Larger perfusion defects with exercise compared with dipyridamole SPECT (exercise-dipyridamole mismatch) may reflect differences in epicardial and microvascular coronary dysfunction: When the stressor matters

Background Previous studies have reported larger myocardial perfusion defects with exercise as compared with dipyridamole. The aim of this study was to assess the hypothesis that this mismatch may reflect differences in epicardial and microvascular coronary vasomotor function. Methods and Results The response to intracoronary acetylcholine, nitroglycerin, and adenosine was studied in 36 patients with suspected angina and normal or near-normal coronary angiography findings who underwent both exercise and dipyridamole perfusion imaging. Of the patients, 27 (75%) had reversible defects with exercise (group I) and 9 had normal scans or nonreversible defects (group II). Repeated imaging with dipyridamole showed significant improvement or disappearance of perfusion defects in group I patients. The mean summed difference score (SDS) decreased from 5.52±3.19 with exercise to 1.11±1.60 with dipyridamole (P=.0001) in group I and did not change in group II. An abnormal epicardial response to acetylcholine, reflecting endothelial dysfunction, occurred in 93% of group I patients compared with only 33% of group II patients (χ², P=.002) and was significantly related to exercise SDS (r=0.49, P=.002) but not to dipyridamole SDS. By contrast, most patients showed normal epicardial and microvascular responses to the mainly non-endothelium-dependent vasodilators nitroglycerin and adenosine with no differences in coronary flow reserve between groups (2.91±0.72 vs 2.98±0.52, P=.79). Conclusions Exercise-dipyridamole perfusion mismatch may reflect differences in epicardial endothelial and microvascular dysfunction.     

Detection and reproducibility of mental stress—induced myocardial ischemia with Tc-99m sestamibi SPECT in normal and coronary artery disease populations

BACKGROUND: Mental stress-induced ischemia, as detected by radionuclide studies, has yielded reversible ischemia in only 30% to 60% of patients with exercise-induced ischemia. Little is known about the reproducibility of myocardial perfusion imaging in detecting mental stress-induced ischemia. The purpose of this study was to further evaluate the occurrence and reproducibility of mental stress-induced ischemia in patients with coronary artery disease (CAD) and in normal control subjects with a low likelihood of CAD by using sestamibi single photon emission computed tomography (SPECT) imaging. METHODS AND RESULTS: A total of 40 patients were enrolled in this study: 19 patients with CAD and typical angina or reversible ischemia (positive exercise treadmill study or positive adenosine thallium study) and 21 normal control subjects underwent mental stress testing as well as myocardial perfusion imaging. The subjects were given a speaking task, and SPECT imaging was subsequently performed. Two experienced readers compared mental stress imaging with a resting image using a 20-segment cardiac model. Hemodynamic changes in blood pressure and heart rate with mental stress were also measured in all subjects. Each patient with CAD also underwent repeat mental stress testing and myocardial imaging approximately 2 weeks later. Of the 19 patients with CAD and typical angina or with evidence of reversible ischemia, 16 (84%) demonstrated ischemia with mental stress, as detected by sestamibi SPECT imaging. The mean number of new or worsened perfusion defects attributable to mental stress was 3.5, with a mean severity of 1.7. These results were also reproducible. With repeated mental stress testing and myocardial imaging, 12 of the 16 CAD patients (75%) demonstrated evidence of myocardial ischemia. None of the 21 normal control subjects had evidence of mental stress-induced myocardial ischemia. Mental stress also induced reproducible and significant hemodynamic changes in CAD patients. CONCLUSIONS: In patients with known CAD with typical angina or with evidence of reversible ischemia despite taking medications, mental stress was very effective in inducing myocardial ischemia, as detected by sestamibi SPECT imaging. Mental stress was also found to elicit significant hemodynamic responses. Furthermore, these findings demonstrated good reproducibility.     

