Prognostic value of stress myocardial perfusion imaging using adenosine triphosphate at the beginning of haemodialysis treatment in patients with end-stage renal disease

In Vivo assessment of hypertensive nephrosclerosis using ultrasound localization microscopy

PURPOSE

As a typical chronic kidney disease (CKD), hypertensive nephrosclerosis (HN) is a common syndrome of hypertension, characterized by chronic kidney microvascular damage. Early diagnosis of microvascular damage using conventional ultrasound imaging encounters challenges in sensitivity and specificity owing to the inherent diffraction limit. Ultrasound localization microscopy (ULM) has been developed to obtain microvasculature and microvascular hemodynamics within the kidney, and would be a promising tool for early diagnosis of CKD.

METHODS

In this study, the advantage of quantitative indexes obtained by using ULM (mean arterial blood flow speeds of different segments of interlobular arteries) over indexes obtained using conventional clinical serum (β2-microglobulin, serum urea nitrogen and creatinine) and urine (24-hour urine volume and urine protein) tests and ultrasound Doppler imaging [peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI)] and contrast-enhanced ultrasound imaging [CEUS; rise time (RT), peak intensity (IMAX), mean transit time (mTT) and area under the time-intensity curve (AUC)] for early diagnosis of HN was investigated. Examinations were carried out on 6 spontaneously hypertensive rats (SHR) and 5 normal Wistar-Kyoto (WKY) rats at the age of 10 weeks.

RESULTS

The experimental results showed that the indicators derived from conventional clinical inspections (serum and urine tests) and ultrasound imaging (PSV, EDV, RI, RT, IMAX, mTT and AUC) did not show significant difference between hypertensive and healthy rats (p > 0.05), while the TTP of the SHR group (28.52 ± 5.52 s) derived from CEUS is significantly higher than that of the WKY group (18.68 ± 7.32 s; p < 0.05). The mean blood flow speed in interlobular artery of SHR (12.47 ± 1.06 mm/s) derived from ULM is significantly higher than that of WKY rats (10.13 ± 1.17 mm/s; p < 0.01).

CONCLUSION

The advantages of ULM over conventional clinical inspections and ultrasound imaging methods for early diagnosis of HN were validated. The quantitative results showed that ULM can effectively diagnose HN at the early stage by detecting the blood flow speed changes of interlobular arteries. ULM may promise a reliable technique for early diagnosis of HN in the future. This article is protected by copyright. All rights reserved.

Impaired perfusion in the myocardial microcirculation in asymptomatic patients with Stages 1-4 chronic kidney disease with intrarenal arterial lesions

BACKGROUND

Even mild renal disease is a powerful cardiovascular risk factor. However, the association between these pathophysiologic processes (especially in the early asymptomatic stage) is not known.

METHODS

We recruited 243 asymptomatic patients with Stages 1-4 chronic kidney disease (CKD) without obstructive coronary artery disease (CAD). We distinguished different degrees of severity of intrarenal arterial lesions (IALs) according to the Oxford classification. Myocardial microcirculation perfusion was measured using single-photon emission computed tomography (SPECT). Summed scores of 17 stress and rest image segments produced the summed stress score (SSS) and summed rest score (SRS), respectively. The summed difference score (SDS) was calculated as the difference between the SSS and SRS. Coronary microvascular disease (CMD) was defined as abnormal SPECT (SSS ≥4 or SDS ≥2) in the absence of obstructive CAD.

RESULTS

Participants showed a stepwise increase in CMD severity with IAL aggravation. SSS of no/mild/moderate/severe IALs was 1.64 ± 1.08, 2.56 ± 1.35, 4.42 ± 2.17 and 6.48 ± 3.52, respectively (P < 0.05 for all). SDS of no/mild/moderate/severe IALs was 1.29 ± 0.49, 1.75 ± 0.56, 3.06 ± 1.12 and 4.16 ± 1.85, respectively (P < 0.05 for all). The percentage of subclinical CMD in CKD patients with IALs was significantly higher than in those without IALs (69.57% versus 14.71%; P = 0.01). Multiple regression analysis showed that renal arteriolar hyalinization (odds ratio = 1.578, P = 0.009) was associated independently with subclinical CMD.

CONCLUSIONS

We demonstrated, for the first time, that impaired perfusion in the myocardial microcirculation in asymptomatic patients with Stages 1-4 CKD with IALs. Renal arteriolar hyalinization may be a useful marker of CMD in CKD.

A 2-Year Prospective Study on the Differences in Prognostic Factors for Major Adverse Cardiovascular, Cerebrovascular and Renal Events Between Patients with Mild and Severe Chronic Kidney Disease

Purpose/Method: No studies have reported on prognostic markers in patients with chronic kidney disease (CKD) according to the severity of the disease. Therefore, in this multicenter, prospective trial performed as part of the Gunma CKD SPECT Multicenter Study, we recruited 311 patients with CKD (eGFR < 60 min/mL/1.73 m²) including 50 patients on hemodialysis and followed them for 2 years. The study sample underwent stress ^99mTc-tetrofosmin SPECT for suspected or possible ischemic heart disease. We evaluated the summed stress score (SSS), summed rest score (SRS), summed difference score (SDS) and cardiac function with electrocardiogram-gated SPECT. Then, we compared the differences in prognostic markers for major adverse cardiac, cerebrovascular, and renal events (MACCRE) between patients with mild CKD (30 min/mL/1.73 m² ≤ eGFR <60 min/mL/1.73 m²; n=184) and those with severe CKD (eGFR <30 min/mL/1.73 m²; n=97). Results: Of 281 patients available for analysis, 91 experienced MACCRE. In a multivariate Cox proportional hazards analysis of factors related to MACCRE, in patients with mild CKD the significant prognostic markers were SDS (P=0.002) and end-systolic volume (ESV, P=0.034); and in the patients with severe CKD, they were eGFR (P=0.03) and diabetes-mellitus (DM, P=0.023). Conclusions: Our findings indicate that SDS and ESV are significant prognostic markers for MACCRE in patients with mild CKD and eGFR and DM are significant prognostic markers in patients with severe CKD.

