Influence of coronary artery disease on pulmonary uptake of thallium-201

An increased pulmonary thallium-201 concentration has been observed in exercise stress thallium perfusion imaging in patients with coronary artery disease. To understand the cause of this lung uptake, studies were performed in experimental animals and in patients undergoing stress thallium perfusion imaging. The extraction fraction of thallium-201 by the lungs was measured in a group of eight dogs using a dual isotope technique. Basal thallium-201 extraction fraction at rest was 0.09 ± 0.009. After administration of isoproterenol, it decreased to 0.06 ± 0.02 (difference not significant). After balloon obstruction of the left atrium (which increased mean left atrial pressure and pulmonary transit time) and after administration of acetylcholine as a bolus injection (which prolonged pulmonary transit time only) it increased to 0.19 ± 0.02 (p <0.01).Lung thallium-201 activity was measured in 86 patients who had undergone cardiac catheterization and stress-redistribution myocardial perfusion imaging. The initial/final lung activity ratio was 1.41 ± 0.03 in patients with no significant coronary artery disease, 1.52 ± 0.03 (difference not significant) in patients with single vessel coronary disease, 1.60 ± 0.05 (p <0.05) in those with two vessel disease and 1.59 ± 0.05 (p <0.05) in those with triple vessel disease. Quantitation of lung activity in 30 of these patients indicated that the increased ratio in patients with multivessel coronary artery disease was due to a transient absolute increase in the thallium-201 concentration immediately after maximal exercise. The data imply that increased pulmonary concentration of thallium-201 during exercise is a consequence of left ventricular failure.     

Can myocardial ischemia be recognized by the exercise electrocardiogram in coronary disease patients with abnormal resting Q waves?

This study was performed in order to determine whether exercise-induced myocardial ischemia demonstrated by thallium-201 imaging could be detected by ST segment shifts in patients with abnormal Q waves at rest. Fifty-four patients with coronary artery disease and exercise-induced thallium-201 defects were compared to 22 patients with similar Q wave patterns but without thallium-201 exercise defects and to 14 normal subjects. Exercise data were analyzed visually in the 12-lead ECG and for spatial ST vector shifts. Both ST segment depression observed on the 12-lead ECG and spatial criteria were reasonably sensitive and specific for ischemia when the resting ECG showed no Q waves or inferior Q waves (range 69% to 93%). However, when anterior Q waves were present, ST segment shifts could not distinguish patients with ischemia from those with normal perfusion as determined by thallium imaging.     

Dipyridamole thallium-201 myocardial scintigraphy in coronary diagnosis; a comparison of methods with thallium-201 myocardial scintigraphy after ergometer stress

Two scintigraphic methods, resting dipyridamole and exercise thallium-201 myocardial perfusion imaging, to detect and localize coronary artery stenosis were compared in 32 patients suffering from coronary artery disease. The sensitivity of detecting a greater than 50% coronary stenosis was 94% for exercise thallium-201 perfusion imaging and 88% for dipyridamole thallium-201 perfusion imaging. The overall sensitivity and specificity of localizing a greater than 50% coronary stenosis by the two methods were also not significantly different. The results of the two scintigraphic methods were independent of the severity of coronary artery disease. Dipyridamole thallium-201 myocardial perfusion imaging provides a useful and safe alternative test for detecting and localizing coronary artery stenosis in patients unable to perform maximal exercise.     

The Value of Exercise Electrocardiography and Exercise Thallium-201 Myocardial Perfusion Scanning in Determining the Presence of Single Vessel Coronary Artery Obstruction

Summary: In 39 patients with single vessel coronary artery disease and no previous myocardial infarction, exercise thallium-207 myocardial perfusion scanning and 12 lead exercise electrocardiography (ECG) were compared to see how reliably each method identified the site of coronary artery obstruction. Significant (≥ 70% diameter) stenosis was present in the left anterior descending (LAD) coronary artery in 21 patients, in the right coronary artery (RCA) in 14 patients and in the left circumflex (LCX) in four patients. Thallium defects on the scan in the septa1 (SEPT), anteroseptal (ANT SEPT) and anterior (ANT) segments correlated (P < 0.0005) with LAD disease and defects in the inferior (INF), posteroinferior (POST INF), and posterior (POST) segments correlated (P < 0.0005) with RCA or LCX disease. Exercise induced ST segment elevation in VI and/or AVL correlated with LAD disease. The site of ischaemic ST depression did not correlate with disease in any vessel. ST segment depression in leads L2, 3, AVF (67%) and in leads V4–6 (67%) was most sensitive for detecting patients with LAD disease and ST depression in leads V4–6 was most sensitive (56%) for detecting patients with RCA or LCX disease but neither differentiated LAD from RCAILCX disease.
During exercise induced ischaemia, the site of ST segment depression on the 12 lead exercise ECG will not identify the area of ischaemia in patients with single vessel disease but thallium defects will. In contrast to ST depression, ST elevation in V1 and/or AVL may identify LAD stenosis.     