Accuracy of exercise testing in the assessment of the severity of myocardial ischemia as determined by means of technetium-99m tetrofosmin SPECT scintigraphy

BACKGROUND: The separation of patients with suspected or known coronary artery disease into low- and high-risk subgroups by means of noninvasive testing is highly relevant in the selection of patients who require further diagnostic or therapeutic investigation. We evaluated whether exercise electrocardiographic variables during exercise testing might be a means of predicting the severity of myocardial ischemia as assessed with myocardial scintigraphy. METHODS AND RESULTS: We retrospectively reviewed 816 consecutive patients (mean age, 57+/-10 years) who underwent exercise technetium-99m tetrofosmin single photon emission computed tomography (SPECT) for the assessment of suspected or known coronary artery disease. Eight independent significant predictors of the extent and severity of reversible perfusion defects (ischemic perfusion score), which when integrated in a diagnostic algorithm satisfactorily discriminated patients with no reversible perfusion defects (sensitivity, 75%; specificity, 80%) and patients with severe impaired myocardial perfusion (> or =11 ischemic perfusion score; sensitivity, 77%; specificity, 82%), were identified by means of stepwise discriminant analysis. However, patients with mildly to moderately impaired myocardial perfusion (> or =21 but <11 ischemic perfusion score) were poorly discriminated (sensitivity, 50%; specificity, 78%). The set of variables that were significant (P<.0001) for prediction included sex, myocardial infarction, exercise angina, the maximal amount of ST segment depression, rate-pressure product threshold criteria, slope of ST segment depression, ST/heart rate index, and peak exercise heart rate. CONCLUSIONS: The results of the use of clinical and electrocardiographic exercise variables satisfactorily agrees with the results from scintigraphy only for patients with no reversible perfusion defects and with severely impaired myocardial perfusion. However, it fails as an approach with universal applicability.     

QRS score versus ST-segment changes in patients undergoing Tl-201 scintigraphy using dipyridamole infusion

BACKGROUND: ST-segment changes after dipyridamole infusion followed by handgrip isometric stress lack diagnostic value, because of the low sensitivity for the detection of coronary artery disease (CAD). In addition, an abnormal QRS score during exercise had a greater diagnostic ability than ST-segment changes to detect CAD. This study was undertaken to compare QRS score values with ST-segment changes during thallium 201 scintigraphy via dipyridamole infusion. METHODS AND RESULTS: In this study 128 patients (101 men and 27 women), aged 53 to 72 years (mean, 59 +/- 8 years), underwent Tl-201 scintigraphy after dipyridamole infusion and handgrip isometric stress, as well as coronary angiography. QRS score values and ST-segment changes after dipyridamole infusion and handgrip isometric stress were also estimated. CAD was detected in 96 patients (75%), whereas normal coronary arteries were found in 32 (25%). According to scintigraphic data, 48 patients (37%) had no reversible perfusion defects whereas 80 (63%) had at least 1 reversible perfusion defect. Sensitivities for an abnormal QRS score and ST-segment deviation were 68% versus 18% ( P < .01) for detection of CAD and 75% versus 19% for detection of myocardial ischemia ( P < .01), respectively. Similar specificities were found ( P = not significant). CONCLUSIONS: An abnormal QRS score significantly improves the low sensitivity of ST-segment changes for the detection of myocardial ischemia and CAD by use of Tl-201 scintigraphy with dipyridamole infusion and handgrip isometric stress.     

Simultaneous assessment of myocardial perfusion and function during mental stress in patients with chronic coronary artery disease