Risk stratification based on J-ACCESS risk models with myocardial perfusion imaging: Risk versus outcomes of patients with chronic kidney disease

BACKGROUND

This study aimed to validate the accuracy of major-event risk models created in the multicenter J-ACCESS prognostic study in a new cohort of patients with chronic kidney disease (CKD).

METHODS AND RESULTS

Three multivariable J-ACCESS risk models were created to predict major cardiac events (cardiac death, non-fatal acute coronary syndrome, and severe heart failure requiring hospitalization): Model 1, four variables of age, summed stress score, left ventricular ejection fraction and diabetes; Model 2 with five variables including estimated glomerular filtration rate (eGFR, continuous); and Model 3 with categorical eGFR. The validation data used three-year (3y) cohort of patients with CKD (n = 526, major events 11.2%). Survival analysis of low (< 3%/3y), intermediate (3% to 9%/3y), and high (> 9%/3y)-risk groups showed good stratification by all three models (actual event rates: 3.1%, 9.9%, and 15.9% in the three groups with eGFR ≥ 15 mL/min/1.73 m2, P = .0087 (Model 2). However, actual event rates were equally high across all risk groups of patients with eGFR < 15 mL/min/1.73 m2.

CONCLUSION

The J-ACCESS risk models can stratify patients with CKD and eGFR ≥ 15 mL/min/1.73 m2, but patients with eGFR < 15 mL/min/1.73 m2 are potentially at high risk regardless of estimated risk values.

Prognostic study of cardiac events in Japanese patients with chronic kidney disease using ECG-gated myocardial Perfusion imaging: Final 3-year report of the J-ACCESS 3 study

BACKGROUND

Myocardial perfusion imaging (MPI) is considered useful for risk stratification among patients with chronic kidney disease (CKD), without renal deterioration by contrast media.

METHODS AND RESULTS

The Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (J-ACCESS 3) is a multicenter, prospective cohort study investigating the ability of MPI to predict cardiac events in 529 CKD patients without a definitive coronary artery disease. All patients were assessed by stress and rest MPI with 99mTc-tetrofosmin and data were analyzed using a defect scoring method and QGS software. Major cardiac events were analyzed for 3 years after registration. The mean eGFR was 29.0 ± 12.8 (mL/minute/1.73 m2). The mean summed stress/rest/difference (SSS, SRS, SDS) scores were 1.9 ± 3.8, 1.1 ± 3.0, and 0.8 ± 1.8, respectively. A total of 60 cardiac events (three cardiac deaths, six sudden deaths, five nonfatal myocardial infarctions, 46 hospitalization cases for heart failure) occurred. The event-free survival rate was lower among patients with kidney dysfunction, higher SSS, and higher CRP values. Multivariate Cox regression analysis independently associated SSS ≥8, eGFR <15 (mL/minute/1.73 m2), and CRP ≥0.3 (mg/dL) with cardiac events.

CONCLUSIONS

Together with eGFR and CRP, MPI can predict cardiac events in patients with CKD.

Most Important Prognostic Values to Predict Major Adverse Cardiovascular, Cerebrovascular, and Renal Events in Patients with Chronic Kidney Disease Including Hemodialysis for 2 Years

Patients with chronic kidney disease (CKD) have an increased risk of adverse cardiovascular/cerebrovascular events. The aim of this study is to clarify whether stress myocardial perfusion single-photon emission computed tomography (SPECT) could predict cardiovascular/cerebrovascular events. In the Gunma-CKD SPECT Study, a multicenter prospective cohort trial, 311 patients with CKD (estimated glomerular filtration rate < 60 min/mL/1.73 m2) including 50 patients on hemodialysis underwent stress 99mTc-tetrofosmin SPECT for suspected ischemic heart disease and were followed for 2 years. The primary endpoint was the occurrence of cardiac death (CD), while the secondary endpoint was major adverse cardiovascular/cerebrovascular and renal events (MACCRE). MACCRE occurred in 91 out of 286 patients (CD in 13 and other MACCRE in 78 patients). According to a multivariate Cox analysis, hemoglobin (Hb) and end-systolic volume (ESV) were associated with CD (p < 0.05), while the summed difference score, diabetes mellitus (DM), and Hb were associated with MACCRE (p < 0.05). Kaplan-Meier analysis showed that the CD-free rate was higher in patients with ESV < 105 mL (log-rank, p = 0.0013), Hb > 12 g (log-rank, p = 0.0036), and a summed stress score < 6 (log-rank, p = 0.0058). The MACCRE-free rate was higher in patients with SDS = 0 (log-rank, p = 0.0097), without DM (log-rank, p = 0.0091), and with Hb > 12 g (log-rank, p = 0.0023). Myocardial perfusion SPECT parameters as well as renal anemia and DM can be reliable prognostic markers in patients with CKD including hemodialysis.

