Functional reserves of myocardial perfusion in patients with chronic ischemic heart disease with varying degrees of damage of the coronary arteries

A comparative study of data provided by coronaro-angiography and myocardial perfusion scintigraphy (resting and exercise tests), and clinical/electrocardiographic results of the exercise test in 102 chronic coronary patients demonstrated that non-invasive myocardial perfusion 201Tl scintigraphy combined with threshold bicycle-ergometric exercise adds considerably to the clinico-electrocardiographic assessment of the exercise test and thus helps to detect myocardial blood supply (perfusion) disorders in some of coronary patients with doubtful or negative test results. Reduced functional reserves of myocardial blood supply, as reflected in deficient perfusion at the peak of threshold exercise, are seen in all coronary patients with angiographically intact coronary arteries and in most patients with both the so-called "functionally-insignificant" and marked coronary arterial stenosis (94.7 and 88.3%, respectively).     

Abnormalities of myocardial perfusion in sickle cell disease in childhood: a study of myocardial scintigraphy

Ischaemic complications are common in SS homozygotic sickle cell disease in children, but the heart does not appear to be the target organ. The early detection of myocardial ischaemic in these children could prevent cardiac complications. The authors undertook a study of myocardial perfusion by myocardial scintigraphy in children with sickle cell disease. Twenty-three patients (average age 12 +/- 5 years) underwent Thallium 201 myocardial scintigraphy. Exercise on a bicycle ergometer and/or intravenous injection of dipyridamole were carried out depending on the age. The images (on exercise and late recovery period) were analysed in the 3 standard projections of the left ventricle: short axis, long axis and 4-chamber view. The left ventricular ejection fraction was measured by gamma angiography. Myocardial perfusion was abnormal in 14 patients (61%). The perfusion defects were reversible in the late recovery period in 9 patients and irreversible in 5 patients. The average left ventricular ejection fraction was 63 +/- 9%. Its value was not related to symptoms, haemoglobin level or the results of myocardial scintigraphy. Four patients with perfusion defects were symptomatic (cardiac failure, angina or ventricular tachycardia); 1 patient died and 3 were treated with hydroxyurea. Myocardial scintigraphy was carried out 6 months later and showed improved perfusion in 3 patients. Abnormalities of myocardial perfusion are therefore common in sickle cell disease. Often asymptomatic in childhood, there is a real risk of ischaemic cardiomyopathy and its complications in adulthood. Specific treatment of sickle cell disease with hydroxyurea should be considered in cases with significant abnormalities of myocardial perfusion.     

X-syndrome: myocardial perfusion during stress testing.

Stress T1-201 myocardial scintigraphy was carried out in 16 patients with X-syndrome. 11 patients with ischaemic heart disease (IHD) with single vessel disease served as controls. With bicycle exercise test all 16 pts with X-syndrome had various types of myocardial perfusion abnormalities. These perfusion defects were situated in the vascular beds of different coronary arteries. Myocardial perfusion defects in patients with X-syndrome were similar to those in patients with moderate, but haemodynamically significant, single vessel disease. At the same time, these perfusion defects were significantly less pronounced than those in patients with subtotal occlusion of one coronary artery. Thus, patients with X-syndrome not only have clinical features of IHD (anginal attacks), but have marked stress-induced myocardial perfusion defects.     

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.     

Study of left ventricular function at rest and post-exercise with thallium-201 myocardial scintigraphy synchronized with ECG

ECG-gated Thallium 201 myocardial scintigraphy provides a simultaneous evaluation of left ventricular perfusion and function. The aims of this study were to determine the changes in left ventricular ejection fraction (LVEF) after exercise and at rest 4 hours after exercise and to compare the results with changes in myocardial perfusion and the severity of the coronary artery disease. Sixty-four men with myocardial ischaemia on scintigraphy who had undergone coronary angiography showing significant lesions within 3 months, were compared with 38 normal men. The ejection fraction was calculated with a validated programme (QGS). The change in LVEF between the post-exercise and resting measurement 4 hours after exercise (delta LVEF) was compared in the normal and ischaemic groups (+7 +/- 6.8% vs -5.6 +/- 5%, p < 0.001). The extent of the ischaemia (percentage myocardium unperfused) was significantly greater in the 34 patients who had an over 5% reduction in LVEF on exercise compared with the 30 others who has a less than 5% reductionin LVEF (11.8 vs 6.3%, p < 0.001). There was a linear correlation between the degree of ischaemia and delta LVEF in the 30 patients without a history of infarction (r = -0.76, p < 0.01). The delta LVEF also correlated with the number and site of the coronary lesions. The authors conclude that in this male population, ECG-gated Thallium 201 myocardial scintigraphy can demonstrate a decrease in LVEF after exercise in ischaemic coronary patients whereas it increases in normal subjects. This decrease in LVEF on exercise is correlated with the extent of ischaemia and the severity of the coronary disease and should therefore be taken into account in patient management.     