BACKGROUND: Mental stress (MS) is an important provocateur of myocardial ischemia in many patients with chronic coronary artery disease. The majority of laboratory assessments of ischemia in response to MS have included measurements of either myocardial perfusion or function alone. We performed this study to determine the relationship between alterations in perfusion and ventricular function during MS.Methods and results Twenty-eight patients with reversible perfusion defects on exercise or pharmacologic stress myocardial perfusion imaging (MPI) underwent simultaneous technetium 99m sestamibi single photon emission computed tomography (SPECT) MPI and transthoracic echocardiography at rest and during MS according to a mental arithmetic protocol. In all cases the MS study was performed within 4 weeks of the initial exercise or pharmacologic MPI that demonstrated ischemia. SPECT studies were analyzed visually with the use of a 13-segment model and quantitatively by semiautomated circumferential profile analysis. Echocardiograms were graded on a segmental model for regional wall motion on a 4-point scale. Of 28 patients, 18 (64%) had perfusion defects and/or left ventricular dysfunction develop during MS: 9 (32%) had myocardial perfusion defects develop, 6 (21%) had regional or global left ventricular dysfunction develop, and 3 (11%) had both perfusion defects and left ventricular dysfunction develop. The overall concordance between perfusion and function criteria for ischemia during MS was only 46%. Among 9 patients with MS-induced left ventricular dysfunction, 5 had new regional wall motion abnormalities and 4 had a global decrement in function. In patients with MS-induced ischemia by SPECT, the number of reversible perfusion defects was similar during both MS and exercise/pharmacologic stress (2.8 +/- 2.0 vs 3.5 +/- 1.8, P =.41). Hemodynamic changes during MS were similar whether patients were divided on the basis of perfusion defects or left ventricular dysfunction during MS. CONCLUSIONS: These data indicate the feasibility of simultaneous assessment of perfusion and function responses during MS. Flow and function responses to MS are frequently not concordant. These data suggest that MS-induced changes in perfusion may represent a different phenomenon than MS-induced changes in left ventricular function (either globally or regionally).     

Postischemic stunning after adenosine vasodilator stress

BACKGROUND: Ischemic left ventricular (LV) dysfunction may occur after exercise but is regarded as uncommon after vasodilator stress. We evaluated the prevalence of LV dysfunction after adenosine stress in relation to reversible perfusion defects and angiographic coronary artery disease (CAD). METHODS AND RESULTS: We studied 86 patients referred for clinically indicated adenosine dual-isotope gated single photon emission computed tomography: 43 with 1 or more reversible perfusion defects (reversible defect group) and 43 age- and sex-matched patients with no known CAD and normal LV perfusion and function (control group). Coronary angiography was performed in 36 of 43 patients (84%) in the reversible defect group. Perfusion was interpreted based on 20-segment/5-point summed rest and stress scores. The extent of reversibility was defined by the summed difference score. LV ejection fraction and volumes at rest and 60 minutes after adenosine and segmental wall thickening were quantified by QGS (Cedars-Sinai Medical Center, Los Angeles, Calif). In patients with extensive reversible perfusion defects (summed difference score > or =8), 8 of 25 (32%) demonstrated depressed post-adenosine LV ejection fraction, abnormal segmental wall thickening, end-systolic dilation, and extensive CAD. CONCLUSION: Adenosine is believed to be less likely than exercise to induce ischemia. However, myocardial stunning occurred in one third of the patients with severe reversible defects, consistent with ischemia.     

腺苷与运动负荷心肌灌注显像诊断不典型胸痛心肌缺血的临床价值

目的评价腺苷和运动负荷心肌灌注显像诊断不典型胸痛患者心肌缺血的价值。方法不典型胸痛患者67例行腺苷负荷心肌灌注显像，81例行运动负荷心肌灌注显像，结果分别与冠状动脉（简称冠脉）造影比较，得到显像诊断冠心病心肌缺血的灵敏度、特异性和准确性。结果腺苷负荷心肌灌注显像组67例中，23例冠脉造影有狭窄病变，腺苷负荷心肌灌注显像检出可逆性灌注异常即诊断心肌缺血16例，44例冠脉造影阴性者中，腺苷心肌灌注显像正常41例。腺苷负荷心肌灌注显像诊断冠心病心肌缺血的灵敏度为70％，特异性93％，准确性85％。运动负荷心肌灌注显像组81例中，31例冠脉造影阳性，运动负荷心肌灌注显像检出心肌缺血22例，50例冠脉造影阴性者中，运动负荷心肌灌注显像正常48例。运动负荷心肌灌注显像诊断冠心病心肌缺血的灵敏度为71％，特异性96％，准确性86％。结论腺苷或运动负荷心肌灌注显像出现可逆性灌注异常对诊断不典型胸痛患者冠心病心肌缺血有重要意义。     

