Exercise Exercise Electrocardiogram Research Articles

Perioperative cardiac evaluation for noncardiac surgery noninvasive cardiac testing

Prognostic risk stratification to identify perioperative and long-term cardiac risk in selected patients undergoing noncardiac surgery is part of good clinical practice. Exercise variables associated with significant increased risk include poor functional capacity (eg, <4 metabolic equivalents), marked exercise-induced ST segment shift or angina at low workloads, and inability to increase or actually decrease systolic blood pressure with progressive exercise. Approximately 40% of patients tested before peripheral vascular surgery will have an abnormal exercise electrocardiogram (ECG). The predictive value for a perioperative event, ie, death or myocardial infarction, ranges from 5% to 25% for a positive test and 90% to 95% for a negative test. Whereas exercise cardiac imaging is the modality of choice in patients with a noninterpretable exercise ECG, pharmacological stress imaging should be used in the 30% to 50% of patients who require perioperative noninvasive risk stratification and are unable to perform an adequate level of exercise to test cardiac reserve. Myocardial perfusion variables predictive of increased cardiac events include severity of the perfusion defect, number of reversible defects, extent of fixed and reversible defects, increased lung uptake of thallium-201, and marked ST segment changes associated with angina during the test. The reported sensitivity and specificity of dobutamine-induced echocardiographic wall motion abnormalities in patients with peripheral vascular disease is similar to myocardial perfusion scintigraphy, but the confidence limits are wider due to the smaller sample size in these more recent studies. In conclusion, noninvasive cardiac testing should be used selectively in patients undergoing noncardiac surgery; the results provide useful estimates of short- and long-term risk of cardiac events, and the magnitude of abnormal response on noninvasive testing should be used to formulate decisions regarding the need for coronary angiography and subsequent revascularization.

Prevalence of Unrecognized Silent Myocardial Ischemia and Its Association With Atherosclerotic Risk Factors in Noninsulin-Dependent Diabetes Mellitus

To determine the prevalence of unrecognized silent myocardial ischemia, 925 noninsulin-dependent diabetic outpatients (333 women and 592 men), aged 40 to 65 years, asymptomatic, free from known coronary artery disease (CAD), advanced diabetic retinopathy, and nephropathy, severe hypertension, and poor prognosis disease, underwent exercise electrocardiogram (ECG), followed, if abnormal, by an exercise thallium scintigraphy. The exercise ECG tests were abnormal in 112 patients (12.1%, 31 women, 81 men), of whom 59 (6.4%, 12 women, 47 men) had perfusion defects at thallium scintigraphy. Adopting the more restrictive criteria (positive response to both tests) the prevalence of silent CAD resulted in 6.4%. Multivariate analysis showed that in the whole population and in the men, the associated independent risk factors were age, total cholesterol, proteinuria, and ST-T abnormalities at ECG at rest. This last factor had the highest odds ratio (9.27, confidence interval [CI] 4.44 to 19.38) and was the only one identified also in women. The relevance of ST-T abnormalities at ECG at rest as a predicting factor for silent CAD outlines the importance of a periodical ECG at rest in noninsulin-dependent diabetic patients and suggests an indication of performance of further investigations in presence of these abnormalities.

Prognostic value of heart rate adjustment of exercise-induced ST segment depression in the multiple risk factor intervention trial

