Effort angina pectoris without electrocardiographic changes in coronary disease patients: correlations between scintigraphic and coronary angiographic findings

The absence of electrocardiographic changes during angina is an unusual occurrence. In 15 male patients with exercise-induced angina, the electrocardiogram failed to show the usual ischemic ST-T changes. The exercise thallium-201 myocardial imaging was employed as indicator of the ischemia and the results were correlated with coronary angiographic findings. The exercise thallium-201 myocardial imaging showed an exercise-induced reversible defect in 14 patients and a fixed defect in the remaining 1. Out of 15 patients, 13 had defects involving the infero-apical, posterior and postero-lateral segments. The coronary angiography, performed in all patients but 2, showed single-vessel coronary artery disease in 8 patients and double-vessel disease in 5. A significant circumflex or right coronary artery stenosis was found in all cases except 1; 2 patients had a coexistent left anterior descending coronary artery stenosis and 1 an isolated stenosis of this vessel. It is concluded that the myocardial scintigraphy is useful to assess the ischemic myocardial origin of chest pain in the absence of ST-T changes. The silence of the electrocardiogram might be due to the production of ischemia in not well explored areas, such as the inferior and posterior myocardial segments, and possibly to a smaller extension of ischemia.     

Predicting the extent and location of coronary artery disease during the early postinfarction period by quantitative thallium-201 scintigraphy

The ability of quantitative thallium-201 scintigraphy to predict the extent and location of coronary artery disease before hospital discharge after acute myocardial infarction was evaluated in 52 patients. All patients underwent coronary angiography and serial thallium-201 imaging either at rest (10 patients) or after submaximal exercise stress (42 patients; target heart rate 120 beats/min). Two or three vessel disease was designated if abnormal thallium-201 uptake or washout patterns, or both, were seen in two or three vascular segments, respectively. Of 156 vessels analyzed in the 52 patients, 91 stenoses of 70 percent or greater were found by angiography. Seventy-four (81 percent) of these were predicted by scintigraphy. The specificity of scintigraphy for identifying vessel stenoses was 92 percent. Sensitivity for detecting and localizing stenoses supplying an infarct zone was 96 percent compared with 62 percent for stenoses supplying myocardium remote from the acute infarct. Perfusion abnormalities were more frequently seen in the distribution of vessels with severe (90 percent or greater) stenoses than in those with moderate (70 to 90 percent) stenoses (87 versus 53 percent, p <0.01). Scintigraphy detected a greater proportion of left anterior descending and right coronary arterial stenoses than circumflex stenoses (91 and 87 versus 63 percent, respectively, p <0.006).In the 42 patients who underwent submaximal exercise testing, multivariate analysis of 23 clinical and laboratory variables identified multiple thallium-201 defects as the best predictor of multivessel disease. The predictive accuracy of exercise-induced S-T segment depression was only 45 percent compared with 88 percent (p <0.05) for thallium-201 scintigraphy. Thus, 2 weeks after myocardial infarction, exercise thallium-201 scintigraphy is useful for predicting the extent and location of coronary artery disease, particularly stenoses in the left anterior descending and right coronary arteries. Moreover, thallium-201 imaging at rest is reliable in assessing the extent of coronary disease in hospitalized patients who cannot undergo exercise testing because of unstable angina, uncompensated heart failure, poorly controlled arrhythmias or physical limitations.     

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.     

Exercise-induced ST segment elevation in a patient with effort angina pectoris and normal coronary arteries

A 32 year old woman who complained of exercise-induced chest pain was found to have widespread elevation of the ST segment of the electrocardiogram during exercise testing. Coronary angiography demonstrated no obstructive lesions and no evidence of coronary artery spasm despite ergonovine administration, bicycle ergometry and rapid atrial pacing. Exercise thallium-201 scintigraphy demonstrated no perfusion defects despite ST segment elevation. Radionuclide blood pool imaging revealed a slight decrease in ejection fraction with exercise. The available evidence raises the possibility of small vessel coronary artery disease, either structural or vasotonic, as a cause of this patient's symptoms.     

