Screening patients with chest pain in the emergency department using electron beam tomography: a follow-up study.

OBJECTIVES: The high sensitivity of electron beam tomography (EBT) in the detection of coronary artery calcium (CAC) and obstructive coronary artery disease prompted us to investigate the association between CAC detection and future cardiac events in patients with acute chest pain syndromes requiring hospitalization. BACKGROUND: Three studies have documented that EBT is a rapid and efficient screening tool for patients admitted to the emergency department (ED) with chest pain, but there is a paucity of long-term follow-up data on these chest pain patients. METHODS: We conducted a prospective observational study of 192 patients admitted to the ED of a large tertiary care hospital for chest pain syndromes. Upon admission, patients underwent EBT scanning in addition to the usual care for chest pain syndromes. During the 17-month enrollment period, 221 patients were scanned (54% men with a mean age of 53 +/- 9 years). Average follow-up was 50 +/- 10 months using chart review. RESULTS: Fifty-eight patients had coronary events confirmed by a blinded medical record review. The presence of CAC (a total calcium score >0) and increasing score quartiles were strongly related to the occurrence of hard cardiac events including myocardial infarction and death (p < 0.001) and all cardiovascular events (p < 0.001). Stratification by age- and gender-matching further increased the prognostic ability of EBT (for scores above vs. below the age- and gender-matched CAC scores; odds ratio: 13.1, 95% confidence intervals: 5.62, 35.9). CONCLUSIONS: These data support previous reports demonstrating that the presence of CAC in a symptomatic cohort is a strong predictor of future cardiac events. This study supports the use of EBT in a symptomatic cohort with prompt discharge of those patients with negative scans. Furthermore, the absence of CAC is associated with a very low risk of future cardiac risk events in this population over the subsequent seven years (annual event rate <1%).

Gas exchange responses to continuous incremental cycle ergometry exercise in primary pulmonary hypertension in humans.

In patients suffering from primary pulmonary hypertension (PPH), a raised pulmonary vascular resistance may limit the ability to increase pulmonary blood flow as work rate increases. We hypothesised that oxygen uptake (VO2) may not rise appropriately with increasing work rate during incremental cardiopulmonary exercise tests. Nine PPH patients and nine normal subjects performed symptom-limited maximal continuous incremental cycle ergometry exercise. Mean peak VO2 [1.00 (SD 0.22) compared to 2.58 (SD 0.64) l x min(-1)] and mean VO2 at lactic acidosis threshold [LAT, 0.73 (SD 0.17) compared to 1.46 (SD 0.21 x 1) ml x min(-1)] were much lower in patients than in normal subjects (both P<0.01, two-way ANOVA with Tukey test). The mean rate of change of VO2 with increasing work rate above the LAT [5.9 (SD 2.1) compared to 9.4 (SD 1.3) ml x min(-1) x W(-1), p<0.01)] was also much lower in patients than in normal subjects [apparent delta efficiency 60.3 (SD 38.8)% in patients compared to 31.0 (SD 4.9)% in normal subjects]. The patients displayed lower mean values of end-tidal partial pressure of carbon dioxide than the normal subjects at peak exercise [29.7 (SD 6.8) compared to 42.4 (SD 5.8) mm Hg, P<0.01] and mean oxyhaemoglobin saturation [89.1 (SD 4.1) compared to 93.6 (SD 1.8)%, P<0.05]. Mean ventilatory equivalents for CO2 [49.3 (SD 11.4) compared to 35.0 (SD 7.3), P<0.05] and O2 [44.2 (SD 10.7) compared to 29.9 (SD 5.1), P<0.05] were greater in patients than normal subjects. The sub-normal slopes for the VO2-work-rate relationship above the LAT indicated severe impairment of the circulatory response to exercise in patients with PPH. The ventilatory abnormalities in PPH suggested that the lung had become an inefficient gas exchange organ because of impaired perfusion of the ventilated lung.

