 86% had hypertension, 54% had diabetes, 57% were dyslipidemic) with end-stage renal disease (ESRD) underwent DSE before RT. A standard DSE protocol was used with the administration of 5-50 mug/kg/min incremental doses in 3-minute intervals and up to 1 mg of atropine if needed to reach prespecified end points.

RESULTS

Regional left ventricular wall motion abnormality (WMA) at rest (fixed), with stress (inducible), or both were present in 54, 35, and 18 patients, respectively. In 38 patients who underwent coronary angiography, the sensitivity, specificity, and positive and negative predictive values of inducible WMA for predicting angiographic coronary artery disease (> or = 70% luminal diameter reduction) were 88%, 62%, 65%, and 87%, respectively. Cox regression analysis identified the presence of combined fixed and inducible WMA (ie, resting WMA that did not change during DSE, accompanied by new WMA evident during DSE; hazard ratio [HR] 5.6, P = .012), left atrial enlargement (HR 4.2, P = .002), and aortic valve sclerosis (HR 3.9, P = .013) as independent predictors of 48-month MACE (cardiac death, nonfatal acute myocardial infarction, and coronary revascularization after RT). Patients with all 3 predictors had a 48-month MACE of 60% compared with 5% in those with none (P = .007). Compared with those without WMA, patients with both fixed and inducible WMA had a higher rate of MACE at 48 months (7% vs 33%, P = .004).

CONCLUSION

In RT candidates, DSE can effectively identify those at low and high risk of MACE.

Comparison of dobutamine stress echocardiography, dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging in patients with end-stage renal disease

OBJECTIVES

We sought to assess and compare the diagnostic accuracy and prognostic value of dobutamine stress echocardiography (DSE), dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging (MPI) in patients with end-stage renal disease (ESRD).

BACKGROUND

The optimal stress imaging modality for patients with ESRD has not yet been determined.

METHODS

Forty-nine patients with ESRD underwent DSE, dobutamine SPECT MPI, and adenosine SPECT MPI. The primary endpoint of the trial was concordance between stress tests with respect to the presence or absence of ischemia.

RESULTS

Agreement on the presence or absence of ischemia between adenosine SPECT MPI and DSE was 69% (kappa = .25, P = NS). Agreement on the presence or absence of ischemia between adenosine and dobutamine SPECT MPI was 77% (kappa = .37, P = <.009). Summed stress scores for adenosine and dobutamine SPECT MPI studies were highly correlated (r = .9, P = <.0001). DSE and SPECT MPI results provided incremental prognostic information when added to clinical variables.

CONCLUSIONS

There is moderate concordance between DSE and adenosine SPECT MPI in ESRD patients referred for stress testing. Interobserver agreement was higher for SPECT MPI compared to DSE. Based on these observations, the optimal approach for diagnosing severe coronary artery disease and assessing risk in patients with ESRD has yet to be determined, but appears to warrant further investigation.

Prognostic value of dobutamine stress echocardiography in patients with chronic kidney disease

BACKGROUND

Although dobutamine stress echocardiography (DSE) is cited in clinical guidelines for the evaluation of patients with chronic kidney disease (CKD), there are limited data regarding its prognostic utility in this setting. The current study assesses the prognostic value of DSE in patients with CKD.

METHODS

Four hundred eighty-five patients with CKD (on renal dialysis or with creatinine > 3 mg/mL) who had DSE were followed for 2.3 +/- 1.8 years.

RESULTS

One hundred eighty-eight (39%) patients died during follow-up. Patients with extensive ischemia (affecting > 25% of myocardial segments) had a 1- and 3-year survival rate of 77% and 48%, respectively, compared with 83% and 52% in those with lesser degrees (< or = 25% segments affected) of ischemia and with 88% and 70% in those with a normal DSE. In multivariate analyses, the percentage of ischemic segments on DSE was an independent predictor of all-cause mortality (hazard ratio, 1.40 per 25% increase; 95% CI, 1.16-1.68; P = .001). Inclusion of DSE data improved the predictive value of the best clinical model (chi2, 83.6-97.4; P = .003).

CONCLUSION

In patients with CKD, the percentage of ischemic segments during DSE is an independent predictor of mortality and provides prognostic information that is incremental to clinical data.