Stress SPECT Myocardial Perfusion Imaging in End-Stage Renal Disease

PURPOSE OF REVIEW

Patients with end-stage renal disease (ESRD) have an increased risk of cardiovascular morbidity and mortality. Cardiac risk assessment, though challenging, is critical in these high-risk patients, particularly in the pre-transplant population. In this review, we discuss the burden of coronary artery disease in the ESRD population and review the literature on the diagnostic and prognostic performance, clinical value, and future directions of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in ESRD patients.

RECENT FINDINGS

Stress myocardial perfusion imaging provides incremental prognostic value to clinical data. The AHA/ACCF consensus statement on the cardiac assessment of kidney transplant candidates provides some guidance on the selection of asymptomatic patients for further non-invasive risk stratification. Additionally, the novel selective A_2A receptor agonist vasodilator stress agent, regadenoson, is safe and effective in ESRD and has recently been approved by the Food and Drug Administration for use in this population. Ancillary stress MPI findings, namely heart rate response to vasodilator stress, can provide incremental risk stratification.

SUMMARY

While myocardial perfusion imaging is widely used as a risk assessment tool, its utilization and clinical implications in the ESRD population are controversial. Though stress SPECT-MPI has imperfect diagnostic accuracy in this specific patient population, it is still a valuable non-invasive modality in cardiovascular risk assessment.

Cardiac event risk stratification in patients with end-stage renal disease: Sub-analysis of the B-SAFE study

BACKGROUND

The aim of this study was to investigate whether 123I-labelled β-methyl iodophenyl-pentadecanoic acid (BMIPP) imaging as an abnormal myocardial fatty acid metabolism indicator better predicted fatal and non-fatal cardiac events than conventional predictors [e.g. peripheral artery disease (PAD) and diabetes mellitus (DM)] in haemodialysis patients.

METHODS

In a sub-analysis of the BMIPP SPECT Analysis for Decreasing Cardiac Events in Haemodialysis Patients (B-SAFE) study, 677 asymptomatic patients with ≥1 cardiovascular risk factor and without known coronary artery disease were followed for 3 years. The amount of radioactivity in each 17-left ventricular segment was graded visually and assigned a score from 0 (normal) to 4 (absent). Its total values were designated as baseline summed BMIPP scores. Outcome measures were composite cardiac events.

RESULTS

Cardiac events correlated with age, PAD [hazard ratio (HR): 2.15; p=0.003], DM (HR: 1.76; p=0.006) and summed BMIPP scores (4-8, HR: 1.82; p<0.001; ≥9, HR: 3.49; p<0.001). Cardiac event-free rates decreased with increasing summed BMIPP scores, PAD and DM. Areas under the receiver operating curves (AUCs) indicated that a BMIPP-based model (AUC: 0.656) was more predictive than DM or PAD models (AUC: 0.591); a model with all three was most predictive (AUC: 0.708). The three-year cardiac event-free rates significantly decreased in patients with PAD and/or DM in all summed BMIPP score categories.

CONCLUSIONS

Abnormal myocardial fatty acid metabolism strongly predicts cardiac events in haemodialysis patients; those with PAD or DM are at high risk for cardiac events.

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.

Myocardial perfusion imaging for predicting cardiac events in Japanese patients with advanced chronic kidney disease: 1-year interim report of the J-ACCESS 3 investigation

PURPOSE

Whether myocardial perfusion imaging (MPI) can predict cardiac events in patients with advanced conservative chronic kidney disease (CKD) remains unclear.

METHODS

The present multicenter prospective cohort study aimed to clarify the ability of MPI to predict cardiac events in 529 patients with CKD and estimated glomerular filtration rates (eGFR) < 50 ml/min per 1.73(2) without a definitive diagnosis of coronary artery disease. All patients were assessed by stress-rest MPI with (99m)Tc-tetrofosmin and analyzed using summed defect scores and QGS software. Cardiac events were analyzed 1 year after registration.

RESULTS

Myocardial perfusion abnormalities defined as summed stress score (SSS) ≥4 and ≥8 were identified in 19 and 7 % of patients, respectively. At the end of the 1-year follow-up, 33 (6.2 %) cardiac events had occurred that included cardiac death, sudden death, nonfatal myocardial infarction, and hospitalization due to heart failure. The event-free rates at that time were 0.95, 0.90, and 0.81 for groups with SSS 0-3, 4-7, and ≥8, respectively (p = 0.0009). Thus, patients with abnormal SSS had a higher incidence of cardiac events. Multivariate Cox regression analysis showed that SSS significantly impacts the prediction of cardiac events independently of eGFR and left ventricular ejection fraction.

CONCLUSION

MPI would be useful to stratify patients with advanced conservative CKD who are at high risk of cardiac events without adversely affecting damaged kidneys.