Myocardial perfusion in mitral valve prolapse with arrhythmic syndrome]

Myocardial perfusion was studied in 12 patients with mitral valve prolapse concurrent with cardiac arrhythmias by using two-dimensional 201Tl myocardial scintigraphy at rest and during exercise test. Signs of myocardial ischemia were revealed only in one case. Five patients were found to have steady-state perfusion defects whose extent correlated with the depth of mitral valve prolapse. There was an irregular distribution of myocardial blood flow, which ceased on exercise in 10 out of 12 patients. Patients with ventricular premature contraction displayed a decreased reserve of myocardial blood flow as compared to those with supraventricular premature contraction, presumably by enhancing myocardial perfusion at rest.     

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.     

Changes in myocardial perfusion in ischemic heart disease as affected by nitrong

The effect of nitrong on myocardial perfusion in patients with ischemic heart disease was studied by a new method of myocardial perfusion scintigraphy usingd 201Tl. Myocardial scintigraphy with 201Tl, as an informative and atraumatic method, may be used for objective appraisal of the effect of antianginal agents. It is shown that in comparison to a placebo, nitrong causes a favourable effect on perfusion of the myocardium in patients with ischemic heart disease both at rest and under conditions of increased myocardial blood flow induced by physical exercise.     

Myocardial perfusion imaging for detection of silent myocardial ischemia

Despite the widespread use of the exercise stress test in diagnosing asymptomatic myocardial ischemia, exercise radionuclide imaging remains useful for detecting silent ischemia in numerous patient populations, including those who are totally asymptomatic, those who have chronic stable angina, those who have recovered from an episode of unstable angina or an uncomplicated myocardial infarction, and those who have undergone angioplasty or received thrombolytic therapy. Studies show that thallium scintigraphy is more sensitive than exercise electrocardiography in detecting ischemia, i.e., in part, because perfusion defects occur more frequently than ST depression and before angina in the ischemic cascade. Thallium-201 scintigraphy can be performed to differentiate a true- from a false-positive exercise electrocardiographic test in patients with exercise-induced ST depression and no angina. The development of technetium-labeled isonitriles may improve the accuracy of myocardial perfusion imaging.     

Defect images in stress thallium-201 myocardial scintigraphy in patients with complete left bundle branch block: comparison of exercise stress and pharmacological stress

OBJECTIVES: Stress thallium-201 (201Tl) myocardial scintigraphy can demonstrate perfusion abnormalities, especially in the septum in patients with complete left bundle branch block (CLBBB) even with angiographically normal coronary arteries. Differences in the images between exercise and pharmacological stress 201Tl myocardial scintigraphy were evaluated in patients with CLBBB and normal coronary arteries. METHODS: Forty-five patients with CLBBB underwent exercise stress using treadmill or pharmacological (adenosine triphosphate) stress 201Tl myocardial scintigraphy from October 1997 to February 2003. Patients with myocardial diseases were excluded, such as cardiomyopathy and coronary artery diseases detected by echocardiography and/or cardiac catheterization. The myocardial segment was classified according to the American Heart Association style for coronary artery disease. RESULTS: Peak blood pressure levels and heart rates were significantly higher in the exercise stress group than in the pharmacological stress group (p < 0.001). The rate of defects in stress images was significantly higher in the exercise stress group (72.4%; 21/29 cases) than in the pharmacological stress group (18.8%; 3/16 cases) (p < 0.01). The rate of redistribution of observed defects in delayed images was 76.2% (16/21 cases) in the exercise stress group, and 0% (0/3 cases)in the pharmacological stress group (p < 0.01). The myocardial segments showing defects were different between the exercise stress group and the pharmacological stress group. CONCLUSIONS: Patients with CLBBB showed different frequencies of defects by stress 201Tl myocardial scintigraphy according to the stress method. Moreover, defects also occured in areas other than the septum. Blood pressure and heart rate were involved in the mechanisms of defects in left bundle branch block.     