Importance of coronary collateral circulation in interpreting exercise test results

The Importance of the coronary collateral circulation as a cause of false negative exercise tests was studied in 37 patients who had a 90 percent or greater isolated stenosis of the luminal diameter in one major coronary artery. Sixteen patients had large collateral vessels and 21 patients had either minimal or no collateral circulation. Myocardial scintigraphy was performed in 22 of the 37 patients. The final treadmill time was similar in both groups (521 ± 192 versus 554 ± 144 seconds [mean ± standard error of the mean]). The presence and depth of S-T segment depression was not influenced by the degree of collateralization. The sensitivity of the exercise electrocardiogram was greater for patients with disease in the left anterior descending than in the right or left circumflex coronary arteries (95 versus 60 percent, p <0.03). Among the 22 patients with thallium-201 scintigrams, myocardial perfusion defects were more common in patients without collateral circulation (100 versus 40 percent, p <0.01) and Involved more myocardial segments (p <0.005). The overall sensitivity of exercise electrocardiography for the detection of single vessel stenosis 90 percent or greater was similar to that of myocardial scintigraphy (81 versus 73 percent). In conclusion, large intercoronary collateral vessels are not a cause of false negative exercise electrocardiograms in patients with single vessel disease but are a common cause of false negative scintigrams. Large collateral vessels may limit the quantity and location of myocardial ischemia, but exercise etectrocardtography and thallium-201 scintigraphy may detect different aspects of ischemia.     

Cold pressor thallium-201 myocardial scintigraphy in the diagnosis of coronary artery disease

Thallium-201 myocardial scintigraphy was performed during cold pressor stimulation in 36 patients aged 37 to 69 years. Thirty-one patients had coronary artery disease and 5 patients did not, as confirmed by coronary cineangiography. Thallium-201 (1.5 to 2 mCi) was injected at 30 seconds of the cold pressor stimulation. The product of systolic pressure × heart rate increased from a baseline of 77.4 ± 16 (standard deviation [SD]) to 103.6 ± 17 at 30 seconds of the cold pressor test (p < 0.0005). Transient perfusion deficits developed in 24 of 31 patients with coronary artery disease (sensitivity 77%), and all 5 patients without coronary artery disease had normal scintigrams. The sensitivity in detecting coronary artery disease was 40% in patients with 1 vessel disease, 91% in patients with 2 vessel disease, and 100% in patients with 3 vessel disease. Exercise electrocardiograms (available in 29 of 36 patients) were positive for ischemia in 18 of 24 patients with coronary artery disease and in 1 of 5 patients without coronary artery disease (sensitivity 75% and specificity <80%). Exercise thallium-201 scintigrams, obtained in 16 patients, were positive in 11 patients with coronary artery disease and positive cold pressor thallium-201 scintigrams. Five patients without coronary artery disease and with normal cold pressor thallium-201 scintigrams had normal exercise thallium-201 scintigrams. Coronary cineangiography performed during cold pressor stimulation in 6 patients who had positive cold pressor and exercise thallium-201 scintigrams did not show coronary spasm. Our data indicate that cold pressor thallium-201 scintigraphy offers promise as a noninvasive test in the diagnosis of coronary artery disease and may be used in patients in whom exercise testing is not feasible.     

Idiopathic hypertrophic subaortic stenosis: evaluation of anginal symptoms with thallium-201 myocardial imaging.

The evaluation of angina pectoris in patients with idiopathic hypertrophic subaortic stenosis is difficult in those in the age group prone to coronary artery disease. Ten patients with angina pectoris, normal coronary angiograms and idiopathic hypertrophic subaortic stenosis were studied with thallium-201 myocardial imaging performed in conjunction with submaximal treadmill exercise testing. The resting electrocardiogram demonstrated left ventricular hypertrophy with S-T segment abnormalities in seven patients, thereby vitiating the further increase in S-T segment abnormalities that developed in these patients during exercise or in the postexercise period. Of the three patients with a normal resting electrocardiogram, one had significant exercise-induced S-T segment depression. Thallium-201 myocardial imaging revealed no significant perfusion defects in 9 of the 10 patients (90 percent). In one patient with severe left ventricular hypertrophy significant perfusion defects developed after exercise that were not present at rest. Stress thallium-201 myocardial perfusion imaging is a useful noninvasive technique that assists in ruling out the presence of significant coronary artery disease in patients with idiopathic hypertrophic subaortic stenosis.     

