Effect of intravenous metoprolol or intravenous metoprolol plus glucagon on dobutamine-induced myocardial ischemia.

STUDY OBJECTIVE: To determine the effect of metoprolol on dobutamine stress testing with technetium-99m sestamibi single-photon emission computed tomography imaging and ST-segment monitoring, and to assess the impact of intravenous glucagon on metoprolol's effects. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Community hospital. PATIENTS: Twenty-two patients with known reversible perfusion defects. INTERVENTION: Patients underwent dobutamine stress tests per standard protocol. Before dobutamine was begun, no therapy was given during the first visit, and patients were randomized on subsequent visits to receive metoprolol or metoprolol plus glucagon 1 mg. Metoprolol was dosed to achieve a resting predobutamine heart rate below 65 beats/minute or a total intravenous dose of 20 mg. MEASUREMENTS AND MAIN RESULTS: Metoprolol reduced maximum heart rate 31%, summed stress scores 29%, and summed difference scores 43% versus control. Metoprolol plus glucagon also reduced the maximum heart rate 29% versus control. Summed stress and summed difference scores were not significantly reduced, although they were 18% and 30% lower, respectively, than control. No significant differences were found in any parameter between metoprolol and metoprolol-glucagon. CONCLUSION: During dobutamine stress testing, metoprolol attenuates or eliminates evidence of myocardial ischemia. Glucagon 1 mg, although somewhat effective, does not correct this effect to the extent that it can be administered clinically.

Germany's long-term-care insurance: putting a social insurance model into practice.

A growing population of elderly has intensified the demand for long-term care (LTC) services. In response to the mounting need, Germany put into effect a LTC Insurance Act in 1995 that introduced mandatory public or private LTC insurance for the entire population of 82 million. The program was based on the organizational principles that define the German social insurance system. Those individuals in the public system and their employers each pay contributions equal to 0.85 percent of each employee's gross wages or salary. Ten percent of the population with the highest incomes have chosen the option of purchasing private long term care insurance. Provisions were made for uniform eligibility criteria, benefits based on level of care needs, cost containment, and quality assurance. Over the first four years of its operation, the system has proved financially sound and has expanded access to organized LTC services. The German system thus may serve as an example for other countries that are planning to initiate social LTC insurance systems in other nations.

Noninvasive strategies for the estimation of cardiac risk in stable chest pain patients. The Economics of Noninvasive Diagnosis (END) Study Group.

Effective allocation of medical resources in stable chest pain patients requires the accurate diagnosis of coronary artery disease and the stratification of future cardiac risk. We studied the relative predictive value for cardiac death of 3 commonly applied noninvasive strategies, clinical assessment, stress electrocardiography, and myocardial perfusion tomography, in a large, multicenter population of stable angina patients. The multicenter observational series comprised 7 community and academic medical centers and 8,411 stable chest pain patients. All patients underwent pretest clinical screening followed by stress (exercise 84% or pharmacologic 16%) electrocardiography and myocardial perfusion tomography. Risk-adjusted multivariable Cox proportional hazards models were developed to predict cardiac death. Kaplan-Meier rates of time to cardiac catheterization were also computed. Cardiac mortality was 3% during the 2.5 +/- 1.5 years of follow-up. The number of infarcted vascular territories and pretest clinical risk factors were strong predictors of cardiac mortality, whereas the number of ischemic vascular territories gained increasing importance when determining post-test resource use requirements (i.e., the decision to perform cardiac catheterization). Exertional ST-segment depression in a population with a high frequency of electrocardiographic abnormalities at rest was not a significant differentiator of cardiac death risk. Stable chest pain patients are accurately identified as being at high risk for near-term cardiac events by both physicians' screening clinical evaluation and by the results of stress myocardial perfusion imaging. Disease management strategies for stable chest pain patients aimed at risk reduction should incorporate knowledge of relevant end points in treatment and guideline development.