Effect of aggressive risk factor modification on cardiac events and myocardial ischaemia in patients with chronic kidney disease

OBJECTIVE

To examine whether aggressive risk factor modification in chronic kidney disease (CKD) can limit the development of new ischaemia or reduce cardiac events.

METHODS

Patients with CKD were randomly assigned to either an aggressive risk factor modification strategy (targeted treatment of hypertension, dyslipidaemia, homocysteine, haemoglobin and phosphate) or standard care. An intention to treat analysis was performed on 152 patients who had baseline dobutamine stress echocardiography (DSE), including 107 who had follow-up DSE. Biochemical parameters, cardiac risk factors and investigations (ECG, two-dimensional echocardiography) were recorded at baseline. New ischaemia was classed as new or worsening stress wall motion abnormality between follow-up and baseline DSE. Patients were followed up for the development of new ischaemia or cardiac death, acute coronary syndrome and non-fatal myocardial infarction over 1.8 years.

RESULTS

The development of new ischaemia was common but not different between the standard and aggressively treated groups (15 (21%) v 18 (23%), p = 0.8). Independent predictors of new ischaemia were older age, abnormal ECG, higher systolic blood pressure and lower serum high density lipoprotein cholesterol, but not treatment arm. The standard and aggressively treated groups did not differ in cardiac event rate (10% v 13%, p = 0.6) or all-cause mortality (10% v 19%, p = 0.2). In patients with an abnormal baseline DSE (non-diagnostic, scar or ischaemia), the event rate was similar (22% v 20%, p = 0.9).

CONCLUSION

Aggressive risk factor modification in CKD does not limit the development of new ischaemia or reduce cardiac events in patients with an abnormal DSE.

Clinical, resting echo and dipyridamole stress echocardiography findings for the screening of renal transplant candidates

BACKGROUND

Preoperative screening for coronary artery disease is recommended in high-risk renal transplant candidates. Aim of this study was to prospectively assess the value of a comprehensive risk stratification strategy including clinical, resting echo, and dipyridamole stress echo findings before renal transplantation.

METHODS

The study group consisted of 71 renal transplant candidates (47 men; age 54+/-11 years) fulfilling one or more of the following high-risk clinical criteria: history of coronary artery disease, wall motion abnormalities at resting echo, dialysis dependency lasting >5 years, presence of 2 or more risk factors. Clinical history, resting echo, and dipyridamole stress echo (up to 0.84 mg over 10 min + atropine up to 1 mg) were obtained in all subjects.

RESULTS

Mean number of risk factors was 2.5+/-1.0. Known coronary artery disease and diabetes were present, respectively, in 2 (3%) and 11 (15%) persons. No patient had left ventricular ejection fraction <45%. Left ventricular hypertrophy was found in 53 (74%) cases. Stress echo showed 100% safety and 97% overall feasibility. Inducible ischemia (new wall motion abnormalities) was detected in 3 (4%) subjects. During follow-up (36+/-12 months), 8 (11%) cardiac events occurred: 2 deaths, 2 myocardial infarctions, 3 coronary interventions, and 1 pulmonary edema. The perioperative period and subsequent follow-up (22+/-12 months) was uneventful among 32 patients who received renal transplantation. Four-year event-free survival was 92% in those without ischemia; it was 96% in the non-diabetic population. Diabetes (HR=4.78), age (HR=1.14), and left ventricular mass index (HR=1.02) were independent prognostic indicators among clinical and resting echo variables. The global chi-square of the statistical model was 18.8; it increased to 27.3 (+45%) after the addition of stress echo result.

CONCLUSIONS

Renal transplant candidates can undergo effective stratification of risk by combining clinical, resting echo and dipyridamole stress echo findings.

Atherosclerosis in Dialyzed Patients

In the recent HEMO study, the most common cause of death in dialyzed patients was ischemic heart disease. In Europe there are regional differences, but the mortality due to cardiovascular disease is also very high. The long-lasting controversy whether the high incidence and prevalence of atherosclerotic manifestations (particularly ischemic heart disease) may be explained by known risk factors, or non-traditional risk factors are also involved seems to be partially solved with the increasing evidence that the latter hypothesis is true. Thus, together with classic risk factors such as hypertension, dyslipidemia and diabetes, other situations such as microinflammation, increased concentration of asymmetrical dimethyl-L-arginine, disturbed phosphate metabolism and anemia may represent important risk factors for accelerated atherosclerosis in dialyzed patients.

