Highlights of the 2005 scientific sessions of the American Society of Nuclear Cardiology: Seattle, Washington, September 29-October 2, 2005.
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Biomedical subjects
Publications and source records attributed to Frans J Th Wackers.
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The objective of this study was to determine the relationship of sociodemographics; diabetes-related factors, including diabetes-related microvascular complications; cardiac risk factors; and psychological factors with quality of life (QOL). Participants enrolled at three sites in the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study were invited to participate in this ancillary study. Questionnaires assessing psychological factors were completed by participants, and the remainder of the data was obtained as part of the DIAD study. Many participants had elevated levels of anxiety (n = 91; 82%), depressive symptoms (n = 16; 14%), anger (n = 38; 34%), and hostility (n = 17; 17%). Results of multivariate analyses conducted for each of the eight domains on the Medical Outcomes Study Short Form-36 and two Diabetes Quality of Life domains demonstrated that in the majority of models (42% to 68% of the variance explained), female sex, peripheral or autonomic neuropathy, physical inactivity, higher body mass index, and the presence of depressive symptoms and anxiety were associated with poorer QOL (p = .0001). These findings demonstrate that anxiety, depressive symptoms, and neuropathy are prevalent in older adults with type 2 diabetes. In addition, potentially important correlations were demonstrated between psychological factors, neuropathy, body mass index, and physical inactivity.
As a consequence of acute ischemia and reperfusion in patients with acute ST elevation myocardial infarction, calcium overload inside myocytes not only affects myocardial contraction, relaxation, and myocyte recovery following reperfusion, but also may be related to myocyte necrosis and fatal arrhythmia. MCC-135 is the first in a new class of agents that reduce intracellular calcium overload. Pre-clinical and early clinical studies yielded promising results for patients with ST elevation myocardial infarction. The Evaluation of MCC-135 for Left Ventricular Salvage in Acute MI (EVOLVE) study is a Phase 2a, multicenter, randomized, double-blind, placebo-controlled clinical trial of 2 new doses of MCC-135 (4.5 mg/kg/48 hours and 9.0 mg/kg/48 hours) as adjunct therapy for preservation of left ventricular function and reduction of infarct size in patients undergoing primary percutaneous coronary intervention (PCI) for electrocardiographically moderate-large ST elevation myocardial infarction. The primary endpoint will be left ventricular ejection fraction on Day 5 post myocardial infarction as determined by single photon emission computed tomography (SPECT). Secondary endpoints will include SPECT and echocardiographic assessments, serum cardiac markers, clinical outcomes, and safety measures at specific time points through Day 30 post myocardial infarction. Follow-up clinical and safety assessments will be continued until Day 180. The rationale, design, and methods of the EVOLVE study are described in this paper, along with 2 sub-studies, involving a comparison of pre- and post-PCI measurements with either SPECT or echocardiography, to examine myocardial salvage and the time course of changes in myocardial infarction size and left ventricular function. MINIABSTRACT: The Evaluation of MCC-135 for Left Ventricular Salvage in Acute MI (EVOLVE) study is a Phase 2, multicenter, randomized, double-blind, placebo-controlled clinical trial of two doses of MCC-135, first in a new class of agents that reduce intracellular calcium overload, as adjunct therapy for preservation of left ventricular function and reduction of infarct size in patients with moderate-large STEMI undergoing primary PCI. The rationale, design, and methods of the EVOLVE study, along with two sub-studies, are described in this paper.
Stress myocardial perfusion imaging (MPI) has the potential not only to improve clinical outcomes in diabetic patients, but also to decrease unnecessary use of health care resources. However, before routine screening can be recommended, cost-effectiveness analyses are required to identify patients in whom such testing is appropriate. Nevertheless, MPI is clearly emerging as a valuable tool for improving management of coronary artery disease in all patients with diabetes mellitus.
