Comparison of exercise radionuclide angiocardiography and thallium-201 myocardial perfusion imaging in coronary artery disease

A perspective on standardizing the predictive power of noninvasive cardiovascular tests by likelihood ratio computation: 2. Clinical applications

Likelihood ratio measures may be used as a standard for expressing the predictive power of noninvasive cardiovascular tests, calculated from sensitivity and specificity measures or as ratios of the predictive value odds to pretest odds for positive and negative test results. The positive likelihood ratio, (+)LR, expresses the power of a positive test result to augment an estimate of disease probability independent of the pretest prevalence of disease in a given population; the negative likelihood ratio, (-)LR, expresses the power of a negative test result to augment an estimate of the probability of no disease independent of the pretest prevalence of no disease in the same population. The likelihood ratio principle is applicable to the evaluation of the predictive power of single or combined test results reported for either dichotomous or continuous end points. This part of the perspective exemplifies application of the likelihood ratio principle in a wide variety of testing conditions for coronary artery disease followed by a discussion of the limitations of likelihood ratio computation in test power evaluation. Likelihood ratios provide a more concise and unambiguous standard for calibrating the predictive power of single and combined noninvasive cardiovascular test results than are provided by measures of sensitivity, specificity, and predictive value.

Evaluation of diabetic patients for renal and pancreas transplantation: noninvasive screening for coronary artery disease using radionuclide methods

Pharmacologic stress thallium scintigraphy is commonly performed in the risk assessment of diabetic patients with nephropathy before kidney and/or pancreas transplantation; however, controversy exists regarding the test's accuracy in detecting coronary artery disease. Our purpose was to compare pharmacologic stress thallium scintigraphy and also exercise radionuclide ventriculography with coronary angiography in diabetic patients undergoing evaluation for transplantation. In addition, we also determined the association of the test results with outcome after transplantation. The medical records of 47 patients (mean age, 37+/-9 years) without clinical evidence of coronary artery disease were reviewed. Forty-one patients had pharmacologic stress thallium scintigraphy performed during their evaluation. Sensitivity was 62% and specificity was 76% for detecting > or = 75% coronary artery stenosis (sensitivity was 53% and specificity was 73% for > or = 50% stenosis). Thirty-five patients had exercise radionuclide ventriculography performed. Sensitivity was 50% and specificity was 67% for detecting > or = 75% coronary artery stenosis (sensitivity was 44% and specificity was 63% for > or = 50% stenosis). Thirty patients had both pharmacologic stress thallium scintigraphy and exercise radionuclide ventriculography performed; when either test was abnormal, sensitivity in the detection of > or = 50% or > or = 75% stenosis tended to increase compared with pharmacologic stress thallium scintigraphy alone (0.05<P<0.10), whereas specificity decreased (P<0.01). The incidence of adverse cardiac outcomes was identical for patients with abnormal thallium scintigrams and undergoing transplantation (2/11) compared with patients with normal scintigrams and undergoing transplantation (4/22). We conclude that: (1) pharmacologic stress thallium scintigraphy and exercise radionuclide ventriculography are suboptimal screening tests for coronary artery disease in diabetic patients awaiting kidney and/or pancreas transplantation; (2) using the two radionuclide tests in combination results in a decrease in specificity; and (3) patients with abnormal thallium scintigrams can receive transplants with outcomes similar to those for patients with normal thallium scintigrams.

Evaluation of changes in myocardial perfusion and function on exercise in patients with coronary artery disease by gated MIBI scintigraphy

OBJECTIVE

To investigate the ability of gated methoxy-isobutylisonitrile (MIBI) scintigraphy to measure changes in myocardial function as well as perfusion with exercise.

SETTING

Regional cardiothoracic centre.

PATIENTS

43 presenting with chest pain, 28 with coronary artery disease on angiography, and 15 with normal coronary arteriograms.

RESULTS

Gated perfusion images showed an improvement in detecting regions with stenosed arteries compared with non-gated images (38/55 v 31/55, p < or = 0.01)). Functional analysis showed an increase in fractional shortening of 4.11% in subjects with normal coronary arteries, whereas in those with coronary disease a fall of 0.57% was found (p < or = 0.01). Both perfusion and function imaging showed an improved sensitivity compared with standard exercise testing (p < or = 0.01). When both function and perfusion imaging were analysed all patients with coronary disease were detected. There was agreement in abnormal regions in 33/55 territories supplied by a stenosed artery. Combined perfusion and function detected 49/55 (89%) of abnormal regions, thus improving the overall sensitivity from 38/55 (69%) by perfusion imaging alone (p < or = 0.01).

CONCLUSIONS

Gated methoxy-isobutylisonitrile scintigraphy can successfully evaluate perfusion and function on exercise, so improving the diagnostic usefulness of this agent.

First-pass radionuclide cineangiography: a reevaluation of its sensitivity and limitations in the detection of significant coronary artery disease

The sensitivity of first-pass cineangiography in the detection of significant coronary artery disease (CAD) was recently assessed in 33 patients. No normal controls were studied. Overall sensitivity was 86% with a predictive value of 83% and a 36% false-positive rate. Attainment of an adequate exercise end point increased sensitivity to 92%; failure to achieve this end point diminished sensitivity to 71%. Correlation between first-pass and contrast angiography ejection fractions was high (r = 0.88, p less than .005) with a moderate correlation in wall motion analysis (r = 0.58, p less than .005). The development or the intensification of a wall motion abnormality (WMA) was the single most sensitive indicator of CAD (84%). Presence of WMA plus failure of the ejection fraction to increase by 6% over baseline increased testing sensitivity to 89%. The mean WMA score for patients with CAD was 2.0 +/- 1.5 compared with 0.6 +/- 1.3 for those with normal study results (p less than .01). The first-pass method identified 4 subjects who subsequently had normal findings from catheterization. Data confirm testing sensitivity of the first-pass technique and underscore the apparent limitations of this modality in differentiation of patients with normal vasculature.

