Usefulness of dobutamine stress echocardiography in detecting coronary artery disease in end-stage renal disease

Cardiac risk assessment for end-stage renal disease patients on the renal transplant waiting list

Cardiovascular disease is a leading cause of morbidity and mortality and is becoming more prevalent as the population ages and risk factors increase. This is most apparent in the end-stage renal disease (ESRD) patient population. In part, this is due to cofactors such as diabetes and hypertension commonly predisposing to progressive renal disease, as well as being a direct consequence of having renal failure. Of all major organ failures, kidney failure is the most likely to be managed chronically using renal replacement therapy and, ultimately, transplant. However, lack of transplant organs and a large renal failure cohort means waiting lists are often quite long and may extend to 5-10 years. Due to the cardiac risk factors inherent in patients awaiting transplant, many succumb to cardiac issues while waiting and present an increased per-procedural cardiac risk that extends into the post-transplant period. We aim to review the epidemiology of coronary artery disease in this population and the etiology as it relates to ESRD and its associated co-factors. We also will review the current approaches, recommendations and evidence for management of these patients as it relates to transplant waiting lists before and after the surgery. Recommendations on how to best manage patients in this cohort revolve around the available evidence and are best customized to the institution and the structure of the program. It is not clear whether the revascularization of patients without symptoms and with a good functional status yields any improvement in outcomes. Therefore, each individual case should be considered based on the risk factors, symptoms and functional status, and approached as part of a multi-disciplinary assessment program.

The significance of electrocardiographic changes without echocardiographic evidence of segmental wall motion abnormalities in patients undergoing dobutamine stress echocardiography

Ischemic ECG changes during dobutamine stress echocardiography (DSE) have been reported to have low sensitivity and specificity for detecting myocardial ischemia in the absence of wall motion abnormalities on echocardiography. We present a case of a renal transplant candidate with severe multivessel disease who had ST depressions without any wall motion abnormalities on DSE. Certain studies have shown the sensitivity of DSE is lower in patients with left ventricular hypertrophy and/or end stage renal disease, but the significance of ischemic ECG changes with no evidence of wall motion abnormalities in these patients has not been well studied.

Current practices in coronary artery disease evaluation of renal transplant candidates prior to renal transplantation

Cardiovascular disease is the leading cause of morbidity and mortality in renal transplant recipients and candidates awaiting transplant. Pre-transplant coronary artery disease evaluation can aid in determining transplant candidacy, identifying patients who may benefit from pre-operative cardiac intervention, and implementing measures to reduce perioperative and post-transplant cardiovascular events. However, the choice of investigations and approach in evaluation has yet to be well defined. This article aims to review the evidence for the use of non-invasive investigations and coronary angiography in prognostication, as well as the evidence for revascularization in reducing future cardiac events. The article will also summarize international recommendations and describe the local practice in coronary artery disease evaluation prior to transplant.

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.

Cardiovascular risk assessment in kidney transplantation

Cardiovascular disease (CVD) remains the most common cause of death after kidney transplantation worldwide, with the highest event rate in the early postoperative period. In an attempt to address this issue, screening for CVD prior to transplant is common, but the clinical utility of screening asymptomatic transplant candidates remains unclear. A large degree of variation exists among both transplant center practice patterns and clinical practice guidelines regarding who should be screened, and opinions are based on mixed observational data with great potential for bias. In this review, we discuss the potential risks, benefits, and evidence for screening for CVD in kidney transplant candidates, and also the next steps to better evaluate and treat asymptomatic kidney transplant candidates.