Practical approach to evaluate asymptomatic coronary artery disease in end-stage renal disease patients at the initiation of dialysis

The high prevalence of significant asymptomatic coronary artery disease (CAD) has been reported in patients with end-stage renal disease (ESRD) at the initiation of dialysis. However, the approach to evaluate asymptomatic CAD for these patients has not been established. The aim of this study is to assess the applicability of our practical approach at the initiation of dialysis. We prospectively enrolled 182 consecutive ESRD patients who initiated dialysis. After echocardiography as primary screening, pharmacologic stress thallium-201 scintigraphy and/or coronary angiography (CAG) were performed to diagnose CAD. The patients were classified into two groups: those with coronary artery stenosis by CAG (CAD+ group), those without coronary artery stenosis by CAG or with negative scintigraphy examination (CAD- group). Of the eligible 93 patients without the history of CAD, 22 patients were allocated to the CAD+ group (18 of 26 patients with abnormal echocardiography and 4 of 13 patients with positive scintigraphy examination) and 71 patients to the CAD- group. Patients were followed up for an average of 520 ± 304 days. The event-free survival rate of major adverse cardiac events was significantly lower in the CAD+ group than in the CAD- group (P < 0.001). There was no cardiovascular event including major adverse cardiac events, unstable angina, coronary revascularization or stroke in the CAD- group during the first year of dialysis. Patients without CAD diagnosed by our approach had favorable clinical outcomes. Our approach may be useful for screening of occult CAD in ESRD patients at the initiation of dialysis.

Predictors of cardiovascular events in hemodialysis patients after stress myocardial perfusion imaging

Cardiovascular prognosis in patients under normal stress myocardial perfusion images (MPI) is generally excellent. However, this is not true for patients with chronic kidney disease (CKD) treated by hemodialysis. This study evaluated prognostic factors of adverse cardiovascular events in hemodialysis patients in whom stress MPI was performed. Pharmacological stress MPI was performed in 88 hemodialysis patients, and we retrospectively followed-up for 26 months. Cardiovascular events included cardiac death, nonfatal myocardial infarction, and unstable angina. Cardiovascular events occurred in 16 patients (18%). Univariate Cox regression analysis revealed that peripheral artery disease (PAD) and parameters of stress MPI were significant predictors of cardiovascular events. Multivariate Cox regression analysis revealed that only PAD (hazard ratio=6.54; P=0.002), and abnormal stress MPI (hazard ratio=8.26; P=0.008) were independent and significant predictors of cardiovascular events. Kaplan-Meier analysis showed better prognosis in patients with normal stress MPI than in patients with abnormal stress MPI (P<0.001, log-rank test). However, in patients with normal stress MPI, cardiovascular events occurred in 10 of the 76 patients (13%). Among patients with normal stress MPI, Kaplan-Meier analysis showed that patients with no PAD had better prognosis than patients with PAD (P=0.001, log-rank test). In hemodialysis patients, both PAD and stress MPI were powerful cardiovascular predictors. Normal stress MPI alone cannot guarantee good prognosis in terms of cardiovascular events. Consideration of PAD may improve the predictive value of stress MPI in some patients.

Patients with end-stage renal disease: optimal diagnostic and prognostic performance of myocardial gated-SPECT, initial results

PURPOSE

We investigated the role of Tc-99m sestamibi myocardial perfusion gated single photon emission computed tomography (GSPECT) in identifying those patients with end-stage renal disease (ESRD) in whom optimal diagnosis of coronary artery disease and prediction of cardiac events (CEs) could be achieved.

METHODS

This was a prospective study that included 41 asymptomatic ESRD patients who had been undergoing hemodialysis for 12 months or less (22 men and 19 women) with restricted selection criteria (asymptomatic traditional risk). Tc-99m sestamibi GSPECT was carried out for all patients, whereas coronary angiography (Cath) was carried out only for abnormal GSPECT patients, with a 2-year follow-up for CEs. Twenty individuals matched for age, sex, and BMI formed the control group.

RESULTS

Of the 41 ESRD patients, 13 showed abnormal GSPECT [11/13 with myocardial perfusion defects and left ventricular dysfunction in concordance with Cath and 2/13 with only left ventricular dysfunction (i.e. stunning)] compared with 1/20 in the control group. None of the patients with negative results experienced CEs (negative predictive value 100%); these patients had a 2-year CE-free survival rate of 100% compared with 46% for patients with positive results on GSPECT (P<0.0001; seven GSPECT-positive patients developed CEs during their follow-up). Patients with positive results were more frequently male (P<0.001), were significantly older (P=0.01), and had highly sensitive C-reactive protein levels (P=0.002). Abnormal GSPECT was the only independent predictor of CEs (95% confidence interval, 7.1-46.7; hazard ratio, 46.1; P<0.001).

CONCLUSION

GSPECT exhibited optimum performance for coronary artery disease detection and risk stratification in asymptomatic ESRD patients during their first year of regular hemodialysis who were selected according to our modification of the traditional risk category. This may help in selecting suitable candidates for Cath, revascularization, and future renal transplantation.

Risk stratification of cardiovascular events in patients at all stages of chronic kidney disease using myocardial perfusion SPECT

BACKGROUND

Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Therefore, stratification of the prognostic risk of cardiovascular events is useful for their clinical management. We evaluated the ability of electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) to predict cardiac events among Japanese patients at all stages of CKD including those on hemodialysis.

METHODS

Patients with CKD undergoing ECG-gated myocardial perfusion SPECT to investigate suspected ischemic heart disease were followed up to monitor retrospectively major cardiac events including cardiac death, non-fatal myocardial infarction, and unstable angina pectoris. Summed stress score, summed rest score, and summed difference score were estimated with a 20 segment 5-point scoring model. The severity of CKD was divided into five levels based on estimated glomerular filtration rate (eGFR) revised for the Japanese population.