Identification of coronary thrombus with a IIb/IIIa platelet inhibitor radiopharmaceutical, technetium-99m DMP-444: A canine model.

BACKGROUND: A diagnostic test that could distinguish between stable and unstable coronary atherosclerotic plaques would be useful. We tested the ability of a new glycoprotein IIb/IIIa platelet inhibitor DMP-444, labeled with technetium (Tc)-99 m, to identify platelet-rich thrombus by nuclear imaging in a canine model. METHODS AND RESULTS: Combinations of a flow-limiting stenosis and 0 to 15 minutes of endothelial electrical stimulation at a site in the left anterior descending coronary artery were used to induce varying amounts of thrombus formation. In 10 animals with markedly positive nuclear images after the injection of Tc-99m DMP-444, the presence of platelet-rich thrombus was confirmed postmortem by gross appearance, high nuclear counts, and abundant platelets on electron microscopy. The 10 animals with negative images had lower counts, smaller thrombus weights (P<0.05 for each), and fewer platelets by electron microscopy. CONCLUSIONS: Activated platelets participating in acute thrombus formation can be accurately detected by nuclear imaging using Tc-99 m DMP-444.

Comparison of electrocardiographic-gated technetium-99m sestamibi single-photon emission computed tomographic imaging and rest-redistribution thallium-201 in the prediction of myocardial viability.

Although the combined assessment of perfusion and function using rest electrocardiographic (ECG)-gated technetium-99m (Tc-99m) sestamibi single-photon emission computed tomographic (SPECT) imaging has been shown to improve sensitivity and accuracy over perfusion alone in the prediction of myocardial viability, no data are available comparing this technique with rest-redistribution thallium-201. Thirty patients with coronary artery disease and left ventricular dysfunction (ejection fraction < or = 40%) underwent rest-redistribution thallium-201 and rest ECG-gated Tc-99m sestamibi SPECT imaging before revascularization and rest ECG-gated Tc-99m sestamibi SPECT imaging at 1 or 6 weeks after revascularization. All thallium-201 and Tc-99m sestamibi images were interpreted by a consensus agreement of 3 experienced readers without knowledge of patient identity or time of imaging with Tc-99m sestamibi (before or after revascularization) using a 17-segment model. Concordance between techniques for the prediction of viability was 89% (kappa 0.556 +/- 0.109). With rest-redistribution thallium-201, sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy were 95%, 59%, 88%, 78%, and 86%, respectively. With rest ECG-gated Tc-99m sestamibi SPECT imaging, sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy were 96%, 55%, 87%, 80%, and 86%, respectively (p = NS vs rest-redistribution thallium-201). Although both techniques are comparable for detecting viable myocardium, rest ECG-gated Tc-99m sestamibi SPECT imaging allows direct assessment of both myocardial perfusion and ventricular function, which may be clinically useful in patients who require assessment of myocardial viability.

Cost analysis of diagnostic testing for coronary artery disease in women with stable chest pain. Economics of Noninvasive Diagnosis (END) Study Group.