Evaluation of solid organ transplant candidates for coronary artery disease

Solid organ transplantation has increased in frequency in the United States, having evolved from an area of experimentation into accepted therapy for end-organ failure. As organ transplantation has become more common, the average age of transplant recipients has increased, thus increasing the potential for multiple comorbidities including coronary artery disease (CAD). CAD has been shown to be a major cause of morbidity and mortality in kidney, lung and liver transplant recipients. Identification of CAD in solid organ transplant candidates allows for stratification of short- and long-term risk, ensuring proper use of valuable allograft resources while guiding further patient management. Assessment of asymptomatic transplant candidates for CAD is difficult. Many patients undergo stress echocardiography or nuclear imaging, which have demonstrated inconsistent rates of sensitivity and specificity for the detection of CAD in these patient populations. Cardiac computed tomography is a potential tool for detecting CAD in these populations, but has questionable utility at this time. Coronary angiography has an important role in detecting CAD in high-risk transplant candidates, affecting their long-term management and risk.

Coronary artery disease in patients with chronic kidney disease: a clinical update

Chronic kidney disease (CKD) is an independent risk factor for coronary artery disease (CAD). Coronary artery disease is the leading cause of morbidity and mortality in patients with CKD. The outcomes of CAD are poorer in patients with CKD. In addition to traditional risk factors, several uremia-related risk factors such as inflammation, oxidative stress, endothelial dysfunction, coronary artery calcification, hyperhomocysteinemia, and immunosuppressants have been associated with accelerated atherosclerosis. A number of uremia-related biomarkers are identified as predictors of cardiac outcomes in CKD patients. The symptoms of CAD may not be typical in patients with CKD. Both dobutamine stress echocardiography and radionuclide myocardial perfusion imaging have moderate sensitivity and specificity in detecting obstructive CAD in CKD patients. Invasive coronary angiography carries a risk of contrast nephropathy in patients with advanced CKD. It should be reserved for those patients with a high risk for CAD and those who would benefit from revascularization. Guideline-recommended therapies are, in general, underutilized in renal patients. Medical therapy should be considered the initial strategy for clinically stable CAD. The effects of statins in patients with advanced CKD have been neutral despite a lipid-lowering effect. Compared to non-CKD population, percutaneous coronary intervention (PCI) is associated with higher procedure complications, restenosis, and future cardiac events even in the drug-eluting stent era in patients with CKD. Compared with PCI, coronary artery bypass grafting (CABG) reduces repeat revascularizations but is associated with significant perioperative morbidity and mortality. Screening for CAD is an important part of preoperative evaluation for kidney transplant candidates.

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.

Coronary risk assessment and management options in chronic kidney disease patients prior to kidney transplantation

Cardiovascular disease remains the most important cause of morbidity and mortality among kidney transplant recipients. Nearly half the deaths in transplanted patients are attributed to cardiac causes and almost 5% of these deaths occur within the first year after transplantation. The ideal strategies to screen for coronary artery disease (CAD) in chronic kidney disease patients who are evaluated for kidney transplantation (KT) remain controversial. The American Society of Transplantation recommends that patients with diabetes, prior history of ischemic heart disease or an abnormal ECG, or age ≥50 years should be considered as high-risk for CAD and referred for a cardiac stress test and only those with a positive stress test, for coronary angiography. Despite these recommendations, vast variations exist in the way these patients are screened for CAD at different transplant centers. The sensitivity and specificity of noninvasive cardiac tests in CKD patients is much lower than that in the general population. This has prompted the use of direct diagnostic cardiac catheterization in high-risk patients in several transplant centers despite the risks associated with this invasive procedure. No large randomized controlled trials exist to date that address these issues. In this article, we review the existing literature with regards to the available data on cardiovascular risk screening and management options in CKD patients presenting for kidney transplantation and outline a strategy for approach to these patients.

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.

Perioperative management of patients with renal disease

The patient who has renal disease is susceptible to many potential complications during the perioperative period. The prevention of postoperative acute renal failure (ARF), especially in patients who have existing chronic kidney disease, and management of patients who have end-stage renal disease (ESRD) who are undergoing surgery are challenging. Elimination of risk factors for ARF and early diagnosis of ARF should improve patient outcomes. For patients who have ESRD, a thorough and comprehensive evaluation is necessary to decrease morbidity and mortality associated with the end-organ damage. This article reviews the prevention of postoperative ARF and the perioperative management of patients who have ESRD who are undergoing surgery.