Myocardial perfusion SPECT imaging in patients with myocardial bridging

BACKGROUND: Although myocardial perfusion single photon emission computed tomography (SPECT) imaging is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, only a few patients with myocardial bridging have been evaluated with nuclear techniques. Furthermore, it has been suggested that dipyridamole stress images might underestimate perfusion defects compared with exercise stress images. This study was done to determine the concordance of exercise stress SPECT images with that obtained by dipyridamole stress SPECT images as a means of detecting ischemia in patients with myocardial bridging. METHODS AND RESULTS: Sixteen consecutive patients with angina and normal arteries but myocardial bridging of the left anterior descending artery underwent rest-exercise stress SPECT imaging. Within 2 weeks after angiograms were obtained, only dipyridamole stress images were repeated. The mean angiographic systolic occlusion within the myocardial bridges was 73% +/- 10%. Overall, the prevalence of an abnormal scan was no different in patients who underwent exercise stress myocardial perfusion imaging (MPI) as compared with patients who underwent dipyridamole stress MPI (14/16 [88%] vs 13/16 [81%], respectively; P = .953). Exercise stress MPI showed a higher stress score than dipyridamole stress MPI, but the difference did not reach statistical significance (7.5 +/- 3.3 vs 6 +/- 2.7, P = .147). The strength of agreement among exercise stress MPI and dipyridamole stress MPI studies was good (kappa = 0.765; 95% CI, 0.318 to 1.211; P < .05). CONCLUSIONS: Cardiac SPECT studies can be used effectively for assessing ischemia in patients with angina and myocardial bridging. The evaluation of myocardial perfusion with dipyridamole stress SPECT imaging showed a good agreement with exercise stress SPECT imaging for the detection of ischemia in this group of patients.     

Dipyridamole combined with symptom-limited exercise for myocardial perfusion scintigraphy: image characteristics and clinical role

Although dipyridamole can be used with myocardial scintigraphy to demonstrate reversible perfusion defects, combining exercise with the pharmacologic tool could improve image quality and information yield. The incidence of perfusion defects and the quality of thallium 201 images were reviewed in a series of 820 patients who had been assigned to a specific stress-test mode. Supine bicycle exercise alone was used (group I) where no pharmacologic or physical factors (e.g., beta-blockers, arthritis) limited performance; otherwise, intravenous dipyridamole was followed by symptom-limited exercise (group II). Angiographic correlation was available in 57 patients in group I, and in 158 in group II; of these, 109 performed significant exercise (greater than or equal to 3 min at increasing workloads) following dipyridamole (group IIA), whereas in 49 (group IIB) the exercise phase following dipyridamole was truncated. All test-mode groups were similar with respect to the incidence of ST segment depression during testing, patient throughput, and the sensitivity of perfusion defects. Chest pain and reversible defects were induced more frequently in group II than in group I. In group IIA, splanchnic background activity was lower (P less than 0.001) than in group IIB, and the false-positive rate tended to be lower. Thus, combining exercise with dipyridamole in patients with non-cardiac limitations to exercise enabled the achievement of optimal results for perfusion scintigraphy.     

Dipyridamole combined with symptom-limited exercise for myocardial perfusion scintigraphy: image characteristics and clinical role

Although dipyridamole can be used with myocardial scintigraphy to demonstrate reversible perfusion defects, combining exercise with the pharmacologic tool could improve image quality and information yield. The incidence of perfusion defects and the quality of thallium 201 images were reviewed in a series of 820 patients who had been assigned to a specific stress-test mode. Supine bicycle exercise alone was used (group 1) where no pharmacologic or physical factors (e.g., beta-blockers, arthritis) limited performance; otherwise, intravenous dipyridamole was followed by symptom-limited exercise (group II). Angiographic correlation was available in 57 patients in group I, and in 158 in group II; of these, 109 performed significant exercise ( 3 min at increasing workloads) following dipyridamole (group II A), whereas in 49 (group IIB) the exercise phase following dipyridamole was truncated. All test-mode groups were similar with respect to the incidence of ST segment depression during testing, patient throughput, and the sensitivity of perfusion defects. Chest pain and reversible defects were induced more frequently in group II than in group I. In group II A, splanchnic background activity was lower (P < 0.001) than in group II B, and the false-positive rate tended to be lower. Thus, combining exercise with dipyridamole in patients with non-cardiac limitations to exercise enabled the achievement of optimal results for perfusion scintigraphy.     