Microalbuminuria is a novel atherosclerotic risk factor in patients with type 2 diabetes mellitus (DM) and predicts future cardiovascular events. Endothelial dysfunction and systemic inflammation have been proposed as common links between microalbuminuria and cardiovascular disease. However, no study has assessed the relation between microalbuminuria and vascular dysfunction as measured by brachial artery reactivity (BAR) in DM. We evaluated 143 patients (85 men; mean age 60.0 +/- 6.7 years) with DM (mean duration 8.2 +/- 7.4 years) enrolled in the Detection of Ischemia in Asymptomatic Diabetics study. Subjects were categorized as those with microalbuminuria (ratio of urinary albumin to creatinine 30 to 299 microg/mg creatinine, n = 28) and those with normoalbuminuria (ratio of urinary albumin to creatinine 0 to 29.9 microg/mg creatinine, n = 115). High-resolution ultrasound BAR testing was used to measure endothelium-dependent and endothelium-independent vasodilations. C-reactive protein was measured as a marker of systemic inflammation. Patients with microalbuminuria and normoalbuminuria had similar baseline characteristics, with the exception that those with microalbuminuria had a longer duration of DM (p = 0.03). Endothelium-dependent vasodilation at 1 minute (p = 0.01) and endothelium-independent vasodilation at 3 minutes (p = 0.007) were significantly less in patients with microalbuminuria. In addition, 96% of patients with microalbuminuria and 76% of those with normoalbuminuria had impaired endothelium-dependent vasodilation (<8%, p = 0.01). Microalbuminuria was an independent predictor of endothelium-dependent vasodilation in the entire cohort (p = 0.045) and after excluding patients on hormone replacement therapy (p = 0.01). Levels of C-reactive protein were significantly higher in patients with microalbuminuria than in those with normoalbuminuria (p = 0.02). We conclude that in DM the presence of microalbuminuria is associated with impaired endothelium-dependent and endothelium-independent vasodilations of the brachial artery and a higher degree of systemic inflammation. In addition, microalbuminuria is an independent predictor of endothelial dysfunction in asymptomatic patients with DM, especially in the absence of hormone replacement therapy.
BACKGROUND: Dipyridamole and adenosine cause frequent side effects as a result of nonspecific adenosine receptor stimulation. Selective agonism of the adenosine A2A receptor should result in a similar degree of coronary vasodilation (and thus similar perfusion images) with fewer side effects. METHODS AND RESULTS: In a multicenter, randomized, single-blind, 2-arm crossover trial, 240 patients underwent 2 single photon emission computed tomographic (SPECT) imaging studies in random order, first after pharmacological stress with adenosine and a second study with the selective adenosine A2A receptor agonist binodenoson, using 1 of 4 dosing regimens. Safety, tolerability, and SPECT image concordance between the 2 agents were examined. Exact categorical agreement in the extent and severity of reversible perfusion defects ranged from 79% to 87%, with kappa values from 0.69 to 0.85, indicating very good to excellent agreement between binodenoson and adenosine. The risk of any safety event/side effect was significantly lower with any dose of binodenoson than with adenosine (P< or =0.01) because of a dose-related reduction in subjective side effects, as objective events were infrequent. There was a reduction in the severity of chest pain, dyspnea, and flushing in all binodenoson doses compared with adenosine (P<0.01), and the magnitude of severity reduction was dose-related. CONCLUSIONS: The selective adenosine A2A receptor agonist binodenoson results in an extent and severity of reversible perfusion defects on SPECT imaging similar to nonselective adenosine receptor stimulation, accompanied by a dose-related reduction in the incidence and severity of side effects.
OBJECTIVE: The goal of this study was to determine whether treatment with an aldose reductase inhibitor (ARI) has beneficial effects on asymptomatic cardiac abnormalities in diabetic patients with neuropathy. RESEARCH DESIGN AND METHODS: Diabetic subjects with neuropathy (n = 81) with either a low diastolic peak filling rate or impaired augmentation of left ventricular (LV) ejection fraction (LVEF) during maximal bicycle exercise were identified by gated radionuclide ventriculography. Coronary artery disease, left ventricular hypertrophy, and valvular heart disease were excluded by clinical evaluation, myocardial perfusion imaging, and echocardiography. Subjects were randomized to receive blinded treatment with either the placebo or the ARI zopolrestat 500 or 1,000 mg daily for 1 year. RESULTS: After 1 year of ARI treatment, there were increases in resting LVEF (P < 0.02), cardiac output (P < 0.03), LV stroke volume (P < 0.004), and exercise LVEF (P < 0.001). In placebo-treated subjects, there were decreases in exercise cardiac output (P < 0.03), stroke volume (P < 0.02), and end diastolic volume (P < 0.04). Exercise LVEF increased with ARI treatment independent of blood pressure, insulin use, or the presence of baseline abnormal heart rate variability. There was no change in resting diastolic filling rates in either group. CONCLUSIONS: Diabetic patients with neuropathy have LV abnormalities that can be stabilized and partially reversed by ARI treatment.