Cardiovascular risk assessment among potential kidney transplant candidates: approaches and controversies

Cardiovascular disease is the most common cause of death after kidney transplantation. However, uncertainties regarding the optimal assessment of cardiovascular risk in potential transplant candidates have produced controversy and inconsistency in pretransplantation cardiac evaluation practices. In this review, we consider the evidence supporting cardiac evaluation in kidney transplant candidates, generally focused on coronary artery disease, according to the World Health Organization principles for screening. The importance of pretransplant cardiac evaluation is supported by the high prevalence of coronary artery disease and the incidence and adverse consequences of acute coronary syndromes in this population. Testing for coronary artery disease may be performed noninvasively by using modalities that include nuclear myocardial perfusion studies and dobutamine stress echocardiography. These tests have prognostic value for mortality, but imperfect sensitivity and specificity for detecting angiographically defined coronary artery disease in patients with end-stage renal disease. Associations of angiographically-defined coronary artery disease with subsequent survival also are inconsistent, likely because plaque instability is more critical for infarction risk than angiographic stenosis. The efficacy and best methods of myocardial revascularization have not been examined in large contemporary clinical trials in patients with end-stage renal disease. Biomarkers, such as cardiac troponin, have prognostic value in end-stage renal disease, but require further study to determine clinical applications in directing more expensive and invasive cardiac evaluation.

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.

The diagnostic and prognostic value of tissue Doppler imaging during dobutamine stress echocardiography in end-stage renal disease

OBJECTIVE

To determine whether a quantitative measurement of peak systolic velocity (PSV) during dobutamine stress echocardiography (DSE) detects severe coronary artery disease (CAD) and predicts mortality in patients with end-stage renal disease.

METHODS

One hundred and forty renal transplant candidates had DSE and coronary angiography. DSE analysis was performed using conventional visual wall motion assessment, longitudinal PSV, and combining the two modalities. Failure of PSV to rise by more than 50% predicted an ischemic response. Significant CAD was defined as luminal stenosis greater than 70%.

RESULTS

The number of positive DSE studies according to conventional, PSV, and combined criteria was 41 (30%), 42 (31%), and 46 (34%) respectively. Forty patients (29%) had significant CAD at angiography. The sensitivity, specificity, positive and negative predictive values for conventional DSE analysis were 84, 91, 86, and 90% respectively. The same values for PSV analysis were 86, 92, 86, and 91%, respectively. The same values for the combination of visual and PSV analysis were 88, 94, 87, and 92% respectively. The differences between the three methods were not statistically significant. Sensitivity for single-vessel CAD (P=0.05) and circumflex artery disease (P=0.05) diagnosis was higher with PSV compared with conventional DSE analysis. Failure of PSV to rise by more than 50% during DSE was associated with significantly increased mortality (P=0.001).

CONCLUSION

A quantitative interpretation of DSE, based on the percentage rise of PSV during stress, accurately detects CAD and predicts prognosis in end-stage renal disease.

Clinical utility of myocardial fatty acid imaging in patients with end-stage renal disease

The prevalence of coronary artery disease (CAD) appears to be much higher in patients with end-stage renal disease (ESRD) undergoing dialysis than in a non-ESRD population. Cardiac death due to myocardial ischemia significantly contributes to the high mortality rate of ESRD patients. However, the method for screening for CAD in ESRD patients has not been established, because the frequency of silent myocardial ischemia is high and examinations requiring stress are often difficult to perform among this population. Myocardial fatty acid imaging may be a new modality to detect myocardial ischemia and identify the group at high risk for cardiac death among ESRD patients without adding any stress.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Anaesthesia for renal transplant surgery

Renal transplantation is the preferred therapeutic option for patients with end-stage renal disease. Survival rates are much higher in patients who receive a transplant. Patients with renal failure have significant concomitant medical conditions, such as cardiovascular disease. This article provides an overview of the important issues to be considered in patients undergoing renal transplant, and discusses the anaesthetic management of these patients.