The application of radionuclide ventriculography to cardiac screening

Screening asymptomatic individuals for latent coronary disease often requires sequential testing because exercise electrocardiography typically produces more false positive than true positive results in a population with a low prevalence of coronary disease. Cardiac scintigraphy is a technique that may be employed as a confirmatory test in lieu of coronary arteriography to further evaluate the significance of a positive exercise electrocardiogram. Radionuclide ventriculography was employed in 98 asymptomatic individuals who were considered to be at moderate risk of heart disease after risk factor analysis and exercise electrocardiography. Seventeen (17%) patients had an abnormal study and underwent cardiac catheterization. Seven had coronary artery disease, two had cardiomyopathy, and eight were normal. Eighty-one (83%) patients had a normal study. Because the sensitivity of radionuclide ventriculography is 63-80%, it was postulated that 2 to 5 individuals with disease were missed. Thus, from a population with an 11-14% prevalence of disease, two subsets were identified. A large subset in which a prevalence of 2-6% could be estimated was separated from a much smaller one in which a prevalence of approximately 50% was demonstrated.

Exercise ultrafast computed tomography for the detection of coronary artery disease

Ultrafast computed tomography permits the assessment of global and regional left ventricular function during exercise. To evaluate the feasibility of using this new technique for the diagnosis of coronary artery disease, 27 patients undergoing cardiac catheterization for diagnosis of chest pain were evaluated. Fifteen patients had significant (greater than 50%) coronary artery stenosis by quantitative coronary angiography. One vessel disease was found in 12 patients and multivessel disease in 3. Fourteen (93%) of the 15 patients with significant coronary stenosis had a decrease in ultrafast computed tomographic ejection fraction during exercise from (mean +/- SD) 65 +/- 7% to 60 +/- 7% (p less than 0.001). The tomographic ejection fraction increased greater than 5% units during exercise in 10 (83%) of the 12 patients with normal coronary arteries. The mean tomographic ejection fraction in this group was 68 +/- 6% at rest and 75 +/- 6% at peak exercise (p less than 0.001). Regional wall motion was quantified by analyzing the segmental ejection fraction of 12 30 degree pie segments at each tomographic level of the left ventricle. A new regional wall motion abnormality developed during exercise in 12 (86%) of 14 patients with coronary artery disease; one patient was excluded because of a technical problem in data storage. Eleven (93%) of the 12 patients with normal coronary arteries had normal wall motion during exercise. In no patient with ischemic heart disease were both variables, ejection fraction response and regional wall motion, normal. Exercise ultrafast computed tomography appears to be a useful technique for the evaluation of coronary artery disease in patients with chest pain and predominant single vessel coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angioplasty and left ventricular function in single vessel coronary artery disease

Left ventricular function was investigated in 86 patients with single vessel coronary artery disease before and three to six months after successful angioplasty. Before angioplasty thallium-201 perfusion scintigraphy and technetium-99m gated equilibrium ventriculography in most patients showed that stress testing (exercise and ice water stimulation and isometric handgrip respectively) induced myocardial perfusion defects that were associated with a mean (SD) drop in left ventricular ejection fraction from 64 (6)% to 56 (7)%. After angioplasty there was residual coronary stenosis of less than or equal to 20% of the diameter of the vessel in 78 patients (group 1) and of between 20 and 50% in eight patients (group 2). After the procedure the perfusion defects seen during stress resolved in 86% of group 1 and in 87% of group 2. Despite the apparent improvement in myocardial perfusion left ventricular dysfunction persisted in group 2--that is during stress the left ventricular ejection fraction fell from 65% (6) to 56% (5). In group 1, on the other hand, the improvement in myocardial perfusion was associated with significant improvement in left ventricular function with a normal increase in ejection fraction from 63 (5) at rest to 67 (6) during stress. Radionuclide studies, one to six weeks after angioplasty in 30 group 1 patients showed continuing left ventricular decompensation during stress in nine (30%) of them despite correction of perfusion defects. But reinvestigation three to six months after the procedure showed recovery of left ventricular function with an increase in ejection fraction from 66 (5) at rest to 69 (7) during stress. These data indicate that coronary angioplasty procedures that give a residual stenosis of </= 20% improve myocardial perfusion and the response of the left ventricle to stress. The functional improvement may be delayed for up to three months, however, possibly because arterial healing at the angioplasty site is delayed. On the other hand, when the residual stenosis is between 21 and 50% of the diameter of the vessel subclinical left ventricular dysfunction during stress may persist indefinitely.

The detection of coronary artery disease: a comparison of exercise thallium imaging and exercise equilibrium radionuclide ventriculography

This study compared the accuracy of rest and exercise gated equilibrium technetium ventriculography with exercise thallium imaging in 50 consecutive male patients undergoing routine coronary angiography for the evaluation of chest pain. No patients were excluded on the basis of prior myocardial infarction, nature of angiographically defined coronary disease or symptoms. Antianginal therapy was continued in all patients. Eight patients had normal coronary arteries, 9 had single vessel, disease, 20 had double vessel disease and 13 had triple vessel disease. Sixteen patients had previously documented myocardial infarction. Using exercise radionuclide ventriculography, 34 patients with coronary disease were detected resulting in a sensitivity of 81%; 6 patients with normal coronary arteries had normal scans, a specificity of 75%, with a predictive accuracy of 80%. In comparison, thallium imaging detected 42 patients with coronary disease resulting in a sensitivity of 100%. Six patients with normal coronary arteries had normal thallium images resulting in a specificity of 75% and a predictive accuracy of 96%. These results suggest that exercise thallium imaging is a more accurate investigation than exercise equilibrium radio-nuclide ventriculography and is the investigation of choice in the noninvasive detection of coronary artery disease.

