Thallium-201 myocardial scintigraphy and left ventricular function at rest in patients with rest angina pectoris

The purpose of this study was to examine the rest thallium-201 perfusion pattern during angina-free periods in 40 patients with rest angina pectoris secondary to coronary artery disease (greater than or equal to 70% diameter narrowing). Seventeen patients had previous Q wave myocardial infarction. The perfusion defects were considered fixed or reversible, depending on the absence or presence of redistribution in the 4-hour delayed images. There were 40 perfusion defects (26 fixed and 14 reversible) in 27 patients whereas 13 patients had normal scans. Reversible perfusion defects were present in 10 patients (25%). Of the 26 fixed perfusion defects, 17 did not have corresponding Q waves. Occluded vessels (63%) had more perfusion defects than vessels with subtotal occlusion (30%) (p less than 0.01). The perfusion defect size was larger in patients with lower ejection fraction than in patients with higher ejection fraction. We conclude: (1) perfusion defects are common in patients with rest angina and are reversible in 25% of patients indicating reduced regional coronary blood flow; (2) the degree of stenosis affects the presence of perfusion defect; (3) fixed defects may be present without corresponding Q waves; and (4) global left ventricular function is related to the size of perfusion defects.     

Comparative study of myocardial ischemia during angina at rest and on exertion using thallium-201 scintigraphy

To compare the results of thallium-201 myocardial scintigraphy during angina at rest with those observed during effort angina, 81 patients were selected in whom the existence of acute myocardial ischemia was indicated both by typical transient S-T segment or T wave changes and by typical anginal pain. In these patients, scintigrams were obtained during 58 attacks of angina on effort (group 1) and during 40 attacks of angina at rest (group 2); 16 patients were studied during both types of angina. The attack at rest was spontaneous in 20 patients and induced by ergonovine maleate in 20 patients.In the presence of S-T segment elevation or transient normalization of inverted T waves, scintigrams were positive in all 24 studies at rest and in 19 of 20 studies during exercise. By contrast, in the presence of S-T segment depression scintigrams were positive in 14 (95 percent) of 15 studies during angina at rest, but in only 20 (53 percent) of 38 during angina on effort. Neither the degree of S-T segment changes nor their duration after injection of thallium was significantly different in resting studies relative to exercise studies, but the heart rate and double product were consistently higher during exercise.The marked difference in sensitivity in detecting ischemia in angina at rest with S-T segment depression compared with detection during exertional angina, even in the same patients, suggests that different pathogenetic mechanisms are responsible for the attack. Conversely, a similar mechanism operating in angina at rest and on exertion during S-T segment elevation and normalization of T waves is suggested by the similarity of thallium-201 scintigraphic findings in this situation. The findings are compatible with the hypothesis of a regional reduction in myocardial blood flow in angina at rest, independently of the direction of S-T segment change, and in exertional angina with S-T segment elevation or normalization of inverted T waves; they suggest an inadequate increase in myocardial blood flow in angina on effort with S-T segment depression.     

Effect of beta-blocker therapy on myocardial perfusion defects in thallium-201 scintigraphy in patients with dilated cardiomyopathy

BACKGROUND: The beneficial effects of beta-blocker therapy in patients with heart failure have been confirmed. However, the effects of beta-blockers on myocardial perfusion defects are unclear. The aim of this study was to evaluate the effect of beta-blockers on myocardial perfusion defects estimated by thallium-201 myocardial scintigraphy in patients with dilated cardiomyopathy (DCM) and to investigate the relationships between beta-blocker treatment and myocardial damage and cardiac function. METHODS:201Tl and echocardiography were performed in 37 patients before and after 6 months of beta-blocker therapy. Extent score (ES) by 201Tl was used to quantitate myocardial perfusion defects before and after treatment. RESULTS: ES was significantly decreased by beta-blocker therapy. According to the change in ES, DCM patients were classified into three groups, patients who improved, patients showing no change and patients who deteriorated. In the improvement and no-change groups, beta-blocker therapy induced a reduction in left ventricular dimensions and an associated increase in ejection fraction. However, in the deterioration group, left ventricular dimensions and ejection fraction were unchanged. There was a significant relationship between the change in left ventricular dimension at end-diastole and the change in ES. CONCLUSIONS: beta-Blocker therapy could attenuate myocardial perfusion defects in some patients with DCM. The improvement in left ventricular function associated with beta-blocker therapy may be related to the attenuation in myocardial perfusion defects.     

