The diagnostic and prognostic value of exercise electrocardiography in asymptomatic subjects and stable symptomatic patients

In asymptomatic patients, the use of exercise ECG testing for the detection of subclinical coronary artery disease has considerable theoretical appeal, but its practical application is severely hampered by the constraints of Bayes' theorem. Serial exercise ECGs do not appear to offer significant improvement in this regard. Thallium-201 perfusion scintigraphy performed in conjunction with an exercise ECG can greatly improve the predictive value of such testing, although at considerable cost. Screening strategies with promise are those that reserve exercise testing for individuals at greater-than-average risk for subclinical coronary artery disease (eg, patients with multiple coronary risk factors) or that prescribe sequential testing, where only those with an abnormal exercise ECG are subjected to thallium-201 scintigraphy. At present, the optimal method of identifying asymptomatic individuals at high risk of a major cardiac event remains undefined. The use of maximal-effort stress testing has stood the test of time in the evaluation of patients with stable symptoms suggestive of coronary artery disease. This is particularly true when variables other than the ECG response to exercise are considered. The independent contribution of exercise angina remains controversial; however, recent studies indicate that it correlates with a more severe symptom pattern and more extensive coronary artery disease. Prognostic stratification in these studies was improved by considering both subjective and objective manifestations of ischemia. Although exercise ECG testing has been shown to have important prognostic value after acute myocardial infarction, exercise thallium-201 scintigraphy offers several potential advantages for asymptomatic post-myocardial infarction patients, several of which this paper reviews. The more optimal prognostic efficiency of thallium-201 scintigraphy is due in part to the fact that the error rate in falsely classifying patients at low risk is substantially smaller with scintigraphy than with stress electrocardiography. Because of this, there appears to be adequate rationale for recommending exercise perfusion imaging, rather than exercise ECG testing alone, as the preferred method for evaluating mortality and morbidity risks after acute myocardial infarction.     

Enhanced detection of ischemic but viable myocardium by QT interval dispersion on treadmill exercise electrocardiograms of patients with healed anterior wall myocardial infarcts

BACKGROUND: The presence of ischemic but viable myocardium in infarcted areas is an important indication for coronary revascularization, but is often difficult to detect with the use of treadmill exercise electrocardiography (ECG). HYPOTHESIS: QT interval dispersion (QTd) is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarcted areas. METHODS: Forty-five patients with Q-wave anterior wall myocardial infarctions who underwent treadmill exercise ECG, exercise reinjection thallium-201 (201Tl) scintigraphy, radionuclide angiocardiography, and coronary angiography 1 month after infarction were enrolled in this study. The presence of viable myocardium in the infarct area was determined by exercise reinjection 201Tl scintigraphy. Patients who had no redistribution in the infarct area after reinjection were included in Group 1, and those with redistribution were included in Group 2. RESULTS: QTd immediately after exercise, and the difference between QTd before and immediately after exercise, were significantly greater in Group 2 than in Group 1. The sensitivity, specificity, and accuracy of conventional ST-segment depression criteria for detecting viable myocardium in the infarct area were 48, 64, and 56%, respectively. The measurement of QTd immediately after exercise (abnormal: > or = 70 ms; normal: < 70 ms) improved the sensitivity, specificity, and accuracy to 78, 82, and 80%, respectively. CONCLUSIONS: This novel diagnostic method using QTd-based criteria significantly improves the clinical usefulness of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarct areas in patients with healed Q-wave anterior wall myocardial infarctions.     

The detection of myocardial ischemia by thallium-201 myocardial scintigraphy in patients with multiple coronary arterioventricular connections.

The question of whether myocardial ischemia could be induced in 5 patients with multiple coronary arterioventricular connections by thallium-201 (201Tl) exercise stress myocardial scintigraphy was investigated. Both ST-T changes on ECG and transient myocardial perfusion defects in myocardial scintigrams were observed in 2 patients (40%). In previous reports, all multiple coronary arterioventricular connections, which were shown in angiograms, have been regarded as either Thebesian veins or embryonic sinusoids. However, it is unlikely that Thebesian veins cause myocardial ischemia judging from anatomy. If the vessels cause myocardial ischemia, they should be regarded as multiple coronary arterioventricular fistula. Angiography itself cannot differentiate multiple coronary arterioventricular fistula from Thebesian veins or remnants of embryonic sinusoids. Exercise stress myocardial scintigraphy has a high potential to detect myocardial ischemia due to intracoronary steal. Exercise stress myocardial scintigraphy was used to demonstrate myocardial ischemia in multiple coronary arterioventricular connections. It is concluded that exercise stress myocardial scintigraphy is a reliable test to differentiate multiple coronary arterioventricular fistula from Thebesian veins or remnants of embryonic sinusoids in clinical practice.     