RESULTS

The follow-up period was 25.8 ± 11.0 months. Sixty-two major cardiac events (cardiac death, n=30; non-fatal myocardial infarction, n=13; unstable angina pectoris, n=19) developed in 2243 patients during the first year of follow-up. The findings of multivariate Cox proportional hazards regression analysis indicated that diabetes, eGFR, the summed difference score, and summed stress score were significant independent predictors of cardiac events. The major cardiac event rate at one year increased in proportion to the progression of CKD stage. The major cardiac event-free survival rate decreased steeply over time in patients with CKD stage 5 compared with those who had CKD stages 4 or less.

CONCLUSION

Myocardial perfusion SPECT can contribute to the prediction of cardiac events and survival in patients at all stages of CKD including those on hemodialysis.

Cardiac risk assessment by gated single-photon emission computed tomography in asymptomatic end-stage renal disease patients at the start of dialysis

OBJECTIVES

This study assessed the impact of cardiac risk assessment using gated single-photon emission computed tomography (SPECT) on cardiac events in end-stage renal disease (ESRD) patients.

METHODS

We evaluated 215 asymptomatic patients who began dialysis between January 2005 and April 2009. Baseline electrocardiography and echocardiography were performed in all the patients. The subjects were stratified into low- and high-risk groups according to the baseline cardiac status, and gated SPECT was additionally recommended for the high-risk patients.

RESULTS

The study population consisted of 50 low- and 165 high-risk patients undergoing SPECT. Among the high-risk patients, 75 (45.5%) showed perfusion defects on SPECT and their overall cardiac-event rate per person-year of follow-up was 15.0%, significantly higher than 4.5% in high-risk group without perfusion defect and 1.2% in low-risk group. The presence of perfusion defect was a significant independent predictor of adverse cardiac events [hazard ratio (HR) 2.11; 95% confidence interval (CI) 1.05-4.24; P = .035]. When gated SPECT was added to the clinical and the echocardiographic variables, the prognostic stratification significantly improved (P < .001). However, coronary revascularization was not associated with improved cardiac event-free survival (HR 0.62; 95% CI 0.26-1.52; P = .296).

CONCLUSIONS

Gated SPECT may provide additional prognostic information for cardiac risk stratification, particularly among high-risk patients starting dialysis.

Relationship of haemodialysis therapy duration and cardiac adrenergic system function assessed by iodine-123 metaiodobenzylguanidine imaging in haemodialysed nondiabetic patients

OBJECTIVE

The aim of the study was to evaluate the relationship of haemodialysis therapy duration with the function of the cardiac adrenergic system in nondiabetic patients.

METHODS

Thirty haemodialysed male patients were enrolled in this study; all patients were evaluated by myocardial perfusion imaging at rest and after dynamic stress, with the assessment of left ventricular ejection fraction (LVEF) at rest and after stress and summed stress score (SSS). Single photon emission computed tomography and planar iodine-123 metaiodobenzylguanidine myocardial scintigraphy were also performed in all the patients. Semiquantitative analysis of iodine-123 metaiodobenzylguanidine myocardial uptake was expressed as the routine heart-to-mediastinum ratio (HMR): 15 min [early HMR (eHMR)] and 4 h [delayed HMR (dHMR)] post administration as well as the washout rate. Twenty-four hours of Holter studies were carried out and heart rate variability was evaluated.

RESULTS

Significant correlations (Spearman's tests) were found between the duration of haemodialysis treatment and the following ratios: eHMR (P=0.03; r=-0.378), dHMR (P=0.04; r=-0.367) and washout rate (P=0.05; r=0.352). Further significant correlations were found between eHMR and LVEFs (P=0.03; r=0.379), SSS (P=0.01; r=-0.429) and between dHMR and LVEFs (P=0.005; r=0.496), LVEFr (P=0.03; r=0.379) and SSS (P=0.02; r=-0.404).

CONCLUSION

The duration of haemodialysed patients appears to be an important factor influencing the cardiac sympathetic nervous system.

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 risk stratification of myocardial ischaemia evaluated by gated myocardial perfusion SPECT in patients with chronic kidney disease

PURPOSE

The aim of this study was to identify useful predictors of cardiac events in patients with chronic kidney disease (CKD).

METHODS

Among 4,031 patients identified from the Japanese Assessment of Cardiac Events and Survival Study (J-ACCESS) database with suspected or known ischaemic heart disease, we selected 820 with an estimated glomerular filtration rate (eGFR) of < 60 ml/min per 1.73 m(2).

RESULTS

A total of 75 cardiac events developed among these 820 patients. The incidence of cardiac events was higher in the group with a lower eGFR. Multivariate Cox analysis indicated that age, diabetes mellitus, end-systolic volume, summed stress score (SSS) and eGFR were predictors of cardiac events. Event rates of patients with SSS >or= 9 were significantly higher in groups with lower eGFR values (< 40 and 40-49 ml/min).

CONCLUSION

The SSS value (>or= 9) is a reliable predictor of cardiac events and myocardial single photon emission computed tomography has incremental value for predicting cardiac events and survival in CKD.

Predictive Value of Myocardial Perfusion Single-Photon Emission Computed Tomography and the Impact of Renal Function on Cardiac Death

Background— Patients with chronic kidney disease (CKD) have worse cardiovascular outcomes than those without CKD. The prognostic utility of myocardial perfusion single-photon emission CT (MPS) in patients with varying degrees of renal dysfunction and the impact of CKD on cardiac death prediction in patients undergoing MPS have not been investigated.