Clinical Indications for Thallium-201 Myocardial Perfusion Scanning*

Abstract: Clinical indications for Thallium-201 myocardial perfusion scanning. R. F. Dunn and D. T. Kelly, Aust. N.Z. J. Med., 1982, 12, pp. 294–301. Thallium-201 myocardial perfusion scanning can assess regional myocardial perfusion noninvasive^. As it is both time-consuming and expensive its use should be restricted to specific diagnostic problems. The clinical indications in known or suspected coronary artery disease are reviewed. In suspected coronary artery disease thallium scanning is most useful in patients with chest pain when the exercise ECG is uninterpretable, in men with probable angina but a negative exercise ECG, or conversely a positive exercise ECG without typical angina, and in women with probable angina and either a positive or a negative exercise ECG. In known coronary artery disease, thallium scanning may help determine the functional significance of a coronary obstruction found at angiography and may determine the site of myocardial ischaemia when multiple obstructions are present.     

Prognostic value of exercise thallium scintigraphy in patients with good exercise tolerance and a normal or abnormal exercise electrocardiogram and suspected or confirmed coronary artery disease.

Exercise thallium scintigraphy is widely used to assess prognosis in patients with suspected or proven coronary artery disease. The incremental prognostic value of this technique in patients who have good exercise tolerance has not been well studied. Two hundred ninety-nine patients with known or suspected coronary artery disease without prior myocardial infarction or revascularization procedure referred for exercise myocardial perfusion imaging and able to exercise to greater than or equal to stage III of the Bruce protocol were included. After a mean follow-up of 50 +/- 10 months, there were 15 cardiac events (5%). The incidence of cardiac events was 10 versus 3% (p less than 0.001) in patients with an abnormal versus normal thallium-201 scan, and 9 versus 3% (p = 0.03) for an abnormal versus normal exercise electrocardiogram. When the 185 patients with a normal exercise electrocardiogram were examined, the incidence of cardiac events was 3% (5 of 150) in patients with a normal scan versus 0% (0 of 35) in patients with an abnormal scan. In the 114 patients with an abnormal exercise electrocardiogram, an abnormal thallium-201 scan was predictive of cardiac events (18% [8 of 44] versus 3% [2 of 70]; p = 0.006). Stepwise logistic regression analysis selected an abnormal thallium-201 scan and abnormal exercise electrocardiogram, low peak exercise heart rate, and male gender as independent variables associated with a significant increased risk of cardiac events. Thus, in patients with known or suspected coronary artery disease and good exercise tolerance, the addition of thallium-201 imaging in patients with an abnormal exercise electrocardiogram provides useful prognostic information.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise two-dimensional echocardiography for diagnosis of coronary artery disease

To improve ultrasound images during exercise 2-dimensional echocardiography (2-D echo), a device was developed to hold the transducer and maintain its orientation relative to the heart. The value of this technique in detecting wall motion abnormalities and changes in ejection fraction was evaluated in 54 men undergoing stress test for angina. Thallium-201 scanning, electrocardiography and exercise 2-D echo were recorded concurrently. Technically satisfactory echo studies were obtained in 47 patients (87%). The sensitivity and specificity of exercise echo in the detection of myocardial ischemia as judged by wall motion abnormalities were 100% and 93%, respectively. Sixteen patients with normal thallium scans increased their ejection fraction (EF) estimated by echo (from 52 +/- 1% at rest to 67 +/- 1% at maximal exercise, p less than 0.001); all showed an increase of 5% or more. In contrast, 11 patients who had reversible thallium scan defects showed a consistent decrease in EF (from 53 +/- 2% at rest to 43 +/- 2% during exercise, p less than 0.001); 20 patients with irreversible thallium scan defects showed no specific trend in the EF (48 +/- 2% at rest and 50 +/- 2% during exercise, difference not significant). Changes in heart rate and blood pressure did not distinguish the 3 groups of patients. Our technique of exercise 2-D echo may be useful for detecting wall motion abnormalities and EF changes during exercise and possibly enhance the sensitivity of thallium scanning in the noninvasive diagnosis of coronary artery disease.     