Thallium-201 myocardial perfusion studies in patients with the mitral valve prolapse syndrome

To determine whether regional myocardial ischemia plays a role in patients with the mitral valve prolapse syndrome, we examined myocardial perfusion with exercise stress testing and thallium-201 myocardial scintigraphy. Twelve patients were studied, 11 women and one man aged 18 to 56 years, mean age 30 years. In all patients, mitral valve prolapse was documented by echocardiography or phonocardiography. Patients over 35 years of age underwent cardiac catheterization. Electrocardograms disclosed abnormalities during maximal exercise in eight of the 12 patients. In two patients, angina developed during exercise. Thallium-201 (²⁰¹TI) scintigrams were normal in the 11 patients with presumed or documented normal coronary arteries. One patient, in whom an apical defect was demonstrated on scintigraphy, had significant disease of the left main and left anterior descending coronary artery. Repeat testing after successful aortocoronary bypass grafting revealed improved exercise capacity and a normal ²⁰¹TI myocardial scintigram. The data indicate that patients with mitral valve prolapse alone do not have regional myocardial ischemia and that the presence of a defect on ²⁰¹TI myocardial scintigraphy following maximal stress testing would suggest the existence of concomitant coronary artery disease.     

Exercise stress myocardial perfusion scintigraphy with thallium-201.

We performed exercise stress scintigraphy with thallium-201 in 88 patients including 31 patients of effort angina and nine patients of old myocardial infarction without angina. Sensitivity of exercise stress scintigraphy to detect effort angina was 77%, whereas sensitivity of exercise stress ECG was only 44.5%. The combination of stress scintigraphy with stress ECG enhanced sensitivity up to 87%. Exercise stress scintigraphy was useful particularly in cases with one vessel disease and those who failed to achieve sufficient exercise stress. Besides exercise stress scintigraphy did not show false positive response, differing from exercise stress ECG. Myocardial imaging is a method which shows the balance between myocardial perfusion demand and supply.     

Serial Exercise Thallium Myocardial Perfusion Scanning and Exercise Electrocardiography in the Diagnosis of Coronary Artery Disease*

Summary: Serial exercise thallium-201 myocardial perfusion scanning (exercise and 4-hour redistribution) was compared to rest and exercise electrocardiography (ECG) for the detection of coronary artery disease in 125 patients with known or suspected coronary artery disease. All patients underwent coronary arteriography and 108 were found to have significant coronary artery lesions. The serial exercise thallium scan was significantly more sensitive than rest and exercise ECG in detecting coronary artery disease (94% v. 83% P <0.01). The sensitivity of a reversible thallium perfusion scan abnormality and a positive exercise ECG for detecting exercise induced myocardial ischaemia in coronary artery disease was similar (69% v. 63%). The exercise thallium scan complemented the exercise EGG, and the sensitivity of the combined test was significantly greater than the exercise ECG alone (84% v. 63% P<0.001). The specificity for coronary artery disease of the exercise ECG was 65% and that of the exercise thallium-201 myocardial perfusion scan was 82% (P = NS). Thallium-201 myocardial perfusion scanning complements the rest and exercise ECG in the non-invasive detection of coronary artery disease.     

Assessment of percutaneous transluminal coronary angioplasty by atrial pacing and thallium-201 myocardial imaging: a case report

Combined atrial pacing and thallium-201 scintigraphy were performed in a man with multiple coronary artery lesions unable to perform exercise stress testing. Severe angina and ischemic ST depression in the inferior and anterior ECG leads occurred at a peak double product of 22,400 beats-mm Hg/min; thallium-201 scintigraphy showed reversible perfusion defects of the inferior, posterior, and septal segments. After angiographically successful angioplasty of a 95% right coronary artery lesion, repeat atrial pacing/thallium-201 scintigraphy (peak double product 27,750 beats-mm Hg/min) produced mild angina no ST depression in the inferior leads, and a normal thallium-201 scan. This case illustrates the value of the atrial pacing/thallium-201 stress test for evaluating the need for, and results of, coronary angioplasty in patients unable to perform exercise stress testing.     