Evaluation of post-stress left ventricular dysfunction and its relationship with perfusion abnormalities using gated SPECT in patients with cardiac syndrome X

OBJECTIVE: Cardiac syndrome X defines patients with typical angina, a positive exercise ECG stress test and angiographically documented normal coronary arteries. In previous studies, post-stress prolonged left ventricular dysfunction (PLVD) using gated SPECT (G-SPECT) had been well correlated with myocardial perfusion abnormalities and degree of stenotic vessels in CAG in patients with coronary artery disease. However, evaluation of left ventricular myocardial perfusion, wall motion and left ventricular ejection fraction (LVEF) in patients with cardiac syndrome X, using G-SPECT had not been studied yet. Thus, the aim of this study was to analyse PLVD using (99m)Tc-MIBI GSPECT in patients with cardiac syndrome X. METHODS: Of the patients in whom G-SPECT was performed in our institution between 2004 and 2006, 17 patients with anginal chest pain, positive exercise ECG stress test and normal coronary angiograms were retrospectively included to the study (group I). Fifteen patients with normal myocardial perfusion and another 15 patients with ischaemia on G-SPECT were selected as control groups (groups II and III). (99m)Tc-MIBI G-SPECT was performed for all patients according to 2 day (stress-rest) protocol. Stress and rest LVEF were derived automatically (SLVEF and RLVEF). Difference LVEF (DLVEF) (stress-rest) was calculated. Semiquantitative analyses were made both for myocardial perfusion and wall motion (WM), using a 20-segment model and a 5-point scoring system. DLVEF, perfusion and WM scores of all groups were compared among three groups and relationship between DLVEF, perfusion and WM scores were evaluated. RESULTS: Abnormal perfusion were detected in eight (47.1%) of patients, while the remaining nine (52.9%) had normal myocardial perfusion, in group I. Six of 17 (35.3%) patients in group I had post-stress WM abnormalities. Mean of DLVEF values were -3.1+/-3.0%, 4.4+/-2.0% and -6.0+/-5.1% in groups I, II and III, respectively (P<0.05 for group II vs. group I and group III; P>0.05 for group I vs. group III). LVEF response impairment (< or =5% increase from rest to post-stress images) was found in 17 (100%), seven (46.6%), 14 (93.3%) of patients in groups I, II and III, respectively. CONCLUSION: Abnormal myocardial perfusion, concordant transient segmental WM abnormalities and LVEF response impairment are not uncommon in patients with cardiac syndrome X of this cohort of the study population. Therefore, post-stress prolonged stunning may be attributed to these findings in some of cardiac syndrome X patients as in true ischaemic patients. However, further studies with larger number of subjects and long-term follow-up are necessary to support these findings.     

Clinical significance of myocardial perfusion abnormalities in patients with varying degree of coronary artery stenosis