Exercise thallium-201 myocardial imaging in left main coronary artery disease: Sensitive but not specific

To determine the usefulness of thallium-201 scintigraphy for identifying left main coronary artery disease, the results of scintigraphy at rest and during exercise were compared in 24 patients with 50 percent or greater narrowing of the left main coronary artery and 80 patients with 50 percent or greater narrowing of one or more of the major coronary arteries but without left main coronary involvement. By segmental analysis of the scintigrams, perfusion defects were assigned to the left anterior descending, left circumflex or right coronary artery, singly or in combination, and the pattern of simultaneous left anterior descending and circumflex arterial defects was used to identify left main coronary artery disease. Of the 24 patients with left main coronary artery disease, 22 (92 percent) had abnormal exercise scintigrams. Despite this high sensitivity, the pattern of perfusion defects was not specific; the “left main pattern” was found in 3 patients (13 percent) with left main coronary artery disease but also in 3 (33 percent) of 9 patients with combined left anterior descending and left circumflex arterial disease, 4 (19 percent) of 21 patients with three vessel disease and 3 (6 percent) of 50 patients with one or two vessel disease but excluding the group with left anterior descending plus left circumflex arterial disease.The pattern of perfusion defects in the patients with left main coronary artery disease was determined by the location and severity of narrowings in the coronary arteries downstream from the left main arterial lesion. Concomitant lesions in other arteries were found in all patients with left main coronary disease (one vessel in 1 patient, two vessels in 7 patients and three vessels in 16). For this reason, it is unlikely that even with improvements in radiopharmaceutical agents and imaging techniques, myocardial perfusion scintigraphy will be sufficiently specific for definitive identification of left main coronary artery disease.     

Thallium-201 myocardial scintigraphy in patients with Wolff-Parkinson-White syndrome

Wolff-Parkinson-White syndrome (WPW) is known to cause abnormal rest electrocardiogram and stress test. Thallium-201 myocardial scintigraphy has been particularly indicated for the noninvasive evaluation of coronary artery disease in these patients. The study group consisted of 11 WPW patients with abnormal ST-segment depression at rest electrocardiogram and/or stress test, with the absence of signs or symptoms of coronary artery disease. All the patients underwent exercise thallium-201 imaging associated with stress test by bicycle ergometer: 7 of them had ST-segment depression, but without other signs or symptoms of coronary artery disease. Transient and moderate myocardial perfusion defects were found in 5 of 11 patients. Perfusion defects in patients with WPW could derive from dyssynergy of ventricular activation, which could modify myocardial perfusion scintigraphy despite the absence of angiographic coronary stenosis. Previous reports and our data concluded that transient perfusion defects during exercise thallium-201 testing in WPW patients without cardiovascular disease may be observed. Thus, thallium-201 myocardial scintigraphy could present some limitations as a helpful adjunctive method for assessment of coronary artery disease in WPW patients.     

Atrial pacing and thallium-201 scintigraphy in patients with chest pain: correlation with coronary anatomy

Atrial pacing and thallium-201 scintigraphy were performed in 72 patients referred for evaluation of chest pain. Coronary artery disease (CAD) was present in 63 patients, as documented by cardiac catheterization performed at the same time or within 2 months of atrial pacing. Nine patients had no or insignificant (less than 50% stenosis) CAD. The sensitivity of pacing-induced angina for CAD was 51%, and was 49% for ST depression. Specificities were 89% and 78%, respectively. A reversible perfusion defect was seen in 54% of patients with CAD (specificity 89%), and a fixed defect in 29% (specificity 100%). The sensitivity of an abnormal thallium-201 scan (one or more reversible or fixed defects) was 79% (p less than 0.05 compared to angina or ST depression). Combined sensitivity of ST depression and/or an abnormal thallium-201 scan was 87%. There were no significant changes in any of these sensitivities as the number of vessels with CAD increased. Thallium-201 scintigraphy correctly identified 11 of 19 (58%) patients with single-vessel disease as having CAD in only one vessel, but underestimated the extent of disease in all but a few patients with multivessel disease. The sensitivity of perfusion imaging to identify lesions in specific vessels ranged from 27% (circumflex) to 57% (right coronary artery). Specificities were 100% for circumflex, 78% for anterior descending, and 83% for right coronary artery lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence of impaired myocardial perfusion and abnormal left ventricular function during exercise in patients with isolated systolic narrowing of the left anterior descending coronary artery

