Diagnosis of coronary artery disease with exercise radionuclide imaging: state of the art

Comparison of supine versus prone tomographic myocardial imaging. Effect on false-positive rate

As in most other nuclear medicine facilities, tomographic myocardial imaging was started here with the patients in the supine position. However, previous planar imaging experience indicated a high number of false-positive results using the supine position for left lateral views of the myocardium. Evaluating the accuracy of supine position SPECT imaging was considered necessary. In 1991, 228 myocardial imaging procedures were performed during a period of 3 months. Coronary arteriography followed within 3 months in 67 of these patients, permitting evaluation of the accuracy of the imaging procedure interpretations. These correlations revealed the accuracy of myocardial imaging to be only 73%. This was caused mainly by a rather large number of false-positive results (24%) occurring mostly in the inferior-posterior wall. A similar comparison was performed in 1992 after a change to prone position for routine tomographic myocardial imaging with 63 of 295 patients undergoing coronary arteriography. These data revealed an increase in the overall accuracy to 81% and a decrease in the false-positive results to 16%. The improvements were almost entirely in the inferior-posterior regions with no significant change in the false-positive results in the anterior wall. These findings provide convincing evidence that the prone position should be selected for tomographic myocardial imaging.

Assessment of mitral regurgitation using gated radionuclide ventriculography: analysis of left atrial time activity curve

The authors analyzed the left atrial (LA) time activity curve (TAC) in 18 normal subjects and 30 patients with mitral regurgitation (MR) to assess the usefulness of radionuclide ventriculography (RNV) in detecting MR. The LA TAC was generated from gated blood pool images using phase and amplitude images. The configuration of normal LA TAC was M shaped. The first peak and last peak of LA TAC were represented as points B and D, respectively. In addition, the trough following B was named point C. The presence and severity of MR was analyzed by use of three methods: (1) analysis of LA TAC, (2) analysis of left ventricular TAC, and (3) measurement of the stroke count ratio of left ventricle to right ventricle. In the diagnosis of MR using RNV, the rapid emptying fraction [REF:(B-C)/(B-A)] of LA TAC was the most sensitive index compared with the other two methods. The sensitivity and specificity of MR with Sellers' II degrees or more were 0.84 and 0.90 in LA TAC but were 0.42 and 0.90 in the count method.

Quantitative phase analysis in the assessment of coronary artery disease

The phase image in radionuclide ventriculography shows the timing of ventricular contraction and is valuable in the detection of abnormalities induced by coronary artery disease. The image is usually interpreted subjectively, and in the present study a histogram of left ventricular phase values was used to make interpretation more objective. The left ventricular ejection fraction and the standard deviation, skewness, and kurtosis of the phase histogram were measured at rest, during isometric exercise, and during the final two stages of maximal dynamic exercise in 25 controls and 27 patients with coronary artery disease without previous infarction. The ejection fraction and the standard deviation of the phase had the same predictive accuracy for the presence of disease when measured during the penultimate stage of dynamic exercise (89%) as during the final stage, but their accuracy was lower during maximal exercise (77%) because of motion artefact at high exercise levels. Skewness and kurtosis of the histogram were of no value for the detection of disease, and isometric exercise was of only limited value. It is concluded that the phase histogram provides an objective measurement of the synchronicity of left ventricular contraction and can increase sensitivity for the detection of abnormality. Data should be acquired at all stages of dynamic exercise, and the penultimate stage should be used if there is any doubt about the validity of the final stage.

Silent ischemia: a relevant problem in patients with coronary artery disease?

Awareness of silent myocardial ischemia has greatly increased during the last few years in the medical community. Methods for its detection include exercise testing, Holter monitoring, and, more specifically, Thallium-201 scintigraphy, 2D-echocardiography, and multigated radionuclide ventriculography with phase analysis, all during rest and exercise. Cohn's classification of silent ischemia has proven very useful in highlighting the magnitude of the problem. It can be estimated that about 2% to 4% of apparently healthy middle aged males in industrialized European countries are prone to asymptomatic ischemic episodes. Prognosis of silent myocardial ischemia has been evaluated in prospective and retrospective studies. Most authors come to the conclusion that ischemia is the key finding, whether painful of asymptomatic. Even present understanding of pain perception from the ischemic myocardium is incomplete; the high prevalence and the relation with myocardial infarction and sudden cardiac death make silent myocardial ischemia one of today's most relevant problems.