Prediction of the extent of coronary artery disease with the evaluation of left ventricular wall motion abnormalities during atrial pacing. A cross-sectional echocardiographic study

In patients with coronary artery disease, left ventricular performance during stress is affected by the degree of coronary stenosis. In order to verify whether there exists a relationship between the extent of wall motion abnormalities detectable during atrial pacing and the degree of coronary obstruction, 76 patients, without previous myocardial infarction, were studied. Each patient underwent cross-sectional echocardiography during transesophageal atrial pacing and exercise electrocardiography before coronary angiography. Of the 76 patients, 46 had significant coronary artery disease (stenosis greater than or equal to 75% of at least one major coronary vessel), while 30 had normal coronaries or a stenosis of less than 75%. Eighteen patients had single-, 14 had two- and 14 had three-vessel disease. For each patient a coronary score was obtained: the score used took into consideration the site, number and severity of the stenosis. This score was then correlated with the wall motion score, obtained from the analysis of 9 segments of the left ventricle. A weak correlation was obtained between wall motion score at rest and coronary score (r = -0.42), while the correlation between coronary score and the difference between wall motion score at rest and during transesophageal atrial pacing was slightly better (r = 0.53); this correlation further improved if wall motion score during pacing was considered (r = -0.63). If the patients with discordant diagnostic tests (echocardiography during transesophageal atrial pacing and exercise electrocardiography) were excluded, the correlation coefficient between coronary score and wall motion score during pacing increased even more (r = -0.77).

IN CONCLUSION

(1) analysis of wall motion of the left ventricle during atrial pacing is useful for the non-invasive evaluation of the severity of coronary disease; (2) cross-sectional echocardiography during atrial pacing, apart from being a useful diagnostic tool, is also a help in judging the degree of severity of coronary artery disease.

Evaluation of coronary artery disease by an improved method of exercise electrocardiography: the ST segment/heart rate slope

Analysis of the rate-related change in exercise-induced ST segment depression, the ST/HR slope, has been shown to significantly improve the accuracy of the exercise ECG for the identification of patients with coronary artery disease and for the recognition of patients with stable angina pectoris who have anatomically or functionally severe coronary artery obstruction. This method, in effect, normalizes the extent of ST segment depression for heart rate, which serves as an index of exercise-induced augmentation of myocardial oxygen demand. While preserving the specificity of the exercise ECG at greater than 90%, an ST/HR slope value of 1.1 microV/bpm as an upper limit of normal improved exercise test sensitivity from 57% to 91% in patients with stable angina who were examined using standard Bruce protocols and three monitoring leads. In addition, an ST/HR slope value of 6.0 microV/bpm was found to partition patients with and without three-vessel coronary artery disease with a sensitivity of 78%, specificity of 97%, positive predictive value of 93%, and overall test accuracy of 90%. No other criteria based on standard ECG interpretation performed as well as the ST/HR slope for the recognition of three-vessel disease in these patients. Further, patients with high ST/HR slopes who did not have three-vessel coronary disease could be shown to have functionally severe two-vessel disease by radionuclide cineangiography. These data suggest that the ST/HR slope can improve the evaluation and management of patients with possible coronary disease. Additional improvement in ST/HR slope accuracy and applicability is likely to result from modification of exercise protocols to reduce heart rate increments between stages, an increase in monitoring leads to include CM5, and computer analysis of the ST segment depression.

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.

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

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

Assessment of single vessel coronary artery disease: results of exercise electrocardiography, thallium-201 myocardial perfusion imaging and radionuclide angiography

The sensitivity of the commonly used stress tests for the diagnosis of coronary artery disease was analyzed in 46 patients with significant occlusion (greater than or equal to 70% luminal diameter obstruction) of only one major coronary artery and no prior myocardial infarction. In all patients, thallium-201 perfusion imaging (both planar and seven-pinhole tomographic) and 12 lead electrocardiography were performed during the same graded treadmill exercise test and radionuclide angiography was performed during upright bicycle exercise. Exercise rate-pressure (double) product was 22,307 +/- 6,750 on the treadmill compared with 22,995 +/- 5,622 on the bicycle (p = NS). Exercise electrocardiograms were unequivocally abnormal in 24 patients (52%). Qualitative planar thallium images were abnormal in 42 patients (91%). Quantitative analysis of the tomographic thallium images were abnormal in 41 patients (89%). An exercise ejection fraction of less than 0.56 or a new wall motion abnormality was seen in 30 patients (65%). Results were similar for the right (n = 11) and left anterior descending (n = 28) coronary arteries while all tests but the planar thallium imaging showed a lower sensitivity for isolated circumflex artery disease (n = 7). The specificity of the tests was 72, 83, 89 and 72% for electrocardiography, planar thallium imaging, tomographic thallium imaging and radionuclide angiography, respectively. The results suggest that exercise thallium-201 perfusion imaging is the most sensitive noninvasive stress test for the diagnosis of single vessel coronary artery disease.