Coronary angiography is the best predictor of events in renal transplant candidates compared with noninvasive testing

Guidelines for the detection of coronary artery disease (CAD) and assess of risk in renal transplant candidates are based on the results of noninvasive testing, according to data originated in the nonuremic population. We evaluated prospectively the accuracy of 2 noninvasive tests and risk stratification in detecting CAD (>or=70% obstruction) and assessing cardiac risk by using coronary angiography (CA). One hundred twenty-six renal transplant candidates who were classified as at moderate (>or=50 years) or high (diabetes, extracardiac atherosclerosis, or clinical coronary artery disease) coronary risk underwent myocardial scintigraphy (SPECT), dobutamine stress echocardiography, and CA and were followed for 6 to 48 months. The prevalence of CAD was 42%. The sensitivities and negative predictive values for the 2 noninvasive tests and risk stratification were <75%. After 6 to 48 months, there were 18 cardiac events, 9 fatal. Risk stratification (P=0.007) and CA (P=0.0002) predicted the crude probability of surviving free of cardiac events. The probability of event-free survival at 6, 12, 24, 36, and 48 months were 98%, 98%, 94%, 94%, and 94% in patients with <70% stenosis on CA and 97%, 87%, 61%, 56%, and 54% in patients with >or=70% stenosis. Multivariate analysis showed that the sole predictor of cardiac events was critical coronary lesions (P=0.003). Coronary angiography may still be necessary for detecting CAD and determining cardiac risk in renal transplant candidates. The data suggest that current algorithms based on noninvasive testing in this population should be revised.

Prognostic value of myocardial perfusion studies in patients with end-stage renal disease assessed for kidney or kidney-pancreas transplantation: a meta-analysis

The prognostic utility of myocardial perfusion studies (MPS) such as thallium scintigraphy and dobutamine stress echocardiography (DSE) for stratifying cardiac risk among candidates for kidney or kidney-pancreas transplantation is uncertain. This study is a meta-analysis to determine the prognostic significance of MPS results on future myocardial infarction (MI) and cardiac death (CD) in patients with end-stage renal disease (ESRD) assessed for kidney or kidney-pancreas transplantation. MEDLINE was searched using combinations of MeSH headings and text words for transplantation, coronary artery disease, prognosis, end-stage renal disease, and noninvasive cardiac testing (nuclear scintigraphy and DSE) for primary studies. Studies were included if they reported MPS results and cardiac events in patients assessed for kidney or kidney-pancreas transplantation. Methodologic study quality and outcome data were independently abstracted in duplicate by two researchers. The relative risks (RR) of MI and CD were calculated using a random effects model. Twelve articles met all inclusion criteria; 12 studies reported CD, and 9 reported MI. In eight studies, thallium scintigraphy was used (four with pharmacologic stress, four with exercise stress), whereas four used DSE. When compared with negative tests, positive tests had a significantly increased RR of MI (2.73 [95% CI, 1.25 to 5.97]; P = 0.01) and CD (2.92 [95% CI, 1.66 to 5.12]; P < 0.001). Subgroup analyses of studies of diabetic patients indicated that positive tests were associated with a RR of CD 3.95 (95% CI, 1.48 to 10.5; P = 0.006) and a RR of MI 2.68 (95% CI, 0.95 to 7.57; P = 0.06) when compared with negative tests. In studies evaluating mixed populations of diabetic and nondiabetic patients, positive tests were associated with a RR of CD 2.52 (95% CI, 1.25 to 5.08; P = 0.01) and with a RR of MI 2.79 (95% CI, 0.85 to 9.21; P = 0.09) when compared with a negative test. The presence of reversible defects was associated with an increased risk of MI in diabetic patients and of CD in both subgroups; fixed defects were associated with an increased risk of CD but not MI. It is concluded that positive MPS are useful in identifying patients with significantly increased risk of future MI and CD in both diabetic and nondiabetic ESRD patients.

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.

Screening for coronary artery disease

Unidentified coronary artery disease remains a significant cause of premature death and morbidity during the prime of life. The availability of effective interventions for the management of ischemia has provoked new interest in screening for this condition in asymptomatic patients, in the hope of reducing the burden of this condition. Although widespread use of stress testing is ineffective, the use of imaging techniques may offer better accuracy for detection of ischemia. Other tests that identify evidence of atheroma in the peripheral or coronary circulation may be useful to identify patients at risk.