Exercise-induced precordial ST-segment depression in prior inferior myocardial infarction with single-vessel disease; with special reference to its mechanisms and distinction from multi-vessel disease

We investigated the mechanisms of exercise-induced precordial ST-segment depression on the electrocardiogram in prior inferior myocardial infarction with single-vessel disease and attempted to differentiate the ST-segment depression between single- and multi-vessel disease. Subjects included three groups: group Ia (n = 11), inferior myocardial infarction with single-vessel disease that showed no precordial ST-segment depression; group Ib (n = 7), inferior myocardial infarction with single-vessel disease accompanied by precordial ST-segment depression; and group II (n = 10), inferior myocardial infarction with multi-vessel disease. The subjects underwent 12-lead exercise electrocardiography, stress Tl-201 myocardial imaging and stress radionuclide ventriculography. Exercise-induced precordial ST-segment depression observed in group Ib was associated with large infarction and infarction extending into the inferoseptal wall of the left ventricle on myocardial image. On stress ventriculography, worsening of the septal wall motion was more frequently observed in group Ib than in group Ia. Coronary arteriography revealed a higher rate of rich collateral vessels to the infarcted zone in group Ib than in group Ia. When we compared the diagnostic ability for detecting multi-vessel disease in prior inferior myocardial infarction, although sensitivity was not different among three tests, both exercise electrocardiography and radionuclide ventriculography had poor specificity and predictive value compared to stress Tl-201 myocardial imaging. Thus we concluded that exercise-induced precordial ST-segment depression observed in prior inferior myocardial infarction with single-vessel disease should reflect a peri-infarctional ischemia located in the inferoseptal wall of the left ventricle, and that stress Tl-201 myocardial imaging is the most accurate method for diagnosing multi-vessel disease in prior inferior myocardial infarction.

The value of exercise tests in the follow-up of patients who underwent transluminal coronary angioplasty

We describe the functional and anatomical follow-up of 25 patients who underwent percutaneous transluminal coronary angioplasty in our hospital. In addition, the relative value of different non-invasive methods in predicting a restenosis in the late follow-up period is described. Before angioplasty all patients had subjective and objective signs of coronary artery disease, mainly due to proximal circumscript one-vessel disease. The anatomical evolution was studied by angiographic investigation before, early and late after angioplasty. At the same time intervals we determined the functional level as based on history, exercise electrocardiography, thallium-201 scintigraphy at rest and maximal exercise and technetium ejection fraction determination at rest and maximal exercise. Our data show that angioplasty is a good method of treatment for a selected group of patients with coronary artery disease. The mean stenosis of the dilated vessel decreased significantly from 83% before to 38% late after angioplasty (P less than 0.001). Furthermore the functional status of the patients improved as reflected by the decrease in anginal complaints (P less than 0.001), the increase in negative exercise electrocardiograms (0.01 less than P less than 0.02), exercise level (0.01 less than P less than 0.02) and ejection fraction difference between rest and maximal exercise (P less than 0.001) and the decrease in thallium ischemic defects (P less than 0.001). Comparison of the different non-invasive methods shows that the evolution of the ejection fraction difference between rest and exercise is the most reliable way to discover a possible restenosis in the late follow-up period.

Slow regional clearance of myocardial thallium-201 in the absence of perfusion defect: contribution to detection of individual coronary artery stenoses and mechanism for occurrence

As a result of the "spatially relative" nature of perfusion defect analysis of stress-redistribution thallium-201 (201Tl) scintigrams, hypoperfused myocardial segments may not appear as perfusion defects but they may demonstrate a slow washout rate of 201Tl that can be analyzed in a "spatially nonrelative" manner. Quantitative analysis of perfusion defects and slow washout rate of 201Tl was performed on scintigrams from 116 consecutive patients with adequate exercise tests, defined as achievement of 85% or more of age-predicted maximum heart rate or development of angina or ST segment depression. A total of 232 diseased and 116 nondiseased vessels were found in the patients. Additional analysis of slow washout rate significantly (p less than .05) improved sensitivity for detection of disease in the left anterior descending (from 74% to 82%), left circumflex (from 40% to 61%), and right coronary arteries (from 78% to 90%) without significant loss of specificity. This improvement resulted from the additional detection of 32 of 232 (14%) diseased vascular distributions when the isolated slow washout rate of 201Tl was also determined. In nine of these 32, isolated slow washout rate was associated with another region with isolated slow washout rate in the contralateral myocardial segment. Coronary arteriography revealed similar degrees of stenosis in the vessels supplying these segment pairs. In 13 of 32 cases, a perfusion defect and a slow washout rate were found in the contralateral segment.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of thallium-201 imaging on clinical assessment and management of patients with chest pain

