Use of dobutamine echocardiography for cardiac risk stratification of patients with chronic renal failure

Diastolic dysfunction and impaired cardiac output reserve in dysmetabolic nonhuman primate with proteinuria

BACKGROUND

Cardiorenal complications are common in patients with dysmetabolism and diabetes. The present study aimed to examine if a nonhuman primate (NHP) model with spontaneously developed metabolic disorder and diabetes develops similar complications to humans, such as proteinuria and cardiac dysfunction at resting condition or diminished cardiac functional reserve following dobutamine stress echocardiography (DSE).

METHODS AND RESULTS

A total of 66 dysmetabolic and diabetic cynomolgus (Macaca fascicularis) NHPs were enrolled to select 19 NHPs (MetS) with marked metabolic disorders and diabetes (fasting blood glucose: 178 ± 18 vs. 61 ± 3 mg/dL) accompanied by proteinuria (ACR: 134 ± 34 vs. 1.5 ± 0.4 mg/mmol) compared to 8 normal NHPs (CTRL). Under resting condition, MetS NHPs showed mild left ventricular (LV) diastolic dysfunction (E/A: 1 ± 0.06 vs. 1.5 ± 0.13), but with preserved ejection fraction (EF: 65 ± 2 vs. 71 ± 3%) compared to CTRL. DSE with an intravenous infusion of dobutamine at ascending doses (5, 10, 20, 30 and 40 μg/kg/min, 7 min for each dose) resulted in a dose-dependent increase in cardiac function, however, with a significantly diminished magnitude at the highest dose of dobutamine infusion (40 μg/kg/min) in both diastole (E/A: -12 ± 3 vs. -38 ± 5%) and systole (EF: 25 ± 3 vs. 33 ± 5%) as well as ~42% reduced cardiac output reserve (COR: 63 ± 8 vs. 105 ± 18%, p < 0.02) in the MetS compared to CTRL NHPs.

CONCLUSION

These data demonstrate that MetS NHPs with cardiorenal complications: proteinuria, LV diastolic dysfunction and preserved LV systolic function under resting conditions displayed compromised cardiac functional reserve under dobutamine stress. Based on these phenotypes, this NHP model of diabetes with cardiorenal complications can be used as a highly translational model mimic human disease for pharmaceutical research.

Cardiovascular evaluation in advanced chronic kidney disease

Patients with chronic kidney disease (CKD) display an increased cardiovascular comorbidity, which is often underdiagnosed. Thus, effective cardiovascular diagnostic testing is of particular importance for this group of patients. Data from prospective randomized trials with cardiovascular diagnostic testing in CKD patients and improved outcome are limited. Diagnostic stress testing for CKD patients requires special consideration. Guidelines recommend cardiovascular diagnostic testing for patients undergoing an evaluation before transplantation.

[Cardiovascular diagnostic testing in advanced chronic kidney disease: which tests are useful?]

Against the background of drastically increased cardiovascular comorbidity in patients with chronic kidney disease (CKD), an effective cardiovascular diagnostic approach appears essential. However, patients with CKD are often underdiagnosed. Prospective randomized studies showing an improved outcome for cardiovascular diagnostic in patients with CKD are limited. Special attention is paid to stress diagnostics in CKD patients. Guidelines recommend cardiovascular diagnostic evaluation prior to inclusion on the transplantation waiting list.

Myocardial Ischemia Assessment in Chronic Kidney Disease: Challenges and Pitfalls

Coronary artery disease is the leading cause of mortality and morbidity in the chronic kidney disease (CKD) population and often presents with atypical symptoms. Current diagnostic investigations of myocardial ischemia in CKD lack sensitivity and specificity or may have adverse effects. We present a case vignette and explore the challenges of diagnostic myocardial stress investigation in patients with CKD.

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.

[Uselessness of high-sensitivity cardiac troponins to improve diagnostic accuracy of dobutamine stress echocardiography in high-risk diabetic patients]

BACKGROUND AND AIM

Dobutamine stress echocardiography (DSE) is a well-established noninvasive stress modality for the detection and evaluation of coronary artery disease in diabetic patients. High-sensitivity cardiac troponin T recently emerged as a highly sensitive dosage for the detection of ischemia. The aim of the study was to examine whether high-sensitivity cardiac troponin T may improve the diagnostic accuracy of silent ischemia by DSE in high-risk diabetic patients.