The role of “Ischemic ST-segment Counterpoise” in rendering the response of exercise electrocardiogram falsely negative

Exercise electrocardiogram (ECG) has a high rate of false negative results in comparison with simultaneously performed thallium-201 perfusion scintigraphy, particularly in patients with single-vessel coronary artery disease, low exercise workload, inadequate heart rate rise, and resting ECG abnormalities. We present the case of a patient in whom thallium-201 SPECT scintigram revealed equally extensive and severe myocardial ischemia in two myocardial planes opposite each other. The accompanying exercise ECG did not disclose ischemic changes despite the adequacy of heart rate rise in this patient with severe right and left anterior descending coronary artery disease. We propose, as an explanation for this phenomenon, that in this patient the ischemic ST-segment vectors of equal magnitude and direction but of opposite sense, generated during stress, cancelled each other (“ischemic ST-segment counterpoise”), thus rendering the exercise ECG normal.     

Uncomplicated first myocardial infarction: strategy for comprehensive prognostic studies

To evaluate the prognostic role of combined cardiac studies (submaximal exercise test, thallium-201 scintigraphy, radionuclide exercise ventriculography, two-dimensional echocardiography, Holter monitoring and cardiac catheterization) in patients with a first acute myocardial infarction without complications during hospital admission, 115 consecutive patients aged less than 65 years were prospectively evaluated. The studies were carried out before hospital discharge and the patients were then clinically followed up for 12 months. During the follow-up period, 69 patients (60%) developed complications, which were severe in 23 (20%). Half of all complications and 70% of severe complications developed during the 1st follow-up month. Logistic regression analysis disclosed that the combination of studies with the highest predictive power for complications (probability of complications 99%) and severe complications (probability of severe complications 95%) was the association of exercise test + thallium-201 + echocardiogram. Four decision models (exercise test + echocardiography, exercise test + radionuclide ventriculography, thallium-201 scintigraphy + echocardiography, thallium-201 scintigraphy + radionuclide ventriculography) allowed the stratification of all patients in a particular risk category (high, intermediate or low). The best decision model was the association of thallium-201 scintigraphy + radionuclide ventriculography (probability of complications if both tests were positive 84%; probability of absence of severe complications if both tests were negative 88%), but there were no significant differences with the other models. Any association of a test detecting residual ischemia or functional capacity, or both (exercise test or thallium-201) and a test assessing ventricular function (echocardiography or radionuclide ventriculography) results in significant prognostic information in patients with an uncomplicated first acute myocardial infarction. Additional cardiac catheterization does not improve the predictive power of noninvasive studies, which should ideally be performed before hospital discharge because most complications develop during the 1st follow-up month.     

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.     

Single dose myocardial perfusion imaging with thallium-201: application in patients with nondiagnostic electrocardiographic stress tests.

The rote of the single dose technique of myocardial perfusion imaging with thallium-201 in evaluating patients with suspected coronary artery disease was studied in 128 patients undergoing diagnostic coronary arteriography. Significant coronary disease (70 percent or more luminal stenosis) was present in 95 patients. Exercise scans were compared with 4 hour redistribution scans for the presence of new defects with exercise. Myocardial perfusion imaging was significantly more sensitive (85 versus 64 percent, P < 0.01) and more accurate (84 versus 71 percent, P < 0.05) than stress electrocardiography in detecting coronary disease.The patients were classified into two groups: group I,89 patients with diagnostically adequate stress electrocardiograms (that is, positive for ischemia or negative at 85 percent or more predicted maximal heart rate), and group II, 39 patients with nondiagnostic stress electrocardiograms (that is, uninterpretable because of intraventricular conduction disturbance or inadequate because of absence of ischemic S-T depression but failure to achieve 85 percent of predicted maximal heart rate). The sensitivity (87 percent), specificity (85 percent) and accuracy (87 percent) of myocardial perfusion imaging in detecting coronary disease in group I were not significantly different from the results of stress electrocardiography alone (88 percent sensitivity, 85 percent specificity and 88 percent accuracy). in group II scintigraphy was 81 percent sensitive, 69 percent specific and 77 percent accurate in detecting coronary disease; these results were not significantly different from those in group I.These data indicate that myocardial perfusion imaging with thallium-201 is more sensitive and more accurate than stress electrocardiography in detecting coronary artery disease but offers no advantage for this purpose in patients with diagnostically adequate stress electrocardiograms.     

Prognostic value of thallium-201 exercise scintigraphy in low-risk patients after Q-wave myocardial infarction: comparison with exercise testing and catheterization.