The histories, rest, and exercise ECG results of 60 patients without myocardial infarction complaining of chest pain were submitted to 6 physicians (3 cardiologists and 3 noncardiologists) who were unaware of the angiographic findings. The physicians were requested to estimate the probability of coronary artery disease present in percentages and to assess the need for coronary angiography on a five-point scale (1 = definitely not indicated, 5 = definitely indicated). After obtaining the results of thallium-201 imaging following dipyridamole (0.50 mg/kg intravenously) administration, the physicians were again requested to estimate probability and need for angiography. In the 43 patients with coronary artery disease the judgment of probability was increased significantly after 201Tl from 75.6 +/- 20.2% to 82.9 +/- 23.2% (p less than 0.001) and the need for angiography from 4.3 +/- 0.9% to 4.5 +/- 0.9% (p less than 0.001). In the subgroup of patients with atypical angina the relative change in probability was higher than in other subgroups of patients with coronary artery disease. In the 17 patients with normal coronary arteries the probability estimation fell after 201Tl from 36.7 +/- 22.0% to 24.8 +/- 21.0% (p less than 0.001), the need for angiography was decreased from 2.7 +/- 1.1% to 2.2 +/- 1.2% (p less than 0.001). With the 201Tl information, cardiologists performed a better diagnostic differentiation of patients with and without coronary artery disease than noncardiologists. The study demonstrates the improvement of clinical diagnosis in patients with chest pain by thallium-201 imaging and confirms the favorable influence of the method on the management of the patients in terms of indications for coronary angiography.

Peak exercise and immediate postexercise imaging for the detection of left ventricular functional abnormalities in coronary artery disease

Eleven patients without significant coronary artery disease (CAD) (group A), 22 patients with significant CAD and no prior myocardial infarction (MI) (group B), and 10 patients with CAD and a previous MI (group C) were imaged at rest, at peak exercise and immediately after exercise by first-pass radionuclide angiography. At peak exercise, mean left ventricular (LV) ejection fraction (EF) did not change significantly in group A or C and decreased significantly in group B. However, in all groups mean LVEF increased significantly immediately after exercise. Examination of potential criteria for an abnormal LVEF response showed that changes from rest to peak exercise were sensitive for detection of CAD but were not specific. Postexercise criteria were more specific but relatively insensitive: 15 of 32 patients (47%) with CAD showed a normal (greater than 5% increase over rest) response after exercise. Similarly, a regional abnormality at peak exercise was 100% sensitive, compared with a sensitivity of 78% after exercise for the whole group, and only 68% in patients without prior MI. Seven patients would have been misclassified as normal if postexercise imaging alone had been performed. The likelihood of an abnormal postexercise EF response was related to the extent of CAD: No patient with 1-vessel, 8 of 17 with 2-vessel and 9 of 12 with 3-vessel CAD showed such a response. Peak exercise imaging is necessary to achieve maximal sensitivity for the detection of CAD, and a high false-negative rate will be obtained if postexercise imaging only is used. The combination of peak exercise and postexercise imaging may be of value in assessing the severity of CAD.

Cardiokymography during exercise testing: a new device for the detection of coronary artery disease and left ventricular wall motion abnormalities

The cardiokymograph (CKG) is a device that has been shown to reflect left ventricular (LV) wall motion abnormalities. Its accuracy in detecting coronary artery disease (CAD) during treadmill exercise testing was assessed in 204 consecutive patients undergoing coronary arteriography. Of the 188 patients with a technically adequate CKG, 146 (78%) had significant CAD. The sensitivity and specificity were similar for both the exercise electrocardiogram (ECG) (66% and 86%, respectively) and the exercise CKG (73% and 95%, respectively). An abnormal exercise CKG was significantly more common in patients with 3-vessel CAD than in those with 1-vessel disease (97% versus 52%, respectively; p less than 0.001) and in patients with left anterior descending disease than in those without (85% versus 26%, respectively; p less than 0.001). Seventy patients showed both an abnormal exercise ECG and CKG; all had CAD and 86% had multivessel CAD. Forty-eight patients demonstrated a normal exercise ECG and CKG; 29% had CAD but only 6% had multivessel CAD. Among 55 patients who had simultaneous exercise radionuclide ventriculography, new septal or apical wall motion abnormalities were found in 79% (23 of 29) of patients with an abnormal CKG compared with 19% (5 of 26) of patients with a normal CKG (p less than 0.001). Thus, the CKG during exercise testing accurately reflects LV wall motion abnormalities and can be used to improve the diagnostic accuracy of exercise testing as an additional marker of myocardial ischemia.