OBJECTIVES: (1) To identify myocardial perfusion abnormalities in a cohort of patients having coronary artery disease (CAD) risk factors, with either suspected or clinical evidence of ischaemic heart disease (IHD), and with varying degree of coronary artery stenosis. (2) To evaluate the clinical significance of the extent and severity of perfusion abnormalities assessed by myocardial perfusion scintigraphy (MPS) in relation to the anatomical location of coronary stenosis demonstrated by five-vessel selective coronary angiography (SCA). METHODS: One hundred and thirty-eight patients (106 male, 32 female) with suspected or clinical evidence of IHD underwent diagnostic evaluation at the Central Hospital of Nicosia, between November 2002 and August 2003. The diagnostic work-up included clinical examination, exercise tolerance test, SCA and myocardial perfusion scintigraphy (MPS) using either Tl chloride or Tc-tetrofosmin. RESULTS: Based on the results of SCA, patients were divided into five groups on the basis of stenosis as cross-sectional area of coronary artery lumen and its haemodynamic significance, ranging from group 1=less than 50% coronary stenosis to group 5=100% stenosis (occlusion). Nine of 11 (40.9%) patients with angiographically normal coronary arteries (group 1) had moderate inducible reversible ischaemia on MPS and 9/47 (19.1%) patients with insignificant coronary stenosis (less than 75% stenosis=group 2) had fixed perfusion defects, compatible with previous myocardial infarction. The extent of perfusion abnormalities in post-stress MPS patients from group 2 was not found to be statistically significant (P>0.05) when compared to patients belonging to groups 3, 4 and 5. However, the extent of perfusion abnormalities between patients from group 2, when compared to groups 3, 4 and 5 demonstrated significant statistical difference (P<0.05) on post-rest MPS studies. Furthermore, there was no significant statistical correlation between anatomical location of coronary stenosis and severity of perfusion abnormalities in the corresponding myocardial segments. CONCLUSION: Patients with CAD risk factors, and coronary arteries with insignificant stenosis on angiography, may demonstrate inducible reversible myocardial ischaemia. This is suggestive of coronary endothelial dysfunction. Patients with insignificant coronary artery stenosis and no previous history of adverse coronary events may demonstrate features of previous myocardial infarction on MPS. The severity of perfusion defects demonstrated by MPS may be independent of the anatomical location of coronary artery stenosis.     

Clinical significance of diastolic function as an indicator of myocardial ischemia assessed by 16-frame gated myocardial perfusion SPECT

Objective  Studies have suggested that ischemia-induced diastolic dysfunction persists longer than systolic dysfunction. We examined whether global left ventricular (LV) diastolic function during stress testing assessed by 16-frame gated myocardial perfusion single-photon emission computed tomography (SPECT) is useful as an indicator of myocardial ischemia. Methods  Thirty-nine patients underwent 16-frame technetium-99m (Tc-99m) quantitative gated SPECT (QGS), including treadmill exercise testing for suspected ischemic heart disease. Diastolic parameters of the first-third filling fraction (1/3FF), and the peak filling rate (PFR) were calculated by a time-volume curve from the QGS data. Results  The patients were divided into four groups, namely, IS, NL, DN, and DD, on the basis of tracer accumulation and the LV ejection fraction (LVEF) at rest. In the IS group (reversible tracer uptake reduction suggesting ischemia; n = 11), LVEF, 1/3FF, and PFR after stress were significantly lower than those at rest, whereas in the NL group (normal perfusion; n = 10) and DN group (fixed tracer uptake reduction with normal systolic function; EF ≥ 60% at rest; n = 10), LVEF, 1/3FF, and PFR after stress did not differ from those at rest. However, in the DD group (fixed tracer uptake reduction with cardiac dysfunction; EF < 60%, average 47.1%; n = 8), LVEF, 1/3FF, and PFR were significantly altered after stress. Conclusions  Altered global LV diastolic function during stress assessed by 16-frame gated myocardial perfusion SPECT is useful for the detection of myocardial ischemia. However, similar findings are observed in patients with cardiac dysfunction but without detectable ischemia. Our findings do suggest that tests should be performed with caution to determine whether ischemia exists on the basis of altered global LV function after stress in patients with cardiac dysfunction.     

The prevalence and the clinical characteristics of silent myocardial ischemia detected by stress thallium scintigraphy]

The prevalence of silent myocardial ischemia was retrospectively assessed in a group of 100 consecutive patients with angiographically proved coronary artery disease, and diagnostic ECG, by symptom-limited exercise thallium-201 scintigraphy. Twenty-four patients had no evidence of ischemia despite adequate exercise level. So among 76 patients with exercise induced ischemia, only 33 patients (43%) stopped exercise due to anginal pain (symptomatic ischemia: Group 3). And 43 patients with asymptomatic ischemia composed of 23 patients (30%) with ECG change (Group 2B) and 20 patients (26%) without ECG change (Group 2A). Patients background including the history of old myocardial infarction and diabetes mellitus, were similar among Group 2A, 2B, and Group 3. And our major observation was that the extent and severity of quantified SPECT perfusion defects was nearly identical between 3 groups Thus in this study group, there was a rather high prevalence rate of silent ischemia (57%) by exercise thallium-201 criteria. Patients with silent ischemia, associated with positive and negative exercise ECG findings, and those with exercise angina had similar background and comparable amount of jeopardized myocardium.     