METHODS AND RESULTS

Twenty-one patients with long-standing (>10years) and/or complicated type II DM but no established CAD were included. In addition to DSE, venous blood samples for measurement of hs-cTnT were collected prior to DSE, 6hours and 24hours after the test. Troponins were deemed positive if>1.5 upper limit for normality. Patients with positive troponins underwent coronary angiography or CT scan regardless of the result of DSE. Among the 21 patients, 7 had positive troponins measured 6hours after stress, (mean peak troponin=44.5). DSE were negative in all of them. Mean age was 64years significantly higher than patients with negative troponins. No differences were noted between the groups in terms of epidemiological, clinical or echocardiographic characteristics. Patients with positive cardiac troponins were evaluated for the presence of coronary lesions but none of them had significant disease. After an 18-month mean follow-up, no adverse cardiac events were noted in either group.

CONCLUSION

In high-risk diabetic patients, the measurement of hs-cTnT during DSE does not improve the sensitivity at least in those with negative DSE tests.

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.

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.

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.

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.

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.

Cardiac assessment for renal transplantation

Cardiac death is common in patients with end-stage renal failure. Screening for coronary artery disease prior to renal transplantation is advisable in high-risk patients. The optimal screening test has not been defined; however, myocardial perfusion studies are more sensitive than exercise electrocardiography and are less invasive than coronary angiography, which remains the gold standard. The management of coronary artery disease prior to transplantation is contentious. Revascularization of coronary artery stenoses is associated with high mortality and morbidity in the renal failure population, and there is little data to indicate that most patients with asymptomatic coronary lesions will benefit from prophylactic coronary intervention. In addition, beta-blockers and aspirin are under-utilized in the renal population. This paper reviews the literature and proposes algorithms for the cardiac assessment and management of patients prior to renal transplantation.

Cardiovascular events and investigation in patients who are awaiting cadaveric kidney transplantation

The optimal strategy for cardiovascular (CV) disease surveillance in kidney transplant candidates is uncertain. In this observational study of 604 wait-listed patients in British Columbia, the risk for CV event in diabetic and nondiabetic candidates was 12.7 and 4.5% per year, respectively. CV event rates were relatively constant during the first 3 yr of wait-listing (5.3 to 6.6 per 100 patient-years; 95% confidence interval [CI], 3.7 to 9.3) but rose dramatically during the peritransplantation period (39.6/100 patient-years; 95% CI, 20.6 to 76.1) and remained high throughout the first posttransplantation year (4.0 per 100 patient-years; 95% CI, 2.2 to 7.5). The results of noninvasive cardiac investigations before wait-listing were not predictive of the time to CV event after wait-listing. The practice of surveillance cardiac investigation in wait-listed patients on the basis of ongoing clinical assessment of cardiac risk resulted in fewer investigations (n = 171) than with the recommended practice of periodic screening on the basis of waiting time alone (n = 530) and was not associated with an increased frequency of CV events (CV event rate in patients with and without the recommended frequency of investigation was 9.9 [95% CI, 7.1 to 13.7] and 6.7 [95% CI, 5.2 to 8.7] per 100 patient-years). It is concluded that transplant candidates are at high risk for CV events particularly during the perioperative period. Initial cardiac investigations have limited value in guiding the timing of patient reevaluation after wait-listing. Periodic surveillance cardiac investigation after wait-listing may be unnecessary and requires further study.

Management of heart failure and coronary artery disease in patients with chronic kidney disease

Cardiovascular disease (CVD) is a major contributor to the mortality and morbidity of patients who suffer from chronic kidney disease (CKD). Heart failure and ischemic heart disease (IHD) are both highly prevalent in this population. The diagnosis of myocardial dysfunction is usually based on echocardiography. As in the general population, systolic dysfunction is treated with a combination of diuretics, renin-angiotensin system blockade, and beta-receptor antagonists. Diastolic dysfunction is best managed by eliminating the cause. Non-invasive tests for coronary artery disease (CAD) may be less reliable in patients with renal disease compared with nonuremic patients. Medical therapy of IHD in this population is generally similar to that for other patient groups, but surgical revascularization appears to carry a higher risk of complications with poorer clinical outcomes. The choice of revascularization procedure (coronary artery bypass grafting versus percutaneous transluminal angioplasty) should be based on the specific coronary anatomy of a given patient as well as a consideration of other comorbid factors.

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.

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.