BACKGROUND: Seven clinical sites compiled data from 4638 women who were referred directly to coronary angiography (catheterization-first strategy; n = 3375) or who underwent stress myocardial perfusion imaging (MPI) first (n = 1263) followed by coronary angiography if at least one reversible myocardial perfusion abnormality was detected. The study examines the cost minimization potential of these available invasive and noninvasive diagnostic strategies in women with chest pain. METHODS AND RESULTS: Women in both groups were subclassified by the core laboratory as being at low (<0.15), intermediate (0.15 to 0.60), or high (>0.60) pretest likelihood for coronary artery disease (CAD). Among the catheterization-first patients, at least one coronary stenosis >70% was present in 13% of low likelihood patients, 29% of intermediate likelihood patients, and 52% of patients with high CAD likelihood. Perfusion abnormality rates in the MPI-first group were 23% in low likelihood patients, 27% in intermediate likelihood patients, and 34% in high CAD likelihood patients. Of the MPI-first subset, 50%, 55%, and 76%, respectively, underwent catheterization in at least one coronary stenosis >70%. Cardiac death rates ranged from 0.5% to 2.2% in patients with CAD and did not differ from the 2 testing strategies (P = not significant). The composite cost per patient of diagnostic testing plus follow-up medical care over a period of 2.5 +/- 1.5 years (calculated for both strategies from inflation-corrected Medicare charges, adjusted for institutional cost-charge ratios) ranged from $2490 for patients with low likelihood to $3687 for patients with high likelihood with the catheterization-first strategy and from $1587 to $2585 for patients undergoing MPI first (P < .01 between risk subsets and strategies). CONCLUSIONS: In women referred for diagnostic evaluation of stable chest pain, MPI followed by selective coronary angiography in patients with at least 1 perfusion abnormality minimizes the near-term composite cost per patient compared with a direct catheterization-first strategy, regardless of pretest CAD likelihood.

Comparison of acute rest myocardial perfusion imaging and serum markers of myocardial injury in patients with chest pain syndromes.

BACKGROUND: Newer diagnostic modalities such as serum markers and acute rest myocardial perfusion imaging (MPI) have been evaluated diagnostically in patients with chest pain in the emergency department (ED), but never concurrently. We compared these two modalities in distinguishing patients in the ED with symptomatic myocardial ischemia from those with non-cardiac causes. METHODS: Serum markers and acute technetium-99m sestamibi/tetrofosmin rest MPI were obtained in 75 patients admitted to the ED with chest pain and nondiagnostic electrocardiograms. Venous samples were drawn at admission and 8 to 24 hours later for total creatine kinase, CK-MB fraction, troponin T, troponin I, and myoglobin. Three nuclear cardiologists performed blinded image interpretation. Coronary artery disease (CAD) was confirmed either by diagnostic testing or by the occurrence of myocardial infarction (MI). RESULTS: Acute rest MPI results were abnormal in all 9 patients with MI. An additional 26 patients had objective evidence of CAD confirmed by diagnostic testing. The sensitivity of acute rest MPI for objective evidence of CAD was 73%. Serum troponin T and troponin I were highly specific for acute MI but had low sensitivity at presentation. Individual serum markers had very low sensitivity for symptomatic myocardial ischemia alone. In the multivariate regression model, only acute rest MPI and diabetes were independently predictive of CAD. CONCLUSION: At the time of presentation and 8 to 24 hours later, acute rest MPI has a better sensitivity and similar specificity for patients with objective evidence of CAD when compared with serum markers.

Early dipyridamole (99m)Tc-sestamibi single photon emission computed tomographic imaging 2 to 4 days after acute myocardial infarction predicts in-hospital and postdischarge cardiac events: comparison with submaximal exercise imaging.

BACKGROUND: Because of its brief hemodynamic effects and minor effect on determinants of myocardial oxygen demand, vasodilator stress myocardial perfusion imaging (MPI) can be applied very early after acute myocardial infarction (AMI) for risk stratification, allowing management decisions to be made earlier and thus potentially shortening hospitalization stays, reducing costs, and preventing early cardiac events. This multicenter randomized trial compared the prognostic value of early dipyridamole MPI and standard predischarge submaximal exercise MPI in patients who presented with AMI. METHODS AND RESULTS: Patients who presented with their first AMI (n=451) were randomized in a 3:1 ratio to undergo either both an early (day 2 to 4) dipyridamole (99m)Tc-sestamibi MPI study and a predischarge (day 6 to 12) submaximal exercise (99m)Tc-sestamibi MPI study or only the predischarge study. Multivariate predictors of in-hospital cardiac events included nuclear imaging summed stress and summed reversibility scores and peak creatine kinase. For postdischarge cardiac events, multivariate predictors in patients undergoing dipyridamole MPI included only the summed stress, reversibility, and rest imaging scores and anterior MI. For a given summed stress score, the interaction of reversibility score further improved the predictive value. Dipyridamole MPI showed better risk stratification than submaximal exercise MPI. CONCLUSIONS: Dipyridamole MPI very early after MI predicts early and late cardiac events, with superior prognostic value compared with submaximal exercise imaging. The extent and severity of the stress defect and reversibility of the defect were the most important predictors of cardiac death and recurrent MI. This technique can allow management decisions to be made earlier with regard to AMI patients and could have important economic impact if applied widely.