Comparative analysis of the diagnostic and prognostic value of exercise ECG and thallium-201 scintigraphic markers of myocardial ischemia in asymptomatic and symptomatic patients

A considerable amount of data now exists that indicates that exercise ECG--due to its suboptimal sensitivity and specificity--has limited diagnostic and prognostic value in asymptomatic subjects, patients with chest pain of unclear etiology or those with chronic stable angina pectoris, and in patients recovering from acute myocardial infarction. Because of this and the well-recognized advantages of thallium-201 scintigraphy, there appears to be a strong rationale for recommending exercise perfusion imaging, rather than exercise ECG alone, as the preferred method for detecting CAD and staging its severity. This recommendation seems justified given the fact that (1) thallium-201 scintigraphy is far more sensitive and specific in detecting myocardial ischemia than exercise testing; (2) unlike stress ECG, thallium-201 scintigraphy can localize ischemia to a specific area of areas subtended by a specific coronary artery; and (3) thallium-201 scintigraphy has been shown to be more reliable to risk stratification of individual patients than exercise testing alone. The more optimal prognostic efficiency of thallium-201 scintigraphy is due, in part, to the fact that the error rate in falsely classifying patients as low-risk is substantially and significantly smaller with thallium-201 scintigraphy than with stress ECG.     

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-induced thallium-201 myocardial perfusion defects in angina pectoris without significant coronary artery stenosis

We performed exercise thallium-201 myocardial scintigraphy in 32 patients with angina pectoris to study the incidence of perfusion defects, who had no significant organic stenosis on coronary angiography. None of them had myocardial infarction or cardiomyopathy. Thallium-201 myocardial scintigraphy and 12-lead ECG recording were performed during supine bicycle ergometer exercise. Perfusion defects in thallium-201 scintigrams in SPECT images were assessed during visual analysis by two observers. In the coronary angiograms obtained during intravenous infusion of nitroglycerin, the luminal diameter of 75% stenosis or less in the AHA classification was regarded as an insignificant organic stenosis. Myocardial perfusion defects in the thallium-201 scintigrams were detected in eight (25%) of the 32 patients. Six of these eight patients had variant angina documented during spontaneous attacks with ST elevations in standard 12-lead ECGs. Perfusion defects were demonstrated at the inferior or inferoposterior regions in six patients, one of whom had concomitant anteroseptal defect. The defects were not always accompanied by chest pain. All but one patient demonstrating inferior or inferoposterior defects showed ST depression in leads II, III and aVF on their ECGs, corresponding to inferior wall ischemia. The exception was a case with right bundle branch block. Thus, 25% of the patients with angina pectoris, who had no evidence of significant organic stenosis on their coronary angiograms, exhibited exercise-induced perfusion defects in their thallium-201 scintigrams. Coronary spasms might have caused myocardial ischemia in these patients.     

Assessment of myocardial perfusion with thallium-201 scintigraphy in exercise-induced left bundle branch block: diagnostic value and clinical significance.

Myocardial perfusion scintigraphy with thallium-201 was performed in 33 subjects (mean age 45 years, range 28-61) with exercise-induced, rate-dependent left bundle branch block (LBBB) in order to assess both the value of Thallium-201 myocardial imaging for the diagnosis of coronary artery disease (CAD) and the pathogenesis (ischaemic or not) of the conduction defect. Of the 33 patients evaluated, 16 had chest pain suggestive of CAD and 17 were asymptomatic. None had a history of prior myocardial infarction or clinical and echocardiographic signs of heart disease. LBBB appeared at a heart rate ranging from 70 to 160 b.min-1. Eighteen patients showed repolarization abnormalities (ST segment depression with deep inverted T waves) compatible with ischaemia, after QRS normalization. Thallium-201 myocardial uptake was normal in 12 subjects; in the remaining 21, reversible Thallium-201 defects were demonstrated in the septum (18 patients), septum and apex (2), and septum and infero-apical wall (1). No patient had irreversible defects and all had normal coronary angiography, with negative ergonovine tests for coronary artery spasm. The patients were followed up for a mean of 43 months (range 16-80). One patient died from sudden death, but no cardiac event occurred in the other patients. In conclusion, exercise Thallium-201 myocardial scintigraphy showed a high prevalence (64%) of reversible perfusion defects in a group of patients with exercise-induced LBBB without any evidence of CAD at angiography or coronary spasm at ergonovine test. Moreover, follow-up showed a relatively low rate of major cardiac events.     

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.     