Seven men ranging in age from 35 to 63 years with a chest pain syndrome and cineangiographically documented systolic narrowing of the left anterior descending coronary artery underwent thallium-201 myocardial scintigraphy and gated cardiac blood pool imaging. Grade II (50 to 75 percent) systolic coronary arterial constriction was present in three patients and grade III constriction (greater than 75 percent) in four. Three of the four patients with grade III constriction had an exercise-induced perfusion abnormality in the thallium-201 scintigram and an impaired left ventricular ejection fraction response during exercise. (In two patients the left ventricular ejection fraction did not change and in one patient it decreased.) Each of the three patients with grade II constriction had normal thallium-201 perfusion and a normal increase in ejection fraction during exercise. These data provide evidence of abnormal myocardial perfusion and impaired left ventricular function during exercise in patients with high grade systolic coronary arterial narrowing.     

Correlation of thallium-201 scintigrams with coronary anatomy: factors affecting region by region sensitivity.

Myocardial perfusion scintigraphy, performed after administration of thallium-201 during exercise, has come into widespread use for evaluating patients with coronary artery disease. Previous studies indicate that it is both sensitive and highly specific. However, thallium-201 scintigraphy evaluates relative rather than absolute perfusion and may therefore be misleading in estimating the extent of coronary disease. This study evaluated the effect of the number and location of diseased vessels, the severity of coronary stenosis and the presence of previous infarction on the overall and regional sensitivity of scintigraphy in 78 patients. The overall sensitivity and specificity levels were 89 and 93 percent, respectively; vessel by vessel, the respective values were 67 and 96 percent. Scintigraphy had greater overall sensitivity in patients with multivessel disease than in those with single vessel disease, but in individual patients the regional sensitivity was not affected by the number of vessels involved. Scintigraphy correctly indicated the number of diseased vessels in only a minority of patients. Left circumflex arterial obstructions were frequently not detected (sensitivity 45 percent compared with 75 percent for other major arteries). Perfusion abnormalities were much more likely to be present (80 versus 39 percent, P < 0.01) in the distribution of vessels with severe (more than 90 percent) stenosis than in that of vessels with moderate (70 to 90 percent) stenosis. A greater proportion of both patients and regions with old infarctions were judged scintigraphically abnormal. However, these differences were not significant and reflected only the infarcted regions themselves, because other jeopardized vessels were detected with the same frequency in patients with and without infarction.The findings indicate that the sensitivity of exercise thallium-201 scintigraphy, despite its relative nature, is not impaired by the presence of widespread coronary disease or areas of old infarction. The most important factor determining the regional sensitivity of scintigraphy is the severity of the corresponding stenosis, and the major factor affecting sensitivity in an individual patient is the number of vessels involved.     

Thallium-201 myocardial perfusion scintigraphy to evaluate patients after coronary bypass surgery.

To determine the utility of thallium-201 stress scintigraphy in assessing the results of coronary bypass surgery, chest pain, stress electrocardiograms and scintigrams were evaluated in 27 patients postoperatively. These findings were compared with coronary angiographic data in which a significant postoperative lesion was defined as 75 percent or more stenosis in a graft, its distal vessel or in an ungrafted native vessel. As an indicator of postoperative coronary lesions, chest pain lacked sensitivity (60 percent) and was nonspecific (20 percent). The stress electrocardiogram had poor sensitivity (60 percent) and good specificity (86 percent) but was not helpful in six patients who had equivocal or suboptimal tests. The scintigram had good sensitivity (77 percent) and was highly specific for the diagnosis of coronary stenosis. It was significantly more specific than chest pain (P less than 0.01), gave excellent localizing information and added to the accuracy of both conclusive and inconclusive stress tests. In nine patients with preoperative stress scintigrams, comparison of pre- and postoperative studies reflected the éffects of bypass surgery on coronary perfusion. Scintigraphy is a useful technique for the noninvasive evaluation of the patient after coronary bypass surgery, and postoperative scintigraphy alone is of great value in documenting surgical results.     