In a prospective study of 100 consecutive patients discharged after a Q-wave myocardial infarction, the value of reversible ischemia on thallium-201 scintigraphy to assess the risk of cardiac events (death or reinfarction) during 4 years was compared with variables from exercise testing and cardiac catheterization. Patients with markedly impaired left ventricular function [ejection fraction (EF) < or = 0.30] were excluded. During follow-up there were 20 cardiac events (10 cardiac deaths and 10 reinfarctions). Thallium-201 scintigraphy was significantly better than all exercise test variables and better than an EF < 0.40, with good sensitivity and specificity (75 and 51%, respectively). Exercise-induced reversible ischemia on scintigraphy yielded the same information as the presence of multivessel disease. Exercise test variables were of limited value to assess prognosis. Thus, thallium-201 scintigraphy can be used as the only tool to predict future cardiac events in low-risk patients after a Q-wave myocardial infarction.     

Comparison between dobutamine echocardiography and thallium-201 scintigraphy in detecting residual stenosis,ischemia, and necrosis in patients with prior myocardial infarction

Background: Following the first attempts to detect myocardial ischemia with two-dimensional echocardiography stress testing, pharmacologic stress using dobutamine infusion has become an alternative to echocardiography exercise testing for evaluation of coronary artery disease. It has been shown that stress echocardiography has a diagnostic accuracy similar to that of an exercise thallium test. Other studies, however, indicated that radionuclide myocardial perfusion imaging was more sensitive than exercise or pharmacologic stress echocardiography for detection of ischemia or jeopardized myocardium. Hypothesis: The aim of the present study was to determine the ability of dobutamine stress echocardiography in comparison with thallium-201 scintigraphy to identify multivessel disease and the presence of myocardial scar and ischemia in 60 consecutive patients who suffered a first myocardial infarction (MI). Methods: Patients were evaluated by coronary angiography and ventriculography, thallium-201 (²⁰¹Tl) tomographic scintigraphy, and dobutamine echocardiography within 3 months of a first MI. Forty-seven had Q-wave MI and 13 had non-Q-wave MI. Eleven patients were excluded from final analysis—7 because of failure to achieve target heart rate in spite of the use of atropine, and 4 because of high blood pressure following the infusion of dobutamine. Results: Dobutamine echocardiography showed an overall sensitivity of 43% for detection of coronary artery lesions of 50–74% diameter stenosis and ²⁰¹Tl scintigraphy showed a sensitivity of 71%. For detection of lesions of ≥75% diameter stenosis, dobutamine echocardiography showed a sensitivity of 52% and ²⁰¹Tl a sensitivity of 70%. Overall agreement between wall motion and myocardial perfusion for detection of necrosis and/or ischemia in the infarct area was 40.4% with a kappa coefficient of 0.09 (p = 0.13). For detection of ischemic myocardium outside the infarct zone, overall agreement was 78.6% with a kappa coefficient of 0.49 (p<0.0001). Conclusion: Dobutamine echocardiography results showed a lower sensitivity than myocardial perfusion images in predicting multivessel coronary artery disease, and there was poor agreement between both methods in identifying necrosis or ischemia.     

Safety and diagnostic accuracy of adenosine thallium-201 scintigraphy in patients unable to exercise and those with left bundle branch block.

Three hundred forty consecutive patients (mean age 69 +/- 9 years) were evaluated with adenosine tomographic thallium-201 scintigraphy for suspected coronary artery disease. Minor side effects occurred in 91% of patients. Out of 28 patients (8%) with potentially serious side effects, 28 had significant atrioventricular (AV) block (second-degree, 24 patients; third-degree, four patients; syncope occurred in two patients). Acute bronchospasm and severe refractory angina pectoris occurred in one patient each. All side effects were transient and without sequelae. One hundred twenty-one patients underwent coronary angiography within 9 days of adenosine thallium imaging. The predictive accuracies of adenosine thallium imaging for identifying and localizing ischemia to a specific coronary distribution were: left anterior descending = 88%, left circumflex = 84%, right coronary = 88%. The predictive accuracy of adenosine thallium imaging in patients with left bundle branch block was 91%, and was higher than the 71% predictive accuracy noted in 39 patients who underwent exercise thallium testing (p = 0.04). It is concluded that adenosine thallium-201 myocardial scintigraphy was (1) highly accurate for the detection and localization of significant coronary artery disease; (2) it was more accurate at detecting ischemia in patients with left bundle branch block than exercise thallium testing, and (3) subjective side effects were common and were of no diagnostic importance; transient AV block occurred occasionally.     

