Supine bicycle stress echocardiography versus tomographic thallium-201 exercise imaging for the detection of coronary artery disease

A meta-analytic comparison of echocardiographic stressors

BACKGROUND

The relative performance of alternative stressors for stress echocardiography for the diagnosis of coronary artery disease (CAD) is not well established.

METHODS

All studies published between 1981 to December 2001 who met inclusion criteria were included in this analysis. We performed a summary receiver operator characteristic (SROC) analysis and calculated weighted mean of the likelihood ratio and sensitivity/specificity. A covariate analysis using meta-regression methods was also performed.

RESULTS

Forty-four studies presented data on Exercise, 11 on Adenosine, 80 on Dobutamine, 40 on Dipyridamole, 16 on transatrial pacing transesophageal echocardiography (Tap-TEE), and 7 on transatrial pacing transthorasic echocardiography (Tap-TTE). SROC analysis showed that the following order of most discriminatory to least: Tap-TEE, Exercise, Dipyridamole, Dobutamine and Adenosine. Weighted means sensitivity/specificity were Exercise: 82.6/84.4%, Adenosine: 68.4/80.9%, Dobutamine: 79.6/85.1%, Dipyridamole: 71.0/92.2%, Tap-TTE: 90.7/86.1%, and Tap-TEE: 86.2/91.3%. Covariate analysis showed that the discriminatory power of Exercise decreased with increasing mean age.

CONCLUSIONS

Tap-TEE is a very accurate test for both ruling in and ruling out CAD although its invasiveness may limit its clinical acceptability. Exercise is a well-balanced satisfactory test for both ruling in and ruling out but performance might be lower for the elderly. Dobutamine offers a reasonable compromise for Exercise. Dipyridamole might be good for ruling in but not for ruling out CAD. The incapability in ruling-out CAD was a major problem in clinical application of the stress. Adenosine was the least useful stressor in diagnosing CAD.

Cardiac imaging in women: use of radionuclide myocardial perfusion imaging and echocardiography for acute chest pain

Evidence for the value of noninvasive cardiac imaging in patients for the detection of ischemic heart disease has traditionally come from trials using male patients. The application of such technology for women is often presumptive. Because there is an overall lower prevalence of ischemic heart disease in women, difference in body habitus, and smaller heart size, cardiac imaging in women presents unique challenges for imaging specialists and cardiologists. With the introduction of technetium-99 meters perfusion agents, gated single-photon emission computed tomography, and attenuation correction, myocardial perfusion imaging (MPI) in women has achieved a high sensitivity and specificity for the detection of coronary artery disease similar to that observed in men. With harmonic imaging and myocardial contrast agents, two-dimensional echocardiography offers comparable diagnostic accuracy in women. More importantly, MPI and stress echocardiography have prognostic value in predicting future cardiovascular events. The severity and extent of the single-photon emission computed tomography myocardial perfusion defects independently predict future cardiovascular events. Myocardial perfusion rest imaging during acute chest pain has a 99% negative predictive value of subsequent cardiovascular events, and a positive study MPI is the most important predictor for future cardiac events. Both MPI and stress echocardiography can direct high-risk patients to more invasive management or selectively identify lower-risk patients, allowing safe discharge from the emergency department and unnecessary hospitalization. Using a triage approach incorporating MPI or rest echocardiography in patients with acute chest pain results in significant cost savings. However, data on rest imaging in women during acute chest pain are still lacking.

[Physiologic evaluation of coronary circulation. Role of invasive and non invasive techniques]

For many years, the evaluation of the extent and severity of coronary artery disease has been mainly anatomical, carried out by coronary angiography. However, this technique has methodological limitations and interobserver variability is considerable. Quantification of coronary reserve with pressure guidewires and intracoronary Doppler now provides more precise physiologic evaluation of coronary circulation. Myocardial perfusion single proton emission computed tomography and echocardiography, combined with stress and/or pharmacological challenge testing, though they are only semiquantitative techniques, also offer appropriate complements to coronary angiography in the functional evaluation of coronary patients. The aim of this paper is to discuss the clinical value of these techniques.