Myocardial perfusion in coronary disease: thallium-201 planar scintigraphy

This research evaluated the diagnostic and analytic effectiveness of 201-thallium imaging in a group of patients with coronary artery disease, each one of them with different localization, extent and number of coronary vessel obstructions. The thallium-201 imaging was performed immediately after ergometric test and repeated 4 hours later. In a large percentage of patients thallium-201 imaging of reversible and irreversible perfusion defects have been found; thallium-201 scintigraphy showed a greater sensitivity than exercise ECG. With particular evidence 201-Tl imaging showed perfusion defects in a high percentage of patients with obstruction of one and two coronary vessels; in these patients, in the former especially, the results of exercise ECGs showed a lower sensitivity. Both thallium-201 and exercise ECG had a similar sensitivity in patients with obstruction of three coronary vessels. In patients with obstruction of one or two vessels, thallium-201 imaging clearly showed a regional hypoperfusion corresponding to the specific perfusion coronary vessels, while exercise ECG gave aspecific topographic results. Irreversible perfusion defects resulted corresponding to the myocardial segments that were infarcted, but were also observed in patients without previous myocardial infarction.     

Scintigraphic anatomy of coronary artery disease in digital thallium-201 myocardial images.

One hundred and eight patients with single and multiple vessel coronary artery disease confirmed by arteriography were evaluated by exercise thallium-201 (201Tl) myocardial scintigraphy to determine the scintigraphic appearances of specific coronary stenoses. In general proximal stenoses caused more widespread, but not necessarily more severe, myocardial tracer deficit than distal stenoses. In particular, proximal dominant right coronary artery disease was specifically associated with extensive inferior wall tracer deficit in the anterior scintigram, whereas proximal left circumflex disease caused similar tracer depletion best visualised in the left lateral scintigram. A triad of uptake defects was caused by left anterior descending coronary artery disease: viz. apical tracer deficit (anterior view) in 71% lesions, septal tracer deficit (left anterior oblique view) in 83% of lesions, and anterolateral wall tracer deficit (left lateral projection) in 72% of lesions. The last defect has been termed a 'diagonal window' because it was associated with independent disease of the main diagonal branch of the left anterior descending coronary artery or with disease in the main left anterior descending artery situated proximal to this branch. Diagonal window tracer deficit was the most useful scintigraphic sign distinguishing proximal from distal disease in the left anterior descending coronary artery. False negative scintigraphic defects occurred more commonly in patients with triple vessel disease and in association with well-developed coronary collateral vessels. Certain scintigraphic patterns of 201Tl myocardial accumulation appear invaluable in the noninvasive localisation of stenoses within specific coronary arteries and thus may be useful in predicting life-threatening coronary artery disease which should be confirmed by definite coronary arteriography. The digital 201Tl myocardial scintigram also provides an independent functional guide to the interpretation of coronary arteriograms and may be helpful in the planning of aortocoronary bypass graft surgery.     

Segmental quantitative analysis of digital thallium-201 myocardial scintigrams in diagnosis of coronary artery disease. Comparison with rest and exercise electrocardiography and coronary arteriography.

One hundred and forty-nine patients with suspected ischaemic heart disease were evaluated by exercise thallium-201 myocardial scintigraphy (201Tl SMS), single lead exercise electrocardiography, and coronary arteriography. Myocardial distribution of tracer was assessed semi-quantitatively from digital 201Tl scintigrams and compared with tracer distribution in subjects with normal hearts. Fifty-two of 54 (96%) patients with normal coronary arteries had normal myocardial scintigrams whereas three patients had a positive ischaemic exercise electrocardiogram and were scan normal. Conversely, 36 of 95 (38%) patients with coronary artery disease had a positive ischaemic electrocardiogram compared with 94 of 95 (99%) patients who had a positive myocardial scintigram. Disease in specific coronary arteries could be deduced from the topography of myocardial tracer deficit. Disease was predicted correctly in 76 out of 80 (95%) of left anterior descending coronary stenoses, in 48 out of 64 (75%) of right coronary artery stenoses, and in 55 out of 64 (85%) of left circumflex coronary artery stenosis, despite the presence of infarcted myocardium in other territories. Similarly, single vessel disease was predicted correctly in 14 out of 17 (82%) patients and multiple vessel disease in 64 out of 77 (83%) patients. 201Tl SMS with segmental quantitative analysis is a highly sensitive and specific technique in the diagnosis of coronary artery disease and may be useful screening procedure to select patients for further investigation, particularly those with evidence of life-threatening severe left coronary artery disease.     