Objectives.We sought to assess the effect of heart rate adjustment of ST segment depression on risk stratification for the prediction of death from coronary artery disease.Background.Standard analysis of the ST segment response to exercise based on a fixed magnitude of horizontal or downsloping ST segment depression has demonstrated only limited diagnostic sensitivity for the detection of coronary artery disease and has variable test performance in predicting coronary artery disease mortality. Heart rate adjustment of the magnitude of ST segment depression has been proposed as an alternative approach to increase the diagnostic and prognostic accuracy of the exercise electrocardiogram (ECG).Methods.Exercise ECGs were performed in 5,940 men from the Usual Care Group of the Multiple Risk Factor Intervention Trial at entry into the study. An abnormal ST segment response to exercise was defined according to standard criteria as ≥ 100 μV of additional horizontal or downsloping ST segment depression at peak exercise. The ST segment/heart rate index was calculated by dividing the change in ST segment depression from rest to peak exercise by the exercise-induced change in heart rate. An abnormal ST segment/heart rate index was defined as >1.60 μV/beats per min.Results.After a mean follow-up of 7 years there were 109 coronary artery disease deaths. Using a Cox proportional hazards model, a positive exercise ECG by standard criteria was not predictive of coronary mortality (age-adjusted relative risk [RR] 1.5,95% condence interval [CI] 0.6 to 3.6, p = 0.39). In contrast, an abnormal ST segment/heart rate index significantly increased the risk of death from coronary artery disease (age-adjusted RR 4.1, 95% CI 2.7 to 6.0, p < 0.0001). Excess risk of death was confined to the highest quintile of ST segment/heart rate index values, and within this quintile, risk was directly related to the magnitude of test abnormality. After multivariate adjustment for age, diastolic blood pressure, serum cholesterol and cigarettes smoked per day, the ST segment/heart rate index remained a significant independent predictor of coronary death (RR 3.6, 95% CI 2.4 to 5.4, p < 0.001).Conclusions.Simple heart rate adjustment of the magnitude of ST segment depression improves the prediction of death from coronary artery disease in relatively high risk, asymptomatic men. These findings strongly support the use of heart rate-adjusted indexes of ST segment depression to improve the predictive value of the exercise ECG.

Limited value of stress electrocardiographic changes in predicting late 201Tl reversibility

The aim of this study was to assess the relationship between the exercise electrocardiogram (ECG) and late thallium-201 (201Tl) reversibility in a series of 72 consecutive patients with undiagnosed chest pain and an initial persistent perfusion defect on conventional stress/4-h redistribution imaging. We wished to establish the diagnostic accuracy of the exercise ECG in predicting the outcome of late 201Tl reversibility. All 72 patients, of whom 44 (61%) had had a previous myocardial infarction (MI), underwent quantitative planar 201Tl stress-redistribution imaging followed by resting 201Tl imaging 1-4 days later. Fifty (69%) patients showed exercise ECG changes during conventional stress-redistribution imaging, of whom 30 (42%) had a history of previous MI and 20 (28%) had suspected coronary artery disease (CAD). The overall diagnostic accuracy of the exercise ECG in predicting 201Tl reversibility was 83% (60/72 patients): 75% (21/28 patients) in patients with suspected CAD and 87% (39/44 patients) in patients with previous MI. Only the patients with a previous MI and a negative exercise ECG showed 100% accuracy (n = 14). We conclude that reinjection of 201Tl might be withheld in patients with a previous MI and a negative exercise ECG. For patients with previous MI and a positive exercise ECG, and for patients with suspected coronary artery disease regardless of the result of their exercise ECG, reinjection of 201Tl should be strongly considered if the redistribution images are abnormal, because of the suboptimal diagnostic accuracy of the exercise ECG in these patients.

Exercise echocardiography is an accurate and cost-efficient technique for detection of coronary artery disease in women