Use of coronary calcium scanning for predicting inducible myocardial ischemia: Influence of patients’ clinical presentation

Background  The selection of patients for cardiac stress tests is generally based on assessment of chest pain symptoms, age, gender, and risk factors, but recent data suggest that coronary artery calcium (CAC) measurements can also be used to predict inducible myocardial ischemia. However, the potential influence of clinical factors on the relationship between CAC measurements and inducible ischemia has not yet been investigated. Methods and Results  We prospectively performed CAC scanning in 648 patients undergoing exercise myocardial perfusion single photon emission computed tomography. The frequency of ischemia on myocardial perfusion single photon emission computed tomography was assessed according to CAC magnitude after dividing patients according to chest pain symptom class and Bayesian likelihood of angiographically significant coronary artery disease (ASCAD), Estimates of ASCAD likelihood and CAC scores were poorly correlated. The frequency of inducible myocardial ischemia was very low among patients with a low ASCAD likelihood if CAC scores were less than 400. By contrast, the threshold for increasing ischemia occurred at low CAC scores among patients with a high ASCAD likelihood. When characterized by chest pain classification, asymptomatic and nonanginal chest pain patients had a low frequency of ischemia if CAC scores were less than 400, whereas lower CAC scores did not exclude ischemia among typical angina or atypical angina patients. Conclusions  CAC scores predict myocardial ischemia, with a threshold score of greater than 400 among patients with a low likelihood of ASCAD and those who are asymptomatic or have nonanginal chest pain. These data appear to extend the pool of patients for whom CAC scanning may be useful in ascertaining the need for cardiac stress testing. This study was supported by a grant from the Eisner Foundation, Los Angeles. Calif.     

Exercise thallium scintigraphy in aortitis syndrome (Takayasu's arteritis)

It is important for patient management to evaluate coronary arterial involvement in aortitis syndrome. Twenty one cases of aortitis syndrome who experienced chest pain were examined using exercise thallium scintigraphy. The patients were divided into four groups according to the angiographic findings. There were: five patients with left main coronary arterial involvement (group A), four with left or right coronary arterial involvement (group B), nine with aortic regurgitation (group C), and three with pulmonary arterial involvement (group D). In group A and B, all patients had positive ECGs and thallium perfusion defects. Group A patients showed extensive anterolateral perfusion defects, which were compatible with left main coronary arterial involvement. Group C and D patients, who had normal coronary arteries, showed no remarkable perfusion defects although five had positive ECG findings. Thus, the sensitivity and specificity of exercise scintigraphy for detection of myocardial ischemia were 9/9 and 12/12, while those of stress ECG were 9/9 and 7/12 (58%), respectively. It is recommended that exercise thallium scintigraphy be used for detecting clinically occult but significant coronary arterial involvement in aortitis syndrome with chest pain.     

Evaluation of ischemia by exercise stress Tl-201 myocardial SPECT in silent and symptomatic ischemia

Forty patients with ischemic heart disease confirmed by coronary arteriography were performed Tl-201 stress myocardial scintigraphy using SPECT. Fifteen patients had anginal attack during exercise Tl-201 myocardial perfusion study (symptomatic group), and 25 patients had horizontal or downsloping ST segment depression more than 0.1 mV without angina (asymptomatic group). The washout maps were derived from circumferential profile analyses of tomographic short-axis slices, and the data were plotted as a bull's eye map. The patient's washout map was compared with the lower limit of normal (mean--2 SD), and the extent and severity scores were calculated. On visual analysis 87% (13/15) of symptomatic patients showed redistribution, while only 56% (14/25) of asymptomatic patients showed redistribution (p less than 0.05). The extent score was significantly higher in the symptomatic group than in asymptomatic group (37.2 + 23.6 vs. 19.6 + 20.8, p less than 0.05), but severity score was slightly higher in symptomatic group (56.1 + 59.4 vs. 30.0 + 54.8, NS). In conclusion, symptomatic ischemia may be more severe than asymptomatic one and the degree of ischemia may be one of the factors that determine the presence of angina during ischemia.     