Stress echocardiography: technical considerations

Stress echocardiography has evolved into a widely practiced and accepted method for the noninvasive assessment of the status of the coronary anatomy. Furthermore, this modality incorporates the ability to assess left ventricular function, valvular structure and function, intracardiac masses, the pericardium, and hemodynamics. The extent to which this tool can reliably provide useful clinical information is dependent, in part, on optimal performance. The purpose of this report is to provide an overview of those technical considerations that can contribute to the successful operation of a stress echocardiography laboratory. Consideration is given to personnel qualifications, functional requirements of the digital acquisition/storage/replay system, functional integration of the various hardware components, characteristics of the software, physical layout of the facility, and alternatives to treadmill exercise as the stressor. A thorough understanding of the physiologic basis of stress echocardiography, coupled with optimization of resources used in its performance, enable this tool to be an extraordinarily useful and cost-efficient method for comprehensive cardiovascular assessment.

Cost-effectiveness and accuracy of exercise stress echocardiography in the non-invasive diagnosis of coronary heart disease

BACKGROUND

Exercise stress echocardiography (ESE) is a more recent form of totally non-invasive stress testing which like exercise thallium SPECT scintigraphy (ETS) was developed to overcome the known limitations of ECG stress testing, namely the limited diagnostic accuracy and the inability of ECG stress testing to site the region of coronary artery disease (CAD) induced ischaemia.

AIMS

To determine the sensitivity and specificity (and overall accuracy) of ESE in a group of patients referred for ETS imaging and compare the relative costs of each technique.

METHODS

One hundred and fifteen patients referred for ETS consented to a simultaneous ESE. Of this group, 59 patients underwent coronary angiography which was utilised as the gold standard.

RESULTS

The feasibility of ESE was 97% (112 of 115 patients of the total study population and 57 of the 59 patients who underwent coronary angiography). Of the 59 patients undergoing coronary angiography, the sensitivity of ESE and ETS were not significantly different (84.1% versus 91.3% respectively). However, despite the apparent marked difference in specificity (92.3% versus 61.5% respectively), p = NS (Fisher's exact test) as there were only 13 normals in the group who underwent coronary angiography. Overall accuracy was also closely similar (86.0% versus 84.7% respectively) and therefore also not significantly different. By contrast, agreement with coronary angiography as measured by the kappa statistic (kappa +/- SEk) was good for ESE (0.66 +/- 0.11) but only moderate for ETS (0.54 +/- 0.13). Moreover, there was a cost saving of at least $594.00 per patient in favour of ESE.

CONCLUSION

ESE is a totally non-invasive, sensitive, specific and cost-effective imaging modality for the detection and localisation of CAD.

Anatomy of a meta-analysis: a critical review of "exercise echocardiography or exercise SPECT imaging? A meta-analysis of diagnostic test performance"

BACKGROUND

Accurate diagnosis of coronary heart disease has the potential to contribute substantially to cost-effective delivery of health services. Recent work by Fleischmann et al (JAMA 1998;280:913-20) represents an effort to summarize the accuracy of exercise echocardiography and exercise single photon emission computed tomography (SPECT).

METHODS AND RESULTS

A critique of the previous work was constructed, obtaining the 44 articles used. These articles were reviewed and summarized with established techniques for meta-analysis. The studies summarized by Fleischmann et al were found to be significantly heterogeneous (echocardiography and SPECT, both P<.001). In the SPECT cohort, combination of different radioisotopes and reading techniques, and inclusion of reports using experimental techniques, were sources of heterogeneity. In the echocardiography cohort, experimental techniques and an individual series were identified. When the sample was stratified for sources of heterogeneity, it was found that there was no significant difference in diagnostic accuracy between the echocardiography and SPECT techniques used in current clinical practice. Meta-regression with summary receiver operating characteristic curve techniques, after adjustment of the model for multicolinearity and outliers, revealed that there were no significant differences between SPECT as used in current clinical practice and echocardiography.

CONCLUSION

The report by Fleischmann et al contains serious flaws that limit its validity and generalizability.

Diagnostic and prognostic use of stress echocardiography in stable patients

Stress echocardiography is an effective diagnostic and prognostic technique in stable patients with known or suspected coronary artery disease (CAD), myocardial infarction, or chronic left ventricular dysfunction and those undergoing noncardiac surgery. Stress echocardiography is sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events regardless of the clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Stress echocardiography provides incremental prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable to that from radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for one-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.

Diagnostic and Prognostic Use of Stress Echocardiography and Radionuclide Scintigraphy

Stress echocardiography and radionuclide scintigraphy are effective diagnostic and prognostic techniques in patients with known or suspected coronary artery disease (CAD), myocardial infarction (MI), chronic left ventricular dysfunction (LVD), and those undergoing noncardiac surgery. Both are sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events irrespective of clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Both provide incremental diagnostic and prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable with radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for single-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.