The effect of pharmacokinetically guided acute intravenous testosterone administration on electrocardiographic and blood pressure variables.

Previous studies have demonstrated that intravenous testosterone can dilate coronary arteries and increase exercise treadmill time, but the electrocardiographic and hemodynamic effects are unknown. This trial determined the hemodynamic and electrocardiographic effects of dosing intravenous testosterone to achieve a physiologic and a superphysiologic serum testosterone concentration. Twenty men (70.6 +/- 6.2 years) had individualized testosterone bolus and continuous infusions designed to increase the serum testosterone concentration by two (physiologic) and six times baseline (superphysiologic). The men were studied on three occasions when they were randomly allocated to received a placebo, physiologic testosterone regimen, or superphysiologic testosterone regimen. Blood pressures and 12-lead electrocardiograms (ECGs) were taken preinfusion and 28 minutes after initiating the infusion on each visit. The blood pressure (systolic and diastolic) and ECG variables (PR, QRS, QT, QTc, and RR intervals) preinfusion and during the infusion were compared, and the delta changes in the variables were compared between groups. The physiologic testosterone regimen increased the serum testosterone concentration by 2.39 +/- 0.48 times the preinfusion concentration, while the superphysiologic regimen increased it by 6.22 +/- 0.99 times. No significant changes occurred in the blood pressure or ECG variables in any group versus preinfusion values or between the three groups. Exogenously administered intravenous testosterone does not significantly affect the blood pressure or ECG variables when given to achieve physiologic or superphysiologic concentrations.

Impact of limited treadmill exercise on adenosine Tc-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging in coronary artery disease.

Limited exercise combined with dipyridamole increases myocardial perfusion defect severity compared with dipyridamole alone. The impact of limited exercise combined with adenosine on myocardial perfusion defect severity is unknown. This study compares myocardial perfusion defect severity with adenosine alone and adenosine combined with limited exercise. Thirty-two patients with coronary artery disease underwent on separate days and in randomized order technetium-99m sestamibi (25 to 30 mCi) single-photon emission computed tomographic imaging at rest, after adenosine (140 microg/kg/min x 6 minutes), and after adenosine (140 microg/kg/min x 4 minutes) during 6 minutes of modified Bruce treadmill exercise (adenosine-exercise). Radiopharmaceutical was injected at 3 and 5 minutes during adenosine and adenosine-exercise, respectively. Images were interpreted by a consensus agreement of 3 nuclear cardiologists without knowledge of patient identity, stress protocol, or clinical data using a 17-segment model and 5-point scoring system. A summed stress score (SSS), summed rest score (SRS), and summed difference (SSS-SRS) score (SDS) were calculated for each image. Peak stress heart rate and rate-pressure product were higher for adenosine-exercise than adenosine (102 +/- 19 vs 81 +/- 11 beats/min and 13,972 +/- 4,265 vs 10,623 +/- 2,131, respectively; both p <0.001). Sensitivity for detection of > or = 50% coronary stenosis was 75% and 72% for adenosine-exercise and adenosine, respectively (p = NS). There were no differences in SSS and SDS between adenosine-exercise and adenosine (8.2 +/- 5.9 vs 8.1 +/- 6.3 and 4.9 +/- 4.1 vs 5.2 +/- 4.6, respectively; both p = NS). Thus, in patients with coronary artery disease, limited treadmill exercise combined with adenosine does not increase myocardial perfusion defect severity compared with standard adenosine technetium-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging.