OBJECTIVE: To assess the prevalence and clinical predictors of silent myocardial ischemia in asymptomatic patients with type 2 diabetes and to test the effectiveness of current American Diabetes Association screening guidelines. RESEARCH DESIGN AND METHODS: In the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study, 1,123 patients with type 2 diabetes, aged 50-75 years, with no known or suspected coronary artery disease, were randomly assigned to either stress testing and 5-year clinical follow-up or to follow-up only. The prevalence of ischemia in 522 patients randomized to stress testing was assessed by adenosine technetium-99m sestamibi single-photon emission-computed tomography myocardial perfusion imaging. RESULTS: A total of 113 patients (22%) had silent ischemia, including 83 with regional myocardial perfusion abnormalities and 30 with normal perfusion but other abnormalities (i.e., adenosine-induced ST-segment depression, ventricular dilation, or rest ventricular dysfunction). Moderate or large perfusion defects were present in 33 patients. The strongest predictors for abnormal tests were abnormal Valsalva (odds ratio [OR] 5.6), male sex (2.5), and diabetes duration (5.2). Other traditional cardiac risk factors or inflammatory and prothrombotic markers were not predictive. Ischemic adenosine-induced ST-segment depression with normal perfusion (n = 21) was associated with women (OR 3.4). Selecting only patients who met American Diabetes Association guidelines would have failed to identify 41% of patients with silent ischemia. CONCLUSIONS: Silent myocardial ischemia occurs in greater than one in five asymptomatic patients with type 2 diabetes. Traditional and emerging cardiac risk factors were not associated with abnormal stress tests, although cardiac autonomic dysfunction was a strong predictor of ischemia.
This study was designed to evaluate several electromechanical mapping parameters for assessment of myocardial viability and inducible ischemia as defined by dipyridamole single-photon emission computed tomographic (SPECT) imaging at rest in patients with severe ischemic cardiomyopathy. Unipolar voltage, normalized unipolar voltage, bipolar voltage, and fragmentation were compared with tracer uptake at rest and reversibility on stress or rest quantitative technetium-99m sestamibi SPECT imaging in 32 patients with severe ischemic cardiomyopathy (left ventricular ejection fraction 0.24 +/- 0.08). In dysfunctional myocardial segments, logistic regression showed unipolar voltage, normalized unipolar voltage, and bipolar voltage to be predictive of viable myocardium (> or = 60% tracer uptake at rest) and was significantly higher in viable than in nonviable segments (p <0.01). A unipolar voltage of > or = 7.1 mV was the best predictor of viable myocardium. In dysfunctional viable segments, unipolar voltage was significantly higher in reversible than in fixed segments (p <0.001), and a unipolar voltage of > or = 8.5 mV had optimal power for identifying reversibility on dipyridamole SPECT imaging. We conclude that in patients with severe ischemic cardiomyopathy, unipolar voltage can identify viable from nonviable myocardium and reversible from fixed viable defects as defined by dipyridamole technetium-99m sestamibi SPECT imaging.
The assessment of right ventricular morphology and function is of clinical importance in patients with pulmonary disease. Until recently the evaluation of the right ventricle was difficult because of the unusual geometry of the right ventricle. This chapter discusses the various diagnostic modalities available for assessment of right ventricular morphology and function. Although echocardiography is widely used because of its common availability, nuclear magnetic resonance imaging and radionuclide angiocardiography should be considered the gold standards and are preferred when reliable and accurate measures of right ventricular function and morphology are needed.