Advances in Exercise Echocardiography Can This Technique Still Thrive in the Era of Pharmacologic Stress Testing?

In the current literature, pharmacologic stress techniques are the focus of interest and excitement regarding new technologies and new indications such as the diagnosis of viable myocardium. In contrast, exercise echocardiography has evolved less and is less amenable to the introduction of new technologies. This article reviews the indications for exercise echocardiography (especially in contrast to pharmacologic stress), its accuracy relative to other testing, and application to clinical decision making. Exercise echocardiography remains to be well accepted as a diagnostic and risk-assessment technique, and in some clinical situations it provides valuable data that are not available during pharmacologic stress testing.

Exercise echocardiography. Principles, methods, and clinical use

Stress echocardiography is composed of a family of examinations in which various forms of cardiovascular stress are combined with echocardiographic imaging to assist in the diagnosis of coronary artery disease. Exercise cardiography has evolved over the past 20 years into a routinely available clinical tool employed in both university and community hospital settings. This article discusses advantages and disadvantages of using exercise echocardiography.

Clinical application of exercise stress echocardiography: supine bicycle or treadmill?

Although exercise stress echocardiography is currently used to evaluate coronary artery disease (CAD) patients, the best exercise methodology is still undefined. The objectives of the study were: (1) to compare supine bicycle stress echocardiography (SBSE) and treadmill in the evaluation of CAD; and (2) to define, in normal subjects, the different behavior of factors determining MVO2 with treadmill and SBSE. We selected 10 male patients with CAD (group A), and 10 male control subjects (group B). Each patient underwent SBSE and treadmill testing in random order. We studied heart rate, systolic blood pressure, heart rate x systolic blood pressure, and end-diastolic and end-systolic volume indexes. In group A, we also studied wall motion score index (according to the American Society of Echocardiography) and in group B, systolic blood pressure/end-systolic volume index. The results were as follows: Group A: SBSE resulted in significantly lower work load, heart rate, and significantly higher systolic blood pressure, heart rate x systolic blood pressure, end-diastolic volume index, end-systolic volume index, and wall motion score index. SBSE showed wall motion abnormalities in each patient, whereas treadmill did not detect wall motion abnormalities in 4 patients (3 single-vessel; 1 multivessel); of the other 6 patients, 2 showed a lower wall motion score index and 4 did not show any difference in left ventricle kinetics with the 2 methodologies of exercise. Mean acquisition time for postexercise images was 72 +/- 6 seconds. Group B: SBSE resulted in lower work load, heart rate, heart rate x systolic blood pressure, systolic blood pressure/end-systolic volume index, and higher end-diastolic volume index and end-systolic volume index. Systolic blood pressure was similar with SBSE and treadmill testing. In conclusion, our experience suggests SBSE is a highly accurate diagnostic tool for evaluating CAD compared with treadmill testing; the maximum cardiovascular performance can be achieved with lower values of heart rate, suggesting the echo test is more feasible. Treadmill testing could lose important information about the existence, extension, and location of CAD; in contrast, SBSE detects even small, quickly reversible wall motion abnormalities.

Assessment of myocardial perfusion and contractile function by inotropic stress Tc-99m sestamibi SPECT imaging and echocardiography for optimal detection of multivessel coronary artery disease

OBJECTIVE

To assess whether inotropic stress myocardial perfusion imaging, echocardiography, or a combination of the two could enhance the detection of multivessel disease, over and above clinical and exercise electrocardiographic data.

DESIGN

100 consecutive patients investigated by exercise electrocardiography and diagnostic coronary arteriography underwent simultaneous inotropic stress Tc-99m sestamibi SPECT (MIBI) imaging and echocardiography. MIBI imaging and echocardiographic data were analysed using a 12 segment left ventricular model, and each segment was ascribed to a particular coronary artery territory. The presence of perfusion defects with MIBI imaging or of wall thickening abnormality with echocardiography in at least two coronary artery territories at peak stress was taken as diagnostic of multivessel disease. Arteriographic evidence of > or = 50% stenosis was considered significant.

RESULTS

56 patients had multivessel disease. The sensitivity of the combination of MIBI imaging and echocardiography for detecting this was greater than either MIBI imaging or echocardiography alone (82%, 68%, and 68%, respectively; p = 0.005). Clinical and exercise electrocardiographic variables gave an R2 value of 18.2% for predicting multivessel disease. The addition of either MIBI imaging (R2 = 29.2%; p = 0.002) or echocardiography (R2 = 28.8%; p < 0.001) enhanced the detection of multivessel disease, and the inclusion of both had further incremental value (R2 = 34.8%; p = 0.003). Age (p = 0.03), MIBI imaging (p = 0.007), and echocardiography (p = 0.001) were independent predictors of multivessel disease.