核素运动负荷心肌灌注显像诊断冠心病

目的：探讨三种非侵入性冠心病诊断方法的利弊。材料和方法：对５７例冠心病患者进行运动负荷心肌断层显像（ＥＣＴ），同时与动态心电图（ＤＣＧ）、心电图运动试验（ＴＥＴ）进行对比。结果：运动负荷显像示５２例（９１．２％）呈一个或二个以上部位的心肌缺血改变；ＤＣＧ示４１例（７１．９％）心肌缺血，其中２８例伴有心律失常（４９．１％）；ＴＥＴ示３１例（５４．４％）心肌缺血。三种方法比较，对心肌缺血的检出以核素运动负荷心肌断层显像最高。结论：在病人难以接受冠脉造影时，ＥＣＴ结合ＴＥＴ或ＤＣＧ试验将提高诊断冠心病的可靠性。     

Exercise thallium scintigraphy in aortitis syndrome (Takayasu's arteritis)

It is important for patient management to evaluate coronary arterial involvement in aortitis syndrome. Twenty one cases of aortitis syndrome who experienced chest pain were examined using exercise thallium scintigraphy. The patients were divided into four groups according to the angiographic findings. There were: five patients with left main coronary arterial involvement (group A), four with left or right coronary arterial involvement (group B), nine with aortic regurgitation (group C), and three with pulmonary arterial involvement (group D). In group A and B, all patients had positive ECGs and thallium perfusion defects. Group A patients showed extensive anterolateral perfusion defects, which were compatible with left main coronary arterial involvement. Group C and D patients, who had normal coronary arteries, showed no remarkable perfusion defects although five had positive ECG findings. Thus, the sensitivity and specificity of exercise scintigraphy fox detection of myocardial ischemia were ₉ ⁹ and ₁₂ ¹² . while those of stress ECG were ₉ ⁹ and ₇ ¹² (58%). respectively. It is recommended that exercise thallium scintigraphy be used for detecting clinically occult but significant coronary arterial involvement in aortitis syndrome with chest pain.     

Overestimation of postischemic myocardial stunning on gated SPECT imaging: Correlation with echocardiography

Background  Postischemic global and regional left ventricular (LV) dysfunction on stressgated single photon emission computed tomography (SPECT) imaging is attributed widely to myocardial stunning. We sought to determine the specificity of gated SPECT for the detection of myocardial stunning after ischemic stress. Methods and Results  Twenty-seven patients with an ischemic response to stress on dual-isotope exercise SPECT were enrolled prospectively. Transthoracic echocardiography was performed just before stress gated SPECT for assessment of regional wall motion and quantitative LV ejection fraction (LVEF). The 17 myocardial segments for each patient were scored for myocardial perfusion by stress gated SPECT, and regional wall motion by stress gated SPECT and echo. Of the 459 myocardial segments, 41% had perfusion defects, 15% had stress gated SPECT regional wall motion abnormality, 4.8% had poststress echo regional wall motion abnormality, and 3.9% had baseline regional wall motion abnormality. Overall, a stress gated SPECT regional wall motion abnormality had a sensitivity of 100% and a specificity of 89%. Among reversible perfusion defects of moderate severity or more, a stress gated SPECT regional wall motion abnormality had a specificity of 41% and a positive predictive value of 8%. Stress gated SPECT LVEF was similar to poststress echo LVEF for all patients, but significantly lower in patients with reversible perfusion defects of moderate severity or more. Conclusion  Post-stress gated SPECT imaging overestimates global and regional myocardial stunning. Caution should be exercised in interpreting poststress global or regional LV function on stress gated SPECT in scans with reversible ischemia.