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.     

Myocardial perfusion in patients with permanent ventricular pacing and normal coronary arteries

OBJECTIVES: The purposes of this study were to test the specificity of dipyridamole myocardial perfusion scintigraphy in patients with permanent ventricular pacing (PVP) and to evaluate coronary blood flow and reserve in these patients. BACKGROUND: Permanent ventricular pacing is associated with exercise perfusion defects on myocardial scintigraphy in the absence of coronary artery disease (CAD). On the basis of studies in patients with left bundle brunch block, coronary vasodilation with dipyridamole has been proposed as an alternative to exercise testing for detecting CAD in paced patients, but this approach has never been tested. METHODS: Fourteen patients with a PVP and normal coronary arteries underwent stress thallium-201 scintigraphy and cardiac catheterization. In these patients and in eight control subjects, coronary flow velocities were measured in the left anterior descending coronary artery (LAD) and in the dominant coronary artery before and after adenosine administration. RESULTS: In the paced patients, coronary flow velocities in the LAD and in the dominant coronary artery were significantly lower than those in the control subjects. In addition, seven patients showed perfusion defects on dipyridamole thallium-201 single-photon emission computed tomography, with a specificity of 50% for this test. The defect-related artery in these patients had lower coronary flow reserve (2.6 +/- 0.5) as compared with those without perfusion defects (3.9 +/- 1.0, p < 0.05) or the control group (3.5 +/- 0.5, p < 0.05). CONCLUSIONS: Permanent ventricular pacing is associated with alterations in regional myocardial perfusion. Furthermore, abnormalities of microvascular flow, as indicated by reduced coronary flow reserve in the defect-related artery, are at least partially responsible for the uncertain specificity of dipyridamole myocardial perfusion scintigraphy.     

Prognosis of silent myocardial ischemia: follow-up of 100 patients with positive treadmill test and exertion myocardial scintigraphy

Prognosis of asymptomatic myocardial ischemia is largely unknown and the opportunity is still controversial of seeking for patients with silent ischemia. Aim of the present study is to evaluate the prognosis of painless myocardial ischemia documented by exercise test and myocardial scintigraphy. From June 1981 through November 1986, 206 patients without angina, history or ECG signs of old myocardial infarction, presenting a positive (decreases ST greater than or equal to 1.5 mm) exercise treadmill test, underwent exercise Thallium 201 myocardial imaging. Myocardial scintigraphy showed a normal scan in 85 cases and a reversible or fixed perfusion defect in 121. Patients with abnormal scan presenting ischemia at a low to moderate ergometric work-load were treated with betablockers or calcium-antagonist drugs. Out of patients with positive myocardial scintigraphy a sample of the first 100 consecutive subjects was considered. They were 87 men and 13 women aged 28-72 years (mean 54.8) observed during a mean follow up period of 33.1 +/- 1.6 months. Seven patients underwent coronary angiography which showed 3-vessel critical stenosis in 3 cases, 3-vessel lesions plus critical stenosis of the left main coronary-artery in 1 and 2-vessel lesions in 3. Two patients underwent coronary artery bypass surgery. A non fatal myocardial infarction occurred in 1 and 1 became symptomatic for angina, 11 and 20 months respectively after the diagnosis of ischemia. Three patients with ischemia at a low work-load and extensive scintigraphic perfusion defects died of sudden death and one of cancer.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Assessment of coronary hemodynamics and myocardial perfusion in patients with syndrome X by digital subtraction angiography and 201Tl-myocardial scintigraphy]

To evaluate coronary hemodynamics and myocardial perfusion, left coronary digital subtraction angiography (DSA) and Tl-201 myocardial scintigraphy were performed in patients with syndrome X. The coronary circulation time (CCT) was significantly prolonged after the injection of isosorbide dinitrate and contrast medium i.c. Apical T1/2 was also prolonged on ergonovine malate provocation test. We suspected that the vascular response of the coronary peripheral artery was impaired, and microvascular spasm probably existed in patients with syndrome X. The prevalence of abnormal myocardial perfusion defect on exercise Tl-201 SPECT in syndrome X was very high, and coronary hemodynamics was significantly disturbed in the group of syndrome X with abnormal Tl-201 SPECT. Tl-201 lung/heart count ratio significantly increased in syndrome X on treadmill test. Because of this, exercise induced left ventricular dysfunction was suspected. We concluded that the main pathophysiological finding of impaired coronary circulation in syndrome X was microvascular spasm.