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UNLABELLED: Myocardial ischemia is associated with reduced free fatty acid (FFA) beta-oxidation and increased glucose utilization. This study evaluated the potential of dynamic SPECT imaging of a FFA analog, p-(123)I-iodophenylpentadecanoic acid (IPPA), for detection of ischemia and compares retention of IPPA with (18)F-FDG accumulation. METHODS: In a canine model of regional low-flow ischemia (n = 9), serial IPPA SPECT images (2 min per image) were acquired over 52--90 min. In a subset of dogs (n = 6), (18)F-FDG was injected after completing SPECT imaging and allowed to accumulate for 40 min before killing the animals. Flow was assessed with radiolabeled microspheres. Myocardial metabolism was evaluated independently by selective coronary arterial and venous sampling. RESULTS: Serial IPPA SPECT images showed an initial defect in the ischemic region (0.70% plus minus 0.03% ischemic-to-nonischemic ratio), which normalized within 48 min because of the slower IPPA clearance from the ischemic region (t(1/2) = 54.2 plus minus 3.3 min) relative to the nonischemic region (t(1/2) = 36.7 plus minus 5.6 min) (P < 0.05). Delayed myocardial IPPA and (18)F-FDG activities were correlated (r = 0.70; n = 576 segments), and both were maximally increased in segments with a moderate flow reduction (IPPA, 151% of nonischemic; (18)F-FDG, 450% of nonischemic; P < 0.05). CONCLUSION: Serial SPECT imaging showed delayed myocardial clearance of IPPA in ischemic regions with moderate flow reduction, which lead to increased late myocardial retention of IPPA. Retention of IPPA correlated with (18)F-FDG accumulation, supporting the potential of IPPA as a noninvasive marker of ischemic myocardium.
UNLABELLED: A circular 180 degrees acquisition orbit is considered standard for cardiac SPECT imaging. Theoretically, a 360 degrees acquisition orbit is preferred because of more complete Fourier spectral information on projection data. The differential effect of 180 degrees and 360 degrees acquisition orbits on image accuracy (homogeneity and defect size) was assessed quantitatively in phantom studies. METHODS: SPECT imaging with a dual-head gamma camera was performed on normal cardiac phantoms filled with a (99m)Tc solution, using 180 degrees and 360 degrees circular acquisition orbits. The phantoms were placed in the center of the orbit and at 5, 10, and 15 cm off center. Fillable defect inserts of different sizes were placed in the phantom to simulate myocardial perfusion defects. The homogeneity of count distribution in short-axis slices of the normal phantom was analyzed as the percentage of variability. Defects were quantified as a percentage of the entire phantom volume using circumferential count profiles and normal reference profiles. RESULTS: When normal phantoms were placed in the center of the orbit, percentage variability was not different whether a 180 degrees or 360 degrees acquisition orbit was used (4.2% +/- 0.1% vs. 4.4% +/- 0.2%, P = not statistically significant). However when normal phantoms were placed off center, SPECT imaging with a 180 degrees acquisition orbit showed increasing inhomogeneity, both visually and quantitatively (e.g., percentage variability for the 15-cm off-center position was 10.8% +/- 0.1% (P < 0.0001). SPECT imaging with a 360 degrees acquisition orbit showed similar homogeneity visually and quantitatively, whether the phantom was placed in or off the center (e.g., percentage variability for the 15-cm off-center position was 4.6% +/- 0.5%, P = not statistically significant). Quantification of phantom defects acquired with a 180 degrees orbit showed increasing overestimation of defect sizes with increasingly off-center positions. Quantification of phantom defects acquired with a 360 degrees orbit showed no effect from progressively off-center positions, although phantom defect sizes were mildly underestimated. CONCLUSION: SPECT images acquired with a 180 degrees orbit may have significant erroneous inhomogeneity and overestimation of defect size, in particular when the target object is off the center of the orbit, as is commonly seen in clinical cardiac imaging. In contrast, SPECT images acquired with a 360 degrees orbit may provide more accurate quantitative information.
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