Detection of coronary artery disease by thallium scintigraphy in patients with valvar heart disease

In patients with valvar heart disease detection of coronary artery disease by conventional non-invasive methods may be difficult. The usefulness of thallium-201 exercise scintigraphy for detecting coronary artery disease was evaluated in 16 patients with aortic stenosis, 17 with aortic regurgitation, nine with mitral stenosis, and six with mitral regurgitation who were investigated by coronary angiography. Only two of 21 patients with greater than or equal to 50% coronary artery obstruction had normal thallium images. Three patients without angiographic evidence of coronary artery stenoses had perfusion defects demonstrated by thallium scintigraphy. Only one patient with greater than or equal to 75% coronary stenosis had a normal thallium scan. Angina pectoris or ST segment depression evoked by exercise test were not useful in distinguishing patients with coronary artery disease from those with normal coronary vessels. These data suggest that thallium exercise scintigraphy may be a useful non-invasive test for detecting coronary artery disease in patients with valvar heart disease.     

Detection of coronary artery disease by thallium scintigraphy in patients with valvar heart disease.

In patients with valvar heart disease detection of coronary artery disease by conventional non-invasive methods may be difficult. The usefulness of thallium-201 exercise scintigraphy for detecting coronary artery disease was evaluated in 16 patients with aortic stenosis, 17 with aortic regurgitation, nine with mitral stenosis, and six with mitral regurgitation who were investigated by coronary angiography. Only two of 21 patients with greater than or equal to 50% coronary artery obstruction had normal thallium images. Three patients without angiographic evidence of coronary artery stenoses had perfusion defects demonstrated by thallium scintigraphy. Only one patient with greater than or equal to 75% coronary stenosis had a normal thallium scan. Angina pectoris or ST segment depression evoked by exercise test were not useful in distinguishing patients with coronary artery disease from those with normal coronary vessels. These data suggest that thallium exercise scintigraphy may be a useful non-invasive test for detecting coronary artery disease in patients with valvar heart disease.     

Exercise thallium-201 myocardial scintigraphy in women: Correlation with coronary arteriography

Results of exercise thallium-201 myocardial perfusion images, obtained in 60 women suspected of having coronary artery disease, were correlated with coronary angiographic findings. Thirty-two patients had no significant coronary artery disease; 28 patients had severe coronary artery disease defined as 70 percent or greater diameter narrowing of one vessel (14 patients) or multiple vessels (14 patients). The exercise electrocardiogram was positive in 17 patients (9 with and 8 without coronary artery disease), negative in 16 patients (3 with and 13 without coronary artery disease) and inconclusive in 27 patients (16 with and 11 without coronary artery disease). The exercise thallium-201 scintigram showed exercise-induced defects (reversible ischemia) in 21 patients with coronary artery disease, a fixed defect in 1 patient with single vessel disease and previous transmural infarction, but was normal in the remaining 6 patients, who had single vessel disease. The exercise thallium-201 scintigram in subjects with no coronary artery disease was normal in 28, showed an exercise-induced defect in 1 subject and a fixed defect in the remaining 3 subjects. These fixed defects involved the anterolateral segment in the anterior projection and are thought to be due to attenuation of activity by the overlying breasts. Thus, the sensitivity of the exercise electrocardiogram was 32 percent and the specificity 41 percent. In contrast, the sensitivity of exercise thallium-201 scintigraphy was 75 percent and the specificity 97 percent if only exercise-induced defects were considered abnormal and 79 and 88 percent, respectively, if all fixed defects were considered abnormal.It is concluded that exercise thallium scintigraphy is useful in women suspected of having coronary artery disease. Attenuation of activity by breasts may affect the specificity but not the sensitivity. The exercise electrocardiogram is neither sensitive nor specific in this group.     