CONCLUSIONS

The assessment of both myocardial perfusion and contractile function by simultaneous inotropic stress MIBI imaging and echocardiography optimises the non-invasive detection of multivessel disease.

Stress echocardiography for assessing myocardial ischaemia and viable myocardium

Images

Echocardiographic Assessment of Regional and Global Left Ventricular Function Wall-Motion Scoring in Parasternal and Apical Views Versus Apical Views Alone

The aim of the study was to examine the value of echocardiographic wall-motion scoring in apical views as compared to a conventional combination of apical and parasternal views. In 50 consecutive patients referred to coronary arteriography for potential revascularization, echocardiographic digital image loops of the left ventricle (LV) were recorded in parasternal long- and short-axis views and in apical long-axis, two-, and four-chamber views. Eight of 16 standardized LV segments appear both in the apical and in the parasternal views (group 1 segments). The remaining eight segments are visualized in the apical views only (group 2). Using a cross-over design, two cardiologists independently performed regional wall-motion scoring based on apical views, respectively, based on the combination of parasternal and apical views. Using the conventional approach (parasternal and apical views) 98% of the total 800 segments were scored as compared to 95% when using the mere apical approach (P < 0.05); 94% of the 800 segments were scored from both approaches. The regional wall-motion score was identical in 76% of group 1 segments and in 77% of group 2 segments. It diverged, at most, one score in 94% of group 1 segments and in 91% of group 2 segments (P > 0.05). LV ejection fraction (EF) calculated on the basis of average wall-motion score exclusively assessed from the apex differed little from angiographic EF (mean difference 2.0%, 95% confidence limits +/- 6.6%). Intraobserver variability of wall-motion scores (n = 25 patients) was small and almost identical for the two cardiologists. Similarly, interobserver variability was small and identical for apical views and conventional views. We conclude that there is no substantial loss of information when echocardiographic evaluation of regional and global left ventricular function is performed solely from the apical approach.

The Five View Technique for Stress Echocardiography: A Description and Evaluation of Segmental Imaging and Reported Angiographic Data

Stress echocardiography is an accurate means of evaluating ischemic heart disease with sensitivities and specificities equivalent to alternate modalities. The sensitivities to disease of vessels with posterior wall distribution are, however, significantly lower. Studies establishing these figures have used a 4 view digital imaging technique as standard. This study aimed to determine if the use of a 5 view template (4 views plus an apical 3 chamber (3ch) view) significantly improved stress echo results. One hundred consecutive stress echocardiograms using a 5 view format were analyzed by two independent observers. Nine thousand regional wall segments were graded quantitatively and qualitatively and comparisons were made between the 4 and 5 view techniques. Reported angiographic sensitivities of the two techniques were analyzed and compared to the segmental imaging data. The 5 view template was found to increase overall segmental imaging by 30% and imaging of lateral and posterior walls was increased by 50% while the additional poststress cycle was acquired in under 13 seconds. Five view studies reported increased mean sensitivities to left anterior descending coronary artery (LAD) disease of 29.7%, right coronary artery (RCA) disease of 25.7%, and circumflex coronary artery (Cx) disease of 51.6%. This study found that the 5 view technique significantly increased left ventricular segmental imaging, particularly of the posterior and lateral walls, and is associated with increased angiographically determined sensitivity, particularly for vessels with posterior wall distribution when compared to the 4 view technique.

Technical Issues Related to Digital Stress Echocardiography Analysis and Acquisition Stations

Digital acquisition and display of echocardiographic images has facilitated the development of stress echocardiography. This review will outline technical issues involved with digital capture and manipulation of echocardiographic data, referring to currently available commercial equipment. Among the acquisition items to be discussed are the source of the digitized data (direct digital transfer from the echo machine vs video capture); image resolution (spatial and temporal spacing of the digitized data); and EKG triggering options (direct triggering of the QRS complex vs detecting the QRS on the video transfer). During playback, rest and stress images may be displayed at different frame rates, so that systole will occupy approximately the same time interval. Currently available commercial systems are compared with regard to these features, as well as hardware architecture and operating system.