Value and limitations of exercise radionuclide angiography for detecting myocardial ischemia in healed myocardial infarction

Exercise radionuclide angiography was performed in 65 normal subjects (group I), in 31 patients with exercise-induced transient thallium defects after acute myocardial infarction (AMI) (group II), and in 16 patients without exercise-induced transient thallium defects, angina or electrocardiographic changes after AMI (group III). Absolute left ventricular (LV) volumes were measured using a correction for attenuation in each patient. Similar peak heart rate-blood pressure products were achieved in groups II and III. Although the mean LV ejection fraction (EF) response to exercise in group III (increase of 0.11 +/- 0.10 units) closely resembled that of normal persons (increase of 0.14 +/- 0.09 units) and was significantly different from that of group II (decrease of 0.04 +/- 0.12), there was considerable individual variation. An abnormal EF response to exercise, defined as failure of EF to increase by at least 0.05 units, was found in 6 subjects (9%) in group I, 26 patients (84%) in group II, and 2 patients (13%) in group III. End-systolic volume failed to decrease in 10 subjects (15%) in group I, 25 patients (81%) in group II and 7 patients (44%) in group III. New regional wall motion abnormalities were found in no subject in group I, in 16 patients (52%) in group II and in only 1 patient (6%) in group III. Thus, although group responses of EF or end-systolic volume appeared to correlate with the presence or absence of ischemia, some patients with exercise-induced transient thallium defects after AMI responded normally to exercise radionuclide angiography stress testing and some patients without other evidence of exercise-induced ischemia after AMI responded to exercise radionuclide angiography testing abnormally.(ABSTRACT TRUNCATED AT 250 WORDS)

Dopamine: its potential for inducing ischemic left ventricular dysfunction

As an agent potentially capable of inducing ischemia in patients with coronary artery disease, dopamine administered intravenously was evaluated as a pharmacologic stress agent by supine radionuclide angiography, and the results were compared with ergometer exercise. In a preliminary group of 11 subjects (4 normal subjects and 7 patients with coronary disease), dopamine alone was administered in increments of 2.5 micrograms/kg per min to a maximum of 15 micrograms/kg per min. There were significant differences between exercise and dopamine in maximal stress heart rates, 129.3 +/- 30.0 versus 88.0 +/- 35.8 beats/min (p less than 0.05) in normal subjects and 118.9 +/- 21.1 versus 87.6 +/- 22.6 beats/min (p less than 0.05) in patients with coronary disease, as well as in maximal stress rate-pressure products, 213.3 +/- 51.4 versus 155.0 +/- 52.5 mm Hg/min X 10(2) (p less than 0.02) in normal subjects and 216.0 +/- 45.6 versus 161.0 +/- 48.6 mm Hg/min X 10(2) (p less than 0.003) in patients with coronary disease. As a result, in these patients the ejection fraction response was significantly different: -3.3 +/- 4.5% with exercise versus + 6.3 +/- 4.6% with dopamine (p less than 0.05). In a second group of 41 subjects (9 normal subjects and 32 patients with coronary disease), atropine (0.6 mg) was administered intravenously before and after every second dopamine dose increment. This produced statistically similar maximal stress heart rates as compared with exercise in all subjects, rate-pressure products in normal subjects and slightly higher values with dopamine in patients with coronary disease: 200.3 +/- 47.2 versus 183.1 +/- 43.0 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The relation between myocardial ischemia and the ejection fraction response to exercise in patients with normal or abnormal resting left ventricular function

This study examines the relation between myocardial ischemia and the left ventricular (LV) ejection fraction (EF) response to exercise in patients with normal or abnormal resting EF. We studied 69 patients aged 25 to 78 years (mean 52 years) by radionuclide ventriculography (at rest and during peak upright exercise) and by exercise thallium-201 imaging. In 27 patients with resting EF less than 50%, the EF response to exercise was normal (greater than or equal to 5% increase) in 13 patients and abnormal in 14. The thallium scans showed reversible defects in 11 of the 14 patients (79%) with abnormal response but none in any of the patients with normal responses (p = 0.0001). In the 42 patients with resting EF greater than or equal to 50%, the EF response to exercise was normal in 23 and abnormal in 19. Reversible defects were present in 13 of the 19 patients (68%) with abnormal response and in only 3 of 23 patients (13%) with normal response (p = 0.0001). Therefore, an abnormal EF response to exercise was seen in 11 of 11 patients with resting EF less than 50% and in 13 of 16 patients (81%) with resting EF greater than or equal to 50% who had reversible thallium defects; normal EF responses were seen in 13 of the 16 patients (81%) with resting EF less than 50% and in 20 of 26 patients (77%) with resting EF greater than or equal to 50% who had no reversible thallium defects. Thus, in patients with abnormal resting LV function an abnormal EF response to exercise suggests the presence of myocardial ischemia rather than a nonspecific response to stress.

Detection of coronary artery disease by two-dimensional echocardiography and transesophageal atrial pacing

Two-dimensional echocardiography was performed at rest and during rapid transesophageal atrial pacing in 85 patients undergoing coronary arteriography for evaluation of chest pain. Transesophageal atrial pacing was performed with 10 ms pulses of 6 to 27 mA intensity; the rate was progressively increased up to 150 beats/min. Four patients were excluded: two because atrial capture was not achieved and two because of chest discomfort induced during transesophageal atrial pacing. Of the remaining 81 patients, 56 had significant coronary artery disease (greater than or equal to 75% stenosis of at least one major coronary vessel) and 25 had no significant coronary artery disease; 25 of the 56 patients with coronary artery disease had no wall motion abnormalities at rest. The test was considered positive if wall motion abnormalities were detected during pacing. Wall motion abnormalities occurred in 3 of 25 patients without coronary artery disease (specificity 88%) and in 51 of 56 patients with coronary artery disease (sensitivity 91%). Wall motion abnormalities developed in 20 of the 25 patients with coronary artery disease and normal regional wall motion at rest (sensitivity 80%); sensitivity for one, two and three vessel disease was 85% (17 of 20 patients), 94% (15 of 16 patients) and 95% (19 of 20 patients), respectively. In patients without coronary artery disease, wall motion score was 18 at rest and 17.7 +/- 0.9 during pacing (p = NS). In patients with coronary artery disease, wall motion score decreased from 15.2 +/- 3.6 at rest to 11.6 +/- 4.1 during pacing (p less than 0.001). In patients with coronary artery disease and normal regional wall motion at rest, wall motion score decreased from 18 at rest to 14.4 +/- 3.1 during pacing (p less than 0.001). Thus, two-dimensional echocardiography during transesophageal atrial pacing appears both sensitive and specific in detecting patients with coronary artery disease. This new procedure is a feasible and reliable alternative to exercise two-dimensional echocardiography.