Methods and Results— We followed up 1652 consecutive patients who underwent stress MPS (32% exercise, 95% gated) for cardiac death for a mean of 2.15±0.8 years. MPS defects were defined with a summed stress score (normal summed stress score <4, abnormal summed stress score≥4). Ischemia was defined as a summed stress score ≥4 plus a summed difference score ≥2, and scar was defined as a summed difference score <2 plus a summed stress score ≥4. Renal function was calculated with the Modified Diet in Renal Disease equation. CKD (estimated glomerular filtration rate <60 mL · min −1 · 1.73 m −2 ) was present in 36%. Cardiac death increased with worsening levels of perfusion defects across the entire spectrum of renal function. Presence of ischemia was independently predictive of cardiac death, all-cause mortality, and nonfatal myocardial infarction. Patients with normal MPS and CKD had higher unadjusted cardiac death event rates than those with no CKD and normal MPS (2.7% versus 0.8%, P =0.001). Multivariate Cox proportional hazards models revealed that both perfusion defects (hazard ratio 1.90, 95% CI 1.47 to 2.46) and CKD (hazard ratio 1.96, 95% CI 1.29 to 2.95) were independent predictors of cardiac death after accounting for risk factors, left ventricular dysfunction, pharmacological stress, and symptom status. Both MPS and CKD had incremental power for cardiac death prediction over baseline risk factors and left ventricular dysfunction (global χ 2 207.5 versus 169.3, P <0.0001).

Conclusions— MPS provides effective risk stratification across the entire spectrum of renal function. Renal dysfunction is also an important independent predictor of cardiac death in patients undergoing MPS. Renal function and MPS have additive value in risk stratisfying patients with suspected coronary artery disease. Patients with CKD appear to have a relatively less benign prognosis than those without CKD, even in the presence of a normal scan.

Role of myocardial perfusion imaging in patients with end-stage renal disease undergoing coronary angiography

Patients with end-stage renal disease (ESRD) are at high risk of cardiovascular events. This study examined the prognostic power of stress myocardial perfusion imaging (MPI) in 150 patients with ESRD (mean age 53 +/- 9 years; 30% women; 66% with diabetes mellitus) being evaluated for renal transplantation with known coronary anatomy using angiography. Baseline data in addition to perfusion and angiographic parameters were compared between survivors and nonsurvivors. All-cause mortality was defined as the outcome measure. An abnormal MPI result was present in 85% of patients, 30% had left ventricular (LV) ejection fraction (EF) < or =40%, and 40% had multivessel coronary artery disease using angiography. At a mean follow-up of 3.4 +/- 1.5 years, 53 patients died (35%). LVEF < or =40%, LV dilatation (LV end-diastolic volume >90 ml), and diabetes mellitus were associated with higher mortality (all p <0.05). Both total perfusion defect size and mean number of narrowed coronary arteries using angiography were significantly higher in those who died (p <0.05). In a multivariate model, abnormal MPI results (low LVEF or abnormal perfusion) and diabetes alone were independent predictors of death, whereas number of narrowed arteries using coronary angiography was not. Thus, MPI was a strong predictor of all-cause mortality in patients with ESRD. In conclusion, abnormal MPI results independently predicted worse survival and provided more powerful prognostic data than coronary angiography.

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.

Cardiac findings in asymptomatic chronic hemodialysis patients with persistently elevated cardiac troponin I levels

BACKGROUND

The prevalence and significance of higher than normal cardiac troponin I (cTnI) levels in asymptomatic chronic hemodialysis (HD) patients remains a source of discussion. The aim of the present study was to evaluate the prevalence of higher than normal cTnI levels in asymptomatic HD patients, as determined by the last generation of immunoassay, and to perform further cardiological investigations in those patients with persistently elevated cTnI levels.

METHODS

All chronic HD patients in our center who had exhibited no symptoms of coronary artery disease (CAD) during the previous four weeks were screened. cTnI levels were determined before dialysis in all patients using the last generation AccuTnI assay (UniCel DxI 800, Beckman Coulter). The cTnI levels of those patients with elevated cTnI at the screening evaluation were then measured monthly for six months. We were thus able to identify a group of patients with persistently elevated cTnI levels (> 3 consecutive months) who subsequently underwent cardiac echography and dipyridamole-exercise (D-E) thallium testing. If stress myocardial ischemia was detected, a coronary angiography was then performed.

RESULTS

Fifty patients (32 males) were included: mean age 62.8 +/- 13.6 years, 20 (40%) with a history of CAD, and 21 (42%) diabetic. At the initial screening, the mean cTnI concentration was 0.05 +/- 0.06 microg/L and the cTnI levels were higher than normal (> 0.09 microg/L) in six patients (12%). In the follow-up, the cTnI normalized immediately in two patients but remained persistently elevated (range, 0.10-0.48 microg/L) in four (8%). These four patients (all males, one diabetic) had a mean age of 70.2 +/- 6.6 years, and all had heart failure with a history of severe CAD with previous myocardial infarction (n = 4), coronary stenting (n = 3), and/or bypass (n = 2). D-E thallium imaging showed reversible myocardial ischemia in all. The stress ischemia involved one to four cardiac segments and was slight to moderate in three patients and severe in the diabetic patient. A coronary angiogram was performed in all patients, and showed lesions of variable severity: severe three-vessel CAD with severe systolic dysfunction in two patients (including the diabetic), and non-critical/peripheral coronary stenosis in the other two.