心电图运动试验对急性心肌梗塞后患者残余心肌缺血的评价

５２例急性心肌梗塞后２～１２周患者进行次极量蹬车心电图运动试验，心肌缺血发生率为４４．２％。与冠状动脉造影对比，多支病变者阳性率高于单支病变（Ｐ＜０．０１）；与运动２０１铊心肌显像对比，前者阳性率较低（Ｐ＜０．０１）；心电图运动试验中非梗塞区心肌缺血组阳性率高于梗塞周围缺血组（Ｐ＜０．０２５）；ＳＴ段抬高组左室射血分数低于ＳＴ段正常或压低组（Ｐ＜０．０１）。心电图运动试验对诊断梗塞后残余心肌缺血，特别是非梗塞区心肌缺血有一定价值，运动中ＳＴ段抬高可能预示较差的心功能。     

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.     

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.     

Spontaneous changes in thallium-201 myocardial perfusion imaging after myocardial infarction

To examine regional myocardial perfusion after myocardial infarction, 26 patients underwent exercise electrocardiographic testing with thallium-201 myocardial perfusion imaging 3 weeks and 3 months after infarction. At 3 weeks, 9 of 26 patients (35%) had myocardial ischemia by exercise electrocardiographic testing, whereas 18 of 26 (69%) had ischemia by thallium-201 imaging. The thallium-201 scintigrams were scored by dividing each image, in 3 views, into 5 segments, using a 5-point scoring scheme. The exercise thallium-201 score was 44.3 ± 1.2 and increased to 47.3 ± 1.2 in the redistribution study (p < 0.001). Three months after infarction, although there was a significantly greater rate-pressure product which would predict a larger ischemic defect and a decrease in the stress thallium-201 score, the stress score was improved (48.3 ± 1.1, p < 0.001). The redistribution score was similar, that is, 48.9 ± 1.0. The improvement in thallium-201 myocardial perfusion was associated with a loss of stress-induced ischemia in 8 patients (30%). These results indicate that spontaneous improvements in thallium-201 myocardial perfusion imaging may occur after myocardial infarction.     

Improved myocardial ischemia and left ventricular function during exercise after successful percutaneous transluminal coronary angioplasty

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 42 patients with effort angina, 28 (67%) of them underwent successful angioplasty. Treadmill exercise testing, thallium-201 myocardial scintigraphy and radionuclide ventriculography were performed before and after PTCA for evaluation of the improvement of myocardial ischemia and left ventricular function at rest and during exercise. The average exercise duration by treadmill testing in 14 successful cases increased from 14 +/- 4 (mean +/- S.D.) to 16 +/- 2 minutes (p less than 0.05). Sixteen of 28 the patients were studied by thallium-201 myocardial scintigraphy. Before PTCA, regions of decreased thallium-201 uptake after exercise were observed in 12 of the 16 patients. After angioplasty, no distinct defects were recognizable in 9 of the 12 patients, and in the remaining three, a significant decrease in defects was recognized. Fifteen of the 28 patients were studied by radionuclide ventriculography. The mean ejection fraction was 61 +/- 5% at rest and 56 +/- 11% during exercise (N.S.) before PTCA. After angioplasty, the ejection fraction was unchanged at rest (61 +/- 5 to 62 +/- 4%), but increased significantly during exercise (62 +/- 4 to 74 +/- 4%, p less than 0.001). In conclusion, left ventricular function was improved by successful PTCA due to improvement of myocardial ischemia. The long term results require further study.     

Myocardial bridging of the left anterior descending artery: Evaluation using exercise thallium-201 myocardial scintigraphy

Seven patients with myocardial bridging of the left anterior descending coronary artery were evaluated by means of thallium-201 exercise scintigraphy. The degree of systolic narrowing was 60–70% in five patients and 75–80% in two patients. All patients had presented with chest pain. The resting electrocardiogram was normal in six patients; there were ST segment and T-wave abnormalities in one patient. No patient complained of chest pain during exercise. The exercise electrocardiogram was negative in six patients and inconclusive in one patient. Exercise myocardial scans were negative in all seven patients. We conclude that no evidence of ischemia was demonstrated in patients with myocardial bridging of the left anterior descending coronary artery as determined by exercise electrocardiography and stress thallium-201 scintigraphy.