Spectrum of global left ventricular responses to supine exercise. Limitation in the use of ejection fraction in identifying patients with coronary artery disease

Left ventricular function was evaluated with rest and supine bicycle exercise-multigated blood pool scans in 53 patients who had previously undergone coronary angiography for evaluation of a chest pain syndrome. There were 21 normal patients (less than 25% stenosis in any coronary artery, left ventricular end-diastolic pressure less than or equal to 12 mm Hg, and normal left ventriculography) and 32 patients with coronary artery disease (CAD) (greater than 50% narrowing in 1 or more major coronary arteries). Thirty-two (60%) were receiving propranolol at the time of the study. The normal patient group had a significant increase in mean ejection fraction (EF) during exercise (+0.08 +/- 0.09), while the CAD group had no increase (0 +/- 0.11; p less than 0.05). Mean end-systolic volume decreased significantly in the normal group (-5 +/- 8 ml/m2) but demonstrated no significant change in the CAD group (1 +/- 12 ml/m2; p less than 0.05 compared with normal patients). There was no significant change in mean end-diastolic volume in either group. Mean ejection rate, mean peak systolic pressure/end-systolic volume ratio, and mean pulmonary blood volume ratio also differed in the normal versus CAD patients. Despite mean differences, there was considerable overlap in both groups of individual EF responses: 8 of 21 (38%) of the normal group did not have an increase in EF of 0.05 with exercise, while 15 of 32 (47%) of the CAD group did have an increase in EF of 0.05 with exercise. However, the addition of peak systolic pressure/end-systolic volume ratio and pulmonary blood volume (exercise/rest) ratio improved the sensitivity for detecting CAD from 53 to 84% without adversely affecting specificity. Thus, there is a wide spectrum of left ventricular EF responses to supine exercise. In our patient population, EF alone was an insensitive and nonspecific marker of CAD. The addition of other parameters of global left ventricular function, which may be generated using radionuclide angiography, helps distinguish patients with CAD from normal subjects.

The independent value of exercise thallium scintigraphy to physicians

To determine the effect of exercise myocardial scintigraphy with thallium-201 on diagnostic accuracy and the need for coronary angiography, consecutive patients with a variety of clinical presentations were identified. Clinical summaries, including a detailed history, physical examination, and complete data from a standard treadmill exercise test, were presented to 91 cardiologists. The cardiologists assessed the probability of coronary disease and the need for coronary angiography. They were then presented the results of thallium scintigraphy and revised their assessments if warranted. Scintigraphy significantly increased the cardiologists' diagnostic accuracy beyond that attained with other clinical information (p less than 0.0001). The change in accuracy varied from + 4% to + 20% in different patient groups, and was greatest in patients with atypical angina and a positive exercise ECG. Ratings of the need for coronary angiography changed from -13% to +21% in different patient groups. We conclude that exercise thallium scintigraphy can provide independent diagnostic information and influence the need for coronary angiography.

Immediate diagnosis of acute myocardial infarction by two-dimensional echocardiography

To define the role of portable two-dimensional echocardiography (2-D echo) in the immediate diagnosis of acute chest pain syndrome, 80 consecutive patients were studied. Adequate 2-D echo studies were obtained in 65 (81%). Thirty-three patients had clinical evidence of transmural or nontransmural acute myocardial infarction (AMI), 18 of whom had nondiagnostic initial ECGs. Thirty-two did not have a clinical AMI. Thirty-one of the 33 (94%) patients with clinical AMI had regional wall motion abnormalities on the initial 2-D echo; the other two had uncomplicated nontransmural AMIs, diagnosed only by ECG in one and by ECG and moderate elevation of CK-MB isoenzyme in the other. Twenty-seven of the 32 patients without clinical AMI had normal regional wall motion on the initial 2-D echo and none had a complication (severe arrhythmia, recurrent pain, heart failure or death) during the hospital course. Conversely, 10 of the 36 patients with initial 2-D echo regional wall motion abnormalities had a complication (p less than 0.05). Thus, in patients with acute chest pain syndrome, an initial 2-D echo that shows no regional wall motion abnormality suggests that such patients will not develop an AMI or clinical complication during the hospital course. An initial 2-D echo with regional wall motion abnormality identifies a high-risk group of patients who are likely to have AMI and important cardiac complications and may, therefore, benefit from admission to an intensive care unit.

Two dimensional echocardiographic evaluation of exercise-induced left and right ventricular asynergy: correlation with thallium scanning

Adequate real time two dimensional echocardiograms were prospectively obtained before and immediately after graded treadmill exercise testing in 41 of 48 patients who underwent cardiac catheterization for suspected coronary artery disease. Findings were correlated with thallium perfusion scans performed 5 to 10 minutes and 3 hours after the same exercise test. Exercise-induced wall motion abnormalities were detected in 19 of 23 patients with significant coronary artery disease and no prior myocardial infarction as well as in all 5 patients with known previous infarction. Three patients with coronary artery disease experienced new isolated right ventricular asynergy with exercise that would have been missed if only the left ventricle had been evaluated. Exercise-induced thallium perfusion defects showed good correlation with exercise-induced asynergy as detected with echocardiography. Two dimensional echocardiography performed immediately after treadmill stress testing is a feasible and rewarding technique in the evaluation of patients suspected to have coronary artery disease.