Risk factors for mortality in diabetic nephropathy patients accepted for transplantation

BACKGROUND

There is a high incidence of silent coronary artery disease (CAD) in patients with diabetes. We wanted to investigate risk factors for mortality, and especially CAD, in a well-defined cohort of diabetic nephropathy transplant candidates accepted for transplantation.

METHODS

From 1999 through 2004, 155 patients underwent work up for living or deceased kidney (KA) or simultaneous pancreas-kidney (SPK) transplantation. The work up included coronary angiography for all patients and 136 were accepted. Mean (SD) age was 50 (12) years, 62% had type 1 diabetes, 73% were males, and 34% were on dialysis. Mean follow-up from time of acceptance for transplantation was 3.6 (1.9) years.

RESULTS

Survival of KA transplanted patients was 97% at 1 year, 89% at 3 years, and 76% at 5 years, whereas in SPK patients 100%, 94%, and 90%, respectively (P=0.065). One- and 3- year survival was only 57% and 20% in those remaining wait-listed (P<0.001). In univariate analysis mortality was associated with KA transplantation (hazard ratio [HR]=0.30, P=0.011) and SPK transplantation (HR=0.10, P=0.001), and age (HR=1.04, P=0.014). In multivariable analysis, KA transplantation (HR=0.28, P=0.006), SPK transplantation (HR=0.09, P=0.001), age (HR=1.06, P=0.002), type 2 diabetes (HR=0.14, P=0.003), and duration of diabetes (HR=0.94, P=0.019) were parameters associated with mortality.

CONCLUSIONS

The only modifiable risk factor was transplantation with risk reduction up to 90%. CAD was not a risk factor for mortality when medically treated and revascularized according to standard guidelines.

Stress echocardiography for risk stratification in patients with end-stage renal disease undergoing renal transplantation

BACKGROUND

The predictive accuracy of stress echocardiography (SE) for adverse cardiac events has been variable in the population with end-stage renal disease undergoing renal transplantation (RT).

METHODS

We performed a retrospective study of 149 patients who had pretransplant SE before RT between 1997 and 2003. Patients were followed up for a mean of 2.85 years for major adverse cardiovascular events (MACE).

RESULTS

Of 149 patients studied, 139 had a negative SE, 65% were African American; 12 underwent cardiac catheterization. Only 1 patient required pre-RT revascularization. Sixteen MACE occurred over the follow-up period. SE had 37.5% sensitivity, 95.3% specificity, 33.3% positive predictive value, and 96.1% negative predictive value for MACE in the first year post-RT. First-year posttransplant event rates were 4.0% versus 30% (P < .001) for patients with a negative SE and positive SE, respectively. Multivariate predictors of MACE were positive SE (hazard ratio [HR] 7.64), hemoglobin less than 11 g/dL post-RT (HR 4.44), and calcium channel blocker use posttransplant (HR 2.90).

CONCLUSIONS

A negative SE has low incidence of MACE in this intermediate- to high-risk patient subset. A positive SE predicts a sevenfold higher risk of cardiovascular events regardless of the need for revascularization before the transplant.

Stress Echocardiography: Abnormal Response of Tissue Doppler?Derived Indices to Dobutamine in the Absence of Obstructive Coronary Artery Disease in Patients with Chronic Renal Failure

BACKGROUND

Abnormal tissue Doppler (TD)-derived indices during dobutamine stress echocardiography (DSE) can predict the presence of coronary artery disease (CAD) in patients with normal renal function. These indices include a reduction in annular systolic velocity (S'), a decrease in early diastolic annular velocity (E'), and prolongation of the time to E'. However, the ability of these indices to detect or exclude CAD in patients with chronic renal failure (CRF) is unclear.