Preview method for electron-beam CT scanning of the coronary arteries.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate a method that uses electron-beam computed tomography to obtain the most appropriate starting level for complete imaging of the coronary tree and to compare it with the existing method. A second aim was to evaluate the spatial location of the coronary arteries relative to different anatomic cardiac and chest landmarks. MATERIALS AND METHODS: Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the traditional preview method. The accuracy of each preview method to encompass the coronary anatomy was compared. RESULTS: All coronary arteries were included in 3-mm scans obtained starting three levels above the origin of the left main coronary artery. The left anterior descending coronary artery extended 3-9 mm above the left main artery in 33 patients (14%). The coronary arteries were encompassed by scans depicting 72-105 mm; thus, with 3-mm sections, up to 35 scans are necessary to cover the entire coronary tree. No stable relationship between the coronary arteries and the pulmonary artery or carina could be found. CONCLUSION: The six-level preview method that identifies the left main coronary artery and begins 9 mm above this level is the most accurate method for depicting the coronary anatomy. No anatomic landmarks in the heart or chest can be used reliably to identify the position of the coronary arteries in individual patients.

Responses to constant work rate bicycle ergometry exercise in primary pulmonary hypertension: the effect of inhaled nitric oxide.

OBJECTIVES: The purpose of this study was to investigate the responses of patients with primary pulmonary hypertension (PPH) to constant work rate exercise and to examine the effect of nitric oxide (NO) inhalation. BACKGROUND: Maximal exercise tolerance is reduced in PPH, but gas exchange responses to constant work rate exercise have not been defined. We hypothesized that increased pulmonary vascular resistance in PPH would reduce the rate of rise of minute oxygen consumption in response to a given work rate. Because NO may lower pulmonary vascular pressures in PPH, we also postulated that inhaled NO might ameliorate gas exchange abnormalities. METHODS: Nine PPH patients and nine matched normal subjects performed 6-min duration constant work rate cycle ergometry exercise (33.9+/-13.4 W). Patients performed two experiments: breathing air and breathing air with NO (20 ppm). Preexercise right ventricular systolic pressure was assessed by Doppler echocardiography. Normal subjects performed the air experiment only. Gas exchange and heart rate responses were characterized by fitting monoexponential curves. RESULTS: In PPH patients, resting right ventricular systolic pressure fell after NO inhalation (from 83.8+/-16.9 to 73.9+/-21.6 mm Hg, p<0.01, analysis of variance with Tukey correction), but not after breathing air alone (from 88.0+/-20.8 to 86.7+/-20.6 mm Hg, p = NS). Nitric oxide did not affect any of the gas exchange responses. Minute oxygen consumption was similar by the end of exercise in patients and normals, but increased more slowly in patients (mean response time [MRT]: air, 63.17+/-14.99 s; NO, 61.60+/-15.45 s) than normals (MRT, 32.73+/-14.79, p<0.01, analysis of variance, Tukey test). Minute oxygen consumption kinetics during recovery were slower in patients (MRT air: 82.50+/-29.94 s; NO, 73.36+/-15.87 s) than in normals (MRT, 34.59+/-7.11 s, p<0.01). Heart rate kinetics during exercise and recovery were significantly slower in patients than in normals. CONCLUSIONS: The cardiac output response is impaired in PPH. Nitric oxide lowered pulmonary artery pressure at rest, but failed to improve exercise gas exchange responses.

Exercise testing and electron beam computed tomography in the evaluation of coronary artery disease.