Comparison of exercise, dipyridamole, adenosine, and dobutamine stress with the use of Tc-99m tetrofosmin tomographic imaging.

PURPOSE: The purpose of this study was to compare defect extent and severity and myocardial uptake with exercise and pharmacologic stress with technetium-99m (Tc-99m) tetrofosmin tomographic myocardial perfusion imaging. BACKGROUND: Detection of stress-induced myocardial perfusion defects depends on both a disparity in blood flow between normal and stenotic vessels and the extraction fraction and linearity of myocardial uptake of the tracer. There are limited clinical data for exercise or pharmacologic stress with Tc-99m tetrofosmin tomographic myocardial perfusion imaging. METHODS: Thirty-one patients with coronary artery disease and 7 with a < 5% likelihood of coronary artery disease underwent on separate days Tc-99m tetrofosmin single-photon emission computed tomographic imaging at rest and after exercise, dipyridamole, adenosine, and dobutamine stress. Images were interpreted by a blinded consensus of 3 experienced readers with a 17-segment model and 5-point scoring system. RESULTS: Compared with exercise, the summed stress score was smaller with dipyridamole (P < .01), and the reversibility score was smaller with both dipyridamole (P < .01) and dobutamine (P < .05), whereas the number of abnormal and reversible segments was less with both dipyridamole (P < .01 and P < .001, respectively) and dobutamine (both P < .05). No significant differences were found in the summed stress or reversibility scores and the number of abnormal or reversible segments between exercise and adenosine. CONCLUSIONS: Compared with exercise, defect extent, severity, and reversibility are less with dipyridamole and dobutamine with Tc-99m tetrofosmin single photon emission computed tomographic imaging.

Gated SPECT imaging.

Gated SPECT imaging has allowed the simultaneous assessment of both perfusion and function through one study. The popularity of this is amply shown by the unprecedented growth of this imaging modality throughout the country. In addition to the benefits that ventricular function adds to perfusion, gated SPECT imaging also adds to the specificity of perfusion imaging. With recent studies showing the benefit of medical therapy to interventional approaches for the treatment of patients with angina, in particular, patients with chronic stable angina, there has been an increased dependence on noninvasive imaging to assess their ischemic burden. Perfusion, with technetium-99m sestamibi SPECT imaging together with gated SPECT imaging has been the modality of choice in the majority of cases because of the ease of performance of these studies and the increased information provided. This has in large part been attributable to the ability of gated SPECT imaging to provide functional data, significantly increasing the use of radionuclide perfusion imaging. This article reviews the method of acquisition, validation, clinical use, and the newer advances of gated SPECT imaging. It gives an appreciation of the benefit that gated SPECT imaging has added in terms of risk stratification and prognosis in many cardiac patients. Under the more recent uses are myocardial viability and the increased utility of gating in this scenario, ischemic versus nonischemic cardiomyopathies, and the quandary that this testing poses to physicians and the dilemma of gated thallium imaging with its inferior image quality.

Multicenter clinical trial to evaluate the efficacy of correction for photon attenuation and scatter in SPECT myocardial perfusion imaging.