OBJECTIVE

To examine the ability of TD-derived indices to detect or exclude the presence of CAD in patients with CRF.

METHODS

We evaluated a total of 30 patients (13 males, mean age 57 +/- 15 years) using both DSE and coronary angiography. This cohort consisted of 12 control patients with normal renal function (mean creatinine 0.5 mg/dL) and 18 patient with CRF (mean creatinine 2.5 mg/dL). At each stage of the DSE, left ventricular (LV) diastolic function was assessed using conventional (peak early (E) and late (A) transmitral, E/A ratio, E-wave deceleration time (DT), and isovolumic relaxation time (IVRT)) and TD-derived indices (lateral annular systolic (S'), early diastolic (E'), and late atrial velocities (A'), time to E' and E/E').

RESULTS

All 30 patients had a normal DSE based on systolic regional function and a normal coronary angiogram. There was no difference in E, A, E/A, DT or IVRT between the two groups at each stage. Despite normal coronaries, patients with CRF demonstrated lower S' and E' velocities at peak stress compared to the control patients (8.0 +/- 2.2 cm/sec vs 15.1 +/- 2.6, P < 0.05 and 6.7 +/- 1.6 cm/sec vs 13.3 +/- 3.1, P < 0.05, respectively). During DSE, the time to E' at peak stress in CRF patients was also prolonged compared to control (400 +/- 44 ms vs 329 +/- 51, P < 0.05). Patients with CRF also had increased filling pressures (as estimated by E/E') as compared to controls at peak stress (14.7 +/- 5.2 vs 7.4 +/- 1.5, P < 0.05, respectively).

CONCLUSION

In patients with CRF, a reduction in TD derived indices does not predict the presence of obstructive CAD.

[Coronary artery disease and coronary angioplasty in chronic hemodialysis patients]

Chronic renal insufficiency leads to many cardiovascular complications and provide worst prognosis, especially when patients need hemodialysis. The atherosclerosis of chronic hemodialysis patients is qualified as "accelerated" by some authors, because of a very fast and large progression. To improve prognosis, it seems to be very important to detect and treat the frequent and serious underlying cardiovascular disease. Because of the high rate of diabetes mellitus, silent ischemia is a very frequent clinical situation. In the other hand, coronary artery disease in chronic hemodialysis patients is frequently complex, with a large coronary extension and high rate of coronary calcifications. Consequently, this disease needs a specific therapeutic approach. Even though, percutaneous coronary interventions (PCI) are more complex in this population, it provides good results, and improves patient's prognosis. However, the rate of complications of the vascular approach and the rate of restenosis is high. New devices, such as Drug Eluting Stents (DES) can critically decrease restenosis rate, and closure devices for trans-femoral approach, provides very encouraging results in this high risk population. Despite, good results of PCI with DES use, the mortality is still high in this population. To improve our efficiency, we have to progress in our therapeutic strategies and optimize medical approach to treat the important biological perturbations.

Routine coronary angiography in diabetic nephropathy patients before transplantation

We evaluated the incidence of significant coronary artery stenoses (CAS), angina pectoris (AP), revascularization and associated risk factors in 155 consecutive diabetic nephropathy transplant candidates. Kidney and kidney-pancreas transplant candidates with diabetes for more than 10 years and/or retinopathy and/or biopsy verified diabetic nephropathy were included. The inclusion period was 1999-2004. Seventy-two percent of patients were male. Sixty-one percent had type 1 diabetes and 39% had type 2 diabetes and mean age was 46 years (+/-10) and 58 years (+/-11), respectively. History of heart disease was present in 34% of patients, 34% had cerebro-vascular and/or peripheral atherosclerotic disease, and 51% had neither. Fifty-five percent had a smoking history and 46% were on dialysis. Significant CAS was found in 45% of patients, of whom 17% had AP. No patients below 35 years of age had significant CAS (n = 11, p = 0.001). Revascularization was performed in 57% of patients with significant CAS. The only risk factor for significant CAS in multiple logistic regression was age (p = 0.046). Approximately half of the patients had significant CAS, and half of these underwent revascularization. Most patients with CAS did not have symptoms of myocardial ischemia. The data justify screening diabetic nephropathy transplant candidates with coronary angiography before transplantation.