CONCLUSIONS

Among the asymptomatic HD patients in our center, we identified four (8%) with persistently elevated cTnI levels, as determined using the last generation AccuTnI assay. All of them had a history of severe CAD with heart failure and exhibited reversible myocardial ischemia upon D-E thallium imaging; coronary angiography revealed coronary lesions of variable severity. Overall, our data indicate that persistent low-grade cTnI elevation occurs in HD patients having longstanding severe cardiac disease, but, from our data, it is difficult to reach a conclusion as to the best clinical approach for this group of patients.

Predictors of survival in patients with end-stage renal disease evaluated for kidney transplantation

Cardiovascular disease is the major cause of mortality in patients with end-stage renal disease (ESRD). This study examined the all-cause mortality in 3,698 patients with ESRD evaluated for kidney transplantation at our institution from 2001 to 2004. Mean age for the cohort was 48+/-12 years, and 42% were women. Stress myocardial perfusion imaging was done in 2,207 patients (60%) and coronary angiography in 260 patients (7%). There were 622 deaths (17%) during a mean follow-up period of 30+/-15 months. The presence and severity of coronary disease on angiography was not predictive of survival. Coronary revascularization did not impact survival (p=0.6) except in patients with 3-vessel disease (p=0.05). The best predictor of death was left ventricular ejection fraction, measured by gated myocardial perfusion imaging, with 2.7% mortality increase for each 1% ejection fraction decrease. In conclusion, left ventricular ejection fraction is a strong predictor of survival in patients with ESRD awaiting renal transplantation. Strategies to improve cardiac function or earlier renal transplantation deserve further studies.

Independent risk factors for progression of coronary atherosclerosis in hemodialysis patients

Not uncommonly, hemodialysis patients with normal results in myocardial perfusion tests can still have a cardiac event within 2 years of evaluation. We examined possible risk factors for progression of coronary atherosclerosis in hemodialysis patients. We prospectively evaluated ability of myocardial perfusion imaging carried out under pharmacologic stress to predict 2-year outcomes in 77 hemodialysis patients, specifically thallium-201 single-photon emission computed tomography (SPECT) using high-dose adenosine triphosphate as the stressor. The primary end-point was a cardiac event (cardiac death, non-fatal acute coronary syndrome, or hospitalization for acute ischemic heart failure). Factors independently influencing duration until a cardiac event in hemodialysis patients were identified using stepwise multiple regression analysis. Myocardial perfusion defects were shown in 36 patients. Patients with a perfusion defect were more likely to have cardiac events than those with normal perfusion (78% vs. 15%, P < 0.001). Time until occurrence of a cardiac event in hemodialysis patients showed a significant, independent association with known coronary artery disease [regression coefficient (RC) = -3.391, P = 0.046], elevated C-reactive protein (RC = -5.813, P = 0.005), and a reversible myocardial perfusion defect (RC = -7.386, P < 0.001). An analysis based on the 'best cut-off' of CRP as identified on the basis of the ROC curve augmented the positive and negative predict value of CRP for the prediction of coronary events to 65 and 74%, respectively. Myocardial perfusion SPECT and measuring the plasma concentration of CRP might be useful for the prediction of hemodialysis patients with progression of coronary atherosclerosis.

Incidence and risk factors of coronary heart disease in elderly patients on chronic hemodialysis

AIM

To determine the incidence of coronary heart disease (CHD) in patients (pts) over 65 years (y) and its relation to common risk factors.

METHODS

We retrospectively studied 128 hemodialysis (HD) pts (80 M and 48 F), mean age 73+/-6.5 years, mean time on HD 44.4+/-26.4 months and BMI 25.4+/-3 kg/m2. They were evaluated for: age, sex, smoking, diabetes, hypertension, left ventricular hypertrophy, secondary hyperparathyroidism (SHP), inflammation, as evidence by elevated level of hsCRP, hyperhomocysteinemia (HOC), time on HD, fluid overload and adequacy of HD. Forty-eight pts (37%) had CAD diagnosed by coronary angiography in 22 (46%) and (201)TL-chloride dipyridamole stress test in 26 (54%).

RESULTS

There was a statistically significant correlation between CAD and increasing age (p<0.0001). The relative risk was significantly increased concerning: (1) male over female pts (RR: 1.95, p<0.01), (2) diabetic vs. non diabetic pts (RR: 2.09, p<0.001), (3) patients with SHP over pts with iPTH values<250 pg/ml (RR: 2.16, p<0.001), (4) hypertensive vs. non hypertensive pts (RR: 2.26, p=0.002), (5) smokers vs. non smokers (RR: 1.69, p<0.05), (6) pts with HOC over pts with normal homocysteine values (RR: 2.09, p<0.05), (7) pts with increased CRP levels over pts with normal CRP levels (RR: 1.8, p<0.01), (8) pts undergoing HD for 36 vs. 12 months (RR: 1.71, p=0.03), (9) between pts with inadequate or adequate HD (RR: 1.73, p=0.02). No significant correlation existed between CAD incidence and the other risk factors.

CONCLUSIONS

Coronary heart disease incidence in elderly HD patients increases with age, male sex, diabetes, SHP, hypertension, increased CRP levels, HOC, smoking, time on HD and inadequacy of HD.