Exercise-induced ST-segment changes in lead V1 identify the significantly narrowed coronary artery in patients with single-vessel disease: correlation with thallium-201 scintigraphy and coronary arteriography data

We investigated the correlation of exercise-induced ST-segment changes in lead V1, with the detection of the significantly narrowed vessel that induced ischemia during exercise in myocardial areas supplied by this vessel. We studied 198 patients who underwent exercise testing, thallium-201 scintigraphy, and coronary arteriography. The patients were divided into three groups. In group 1 (ST-segment elevation in lead V1), 84% had left anterior descending coronary artery disease (P<.001); in group 2 (ST-segment depression in lead V1), 76% had right coronary artery disease (P<.001); and in group 3 (no ST-segment changes in lead V1), there were no significant differences concerning the narrowed vessel. Thallium-201 scintigraphy data confirmed the existence of the reversible perfusion defect(s) in an area(s) of myocardium supplied by the respective coronary arteries (P<.001). Exercise-induced ST-segment elevation or depression in V1 may identify the obstructed vessel in patients with single-vessel disease and without prior myocardial infarction.     

Diagnostic accuracy of exercise thallium-201 scintigraphy in men with asymptomatic essential hypertension.

Coronary artery disease is responsible for much of the morbidity and mortality in patients with essential hypertension, and these complications have proven to be relatively resistant to antihypertensive therapy. However, the diagnosis of coronary disease in the hypertensive population has been considered problematic. In the present study, 30 asymptomatic patients with mild to moderate hypertension with positive exercise electrocardiograms (ECG) or stress thallium-201 scintigrams underwent coronary angiography to determine the accuracy of these tests for coronary artery disease. The exercise ECG was positive in 25 subjects, of whom 15 had significant coronary lesions and 10 did not. Thallium-201 scintigraphy proved more accurate: 17 of 18 patients with reversible abnormalities had significant obstructive coronary disease anatomically corresponding to the defect, one patient with a fixed defect had normal coronary arteries and was found to have an idiopathic cardiomyopathy, and 9 of 11 without defects had no significant lesions. The results were similar in populations with and without echocardiographic criteria for left ventricular hypertrophy. These findings indicate that despite previous suggestions to the contrary, thallium-201 scintigraphy can accurately diagnose coronary artery disease in most patients with asymptomatic essential hypertension, and that most asymptomatic hypertensive patients with physiologic evidence of myocardial ischemia have associated coronary artery disease.     

Dipyridamole combined with exercise for thallium-201 myocardial imaging

A new stress test for thallium-201 myocardial imaging in which pharmacological coronary vasodilatation with dipyridamole is combined with dynamic exercise is described. In 38 patients with coronary artery disease the sensitivity, total number of defects, degree of redistribution, and visual quality of thallium-201 imaging were greater after dipyridamole with exercise testing than after exercise alone. When the data from these 38 patients were combined with the results of dipyridamole-exercise imaging in 49 patients in whom exercise electrocardiography had been inconclusive then the technique gave a sensitivity for coronary disease of 87% and a specificity of 92%. Dipyridamole also increased the sensitivity of the exercise electrocardiogram, so that no patient with coronary disease had a strictly negative dipyridamole-exercise stress test. Only five of 214 patients who have now undergone this test have had complications requiring reversal of vasodilatation with aminophylline. The combined use of dipyridamole and exercise in this simple technique is a reliable and safe improvement on standard thallium-201 imaging tests.     

Dipyridamole combined with exercise for thallium-201 myocardial imaging.

A new stress test for thallium-201 myocardial imaging in which pharmacological coronary vasodilatation with dipyridamole is combined with dynamic exercise is described. In 38 patients with coronary artery disease the sensitivity, total number of defects, degree of redistribution, and visual quality of thallium-201 imaging were greater after dipyridamole with exercise testing than after exercise alone. When the data from these 38 patients were combined with the results of dipyridamole-exercise imaging in 49 patients in whom exercise electrocardiography had been inconclusive then the technique gave a sensitivity for coronary disease of 87% and a specificity of 92%. Dipyridamole also increased the sensitivity of the exercise electrocardiogram, so that no patient with coronary disease had a strictly negative dipyridamole-exercise stress test. Only five of 214 patients who have now undergone this test have had complications requiring reversal of vasodilatation with aminophylline. The combined use of dipyridamole and exercise in this simple technique is a reliable and safe improvement on standard thallium-201 imaging tests.