Risk stratification of patients with chronic kidney disease: results of screening strategies incorporating clinical risk scoring and dobutamine stress echocardiography

BACKGROUND

Cardiac disease is the principal cause of death in patients with chronic kidney disease (CKD). Ischemia at dobutamine stress echocardiography (DSE) is associated with adverse events in these patients. We sought the efficacy of combining clinical risk evaluation with DSE.

METHODS

We allocated 244 patients with CKD (mean age 54 years, 140 men, 169 dialysis-dependent at baseline) into low- and high-risk groups based on two disease-specific scores and the Framingham risk model. All underwent DSE and were further stratified according to DSE results. Patients were followed over 20 +/- 14 months for events (death, myocardial infarction, acute coronary syndrome).

RESULTS

There were 49 deaths and 32 cardiac events. Using the different clinical scores, allocation of high risk varied from 34% to 79% of patients, and 39% to 50% of high-risk patients had an abnormal DSE. In the high-risk groups, depending on the clinical score chosen, 25% to 44% with an abnormal DSE had a cardiac event, compared with 8% to 22% with a normal DSE. Cardiac events occurred in 2.0%, 3.1%, and 9.7% of the low-risk patients, using the two disease-specific and Framingham scores, respectively, and DSE results did not add to risk evaluation in this subgroup. Independent DSE predictors of cardiac events were a lower resting diastolic blood pressure, angina during the test, and the combination of ischemia with resting left ventricular dysfunction.

CONCLUSION

In CKD patients, high-risk findings by DSE can predict outcome. A stepwise strategy of combining clinical risk scores with DSE for CAD screening in CKD reduces the number of tests required and identifies a high-risk subgroup among whom DSE results more effectively stratify high and low risk.

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.

A meta-analytic comparison of echocardiographic stressors

BACKGROUND

The relative performance of alternative stressors for stress echocardiography for the diagnosis of coronary artery disease (CAD) is not well established.

METHODS

All studies published between 1981 to December 2001 who met inclusion criteria were included in this analysis. We performed a summary receiver operator characteristic (SROC) analysis and calculated weighted mean of the likelihood ratio and sensitivity/specificity. A covariate analysis using meta-regression methods was also performed.

RESULTS

Forty-four studies presented data on Exercise, 11 on Adenosine, 80 on Dobutamine, 40 on Dipyridamole, 16 on transatrial pacing transesophageal echocardiography (Tap-TEE), and 7 on transatrial pacing transthorasic echocardiography (Tap-TTE). SROC analysis showed that the following order of most discriminatory to least: Tap-TEE, Exercise, Dipyridamole, Dobutamine and Adenosine. Weighted means sensitivity/specificity were Exercise: 82.6/84.4%, Adenosine: 68.4/80.9%, Dobutamine: 79.6/85.1%, Dipyridamole: 71.0/92.2%, Tap-TTE: 90.7/86.1%, and Tap-TEE: 86.2/91.3%. Covariate analysis showed that the discriminatory power of Exercise decreased with increasing mean age.

CONCLUSIONS

Tap-TEE is a very accurate test for both ruling in and ruling out CAD although its invasiveness may limit its clinical acceptability. Exercise is a well-balanced satisfactory test for both ruling in and ruling out but performance might be lower for the elderly. Dobutamine offers a reasonable compromise for Exercise. Dipyridamole might be good for ruling in but not for ruling out CAD. The incapability in ruling-out CAD was a major problem in clinical application of the stress. Adenosine was the least useful stressor in diagnosing CAD.