A format for integrating the interpretation of exercise ejection fraction and wall motion and its application in identifying equivocal responses

The conventional interpretation of ejection fraction change with exercise may be limited because it does not consider the rest value, define equivocal responses or integrate wall motion data reproducibly. Thus, a format was developed for combined interpretation of rest and exercise radionuclide ejection fraction and wall motion by reviewing the reported data for the exercise responses of patients without prior myocardial infarction. The ejection fraction data of 202 normal patients and of 259 patients with coronary artery disease were first fitted to beta distributions. The true positive and false positive rates for coronary disease for each combination of rest and exercise ejection fraction were then determined directly from these distributions. A given rest/exercise ejection fraction combination was "normal" if the false positive rate was greater than the true positive rate, or "abnormal" if the true positive rate was greater than the false positive rate, and "equivocal" when the rates were similar (within a 50% confidence interval). This analytic format, which predicted an inverse relation between rest ejection fraction and the change required with exercise, was then validated prospectively in 854 patients without myocardial infarction (557 with and 297 without angiographic coronary artery disease). Using the conventional criterion of an abnormal test result (less than 0.05 absolute rise in ejection fraction with exercise or a wall motion abnormality), sensitivity was 85 +/- 2% and specificity only 42 +/- 3%. The statistical format had a sensitivity of 70 +/- 2% and specificity of 70 +/- 3%, resulting in a twofold increase in information content. This format has at least two advantages over conventional interpretation: 1) it provides an explicit definition of equivocal responses; and 2) it reproducibly integrates discordant ejection fraction and wall motion responses and allows for the combined analysis of other nonscintigraphic observations, such as age and sex.

Quantitative planar thallium-201 stress scintigraphy: a critical evaluation of the method

The results of quantitative analysis of planar thallium-201 stress scintigraphy are superior to those of visual analysis. The increased sensitivity for detection of coronary artery disease is associated with maintenance of specificity. Consequently, we believe that quantitative analysis is the state-of-the-art for planar 201Tl stress scintigraphy. We emphasize that for reliable and reproducible results, rigorous quality control and strict adherence to a standardized imaging protocol are necessary. An important feature is clarity of display of computer data. In our experience, the most important feature for making quantitative analysis reliable and accessible for a broader user market is simultaneous display of the lower limits of normal with processed patient data. This provides a simple visual impression of the degree and extent of abnormal 201Tl distribution and kinetics relative to the lower limit of normal.

Noninvasive prediction of the angiographic extent of coronary artery disease after myocardial infarction: comparison of clinical, bicycle exercise electrocardiographic, and ventriculographic parameters

To assess alternative criteria for the prediction of multivessel coronary artery disease after myocardial infarction, we compared the clinical, bicycle electrocardiographic, and radionuclide ventriculographic (ejection fraction and wall motion) responses in 110 patients undergoing coronary angiography after myocardial infarction. Ninety-seven of the 110 patients had multivessel coronary artery disease (two or more diseased vessels). Clinical or electrocardiographic abnormalities were observed in 41 of 97 (sensitivity = 43%) patients with multivessel disease, and in only two of 13 (specificity = 85%) patients without multivessel disease. The average information content of these combined clinical and electrocardiographic variables relative to perfect discrimination was 5%. Among the scintigraphic parameters, the conventional criterion for ejection fraction abnormality, a rise of less than 5% had a sensitivity of 72% and a specificity of 62% for multivessel coronary artery disease, while a fall in ejection fraction of 5% or more had a sensitivity of 39% and specificity of 92% for multivessel coronary artery disease. The presence of an exercise wall motion abnormality in the nonadjacent noninfarcted (remote) region had a sensitivity of 82% and specificity of 55% for multivessel coronary artery disease. A more stringent criterion, worsening of remote wall motion with exercise, had a sensitivity of 52% and specificity of 75%. When this latter criterion was combined with a fall in ejection fraction, the sensitivity for multivessel coronary artery disease increased to 62%, specificity remained 75%, and information content increased from 5% to 10%. We conclude that conventional diagnostic criteria for abnormal clinical, bicycle electrocardiographic, or scintigraphic results do not identify patients with additional coronary artery disease after infarction with high accuracy. Two alternative ventriculographic parameters--a fall in ejection fraction and wall motion worsening--are similar to clinical parameters in specificity, but have a higher sensitivity and information content.

The patient with transient ischemic attacks--is this the time for a new therapeutic approach?

Current and future improvements in treatment to prevent cerebral infarction among patients with transient ischemic attacks may reduce neurological morbidity but may not lead to a proportional improvement in life expectancy. Because the long-term primary cause of death in these patients is myocardial infarction, it is most likely that the most important way to prolong survival may be the vigorous investigation of their cardiac status and the treatment of their coronary artery disease, even if asymptomatic.