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.     

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.     

Prognostic significance of large perfusion defects on thallium-201 myocardial scintigraphy in dilated cardiomyopathy

To evaluate the prognostic significance of perfusion abnormalities, particularly large defects, in dilated cardiomyopathy (DCM), we performed thallium-201 myocardial scintigraphy and 24-hour ambulatory ECG monitoring in 27 patients. The abnormal scintigraphic patterns and the presence of ventricular tachycardia (VT) were correlated with causes of death during a follow-up period of 30.0 +/- 19.4 months. Eight patients had large defects (LD), 11 had multiple small defects (MSD), and eight had no defects (NL). The patients with LD had extensive ventricular akinesis in the region of the perfusion defect, significantly elevated LVEDP (LD 20.6 +/- 7.4 mmHg, MSD 15.5 +/- 7.6 mmHg, NL 10.3 +/- 2.3 mmHg: LD vs NL; p less than 0.01, MSD vs NL; p less than 0.05), and reduced ejection fraction (LD 23.9 +/- 9.1%, MSD 32.7 +/- 7.2%, NL 40.3 +/- 7.7%: LD vs MSD; p less than 0.05, MSD vs NL; p less than 0.01). VT was detected in 11 patients; among whom three had LD, six had MSD, and two had no defects. Among seven patients who died during follow-up (five of heart failure, one sudden death, and one non-cardiac death), five had LD and two had MSD. There were no deaths among patients without defects. Among 11 patients with VT, only one died suddenly. In conclusion, large scintigraphic defects correlated well with severe LV dysfunction, and this is an important variable in predicting outcomes in DCM.     

Prognostic role of stress/rest myocardial perfusion scintigraphy in patients with cardiac syndrome x

Aim

The prognostic utility of myocardial perfusion scintigraphy (MPS) in patients with angiographically normal coronary arteries has not been evaluated yet. Our aim was to determine the prognostic role of positive MPS in patients with angina, positive exercise test and smooth coronary arteries (syndrome X).

Methods

A total of 156 patients with angina, positive exercise test, positive MPS and normal coronary arteries and 172 patients with angina and positive exercise test who had negative MPS were selected for study. The primary endpoint was combined all-cause mortality and hospitalizations for cardiac causes. The secondary endpoint was hospitalization for cardiac causes.

Results

Kaplan–Meier analysis showed a greater (p = 0.001) incidence of the primary endpoint in patients with positive MPS, compared to those with negative MPS. Additionally, Kaplan–Meier analysis for cardiovascular hospitalization showed a significant difference (p = 0.003) between the two groups. Cox regression analysis, adjusted for age, sex, BMI and antianginal therapy confirmed a significant risk increase for patients with positive MPS, with a hazard ratio (HR) = 3.20 (CI 95%: 1.14–9.02; p = 0.028). Cox analysis for cardiovascular hospitalization also showed a significant risk increase for patients with positive MPS (HR = 3.19; CI 95%: 1.13–9.00; p = 0.03). Finally, Cox analysis showed that patients with positive MPS tend to have a higher risk to remain symptomatic in the follow-up period (HR = 1.614; CI 95%: 0.999–2.607; p = 0.51).

Conclusions

This study shows that inducible myocardial hypoperfusion at MPS in patients with syndrome X could discriminate patients with a more severe prognosis, especially in terms of further hospitalization and symptomatic burden.     