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.

The transplant recipient for nontransplant surgery

The transplant recipient has traded a life-threatening illness for a chronically immunosuppressed state. Subsequent anesthetic management for non-transplant surgical procedures may be challenging. The anesthesia provider must be aware of the degree of post-transplant organ dysfunction and alter anesthesia techniques accordingly. This article reviews the anesthetic concerns for patients who have undergone a variety of organ transplants.

The renal patient with coronary artery disease

The patient with chronic kidney disease and coronary artery disease (CAD) presents special challenges. This report reviews the scope of the challenge, the hostile internal milieu predisposing to CAD and cardiac events, management issues, unresolved dilemmas, and the need for randomized trials to allow for evidence-based treatment.

Myocardial scintigraphy using a fatty acid analogue detects coronary artery disease in hemodialysis patients

BACKGROUND

Coronary artery disease contributes significantly to mortality in end-stage renal disease (ESRD) patients. Single-photon emission computed tomography (SPECT) using an iodinated fatty acid analogue, iodine-123-methyl iodophenylpentadecanoic acid (123I-BMIPP), can assess fatty acid metabolism in the myocardium. We investigated the ability of 123I-BMIPP SPECT to detect coronary artery disease in hemodialysis patients compared with 201thallium chloride (201Tl) SPECT.

METHODS

We prospectively studied 130 ESRD patients undergoing hemodialysis for a mean of 88.6 months (male/female, 77/53; mean age, 63.8 years). Dual SPECT using 123I-BMIPP and 201Tl was performed, followed by coronary angiography. SPECT findings were graded in 17 segments on a five-point scale (0, normal uptake; 4, none) and assessed as a summed score.

RESULTS

By coronary angiography, 71.5% of patients (93/130) had significant coronary stenosis (> or =75%), and five patients showed coronary spasm without coronary stenosis. When a BMIPP summed score of 6 or more was defined as abnormal, sensitivity, specificity, and accuracy for detecting coronary artery disease by BMIPP SPECT were 98.0%, 65.6%, and 90.0%, respectively; in contrast, these parameters for detecting coronary artery disease by Tl SPECT were 84.7%, 46.9%, and 75.0%, respectively, when a Tl summed score of 1 or more was defined as abnormal. In receiver operating characteristic analysis, the area under the curve was 0.895 in BMIPP and 0.727 in Tl SPECT, respectively.

CONCLUSION

Resting BMIPP SPECT is superior to Tl SPECT for detecting coronary lesions, and provides safe screening for coronary artery disease among maintenance hemodialysis patients.

Dobutamine stress echocardiography for noninvasive assessment and risk stratification of patients with rheumatic mitral stenosis

OBJECTIVES

We sought to evaluate the impact of dobutamine stress echocardiography (DSE) in patients with known rheumatic mitral stenosis (MS) in order to assess its safety, feasibility, and prognostic correlation to well-known clinical outcomes.

BACKGROUND

Noninvasive prognostic assessment of MS still represents an unresolved task in patients with clinically challenging disease.

METHODS

Dobutamine stress echocardiography was performed in 53 patients with MS (8 males; age 37.4 +/- 11.3 years) with no major complications.

RESULTS

During follow-up (60.5 +/- 11.0 months), 29 patients presented with clinical events: 16 hospitalizations, seven cases of acute pulmonary edema, and six symptomatic supraventricular arrhythmias. On multivariate analysis, the diastolic mitral valve mean gradient at peak DSE (DSE-MG) was the best predictor of clinical events (p < 0.008), especially in patients with moderate disease (p < 0.001). The best performance of DSE for the detection of clinical events was obtained at a cut-off value of 18 mm Hg DSE-MG (sensitivity 90%, specificity 87%, and accuracy 90%). The addition of DSE to the conventional cardiology work-up would allow a 17% increment for the detection of high-risk patients in the entire population and a 40% increment in patients with presumed moderate disease.