Comparison of exercise perfusion and ventricular function imaging: an analysis of factors affecting the diagnostic accuracy of each technique

Exercise thallium-201 perfusion scans and gated equilibrium blood pool scans were performed in 120 catheterized patients with a chest pain syndrome. Eighty-six patients had coronary artery disease and 34 patients did not. The effects of gender, propranolol, exercise level, exercise ischemia, history of typical angina, history of previous myocardial infarction, electrocardiographic Q waves, number of diseases vessels and extent of coronary artery obstruction on diagnostic accuracy were evaluated. The overall sensitivity and specificity of thallium scans were 76 and 68%, respectively, and those of gated blood pool scans 80 and 62% (p = not significant). Propranolol decreased the specificity of thallium scans (propranolol = 42%; no propranolol = 87%, p less than 0.05). Thallium scans and anginal history were less sensitive for detecting coronary disease in women (men: thallium = 79%; angina = 77%; women: 54 and 46%, respectively; p less than 0.05). Exercise level did not significantly affect the diagnostic accuracy of either scan. Thallium and gated scans were both highly sensitive (95%) in detecting disease in 20 patients with a prior myocardial infarction, angina and a positive electrocardiogram. The sensitivity of the thallium scan significantly decreased as the number of diseased vessels decreased. Both thallium and gated scans were less frequently positive in patients with atypical angina or no Q waves, but were not significantly influenced by electrocardiographic ischemia. The sensitivity and specificity of both scans were low in 57 patients with the combination of atypical angina, no history of infarction and equivocal stress electrocardiogram thallium = 61 and 63%, respectively; gated = 61 and 67%). When stress thallium scan evaluation included the electrocardiogram and thallium scan interpretation, the diagnostic accuracy was 81%. When all the information from gated scans (wall motion, ejection fraction, pulmonary blood volume) was combined for final gated scan evaluation, the diagnostic accuracy was 83%. When electrocardiographic data were added to all three gated scan variables, diagnostic accuracy was 77%. In conclusion, thallium perfusion and gated blood pool scans have reasonable diagnostic accuracy for coronary artery disease in a group of patients with a moderately high prevalence of disease. However, combined variables from each test are needed to provide reliable diagnostic accuracy.

The influence of bias on the subjective interpretation of cardiac angiograms

Subjective interpretation of angiographic left ventricular regional wall motion is routinely performed with knowledge of the location and extent of coronary artery stenosis. We studied 100 patients with coronary artery disease in order to determine the accuracy of such wall motion assessment relative to a more objective standard based upon computer-assisted left ventricular (LV) ejection fraction and end-systolic fractional shortening referenced to the end-diastolic area centroid. Only 379 of 700 (54%) region-by-region comparisons of wall motion were in precise agreement. Computer-assisted wall motion analysis correlated significantly better with ejection fraction than did subjective analysis (r = 0.82 vs r = 0.61, p less than 0.002). In 56 patients, in whom major discordance was noted, subjective assessment of wall motion correlated significantly better with the presence of coronary artery stenosis (p less than 0.05), but objective assessment correlated significantly better with ejection fraction in these same patients (p less than 0.02). These data suggest that the accuracy of subjective assessment of regional wall motion, relative to global ejection fraction, can be adversely biased by knowledge of the patient's coronary anatomy. Because of the inherently reproducible nature of the algorithmic process, and in light of the better correlation with global function, computer-assisted analysis of regional wall motion might be preferable to conventional subjective assessment.

Analysis of the degree of pulmonary thallium washout after exercise in patients with coronary artery disease

An abnormal increase in pulmonary thallium activity may be visualized on post-stress thallium images in patients with coronary artery disease. Because this increased pulmonary thallium activity usually disappears by the time of redistribution imaging, this study was designed to assess whether measurement of the degree of pulmonary thallium washout between stress and redistribution might improve the detection of increased pulmonary thallium activity in patients with coronary artery disease. Quantitative analysis revealed abnormal (that is, greater than 2 standard deviations of normal values) pulmonary thallium washouts in 59 (64%) of 92 patients with coronary artery disease, but in only 2 (25%) of 8 subjects with angiographically normal arteries (p less than 0.06). By comparison, the visual analysis of pulmonary thallium washout and use of initial pulmonary to myocardial thallium ratio were significantly (p less than 0.05) less sensitive in detecting abnormality in patients with coronary artery disease. Abnormal pulmonary thallium washout was related to both the anatomic extent and functional severity of disease: it occurred with greatest frequency in patients with multivessel disease and in those with exercise-induced left ventricular dysfunction (p less than 0.005). When added to the quantitative analysis of myocardial scintigraphy, the analysis of pulmonary thallium washout increased the detection of coronary artery disease from 84 to 93% (p less than 0.05), but the sample size was too small to assess specificity. Thus, the analysis of pulmonary thallium washout is a useful diagnostic variable because it: 1) provides an objective measurement of abnormal pulmonary thallium activity and is more sensitive than other methods; 2) correlates with both the extent of coronary artery disease and the degree of exercise-induced left ventricular dysfunction, and 3) improves the sensitivity of quantitative myocardial thallium scintigraphy to detect the presence of coronary artery disease.