Risk factors for de novo acute cardiac events in patients initiating hemodialysis with no previous cardiac symptom

An initial major adverse cardiac event (MACE) is an important predictor of future cardiovascular events in patients with chronic kidney disease (CKD). We sought to identify factors influencing occurrence of initial MACE in new maintenance hemodialysis patients without previous cardiac symptoms during the predialysis phase of CKD. Among 112 participating patients with no predialysis cardiac history, 57 underwent coronary angiography, whereas the other 55 underwent stress thallium-201 single-photon emission computed tomography within 1 month of beginning hemodialysis to detect asymptomatic coronary artery disease (CAD). In subsequent follow-up for a median of 24 months, subjects experiencing an initial MACE were compared with those who did not have such an event based on several clinical parameters at the end of predialysis phase. Asymptomatic CAD was present in 47 patients (42%), who had a higher cumulative MACE rate, than subjects without CAD (49 vs 3%, P<0.001). Multivariate Cox's regression analysis showed that three variables independently predicted initial MACE: asymptomatic CAD (hazard ratio or HR, 611.31; 95% confidence interval or CI, 14.07-26549.23; P<0.001), diabetes (HR, 20.41; 95% CI, 2.07-200.00; P=0.010), and each 1 mg/l increment in C-reactive protein (CRP) (HR, 1.94; 95% CI, 1.27-2.94; P=0.002). In conclusion, detection of asymptomatic CAD, presence of diabetes, or elevated CRP at the end of the predialysis phase were significantly associated with occurrence of an initial MACE in CKD patients starting hemodialysis who had no CAD symptoms.

Nuclear Cardiology: Present and Future

Nuclear cardiology has made significant advances since the first reports of planar scintigraphy for the evaluation of left ventricular perfusion and function. While the current "state of the art" of gated myocardial perfusion single-photon emission computed tomographic (SPECT) imaging offers invaluable diagnostic and prognostic information for the evaluation of patients with suspected or known coronary artery disease (CAD), advances in the cellular and molecular biology of the cardiovascular system have helped to usher in a new modality in nuclear cardiology, namely, molecular imaging. In this review, we will discuss the current state of the art in nuclear cardiology, which includes SPECT and positron emission tomographic evaluation of myocardial perfusion, evaluation of left ventricular function by gated myocardial perfusion SPECT and gated blood pool SPECT, and the evaluation of myocardial viability with PET and SPECT methods. In addition, we will discuss the future of nuclear cardiology and the role that molecular imaging will play in the early detection of CAD at the level of the vulnerable plaque, the evaluation of cardiac remodeling, and monitoring of important new therapies including gene therapy and stem cell therapy.

Pathophysiology and therapeutic potential of purinergic signaling

The concept of a purinergic signaling system, using purine nucleotides and nucleosides as extracellular messengers, was first proposed over 30 years ago. After a brief introduction and update of purinoceptor subtypes, this article focuses on the diverse pathophysiological roles of purines and pyrimidines as signaling molecules. These molecules mediate short-term (acute) signaling functions in neurotransmission, mechanosensory transduction, secretion and vasodilatation, and long-term (chronic) signaling functions in cell proliferation, differentiation, and death involved in development and regeneration. Plasticity of purinoceptor expression in pathological conditions is frequently observed, including an increase in the purinergic component of autonomic cotransmission. Recent advances in therapies using purinergic-related drugs in a wide range of pathological conditions will be addressed with speculation on future developments in the field.

Relationship between serum albumin level before initiating haemodialysis and angiographic severity of coronary atherosclerosis in end-stage renal disease patients

BACKGROUND

In patients with chronic kidney disease (CKD), although strong associations have been observed between malnutrition and atherosclerosis, the relationship between serum albumin concentration and angiographic changes of coronary artery disease (CAD) remains poorly explored. The goal of the present study was, in patients with CKD, to clarify the relationship between the angiographic severity of CAD and serum albumin concentration reflecting either inflammation or nutrition or both.

METHODS

In this study, 100 end-stage renal disease (ESRD) patients were enrolled, who commenced long-term dialysis therapy at our hospital and underwent coronary angiography within 3 months of the first haemodialysis (HD) session. Mean age was 63+/-11 years, 20% of the subjects were female and 62% had diabetes. Severity of CAD was evaluated in terms of (i) number of vessels exhibiting CAD (>or=75% stenosis) and (ii) Gensini score (GS). Clinical characteristics and laboratory findings were recorded at initiation of long-term HD therapy. We then evaluated a possible association with the presence and degree of CAD.

RESULTS

Sixty-four patients exhibited signs of CAD. Forty-one among them (64%) had multivessel disease. On univariate logistic regression analysis, age, diabetes and hypoalbuminaemia were significantly associated with multivessel CAD. Univariate linear regression analysis demonstrated a positive correlation of age and diabetes with GS, and an inverse correlation of BMI and serum albumin level with GS. Stepwise regression analysis showed age and serum albumin level to be independently associated with multivessel CAD and GS. The ROC curves demonstrated best cut-off levels of age and albumin for predicting multivessel CAD to be 70 years and 3.15 g/dl, respectively.

CONCLUSION

Hypoalbuminaemia at the initiation of dialysis is an important predictor of advanced CAD, particularly in male and in diabetic patients. It may reflect mainly a state of inflammation. However, malnutrition as a confounding factor cannot be entirely excluded.