OBJECTIVES: This study compared coronary artery calcium (CC) as detected by electron beam computed tomography (EBCT) with conventional stress testing in the evaluation of patients with symptoms suggestive of coronary artery disease (CAD). BACKGROUND: Exercise electrocardiogram treadmill stress testing (treadmill-ECG) is limited by its requirement of a normal resting ECG and the ability of the patient to exercise adequately. The addition of myocardial imaging agents such as technetium improves the sensitivity and specificity but substantially increases the cost and prolongs the testing time. The use of EBCT provides a noninvasive and rapid method for identifying the presence and amount of CC, which has been shown to be related to atherosclerosis, and may provide additional information in combination with more traditional noninvasive testing methods. METHODS: A total of 97 patients underwent technetium stress testing (technetium-stress), treadmill-ECG, and EBCT coronary scanning within three months of coronary angiography for the evaluation of chest pain. RESULTS: The relative risk (RR) of obstructive angiographic CAD for an abnormal test was higher for EBCT (4.53) than either treadmill-ECG (1.72) or technetium-stress (1.96). The low specificity of EBCT (47%) was improved by the addition of treadmill-ECG (83%, p < 0.05). CONCLUSIONS: Electron beam computed tomography has a higher diagnostic ability than either treadmill-ECG or technetium-stress for the detection of obstructive angiographic CAD. Electron beam computed tomography is an accurate and noninvasive alternative to traditional stress testing for the detection of obstructive CAD in symptomatic patients.

Rates of progression of coronary calcium by electron beam tomography.

In this study, we sought to determine the rate of progression of atherosclerosis using coronary calcium scores derived from electron beam tomography (EBT). We studied a variety of disease states (hypertension, high cholesterol, tobacco use, diabetes mellitus) followed for 1 to 6.5 years. We evaluated 299 asymptomatic persons (227 men and 72 women) who underwent 2 consecutive EBT scans at least 12 months apart. The average change in the calcium score (Agatston method) for the entire group was 33.2 +/- 9.2%/year. The treated group (receiving statins) demonstrated an average increase in calcium scores of 15 +/- 8%/year compared with 39 +/- 12%/year for untreated patients (p <0.001). Among the 60 patients on statin monotherapy, 37% had a decrease in the calcium score from baseline to follow-up scan. The relative increase in calcium scores did not vary significantly by gender or risk factors, with the exception of statin-treated hypercholesterolemic subjects. Scores of zero on the initial scan portend a low likelihood of significant calcific deposits on repeat scanning. Only 2 of 81 participants (2%) with scores of zero at baseline had scores >10 on repeat study. In this study, statin therapy induced a 61% reduction in the rate of coronary calcium progression. This study demonstrates that EBT may be a useful tool in assessing efficacy of different interventions to retard progression of atherosclerosis, noninvasively, over relatively short time periods.

Continuous intravenous epoprostenol for pulmonary hypertension due to the scleroderma spectrum of disease. A randomized, controlled trial.

BACKGROUND: Pulmonary hypertension is a progressive and often fatal complication of the scleroderma spectrum of disease for which no treatment has been proven effective in a randomized trial. OBJECTIVE: To determine the effect of epoprostenol on pulmonary hypertension secondary to the scleroderma spectrum of disease. DESIGN: Randomized, open-label, controlled trial. SETTING: 17 pulmonary hypertension referral centers. PATIENTS: 111 patients with moderate to severe pulmonary hypertension. INTERVENTION: Epoprostenol plus conventional therapy or conventional therapy alone. MEASUREMENTS: The primary outcome measure was exercise capacity. Other measures were cardiopulmonary hemodynamics, signs and symptoms of pulmonary hypertension and scleroderma, and survival. RESULTS: Exercise capacity improved with epoprostenol (median distance walked in 6 minutes, 316 m at 12 weeks compared with 270 m at baseline) but decreased with conventional therapy (192 m at 12 weeks compared with 240 m at baseline). The difference between treatment groups in the median distance walked at week 12 was 108 m (95% CI, 55.2 m to 180.0 m) (P < 0.001). Hemodynamics improved at 12 weeks with epoprostenol. The changes in mean pulmonary artery pressure for the epoprostenol and conventional therapy groups were -5.0 and 0.9 mm Hg, respectively (difference, -6.0 mm Hg [CI, -9.0 to -3.0 mm Hg), and the mean changes in pulmonary vascular resistance were -4.6 and 0.9 mm Hg/L per minute, respectively (difference, -5.5 mm Hg/L per minute [CI, -7.3 to -3.7 mm Hg/L per minute). Twenty-one patients treated with epoprostenol and no patients receiving conventional therapy showed improved New York Heart Association functional class. Borg Dyspnea Scores and Dyspnea-Fatigue Ratings improved in the epoprostenol group. Trends toward greater improvement in severity of the Raynaud phenomenon and fewer new digital ulcers were seen in the epoprostenol group. Four patients in the epoprostenol group and five in the conventional therapy group died (P value not significant). Side effects of epoprostenol therapy included jaw pain, nausea, and anorexia. Adverse events related to the epoprostenol delivery system included sepsis, cellulitis, hemorrhage, and pneumothorax (4% incidence for each condition). CONCLUSIONS: Continuous epoprostenol therapy improves exercise capacity and cardiopulmonary hemodynamics in patients with pulmonary hypertension due to the scleroderma spectrum of disease.