Arbutamine vs. exercise stress testing in patients with coronary artery disease: evaluation by echocardiography and electrocardiography

Arbutamine is a new beta-adrenergic agonist with potent chronotropic and inotropic properties developed to pharmacologically induce stress. A prospective trial was conducted in five centers with a total enrolment of 45 patients with angiographically documented coronary artery disease. The primary purpose of the trial was to compare the efficacy of arbutamine with symptom-limited exercise in provoking clinical (angina), electrocardiographic (> or = 0.1 mV ST depression) and echocardiographic (induced wall motion abnormality) evidence of transient stress-induced ischemia. The secondary purpose was to assess the safety of arbutamine in patients with coronary artery disease. Ischemia was induced at a lower heart rate, systolic blood pressure and pressure-rate product during arbutamine infusion than during exercise. Using angina and/or electrocardiographic evidence of ischemia, arbutamine was more sensitive than exercise in detecting myocardial ischemia (77 vs. 58%, P = 0.021). Using echocardiography, the sensitivity for inducing wall motion abnormalities was 88% with arbutamine and 79% with exercise (P = not significant). Echocardiography in combination with angina and/or electrocardiographic evidence increased the sensitivity to 94% using arbutamine and to 88% with exercise. For the patients with multivessel disease, the sensitivity was 97% and 91%, respectively. No serious adverse events, either cardiac or noncardiac, were associated with arbutamine, and no patient had prolonged ischemia. Although exercise is the preferred method of stress for patients who are able to exercise adequately, arbutamine is at least as sensitive as exercise for the diagnosis of myocardial ischemia, and appears to be a safe and effective alternative to exercise testing in patients unable to exercise adequately.

Sonicated albumin in exercise echocardiography: technique and feasibility to enhance endocardial visualization

Left ventricular cavity opacification can be produced by the intravenous injection of sonicated albumin (Albunex 422). A recent study suggested that sonicated albumin may be useful in dobutamine stress echocardiography, but its use in exercise echocardiography has not been reported. The purposes of the study were to assess the feasibility of using Albunex to enhance endocardial visualization and to evaluate the factors affecting Albunex kinetic in exercise echocardiography. Fifteen healthy volunteers underwent two exercise echocardiograms on the same day, with intravenous injection of Albunex during one of the studies. Two injections up to a maximum of 20 ml of Albunex per injection were given to enhance the four- and two-chamber views, both at rest and immediately after exercise. The degree of left ventricular enhancement and the percentages of endocardial visualization were measured in both resting and exercise images. Variables relating to the kinetics of Albunex, which included volume of contrast injected, transit time, heart rate, and cardiac output at the time of image acquisition, were also assessed. There was no difference in the image acquisition time between the two exercise echocardiograms. Albunex produced good left ventricular opacification both at rest and after exercise. More endocardial border was visualized with contrast injection than without (91.2% +/- 11.5% vs 85.8% +/- 14.2%, p = 0.007). The transit times and volumes of Albunex injected were significantly less after exercise than at rest. The parameters were inversely related to heart rate and cardiac output. In conclusion, intravenous injection of Albunex is a promising means to enhance left ventricular endocardial visualization in exercise echocardiography and can be readily incorporated without causing a significant delay in obtaining images after exercise. Whether its use can improve diagnostic accuracy of exercise echocardiography requires further studies.

Predicting the severity of coronary lesions by the continuous recording method of exercise two-dimensional echocardiography

We estimated the severity of coronary artery disease by the continuous-recording method of exercise two-dimensional echocardiography (Ex.2DE) in 56 patients with angiographically significant coronary artery stenosis ( > 50% diameter narrowing) who had undergone both Ex.2DE and coronary angiography. Patients were divided into two groups on the basis of findings of coronary angiography: group 1 had 50% to 89% stenosis (n = 24) and group 2 had 90% or greater stenosis (n = 32). The sensitivity and specificity of Ex.2DE for the detection of ischemic segments were 82% and 88%, respectively in the overall patient population. The sensitivity was 67% in group 1 and 94% in group 2. Hyperkinesis occurred at the beginning of exercise in 21 (88%) of 24 patients in group 1 and 15 (47%) of 32 patients in group 2 (p < 0.05). Our findings demonstrated that patients who did not show hyperkinesis at the beginning of exercise had more severe coronary artery disease. Careful observation of serial wall motion during exercise by the continuous-recording method may provide important information about myocardial ischemia.