Objectives. This study compared the accuracy and cost implications of using exercise echocardiography and exercise electrocardiography for detection of coronary artery disease in women.Background. The specificity of exercise electrocardiography in women is lower than in men. Exercise echocardiography accurately identifies coronary artery disease in women, but its utility in place of exercise electrocardiography is unclear.Methods. One hundred sixty-one women without a previous Q wave infarction underwent exercise echocardiography and coronary angiography. Positive findings were a new or worsening wall motion abnormality on the exercise echocardiogram and ST segment depression >0.1 mV at 0.08 s after the J point on the exercise electrocardiogram (ECG).Results. Coronary artery stenosis >50% diameter narrowing was present in 59 patients; the sensitivity (mean ± SD) of exercise echocardiography was 80 ± 3%. In 48 patients with an interpretable ECG, the sensitivity of exercise echocardiography was 81 ±4%, and that of the exercise ECG was 77 ± 3% (p = 0.50). In 102 patients without coronary artery disease, the overall specificity of exercise echocardiography was 81 ± 4%. In 70 patients with an interpretable ECG, the specificity of exercise echocardiography (80 ± 3%) exceeded that of the exercise ECG (56 ± 4%, p < 0.0004). The accuracy of exercise echocardiography was also greater than exercise electrocardiography (81 ± 5% vs. 64 ± 6%, p < 0.005). Exercise echocardiography stratified significantly more patients of intermediate (20% to 80%) pretest disease probability into the high (>80%) or low (<20%) posttest probability group. In women without a previous exercise ECG, the specificity of exercise echocardiography continued to exceed that of exercise electrocardiography (80 ± 3% vs. 64 ± 3%, p = 0.05). Exercise echocardiography had the best balance between accuracy and cost for the diagnosis of coronary artery disease in women.Conclusions. Exercise echocardiography is more specific than exercise electrocardiography for diagnosis of coronary artery disease in women and is a cost-effective approach to the diagnosis of coronary artery disease because of the avoidance of inappropriate angiography.

Incremental value of exercise electrocardiography and thallium-201 testing in men and women for the presence and extent of coronary artery disease

Our goal was to assess the incremental value of exercise testing in men and women for the diagnosis and extent of coronary artery disease. With data from one center, incremental logistic algorithms were developed and evaluated in a separate set of 865 patients from four centers. Variables included were pretest (age, sex, symptoms, diabetes, smoking, and cholesterol concentration); exercise electrocardiogram (ECG) (ST-segment depression [millimeters], ST-segment slope, peak heart rate, and change in systolic blood pressure); and thallium-201 scintigram (defect presence, reversibility, and intensity of hypoperfusion). End points were coronary disease presence (50% diameter stenosis) and extent (multivessel disease). Accuracy and incremental value were assessed by receiver operating characteristic (ROC) curve analysis. Incremental ROC curve areas for disease presence were pretest 0.75 ± 0.02, post—exercise ECG 0.82 ± 0.01, and post-thallium scintigram 0.85 ± 0.01 and for disease extent were pretest 0.71 ± 0.02, post-exercise ECG 0.76 ± 0.02, and post-thallium scintigram 0.78 ± 0.02 ( p < 0.005 for all increments). Incremental increases in accuracy were similar for men and women. We conclude that when multivariable algorithms derived from one center were applied to a separate group, there was a significant incremental increase in accuracy associated with exercise testing for the presence and extent of coronary disease. This increase in accuracy was similar for men and women.

Exercise echocardiography after coronary artery bypass surgery: Correlation with coronary angiography

Our aim was to assess, in patients after coronary artery bypass surgery, how well exercise echocardiography predicts the presence of vascular compromise on angiography. Because late graft failure frequently occurs after bypass surgery, a reliable noninvasive technique is needed to identify those patients who would benefit from angiographic study. In 182 patients, a total of 213 symptom-limited treadmill exercise electrocardiograms (ECGs) and exercise echocardiograms were performed in association with coronary and bypass angiography 2 weeks to 21 years after bypass surgery. There were more inconclusive exercise ECGs (28%) than exercise echocardiograms (9%). The positive predictive value was 85% for the exercise echocardiogram versus 62% for the exercise ECG; the corresponding negative predictive values were 81% versus 52%. The accuracy of the exercise echocardiogram was linked to the degree of underlying vascular compromise. After excluding cases with nondiagnostic results, due to either submaximal stress or poor image quality, the exercise echocardiogram detected 46 of the 60 cases with vascular compromise in one region (sensitivity 77%) and 47 of the 49 cases with compromise in two or three regions (sensitivity 96%). Similarly, an abnormal exercise echocardiogram had a positive predictive value of 71% for vascular compromise in one region and 98% for compromise in two or three regions. Most false negative exercise echocardiographic results were associated with posterolateral single-region vascular compromise on angiography. This study confirms a high positive and negative predictive value of exercise echocardiography in the detection of vascular compromise in patients after bypass surgery. It is clearly superior to exercise electrocardiography in predicting which patients will have angiographically significant graft or arterial lesions, and it can be used to obtain a better selection of patients for angiographic study.