A simple single slice method for measurement of left and right ventricular enlargement by electron beam tomography.

RATIONALE AND OBJECTIVE: We devised to test the feasibility of measuring the left and right ventricular sizes by non-contrast electron beam tomographic images. METHODS: Ventricular sizes consist of the sum of the intracavitary cavity and myocardial mass for each ventricle. A total of 50-image studies from subjects undergoing contrast-enhanced studies were used to develop the measurement methodology. About 20 contrast studies were used to test the measure. The methodology was then prospectively tested on 75 patients with non-contrast studies to estimate the intra-observer, inter-observer and inter-study reproducibility. RESULTS: Multiple linear regression analysis was completed and the correct regression formulas to calculate ventricular volumes were acquired by using the area and span from the contrast studies. There was excellent correlation between the estimate of LV (r > 0.97, p < 0.001) and RV (r > 0.93, p < 0.001) sizes between measured and calculated (contrast, single slice) left and right ventricular volumes. The intra-observer, inter-observer and inter-study reproducibility demonstrated excellent results with < 7% difference in absolute values and a high correlation (r > 0.89, p < 0.001). CONCLUSION: We conclude that the left and right ventricular sizes can be accurately estimated from a single mid-ventricular slice on non-contrast electron beam tomographic images.

Accurate measures of left ventricular ejection fraction using electron beam tomography: a comparison with radionuclide angiography, and cine angiography.

BACKGROUND: Quantitative determination of ejection fraction is predicated on precise measurement of end-diastolic and end-systolic volumes of the left ventricle. Contrast enhanced electron beam tomography (EBT), with excellent temporal and spatial resolution, has the potential for highly accurate measures of ejection fraction. METHODS: EBT protocol used a short axis scan of the left ventricle (8-12 levels, apex to base) during infusion of iodinated contrast. To assess the accuracy of the measured left ventricular ejection fraction (LVEF), we compared EBT with first-pass radionuclide angiography (RNA) and cine angiography (CINE). RESULTS: A total of 41 patients (26 men and 15 women) underwent all three tests within 1 week. Resting ejection fraction using each modality was assessed in a linear regression model to assess inter-test correlation with the other two modalities. Correlation between CINE and EBT was high (r = 0.90, intercept 4.67, p < 0.001). Similarly, correlation of CINE and RNA (r = 0.87, intercept -5.48, p < 0.001) and between EBT and RNA (r = 0.87, intercept -4.6, p < 0.001) were high. In a subset of those patients with LVEF < or = 40%, correlation was consistently high between EBT and CINE. However, correlations were poor for the comparisons between RNA and CINE (r = 0.40), and between the RNA and EBT (r = 0.47). The mean differences of measured ejection fractions between each of the imaging modality were small. However, there was only modest agreement between each of the comparisons as measured using 95% confidence interval (CI) on Bland-Altman plots. CONCLUSION: These data indicate that the LVEF results are comparable among EBT, RNA, and CINE and can be used interchangeably to assess ventricular function for LVEF > 40%. For LVEF < or = 40%, we demonstrated some disparate results between cine angiography and RNA and between EBT and RNA, indicating that CINE or EBT may provide more accurate assessment.

Safety of EBCT contrast injection studies in severe pulmonary hypertension.