Comparative diagnostic value of a new computerized vectorcardiographic method (cardiogoniometry) and other noninvasive tests in medically treated patients with chest pain

The diagnostic value of cardiogoniometry (CGM), a new computerized vectorcardiographic method, for the identification of coronary artery disease was compared with other noninvasive tests in 48 medically treated patients with chest pain. Coronary angiography revealed one-vessel disease in 18, two- or three-vessel disease in 21, and normal coronary arteries in 9 patients. Cardiogoniometry was less sensitive (63%) than thallium-201 (201T1) scanning (82%), but slightly more sensitive than the exercise ECG (50%) or a recently proposed parameter of exercise performance (50%). On the other hand, specificity was comparable among these tests (exercise ECG 78%, thallium-201 scanning 72%, CGM 67%, new parameter of exercise performance 66%). Moreover, the false negative rate of noninvasive testing was reduced from 8 to 3% when CGM was added to thallium-201 scanning and exercise ECG. Our findings indicate that in view of the easier feasibility with computerized technology, the future role of vectorcardiographic methods such as CGM in the noninvasive diagnosis of coronary artery disease should be redefined.     

Exercise echocardiography after stabilization of unstable angina: correlation with exercise thallium-201 single photon emission computed tomography.

The diagnostic usefulness of predischarge exercise echocardiography in 35 patients with unstable angina who responded to medical therapy was correlated with exercise thallium-201 single photon emission computed tomography (TI-SPECT) performed, on the average, three days after the exercise echocardiography. None of the patients had myocardial infarction prior to hospitalization or before TI-SPECT and none had left bundle-branch block on their rest electrocardiogram (ECG). Exercise echocardiography was positive in 21 patients and TI-SPECT in 24. The results of the two techniques were concordant in 28 of 35 patients (agreement = 80%, k = 0.57 +/- 0.14, p less than 0.001). Wall-by-wall comparison of the distribution of exercise-induced wall motion abnormalities with reversible thallium defects showed complete or partial correlation in all of 19 patients in whom both the tests were positive. A positive exercise ECG and positive exercise echocardiography identified 11 of 11 patients with angiographically verified significant coronary artery disease (CAD) and 11 of 12 patients (92%) with positive TI-SPECT. Thus, exercise echocardiography is a valuable addition to routine predischarge exercise test in the noninvasive diagnosis of myocardial ischemia and shows a good correlation with TI-SPECT in detecting and localizing ischemia in patients with unstable angina stabilized on medical therapy.     

Localization of coronary artery disease with exercise electrocardiography: correlation with thallium-201 myocardial perfusion scanning

In 61 patients with single vessel coronary artery disease (70 percent or greater obstruction of luminal diameter in only one vessel) and no previous myocardial infarction, the sites of ischemic changes on 12 lead exercise electrocardiography and on thallium-201 myocardial perfusion scanning were related to the obstructed coronary artery. The site of exercise-induced S-T segment depression did not identify which coronary artery was obstructed. In the 37 patients with left anterior descending coronary artery disease S-T depression was most often seen in the inferior leads and leads V₄ to V₆, and in the 18 patients with right coronary artery disease and in the 6 patients with left circumflex artery disease S-T depression was most often seen in leads V₅ and V₆. Although S-T segment elevation was uncommon in most leads, it occurred in lead V₁ or aVL, or both, in 51 percent of the patients with left anterior descending coronary artery disease. A reversible anterior defect on exercise thallium scanning correlated with left anterior descending coronary artery disease (probability [p] < 0.0001) and a reversible inferior thallium defect correlated with right coronary or left circumflex artery disease (p < 0.0001).In patients with single vessel disease, the site of S-T segment depression does not identify the obstructed coronary artery; S-T segment elevation in lead V₁ or aVL, or both, identifies left anterior descending coronary artery disease; and the site of reversible perfusion defect on thallium scanning identifies the site of myocardial ischemia and the obstructed coronary artery.     

Merits of stress thallium-201 myocardial perfusion imaging in patients with inconclusive exercise electrocardiograms: Correlation with coronary arteriograms

Stress thallium-201 myocardial perfusion images were obtained in 65 patients with an inconclusive exercise electrocardiogram. All 65 patients underwent coronary angiographic studies. The exercise electrocardiogram was judged inconclusive in 35 patients (54 percent) because submaximal exercise had been performed and in 30 patients (46 percent) who manifested ST-T segment abnormalities at rest. Exercise thallium-201 myocardial perfusion images were abnormal in 20 patients and normal in 45. Nineteen (95 percent) of the 20 patients with abnormal exercise images had severe disease of one or more major coronary arteries. Thirty-seven (82 percent) of the 45 patients with normal exercise images had no significant coronary artery disease; the remaining 8 patients had coronary artery disease. Therefore, 19 of 27 patients with coronary artery disease had abnormal exercise images (sensitivity 70 percent), and 37 of 38 patients without coronary artery disease had normal exercise images (specificity 97 percent). Thallium-201 imaging predicted the correct diagnosis in 56 patients (86 percent). Thus, exercise myocardial imaging with thallium-201 appears to be a useful diagnostic aid in patients with an inconclusive exercise electrocardiogram.     