Thallium scintigraphy in patients with angina at rest

Sixty six patients with angina at rest were investigated by exercise electrocardiography, thallium scintigraphy, and coronary arteriography. A positive exercise electrocardiogram was highly predictive (93%) but poorly sensitive (52%) of coronary artery disease (greater than or equal to 50% stenosis). Thallium scintigraphy was as predictive of the presence of coronary artery disease (91%) but was also highly sensitive (91%). The diagnostic contribution of the thallium scan was greatest in those patients with an inconclusive exercise electrocardiogram without Q waves.     

Efficacy of intravenous dipyridamole with exercise in thallium-201 myocardial perfusion scintigraphy

To assess the feasibility and the value of thallium–201myocardial perfusion imaging with intravenous dipyridamole incombination with low-level exercise, 81 patients with suspectedor proven coronary artery disease were studied. All patientsunderwent coronary arteriography. Significant coronary arterydisease (stenoses 50%) was present in 59 patients (73%); multivesseldisease (double- and triple-vessel desease) was observed in33 patients (42%). The overall sensitivity and specificity ofthe test were 78% and 86%, respectively. Sensititvity and specificityfor detection of multivessel disease were 70% and 92%, respectively.The sensitivity for detecting coronary artery disease in theRCA, LAD, and LCX was 74%, 82% and 48%, respectively, and thespecificity was 85%, 88% and 88%, respectively. With the combinedprocedure no serious side effects were observed. Mild side effectslike headche, vertigo and uausea were seen in 12 patients (15%). Twenty volunteers with a 1% likelihood of significant coronaryartery disease were examined in the same manner to determinethe maximal specificity of the procedure (100%). Thus, the combinationof two different stress procedures (exercise testing and dipyridamoleinfusion) can be performed safely without serious side effects.The presence, location and extent of significnt coronary arterydisease can be assessed to a similar degree as with conventionalexercise thallium-201 scintigraphy, which has major implicationsfor the detection of coronary artery disease in patients whoare unable to perform maximal exercise.     

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.     

Thallium scintigraphy in patients with angina at rest.

Sixty six patients with angina at rest were investigated by exercise electrocardiography, thallium scintigraphy, and coronary arteriography. A positive exercise electrocardiogram was highly predictive (93%) but poorly sensitive (52%) of coronary artery disease (greater than or equal to 50% stenosis). Thallium scintigraphy was as predictive of the presence of coronary artery disease (91%) but was also highly sensitive (91%). The diagnostic contribution of the thallium scan was greatest in those patients with an inconclusive exercise electrocardiogram without Q waves.     

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.     

Effect of regional myocardial perfusion abnormalities on regional myocardial early diastolic function in patients with hypertrophic cardiomyopathy

Summary Nonuniform hypertrophy of the left ventricle is an important factor in regional diastolic dysfunction in patients with hypertrophic cardiomyopathy (HCM). However, the effect of myocardial perfusion abnormalities on regional diastolic dysfunction has not been established in patients with HCM. We investigated the relationship between regional myocardial perfusion abnormalities and regional early diastolic function in 31 patients with HCM and 8 control patients. Short-axis images of the left ventricle recorded by cine magnetic resonance imaging were divided into ten blocks. The time-to-peak-wall-thickness-thinning rate (TPWR) and the wall thickness were measured in each block. Of the 310 blocks from the patients with HCM, 242 (78%) showed normal thallium-201 uptake (group 1), 40 (13%) showed slightly decreased uptake (group 2), and 28 (9%) showed markedly decreased uptake (group 3). There was no difference in the regional wall thickness among the three groups. The TPWR was longer in patients with HCM than in control patients. It was significantly longer in group 3 (190±45ms) than in group 1 (167±36ms) and group 2 (160±31ms). (P<0.01). The linear regression slope of the relationship between the TPWR and the regional wall thickness was significantly steeper in group 3 than in groups 1 and 2 (P<0.05). In conclusion, abnormalities in regional myocardial perfusion, in addition to regional hypertrophy, contributed to the regional early diastolic dysfunction in patients with HCM.     