PURPOSE: There is considerable literature published on noninvasive contrast-enhanced techniques to diagnose pulmonary vascular abnormalities, however little data exists on the safety of contrast injections in patients with elevated pulmonary arterial pressures. We studied the safety of contrast-enhanced electron beam computed tomography (EBCT) in 29 patients with severe pulmonary hypertension. The mean dose of intravenous contrast used was 124 +/- 39 cc. MATERIALS AND METHODS: Subjects underwent EBCT using contrast injected at a rate of 2-4 ml/s. All patients were watched closely for at least 15 min post-procedure prior to being released. Patients had Doppler echocardiograms to estimate pulmonary artery pressure. Right heart catheterization data was collected for patients in which echocardiographic data was unavailable. RESULTS: A total of 29 patients with pulmonary arterial hypertension were studied. There were 17 patients with primary pulmonary hypertension (PPH), and 12 patients with secondary forms of pulmonary hypertension. None of the patients developed complications from their study. CONCLUSION: There is a paucity of data on the safety of contrast injections in patients with severely elevated pulmonary arterial pressures. Contrast-enhanced EBCT was well-tolerated in our diverse series of patients with severely elevated pulmonary arterial pressures. Clinicians concerned about invasive pulmonary angiography should consider contrast-enhanced EBCT as a safe alternative to angiography.

Effect of exercise on left and right ventricular ejection fraction and wall motion.

OBJECTIVE: We evaluated the diagnostic value of response of left and right ventricular ejection fraction and wall motion to exercise using electron beam computed tomography. METHODS AND RESULTS: We attempted to determine the value of exercise electron beam computed tomography for detecting coronary artery disease, including evaluation of the right ventricular ejection fraction and wall motion abnormalities. A study of 35 patients undergoing electron beam tomography exercise cine studies and coronary artery angiography for the evaluation of chest pain was performed. Of the 18 patients with significant coronary disease (> or = 50% luminal diameter stenosis in at least one coronary artery), 17 (94%) had failure to increase global left ventricular ejection fraction with exercise. Fourteen of 18 (78%) developed a wall motion abnormality during peak exercise, and eight (44%) developed a regional right ventricular wall motion abnormality during peak exercise. Of the 17 patients without obstructive disease, 14 (82%) had a increase in ejection fraction > or = 5% and none had an abnormal response in left ventricular wall motion during peak exercise (specificity = 100%). The change in right ventricular ejection fraction with exercise was not a significant predictor of obstructive coronary disease in this study (P=NS). Using different criteria during stress to predict coronary disease, the accuracy was 89% (31/35) using an increase of <5% in ejection fraction, 89% (31/35) using the development of a new or worsened wall motion abnormality, and 91% (32/35) using both left ventricular criteria. CONCLUSION: Our study suggests that exercise electron beam computed tomography appears to be a useful tool for the detection of coronary disease. A increase of <5% in ejection fraction and abnormal left ventricular response to exercise were important predictors, while the exercise induced changes of right ventricular ejection fraction was not a significant predictor of obstructive disease. Both left and right ventricular wall motion abnormalities are useful and important parameters in identifying patients with obstructive disease from those with normal coronary arteries.

Electron beam computed tomography: screening for coronary artery disease.

The need to detect coronary atherosclerosis early in its course has been well recognized by clinicians and epidemiologists for decades. The ability to identify populations with a greater prevalence of coronary disease prior to manifestation of illness would greatly reduce cardiac morbidity and mortality. Electron beam computed tomography (EBCT) uniquely combines the characteristics of speed and excellent density resolution that have led to a rebirth of interest in detecting coronary calcium as a means of screening asymptomatic populations for coronary atherosclerosis. Electron beam computed tomography is noninvasive and widely applicable. It can both detect and quantitate the presence of coronary atherosclerosis. A positive test has diagnostic and prognostic significance, predicting future cardiac events and the extent of atherosclerosis, including the probability of obstructive coronary artery disease (CAD). Multiple studies demonstrate a 6- to 35-fold increased risk of developing a cardiac event with elevated calcium scores. A negative test is highly predictive for excluding obstructive CAD. The cost ranges from $300 to $400, similar to that of an exercise treadmill test. Moreover, scanning for coronary calcium does not require injection of contrast medium, requiring no patient preparation or exercise; therefore, a CT technician can perform the study without supervision. The entire procedure takes < 10 min to perform. These features make EBCT a potential screening test for occult CAD in symptomatic and asymptomatic persons.