Extent and severity of coronary heart disease. Determinations by thallous chloride Tl 201 myocardial perfusion scanning and comparison with stress electrocardiography.

Rest and exercise ECGs are the most widely used "noninvasive" tests for detecting coronary heart disease, but their sensitivity and specificity are suboptimal. Therefore, the diagnostic value of myocardial perfusion scanning using thallous chloride Tl 201 during rest and stress electrocardiography was examined in 95 patients with a chest discomfort syndrome. Overall, thallous chloride Tl 201 perfusion scanning had a sensitivity of 75% and a specificity of 91% for coronary heart disease compared with 56% sensitivity and 86% specificity with exercise-induced ST segment depression on the ECG. Combining rest and stress ECGs resulted in a sensitivity of 71%. In patients with coronary heart disease, perfusion scanning had a sensitivity of 93% for asynergy compared with 58% for exercise-induced ECG ST depression. Rest and stress myocardial perfusion scanning with thallous chloride Tl 201 provides improved sensitivity with good specificity in the diagnosis of coronary heart disease compared with exercise electrocardiography alone.     

Increased lung uptake of thallium-201 during exercise myocardial imaging: Clinical,hemodynamic and angiographic implications in patients with coronary artery disease

To determine the clinical significance of increased thallium-201 activity in the lung immediately after exercise stress, the thallium-201 scans in 227 patients undergoing cardiac catheterization were reviewed. Thallium lung activity on the Initial anterior view images were graded qualitatively as follows: 0 (none) in 175 patients (77 percent); 1+ (moderate—increased activity in the lungs but less intense than that in left ventricular myocardium) in 37 patients (16 percent); and 2+ (severe—activity equal to or greater in intensity than left ventricular myocardlal activity) in 15 patients (7 percent). Increased (1+ or 2+) lung activity was related to (1) a greater number of myocardial segmental thallium defects (probability [p] < 0.05); and (2) increased severity and extent of coronary artery disease (p < 0.05). In addition, 2+ lung thallium activity was associated with: (1) a greater prevalence of prior myocardial infarctions (p < 0.01); and (2) a lower angiographic ejection fraction at rest (p < 0.05). To determine the hemodynamic changes associated with increased lung uptake of thallium-201, supine stress thallium imaging was performed during cardiac catheterization in 12 additional patients. Of these, the five patients with increased lung activity on thallium scanning had a mean pulmonary capillary wedge pressure that increased with exercise from 12 ± 1 (mean ± 1 standard deviation) to 24 ± 3 mm Hg (p < 0.05); cardiac index did not increase with stress. In contrast, seven patients without increased lung thallium activity demonstrated an increase in mean cardiac index (p < 0.05) without an associated rise in pulmonary capillary wedge pressure (at rest = 10 ± 3 mm Hg; during stress = 12 ± 2 mm Hg). In conclusion, increased pulmonary uptake during exercise thallium-201 imaging suggests the development of exercise-induced left ventricular dysfunction. Evaluation of lung activity should be added to the routine interpretation of exercise thallium-201 myocardial imaging studies.     

Quantitative split dose thallium-201 imaging with exercise: a technique for obtaining rest and exercise perfusion images in one setting and markedly reducing the study time

In the current study, a technique for performing serial thallium imaging after two separate tracer injections was applied to exercise thallium imaging, thus allowing the acquisition of rest and exercise images within 1 hour. Twenty-four patients with and 10 patients without significant coronary artery disease were studied. One mCi of thallium-201 was injected intravenously and imaging was performed at rest in three projections. The patient was then stressed and an additional 1 mCi of thallium injected during exercise. Images in the same three projections were collected. After computer realignment, the rest image was subtracted from the exercise image to produce an image representing perfusion during exercise. All 24 patients with coronary artery disease had a positive study, while 9 of 10 without disease had a negative study. The images were then interpreted using a computer method designed to quantitate regional myocardial thallium distribution and redistribution. With quantitative interpretation, 23 of 24 patients with coronary disease had a positive study, while only 1 without disease had a positive study. With qualitative interpretation, 39 (89%) of 44 stenosed coronary arteries demonstrated thallium defects in corresponding myocardial segments, while 54 (93%) of 58 nonstenosed coronary arteries did not. With quantitative interpretation, 38 (86%) of 44 stenosed coronary arteries demonstrated thallium defects in corresponding myocardial segments, while 53 (91%) of 58 nonstenosed coronary arteries did not. A split dose thallium imaging technique that allows imaging before and immediately after exercise, thus markedly reducing the study time, has been validated.     