Gold-195m for serial first pass radionuclide angiocardiography during upright exercise in patients with coronary artery disease

Sequential first pass radionuclide angiocardiography can be performed in rapid succession using gold-195m because of its low radiation dose and short half-life (30.5 seconds). In 25 patients with known or suspected coronary artery disease, first pass studies with gold-195m were obtained using a computerized multicrystal gamma camera at rest (n = 29), at the end of each 3 minute stage of exercise (n = 25) and immediately after exercise (n = 23). In 13 patients, assessment of left ventricular function during exercise with gold-195m was combined with thallium-201 stress scintigraphy. Left ventricular ejection fraction at rest assessed with technetium-99m and gold-195m correlated well (r = 0.93). In addition, repeat left ventricular ejection fractions at rest with gold-195m correlated closely (r = 0.96). Comparing peak exercise left ventricular ejection fraction with ejection fraction at rest, abnormal left ventricular reserve was found in 20 of 25 patients. Various abnormal patterns of left ventricular ejection fraction response were noted, showing the diagnostic potential of serial exercise angiocardiography. Thallium-201 myocardial images, obtained on a single crystal gamma camera after multiple gold-195m injections, were all of good diagnostic quality and were abnormal in 10 of 13 patients. Thus, multiple high count rate first pass studies can be obtained with gold-195m during and after exercise, allowing serial study of physiologic changes in left ventricular function during exercise. Thallium-201 myocardial imaging can be performed using the same exercise test, providing direct comparison of myocardial function and perfusion.

Use of multivariate analysis to improve the accuracy of radionuclide angiography with stress in detecting coronary artery disease in men

A multivariate analysis (MVA) system was derived retrospectively from a population of 76 males with coronary artery disease and 18 control subjects. Posterior probabilities were then derived from such a system prospectively in a new male population of 11 subjects with normal coronary arteries and hemodynamics and 63 patients with coronary artery disease. The sensitivity was 84% compared to that for change in ejection fraction (delta EF) greater than or equal to 5 criterion of 71% (p less than 0.01), the specificity was 91% compared to 73% for the delta EF greater than or equal to 5 criterion (p greater than 0.05), and the correct classification rate was 85% compared to 72% for the delta EF greater than or equal to 5 criterion (p less than 0.01). The significant variables were: change in EF with exercise, percent maximal heart rate, change in end-diastolic volume (delta EDV) with exercise, change in R wave, and exercise duration. Application of the multivariate approach to radionuclide imaging with stress, including both exercise and nuclear parameters, significantly improved the diagnostic accuracy of the test and allowed for a probability statement concerning the likelihood of disease.

Prognostic value of exercise testing for ischaemic heart disease

Images

Computer-enhanced digital angiography: correlation of clinical assessment of left ventricular ejection fraction and regional wall motion

We compared computer-enhanced digital angiography (CEDA) following pulmonary injection of 20 ml Renografin-76 (5 ml/sec) to conventional directly injected left ventriculography (LV) in 13 patients undergoing routine diagnostic catheterization. Left ventricular ejection fraction (LVEF) was determined by planimetry from end-diastolic and end-systolic images by two independent angiographers. The correlation coefficient for LVEF (CEDA vs. LV) was r = 0.75 (p less than 0.005) for observer 1 and r = 0.85 (p less than 0.0005) for observer 2. The interobserver variability for LVEF was very low, resulting in a high correlation coefficient (r = 0.91, p less than 0.0005). Three angiographers independently reviewed both the conventional and CEDA images in a random order for assessment of anterior, apical, and inferior regional wall motion, using a 6-point subjective grading system (198 determinations). The interobserver correlation for subjective assessment of regional wall motion by both LV and CEDA was poor (49% for LV and 59% for CEDA, p = NS). These poor correlations were not improved by excluding any region or angiographer from the analysis. The agreement of regional motion assessments between the two techniques was only 40%. To improve reproducibility of wall motion interpretation, an automated analysis program was developed. First the range of normal contraction was defined from pooled literature data. The movement of any segment of the left ventricular wall could then be determined in millimeters and referenced to the normal range. This method eliminated interobserver variability. In the absence of an acceptable standard of segmental wall motion to which this measurement can be compared, the accuracy of this objective format could not be determined. We conclude that CEDA images allow accurate determination of ejection fraction and that the large interobserver variability of subjective regional wall motion analysis can be overcome by employing more objective formats.

Reproducibility of equilibrium radionuclide ventriculography in patients with coronary artery disease: response of left ventricular ejection fraction and regional wall motion to supine bicycle exercise

To evaluate the reproducibility of ejection fraction (EF) and regional wall motion (RWM) analyses by rest and exercise equilibrium radionuclide ventriculography (RNV) in the presence of coronary artery disease (CAD), 18 patients underwent two maximum, multistage supine bicycle exercise studies separated by an interval of 2 weeks. There were no significant differences in EF between the two studies, both at rest (56.0 +/- 13.8% vs 58.2 +/- 11.7%, p = NS) and with exercise (51.1 +/- 17.6% vs 54.3 +/- 17.6%, p = NS) and a highly significant correlation was shown between the two groups of values (rest r = 0.90, exercise r = 0.93, p less than 0.001). There was no significant difference in the change from rest to exercise (-4.9 +/- 12.0% vs -3.8 +/- 11.5%, p = NS) between the two studies and the correlation was highly significant (r = 0.69, p less than 0.01). The interstudy variabilities were 2.2 +/- 6.1% and 1.2 +/- 7.3% for rest and exercise, respectively, and 2.0 +/- 9.2% for the change from rest to exercise. Ninety-four percent of both rest and exercise regions had similar RWM. Eighty-one percent of the abnormally contracting regions were common to both exercise studies. Utilizing conventional criteria for the diagnosis of CAD, 11 patients had abnormal EF response and nine had abnormal RWM response to exercise on both studies. Combining EF and RWM criteria resulted in the diagnosis of CAD in 15 patients in both studies. We conclude that: (1) there were no significant differences in rest and exercise radionuclide EF and RWM between two supine bicycle exercise studies performed 2 weeks apart in patients with stable CAD and there were significant correlations between the two studies; (2) despite these correlations, the interstudy variabilities emphasize the need for the inclusion of reproducibility studies in all evaluations of interventions by exercise radionuclide ventriculography; and (3) the variations in EF and RWM response to exercise result in lack of uniformity between the two studies regarding the diagnosis of CAD based on conventional RNV criteria.