Simple single-section method for measurement of left and right atrial volumes with electron-beam CT.

RATIONALE AND OBJECTIVES: The authors estimated left and right atrial volumes by using a simple method of measurement with nonenhanced electron-beam computed tomography (CT). MATERIALS AND METHODS: One hundred sixty-four contrast material-enhanced electron-beam CT studies were divided into two groups. Group 1, which included 104 studies, was used to develop the measurement method (i.e., the formulas) for measuring left and right atrial volumes from a nonenhanced study. Group 2 consisted of 60 studies on which the validity of the method was tested. Measurement of left and right atrial volumes was performed on all section levels by tracing the respective atrial borders for each section, then multiplying the area by section thickness and summing the resultant volumes. RESULTS: Calculated left and right atrial volumes were derived by using the biggest atrial area and cephalic-caudal span. The span was equal to section thickness times the number of sections in which the atria were present. Linear regression analysis formulas were acquired with the biggest atrial area and cephalic-caudal span. Left and right atrial calculated volumes were obtained with these formulas and demonstrated a significant good relation (r > .95, P < .001) and a difference of less than 11% (P < .05) in absolute values between measured and calculated volumes. Intraobserver, interobserver, and interstudy reproducibility were excellent, with less than 10% difference in absolute values. CONCLUSION: Left and right atrial volumes can be accurately estimated from a single midventricular section by using nonenhanced electron-beam CT.

Intravenous three-dimensional coronary angiography using contrast enhanced electron beam computed tomography.

Coronary angiography remains the diagnostic standard for establishing the presence, site, and severity of coronary artery disease (CAD). Electron beam computed tomography (EBCT), with its 3-dimensional capabilities, is an emerging technology with the potential for obtaining essentially noninvasive coronary arteriograms. The purpose of this study was to (1) test the accuracy of intravenous coronary arteriography using the EBCT to conventional coronary arteriographic images; (2) establish the inter-reader variability of this procedure; (3) determine the limitations due to location within the coronary tree; and (4) identify factors that contributed to improved image quality of the 3-dimensional EBCT angiograms. Fifty-two patients underwent both EBCT angiography and coronary angiography within 2 weeks. The coronary angiogram and the EBCT 3-dimensional images were analyzed by 2 observers blinded to the results of the other techniques. EBCT correctly identified 43 of 55 significantly stenosed arteries (sensitivity 78%), and correctly identified 118 of 130 of the nonobstructed arteries, yielding a specificity of 91% (p <0.001, chi-square analysis). The overall accuracy for EBCT angiography was 87%. Significantly more left main and anterior descending coronary arteries were adequately visualized than the circumflex and right coronary vessels (p = 0.003). Overall, 23 of 208 (11%) major epicardial vessels were noninterpretable by the blinded EBCT readers, primarily due to motion artifacts caused by cardiac and respiratory motion and poor electrocardiographic gating. The inter-reader variability was similar to that of angiography, and its high accuracy makes this a clinically useful test. This study demonstrates, by using intravenous contrast enhancement, that EBCT can clearly depict the coronary artery anatomy and can permit identification of coronary artery stenosis.

Electron beam computed tomographic coronary calcium scanning: a review and guidelines for use in asymptomatic persons.