BACKGROUND: Soft tissue attenuation is a prominent cause of single-photon emission computed tomography (SPECT) imaging artifacts, which may result in reduced diagnostic accuracy of myocardial perfusion imaging. A method incorporating simultaneously acquired transmission data permits nonuniform attenuation correction and when incorporating scatter correction and resolution compensation may substantially reduce interpretive errors. METHODS AND RESULTS: A prospective multicenter trial was performed recruiting patients with angiographically documented coronary disease (n=96) and group of subjects with a low likelihood of disease (n=88). The uncorrected and attenuation/scatter corrected images were read independently, without knowledge of the patient's clinical data. The detection of >/=50% stenosis was similar using uncorrected perfusion data or with attenuation/scatter correction and resolution compensation (visual or visual plus quantitative analysis), 76% versus 75% versus 78%, respectively (P=NS). The normalcy rate, however, was significantly improved with this new methodology, using either the corrected images (86% vs 96%; P=0.011) or with the corrected data and quantitative analysis (86% vs 97%; P=0.007). The receiver operator characteristic curves were also found to be marginally but not significantly higher with attenuation/scatter correction than with tradition SPECT imaging. However, the ability to detect multivessel disease was reduced with attenuation/scatter correction. Regional differences were also noted, with reduced sensitivity but improved specificity for right coronary lesions using attenuation/scatter correction methodology. CONCLUSIONS: This multicenter trial demonstrates the initial clinical results of a new SPECT perfusion imaging modality incorporating attenuation and scatter correction in conjunction with 99mTc sestamibi perfusion imaging. Significant improvements in the normalcy rate were noted without a decline in overall sensitivity but with a reduction in detection of extensive coronary disease.

Interpretive reproducibility of stress Tc-99m sestamibi tomographic myocardial perfusion imaging.

BACKGROUND: Observer variability has been shown with interpretation of planar thallium-201 images. The interpretive reproducibility of technetium-99m sestamibi tomographic imaging is unknown. This study evaluated the interpretive reproducibility of interpretable Tc-99m sestamibi tomographic images among nuclear cardiologists with a wide range of training and experience. METHODS: Three experienced readers (EX) and 3 less-experienced readers (LEX) interpreted 138 exercise and rest Tc-99m sestamibi tomographic images (101 were abnormal in patients with coronary artery disease [CAD], 37 were normal in patients with <5% likelihood of CAD) twice in random sequence without clinical data. Images of good to excellent quality were randomly selected from a database at 2 nuclear cardiology laboratories. Intraobserver and interobserver agreement for global, left anterior descending (LAD) territory, non-LAD first (normal/abnormal) and second (normal/fixed/reversible) order, and defect extent (normal/single-vessel CAD/multi-vessel CAD) were assessed with percent agreement and Cohen's kappa (kappa) statistic. RESULTS: With regard to intraobserver agreement, first and second order ranged from 87% to 94% and 80% to 90% for global, 82% to 96% and 78% to 95% for LAD, and 88% to 91% and 80% to 90% for non-LAD, respectively. Defect extent ranged from 75% to 90%. There were no differences between EX and LEX for global and non-LAD first and second order, LAD first order, and defect extent. LAD second order was 93% for EX compared with 88% (P = .015) for LEX. With regard to interobserver agreement, first and second order ranged from 73% to 89% and 64% to 85% for global, 73% to 93% and 69% to 91% for LAD, and 76% to 88% and 68% to 84% for non-LAD, respectively. Defect extent ranged from 61% to 82%. Global first and second order ranged from 85% to 87% and 78% to 82% for EX compared with 73% to 84% and 64% to 79% for LEX. LAD first and second order ranged from 89% to 91% and 88% to 89% for EX compared with 73% to 91% and 69% to 70% for LEX. Non-LAD first and second order ranged from 82% to 86% and 76% to 77% for EX compared with 76% to 86% and 68% to 81% for LEX. Defect extent ranged from 69% to 75% for EX compared with 59% to 77% for LEX. CONCLUSIONS: There is moderate to excellent interpretive reproducibility with stress Tc-99m sestamibi SPECT imaging among nuclear cardiologists with a wide range of training and experience.

The noninvasive prediction of cardiac mortality in men and women with known or suspected coronary artery disease. Economics of Noninvasive Diagnosis (END) Study Group.