Diagnostic accuracy of exercise ECG lead systems in clinical subsets of women

The diagnostic accuracy of 14-lead exercise electrocardiography was evaluated in 112 women who had no history of myocardial infarction and underwent coronary angiography. The sensitivity of ST-segment displacement of 0.1 mV or more in any of 14 ECG leads was 0.79 for coronary artery stenosis of at least 70%; the specificity was 0.66. Results were similar using bipolar ECG leads CC5 and CM5 or 11 standard ECG leads. The ST-segment shifts that occurred only during exercise were associated with a 77% false-positive rate (10 of 13). Downsloping ST-segment depression did not provide more diagnostic information than horizontal ST-segment depression in the three clinical subsets of women. In women with typical angina pectoris, ST-segment depression of at least 0.15 mV for 0.08 second after the J point or a final treadmill time less than 360 seconds was predictive of proximal left or multivessel coronary artery disease. In the women with probable angina or nonspecific chest pain, this finding was not of diagnostic value. ST-segment elevation of 0.1 mV or more in leads V1-2 or a VL predicted proximal stenosis of at lest 80% in the left anterior descending coronary artery in all six women with typical angina pectoris. Maximal exercise testing in women with typical angina provides important diagnostic information when 11 standard ECG leads are recorded. In women with probable angina or nonspecific chest pain, diagnostic exercise testing is less useful and bipolar leads CC5 and CM5 are sufficient for most clinical purposes.

Radionuclide angiographic exercise left ventricular performance in chronic aortic regurgitation: relationship to resting echographic ventricular dimensions and systolic wall stress index

Forty-five patients with chronic aortic regurgitation (AR) underwent first-pass radionuclide angiocardiography (RNA) at rest and during upright bicycle exercise, as well as M-mode echocardiography at rest. Abnormal left ventricular (LV) exercise reserve, defined by the absolute change in ejection fraction (EF), was present in 16 of 45 patients (36%). Seven of ten patients with abnormal resting EF (less than 50%) and three of seven symptomatic patients had normal LV exercise responses. Patients with normal LV exercise reserve by RNA had LV dimensions by echo at end diastole (5.9 +/- 0.2 vs 6.5 +/- 0.3 cm, p = NS) and end systole (3.9 +/- 0.2 vs 4.4 +/- 0.3 cm, p = NS) comparable to those in patients wht abnormal LV exercise reserve. However, the mean corrected LV end-diastolic (LVED) radius/wall thickness ratio was significantly greater in AR patients with abnormal LV exercise reserve than in those with normal LV exercise reserve (395 +/- 15 vs 315 +/- 16, p less than 0.01). There data suggest that resting echocardiographic LV dimensions as well as the corrected echo LVED radius/wall thickness ratio have a variable relationship to RNA LV exercise performance in patients with chronic AR.

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.

The prognostic value of submaximal exercise testing with radionuclide ventriculography before hospital discharge in patients with recent myocardial infarction

To test the hypothesis that patients at risk of future cardiac events can be identified by sub-maximal exercise testing with radionuclide ventriculography (RVG), 61 patients were studied a mean of 19 +/- 1.0 days (+/- SEM) after acute myocardial infarction (MI). RVGs were used to measure left ventricular ejection fraction (LVEF), wall motion score (WMS), end-diastolic volume (EDV) and end-systolic volume (ESV), and the ratio of systolic blood pressure to ESV (P/V index) at rest and during submaximal exercise. Frank lead ECGs were analyzed for ST-segment change and arrhythmias. These patients were followed for a mean of 9.6 months (60 for 6 months or more and one for 3 months) to determine the incidence of cardiac death, recurrent MI, unstable or medically refractory angina, persistent congestive heart failure (CHF) or limiting angina; these problems were considered to be important cardiac events. At the 6-month follow-up, 37 patients had important complications: four patients died, five had MI, seven had unstable or medically refractory angina, 11 had persistent CHF and 10 had severe limiting angina. The sensitivity and specificity of RVG in predicting the important postinfarct complications listed above were 95% and 96% for failure to increase LVEF by at least 5 units, 95% and 96% for an increase in ESV of more than 5%, 97% and 88% for failure of the P/V index to increase by more than 35%, and 81% and 88%, respectively, for a decrease in WMS. The sensitivity and specificity of the ECG in predicting important complications were 54% and 58%, respectively. The rest and submaximal exercise RVG variables, the ECG, a history of MI, the location of the infarction, Killip class III, age, sex, and maximal work load performed were analyzed statistically to determine the best predictors of prognosis. The change with exercise in LVEF, ESV and the P/V index were most significant variables in predicting prognosis during the 6-month follow-up period. When patients with subsequent cardiac events were separated into those with death, recurrent MI and unstable or medically refractory angina as major cardiac events, and patients with persistent CHF and limiting angina as less important ("minor") cardiac events, only the peak submaximal exercise LVEF and history of MI were significant in distinguishing these groups. In patients without important cardiac events during the 3- and 6-month follow-up, 70% and 88%, respectively, no abnormality in the responses of LVEF, ESV, or P/V index to submaximal exercise. These results suggest that submaximal exercise testing with RVG is a highly sensitive means of classifying patients at the time of hospital discharge after MI according to the likelihood of having cardiac events during the ensuing 6 months.