Assessment of single vessel coronary artery disease: results of exercise electrocardiography, thallium-201 myocardial perfusion imaging and radionuclide angiography

The sensitivity of the commonly used stress tests for the diagnosis of coronary artery disease was analyzed in 46 patients with significant occlusion (greater than or equal to 70% luminal diameter obstruction) of only one major coronary artery and no prior myocardial infarction. In all patients, thallium-201 perfusion imaging (both planar and seven-pinhole tomographic) and 12 lead electrocardiography were performed during the same graded treadmill exercise test and radionuclide angiography was performed during upright bicycle exercise. Exercise rate-pressure (double) product was 22,307 +/- 6,750 on the treadmill compared with 22,995 +/- 5,622 on the bicycle (p = NS). Exercise electrocardiograms were unequivocally abnormal in 24 patients (52%). Qualitative planar thallium images were abnormal in 42 patients (91%). Quantitative analysis of the tomographic thallium images were abnormal in 41 patients (89%). An exercise ejection fraction of less than 0.56 or a new wall motion abnormality was seen in 30 patients (65%). Results were similar for the right (n = 11) and left anterior descending (n = 28) coronary arteries while all tests but the planar thallium imaging showed a lower sensitivity for isolated circumflex artery disease (n = 7). The specificity of the tests was 72, 83, 89 and 72% for electrocardiography, planar thallium imaging, tomographic thallium imaging and radionuclide angiography, respectively. The results suggest that exercise thallium-201 perfusion imaging is the most sensitive noninvasive stress test for the diagnosis of single vessel coronary artery disease.     

Assessing viable myocardium with thallium-201.

Patients with chronic coronary artery disease and potentially reversible left ventricular dysfunction can often be successfully identified by one or more clinical indicators of myocardial viability, including regional wall motion, systolic wall thickening, regional myocardial perfusion as determined by perfusion tracers, and redistribution of thallium-201. In some patients, however, viable but "hibernating" myocardium will exist even when none of the above are evident. Myocardial viability in this situation can be detected with a high degree of accuracy by the demonstration of preserved metabolic activity by positron emission tomography (PET) scanning. Additionally, modifications of the standard exercise-redistribution thallium protocol may also produce accurate results. These modifications include late thallium-201 redistribution imaging, performed 8-72 hours following initial thallium injection, and thallium reinjection at rest after early (3-4 hours) or late (8-72 hours) redistribution imaging. These methods can identify viable myocardium in many thallium defects that appear to be irreversible on a standard 3-4 hour redistribution image. In addition, serial imaging after administration of thallium-201 at rest may also provide valuable insights into myocardial viability. These imaging modalities have important practical applications in the evaluation and management of patients with coronary artery disease and left ventricular dysfunction.     

Two-dimensional echocardiographic evaluation of ventricular asynergy induced by dipyridamole: correlation with thallium scanning

Myocardial asynergies detected by two-dimensional echocardiography during intravenous administration of Dipyridamole (0.75 mg/kg) were evaluated in 54 patients referred for angiographic evaluation of chest pain. Technically adequate two-dimensional echocardiograms suitable for analysis were recorded in 42 of 54 (77.7%) patients studied. Thallium-201 myocardial perfusion scintigraphy, during dipyridamole test was performed in the same patients. Thirty of the 42 patients studied showed significant coronary narrowing at cardiac catheterization. Dipyridamole-induced wall motion abnormalities and myocardial perfusion defects were detected, respectively, in 19 (63.3%) and 21 (70%) of 30 patients with significant coronary artery disease. Wall by wall comparison of the distribution of dipyridamole-induced echocardiographic asynergy with reversible thallium-201 (201Tl) perfusion defects demonstrated complete correlation in 42 segments examined. Three segments with perfusion defects at thallium scanning did not show asynergy during the test while two segments showing wall motion abnormalities during dipyridamole infusion did not manifest perfusion defects. Our study demonstrates that two-dimensional echocardiography during dipyridamole testing is useful in detecting patients with coronary artery disease. Furthermore, ventricular asynergies detected during the test show a high correspondence with site of myocardial perfusion defects at thallium scanning.