PURPOSE: The association between myocardial perfusion imaging defects and cardiac mortality in women is undefined. We examined whether myocardial perfusion imaging predicted cardiac mortality in men and women and compared this with other variables influencing prognosis. SUBJECTS AND METHODS: Six academic institutions with high-volume nuclear cardiology laboratories consecutively studied 5,009 men aged 62 +/- 12 years (mean ISD) and 3,402 women aged 66 +/- 11 years with symptomatic known or suspected coronary artery disease undergoing exercise (n = 7,486) or pharmacologic stress (n = 925) myocardial perfusion imaging. A pretest clinical risk index was calculated from age, history of myocardial infarction, diabetes, hypertension, and hypercholesterolemia. Myocardial perfusion images were analyzed for stress-induced defects or any defect in the territories of the three major coronary arteries. RESULTS: Stress-induced perfusion defects were seen in 39% of men and 25% of women (P = 0.0001). Extensive stress-induced or fixed defects (>2 vascular territories) were less common in women than men (10% vs 19%, and 4% vs 18%, both P = 0.0001). During a mean of 2.4 +/- 1.5 years of follow-up, 143 patients died of cardiac causes. The clinical risk index and number of territories with perfusion defects were associated with cardiac mortality in women and men. In women undergoing exercise myocardial perfusion imaging, the number of abnormal territories remained the strongest correlate of mortality after adjustment for exercise variables. CONCLUSIONS: The results of myocardial perfusion imaging are important, independent predictors of survival in both women and men.

Influence of arm positioning on rest/stress technetium-99m labeled sestamibi tomographic myocardial perfusion imaging.

BACKGROUND: Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is routinely performed with patients' arms positioned above their heads to avoid potential attenuation artifact and reduced image quality. Currently no data are available to support the use of this practice using 99mTc SPECT MPI: METHODS AND RESULTS: Forty-one patients referred for routine rest/stress MPI were imaged using the standard protocol with arms positioned above their heads and again with their arms at their sides. The patients were injected with 10 to 45 mCi (370 to 1665 MBq) of 99mTc-labeled sestamibi (99mTc-sestamibi), and SPECT images were acquired 30 to 90 minutes later. Thirty patients were imaged on an ADAC Vertex dual-head camera and 11 patients on an ADAC Cirrus single-head camera. Images were interpreted by 3 nuclear cardiologists without knowledge of patient identity, arm position, or camera type using a 17-segment scoring model. No significant differences were noted in the percentage of abnormal study results, reversibility extent, or location of MPI defects between the 2 arm positions in the same patients. Image quality was also similar. CONCLUSION: Arm positioning does not influence the interpretation of 99mTc-sestamibi SPECT myocardial perfusion imaging with regard to image quality or defect location and extent.

Functional assessment with electrocardiographic gated single-photon emission computed tomography improves the ability of technetium-99m sestamibi myocardial perfusion imaging to predict myocardial viability in patients undergoing revascularization.

This study evaluates the use of electrocardiographic (ECG) gated single-photon emission computed tomographic (SPECT) myocardial perfusion imaging for the prediction of viability in patients undergoing revascularization, who have coronary disease and left ventricular dysfunction. Fifty patients underwent technectium-99m (Tc-99m) sestamibi ECG gated SPECT imaging preoperatively at rest and 1 week after revascularization, whereas 36 (72%) also underwent imaging 6 weeks after revascularization. Images were interpreted by the consensus of 3 experienced readers without knowledge of patient identity or time of imaging (pre- or postrevascularization) for perfusion and wall motion using a 17-segment model. Results of perfusion alone were compared with perfusion and wall motion combined. One hundred five coronary artery territories were revascularized, 96 of which were viable and 9 nonviable. Perfusion alone predicted 87 to be viable and 18 nonviable (sensitivity 86%, specificity 55%, positive predictive value 95%, negative predictive value 28%, and overall accuracy 85%). Perfusion and wall motion combined identified 95 territories to be viable (sensitivity 95%; p <0.025; specificity 55%, positive predictive value 96%, negative predictive value 50%, and overall accuracy 91%; p <0.05). Thus, Tc-99m sestamibi ECG gated SPECT myocardial perfusion imaging at rest allows assessment of both perfusion and wall motion, which significantly improves the sensitivity and overall accuracy for determination of viability in comparison with perfusion alone.