Coronary artery disease is the No. 1 cause of death in the developed world. Effective means of treatment such as drug therapy to lower cholesterol levels are available, but clinical application to patients at highest risk remains imprecise. Electron beam computed tomography (EBCT) has been suggested as a means to diagnose subclinical coronary disease and facilitate risk stratification, but no current interpretive consensus exists in clinical practice. We critically reviewed current, pertinent literature regarding EBCT coronary calcium scanning from a clinical perspective and, in particular, studies that evaluated it as a measure of atherosclerotic coronary disease. Additionally, we reviewed studies that quantified the EBCT "calcium score" in relationship to coronary heart disease events. The available data suggest that the EBCT calcium score can help identify persons at higher than anticipated risk of future coronary events: the greater the EBCT coronary calcium score, the greater the extent of atherosclerotic plaque disease. Based on the literature review, we offer EBCT interpretation guidelines as they relate to drug therapy and risk reduction in asymptomatic persons with borderline cholesterol levels. Considerable evidence shows that coronary calcium is specific for atherosclerotic plaque and that it can be sensitively detected and accurately quantified by using EBCT. The coronary calcium score can help guide initiation of clinical prevention programs as part of a risk stratification and management scheme aimed at improving outcomes in patients determined to be at highest risk of coronary disease for their respective age and gender.

Usefulness of electron beam computed tomography scanning for distinguishing ischemic from nonischemic cardiomyopathy.

OBJECTIVES: This study was undertaken to evaluate the ability of electron beam computed tomography (EBCT) to distinguish ischemic from nonischemic causes of cardiomyopathy by evaluating heart failure patients for coronary calcification (CC). BACKGROUND: The etiology of heart failure, whether coronary-induced or nonischemic, may be difficult to discern clinically. Differentiation of ischemic from nonischemic etiology is clinically important for both therapeutic and prognostic implications. With its ability to noninvasively discern and quantitate coronary artery calcification, EBCT correlates well with angiographic stenosis and thus may be useful in distinguishing ischemic and nonischemic cardiomyopathies. METHODS: One hundred and twenty-five patients with cardiomyopathy (ejection fraction <0.40) and known coronary anatomy underwent EBCT coronary scanning to evaluate for CCs within 3 months of coronary angiography. RESULTS: Of the 72 patients who were found to have ischemic cardiomyopathy, 71 patients had CC by EBCT (sensitivity 99%, p < 0.001), mean score 798+/-899. In comparison, among the 53 patients without significant coronary artery disease (CAD) (nonischemic cardiomyopathy), the mean score was significantly lower (17+/-51; p < 0.0001), and 44 patients had a CC score of 0 (no CC present). The specificity of EBCT to exclude CAD in patients with cardiomyopathy was 83%, using a threshold CC score of 0, and 92% for scores <80 (p < 0.001). Overall accuracy for determining the etiology of cardiomyopathy (differentiating ischemic from nonischemic) was 92% for this technique. CONCLUSIONS: This prospective, blinded study indicates that EBCT detected CC accurately and can noninvasively distinguish between cardiomyopathy because of CAD and nonischemic causes of left ventricular dysfunction.

Comparison of exercise electron beam computed tomography and sestamibi in the evaluation of coronary artery disease.

This blinded, single center study prospectively compares exercise electron beam computed tomography (EBCT) with stress technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) in 33 patients undergoing coronary angiography for evaluation of chest pain. Patients undergoing routine cardiac catheterization for the diagnosis of chest pain were imaged at rest using EBCT. Patients exercised on a semi-supine ergometer, and exercise EBCT was immediately followed by injection of Tc-99m sestamibi for assessment of myocardial ischemia. At peak exercise, Tc-99m SPECT, followed immediately by nonionic contrast material, was injected intravenously to directly compare these 2 imaging techniques. Patients were reimaged with Tc-99m SPECT at rest 24 to 48 hours after stress. Exercise EBCT, which was analyzed using a global ejection fraction measure, had a sensitivity of 81% and a specificity of 76%, compared with angiography. Using the development of a new regional wall motion abnormality as evidence of obstructive coronary artery disease (CAD), EBCT yielded a specificity of 100% and a sensitivity of 88%. Reversible perfusion defects identified by SPECT, as evidence of obstructive CAD, revealed a sensitivity of 75% and a specificity of 71%. The specificity of regional wall motion analysis by EBCT was significantly better than SPECT (p <0.01) in this population. This study demonstrates regional wall motion assessed by EBCT to be as sensitive and more specific than SPECT myocardial perfusion imaging in identifying obstructive CAD as defined by angiography.