Stress imaging. Current clinical options for the diagnosis, localization, and evaluation of coronary artery disease

As technology advances, new methods evolve. In this article, the methods of stress testing and related imaging in coronary disease are addressed, and dynamic and pharmacologic stress, direct and indirect methods, are defined and evaluated. The stress imaging methods related to the modalities of scintigraphy and ultrasound are reviewed and their advantages and disadvantages assessed in view of scientific and economic factors.

Comparison of modalities to diagnose coronary artery disease

The purpose of this review is to compare several modalities available for detection of coronary artery disease (CAD). We compare the clinical history, rest/exercise electrocardiogram (ECG), rest/stress left ventricular (LV) function by radionuclide or echocardiographic methods, myocardial perfusion imaging (MPI) by single photon emission computed tomography (SPECT) or positron emission tomography (PET), contrast coronary angiography, magnetic resonance imaging (MRI), spectroscopy (MRS) and angiography (MRA), and ultrafast cine computed tomography (UFCT) to assess LV function, myocardial perfusion, and coronary calcification. We compare the modalities by answering six questions: (1) Does the modality provide unique clinical information? (2) What is the observer error? (3) What are sensitivities and specificities to detect CAD? (4) What patient selection criteria should be applied for each modality? (5) What incremental benefit is obtained from one modality versus another modality? and (6) Where do the modalities fit in the overall scheme of diagnostic testing for CAD? PET MPI appears to be the best noninvasive test for CAD, followed by SPECT thallium-201 and then dobutamine echocardiography. MRA and UFCT may soon play a larger role because they visualize the arteries. Contrast coronary angiography remains the gold standard despite its limitations. Exercise ECG is the least accurate test. The choice of tests critically depends on patient selection--based on clinical history, age, gender, and risk factors to estimate the pretest, clinical probability of CAD.

A consideration of current clinical options for stress imaging in the diagnosis and evaluation of coronary artery disease

The evolution of technology and our health care system, tinctured by advocacy groups for specific imaging modalities, has produced controversy, relating to the optimal stress imaging method for coronary disease evaluation. Stress perfusion scintigraphy and stress echocardiography advocates seem to make claims that each nullify the other. This extensive, in-depth review of the subject presents facts as well as opinion and experience in an effort to assess the full portrait of the issue for consideration by advocates as well as those many yet undecided. The issue is an evolving one, affected strongly by the reader's own experience. The presentation is not meant to be the final word. Rather, it seeks to present a basis for understanding and progress in both fields.

Truly silent ischemia and the relationship of chest pain and ST segment changes to the amount of ischemic myocardium: evaluation by supine bicycle stress echocardiography

OBJECTIVES

The objectives of this study were 1) to determine the relationship between the amount of exercise-induced ischemic myocardium and the presence or absence of chest pain and ST segment depression, and 2) to define the incidence and characteristics of "truly silent ischemia," that is, ischemia that is not manifested by symptoms or electrocardiographic (ECG) findings.

BACKGROUND

There are no prior data relating ischemia to chest pain and ST depression. Thallium-201 imaging studies have evaluated perfusion but not ischemia. In contrast, supine bicycle stress echocardiography demonstrates exercise-induced ischemic dysfunction.

METHODS

Supine bicycle stress echocardiography and arteriography were performed in 130 patients and the severity and geographic extent of ischemic myocardium were compared in three groups. On exercise, Group I patients had both chest pain and ST segment depression (symptomatic ischemia), Group II patients ST depression without chest pain (asymptomatic ischemia) and Group III patients had neither chest pain nor ST depression (truly silent ischemia).

RESULTS

There were no differences among groups in arteriographic characteristics. The incidence of "truly silent ischemia" was 43%. The number of abnormally contracting ischemic segments, average score per segment and sum of scores were virtually identical in Groups I and II and significantly greater than in Group III for the patients (p < 0.01 to < 0.0001), for the vessels as a group (p < 0.01 to < 0.0001) and for the left anterior descending (p < 0.01 to < 0.0001) and right (p < 0.05) coronary arteries. By multivariate analysis, positive findings on the stress ECG was the single most significant variable in relation to the amount of ischemia (p < 0.001); exercise chest pain had no significant relationship.

CONCLUSIONS

Exercise-induced ST segment depression is the single most significant variable in relation to the amount of ischemic myocardium; exercise-induced chest pain is not related to the amount of ischemia. Patients with "truly silent ischemia" constitute almost 50% of patients with coronary artery disease and have less ischemia than do patients with ECG indications of ischemia, with or without chest pain.