Variability of myocardial perfusion defects assessed by thallium-201 scintigraphy in patients with coronary artery disease not amenable to angioplasty or bypass surgery

OBJECTIVES: We sought to assess the variability of results obtained with thallium scintigraphy as a method for tracking the extent of myocardial ischemia in medically refractory patients with angina who are not suitable for coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty. BACKGROUND: New therapies are being evaluated for patients with "no option" angina in whom medical therapy has failed. Nuclear techniques, like thallium scintigraphy, are used in multicenter trials to evaluate whether such therapies improve myocardial perfusion. However, the variability of test results is unknown in this patient group in a multicenter study. METHODS: The Angina Treatments: Lasers And Normal Therapies In Comparison (ATLANTIC) study was a randomized trial of transmyocardial laser revascularization (n = 182). Patients underwent dipyridamole thallium stress tests at baseline and 3, 6 and 12 months after enrollment. The control group (n = 90) was treated with constant medical therapy during the study and is a relevant group to investigate test variability. Test variability over time was quantified by the mean absolute change in the percentage of reversible perfusion defects between baseline and follow-up. RESULTS: Baseline percent myocardium with ischemia averaged 17.0 +/- 13.7% and did not change during follow-up. However, variations in the percent myocardium with reversible perfusion defects over time amounted to an average of 6 to 8 percentage points, or 43% to 55% of the baseline value. Only approximately 13% of this variability was attributable to variability in image reconstruction and analysis. CONCLUSIONS: As demonstrated in the ATLANTIC study, percent myocardial ischemia in control subjects receiving constant medical therapy varied in individual patients by an average of approximately 50%. This may limit the utility of thallium scintigraphy to detect improved myocardial perfusion over time in response to therapy.     

Thallium-201 scintigraphy perfusion defect with dipyridamole in a patient with a myocardial bridge

A patient with myocardial bridging and a thallium-201 scintigraphy perfusion defect after the administration of intravenous dipyridamole is presented. The same patient had a normal perfusion study on exercise stress testing. The effects of coronary vasodilators and dipyridamole on coronary artery flow patterns in patients with myocardial bridging are discussed. We suggest that coronary vasodilators may induce perfusion defects in patients with myocardial bridging and should be avoided in such patients.     

Alterations in myocardial metabolism and function at rest in stable angina pectoris: relations with the amount of exercise-induced thallium-201 perfusion defect

The relation between the amount of exercise-induced ischemia and alterations in left ventricular (LV) function and metabolism at rest was studied in 18 coronary patients with stable angina pectoris. An ischemic defect area score was computed from quantitative exercise thallium-201 (Tl-201) scintigraphy; this estimation of the amount of ischemic myocardium was used to classify the patients in group I (n = 8; score less than 15%, mean 6.7 +/- 2.5%) and II (n = 10; score greater than 15%; mean 27.2 +/- 8.9%). Hemodynamics and metabolism were studied in basal state. No patient had anginal pain during the study, and the extent of angiographic coronary artery disease (CAD) was comparable in the two groups. Heart rate, aortic pressure, coronary blood flow, and myocardial oxygen uptake were also similar in both groups. However, ejection fraction was reduced in group II (51 +/- 13 vs 63 +/- 5%; p less than 0.01) and LV relaxation was impaired as shown by the increase in time-constant of isovolumic pressure fall (55 +/- 16 vs 44 +/- 6 ms in group I; p less than 0.05); the LV end-diastolic pressure was also increased in group II (19 +/- 8 vs 10 +/- 4 mmHg in group l; p less than 0.05). Furthermore, in group II, myocardial lactate uptake was reduced (4 +/- 19 vs 30 +/- 29 mumole/min in group I; p less than 0.01) and the productions of alanine and glutamine were augmented (-7.5 +/- 4.4 vs -4.6 +/- 1.6 mumole/min in group I; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)