CONCLUSIONS

In patients with MS, DSE is a safe and highly feasible stress test. A DSE-MG > or =18 mm Hg identifies a subgroup of high-risk patients in whom a more aggressive approach may be warranted; on the other hand, patients with a DSE-MG <18 mm Hg predicts an uneventful clinical course and may justify a more conservative strategy.

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.

Diagnosis and therapy of coronary artery disease in renal failure, end-stage renal disease, and renal transplant populations

Even though cardiovascular disease is the leading cause of death in patients with CRF and end-stage renal disease (ESRD), ill-conceived notions have led to therapeutic nihilism as the predominant strategy in the management of cardiovascular disease in these populations. The recent data clearly support the application of proven interventions in the general population, such as angiotensin-converting enzyme inhibitors and statins to patients with CRF and ESRD. The advances in coronary stents and intracoronary irradiation have decreased the restenosis rates in renal failure patients. Coronary artery bypass with internal mammary graft might be the procedure of choice for coronary revascularization in these patients. The role of screening for asymptomatic coronary disease is established as a pretransplant procedure, but it is unclear whether this will be applicable to all patients with ESRD. Future studies need to focus on unraveling the mechanisms by which uremia leads to increased cardiovascular events to design optimal therapies targeted toward these mechanisms and improve cardiovascular outcomes.

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.

Perioperative care of the patient with renal failure

Preventing postoperative ARF, especially in subjects with pre-existing chronic kidney disease, and caring for ESRD patients undergoing surgery are challenging and best accomplished by a team comprised of primary care physician, nephrologist, cardiologist, surgeon, anesthesiologist, endocrinologist, and nutritionist. Elimination of risk factors for ARF whenever possible, as well as early diagnosis, may improve the outcome of this devastating illness. Drugs capable of preventing or changing the course of postoperative ARF may be available soon. For uremic patients, a comprehensive approach is necessary to minimize morbidity and mortality imposed by numerous comorbid conditions.

Combined dipyridamole-exercise stress echocardiography for detection of myocardial ischemia in hemodialysis patients: an alternative to stress nuclear imaging

BACKGROUND

Stress nuclear imaging is the noninvasive technique currently used to detect coronary artery disease (CAD) in dialysis patients. Stress echocardiography is recognized as an alternative to stress nuclear imaging for the general population. The aim of this study is to assess the diagnostic accuracy of stress echocardiography for detecting myocardial ischemia in hemodialysis patients.

METHODS

Stress echocardiography and stress technetium-99m-tetrofosmin (Myoview; Amersham International Plc) imaging were performed simultaneously for 66 asymptomatic hemodialysis patients in a single session, using a combination of high-dose dipyridamole and symptom-limited exercise. Coronary angiography was performed in 44 patients with at least one abnormal noninvasive test result or who were considered high-risk despite normal noninvasive test results.

RESULTS

Results for stress echocardiography were abnormal in 15 patients (22%); stress Myoview, in 14 patients (21%); and coronary angiography, in 12 patients (18%). The sensitivity of stress echocardiography for detecting myocardial ischemia (defined as stress Myoview defect) was 86%; specificity, 94%; positive predictive value, 80%; negative predictive value, 96%; and overall accuracy, 92%. The sensitivity of stress echocardiography for detecting CAD (defined as abnormal coronary angiography result) was 83%; specificity, 84%; positive predictive value, 67%; negative predictive value, 93%; and overall accuracy, 84%. Stress echocardiography and stress Myoview did not differ significantly in overall accuracy for detecting CAD (84% versus 91%; P = not significant).

CONCLUSION

In hemodialysis patients, combined dipyridamole-exercise echocardiography is an accurate method to detect both myocardial ischemia and CAD and represents an alternative to stress nuclear imaging.