Computer-assisted exercise ECG analysis: real-time scheduling within MS-DOS on PCs

Computer analysis and monitoring of exercise electrocardiograms (ECG) have been advantageously applied for a long time. Recently, the availability of personal computers (PCs) has also had a significant impact in this field. PCs have been used in the development of a software package for on-line exercise ECG analysis. This paper reveals the core of the application, i.e. a built-in real-time executive. A three-phase design approach is described: first, recognition of the tasks and their structure; second, evaluation of the task time complexities; and third, allocation of the tasks and implementation in C++ in the MS-DOS environment. The performance of the real-time multitasking environment is finally studied for the worst-case situation using a prototype PC installation.

Scintigraphic and electrocardiographic evidence of silent coronary artery disease in asymptomatic hypertension: A case-control study

Objectives. This study was conducted to determine the incidence of physiologically significant coronary artery disease in a group of asymptomatic high risk men with essential hypertension and to assess the validity of noninvasive tests in a subset of these patients undergoing coronary arteriography.Methods. Two hundred twenty-six asymptomatic men (mean age 61 ± 8 years) with essential hypertension and no clinical evidence of coronary artery disease but with at least one additional coronary risk factor were studied prospectively. Fifty age- and risk factor-matched normotensive subjects were evaluated as a control group. After a minimum of 4 days without medication, subject's underwent stress thallium-201 scintigraphy, exercise and 48-h ambulatory electrocardiography, and echocardiography. Coronary angiography was performed in a subset of 34 (40%) of 84 patients with one or more positive test results.Results. A positive thallium-201 scintigram (18% vs. 6%; odds ratio 3.4, confidence interval 0.91 to 10.8, p = 0.056), exercise electrocardiograms (ECGs) (37% vs. 13%; odds ratio 4.1, confidence interval 1.5 to 11.2, p < 0.003) and ambulatory ECG (15% vs. 0%, p < 0.05) were more common in the hypertensive group than in the control group. In the cohort undergoing coronary angiography, thallium-201 scintigraphy was both sensitive and specific for epicardial atherosclerotic coronary disease (90% and 79%, respectively), but positive exercise and ambulatory ECGs occurred frequently in the absence of significant coronary stenoses. In the 39% of hypertensive patients who had mild to moderate left ventricular hypertrophy, positive exercise and ambulatory ECGs occurred at a higher rate.Conclusions. These findings suggests that physiologically significant coronary artery disease occurs more frequently in asymptomatic hypertensive men than in comparable normotensive control subjects. In the subgroup undergoing coronary arteriography, reversible scintigraphic defects were both sensitive and specific for diagnosing epicardial coronary artery disease, but exercise and ambulatory ECGs appeared to yield frequent false positive results, especially when left ventricular hypertrophy was present. These results indicate that patients with “silent” coronary artery disease can be identified among high risk hypertensive patients, but the appropriate application of such screening in clinical practice remains to be determined.

The value of thallium scintigraphy in a district general hospital.

The usefulness of exercise Tl scintigraphy (combined with electrocardiography) in a district general hospital has been assessed in 80 patients in whom a previous exercise electrocardiogram (ECG) had not been definitive. Seventy-five of the patients presented with chest pain and five with no pain but an abnormal ECG. Case notes and test results were examined to establish the clinicians' judgment of the likelihood of having coronary heart disease (CHD) and the patient's outcome. The mean time of follow-up was 27 months. In the majority of patients the test was found to help the clinician come to a decision on the presence or absence of CHD. It was found to be particularly useful in patients with abnormal resting ECGs. There was a shorter time to discharge for patients classified as highly unlikely of having CHD. Only four patients were re-referred following discharge from the outpatient clinic. Nine patients were referred for coronary angiography with five being found to have significant stenosis. None of the 16 patients in whom the exercise ECG was normal had ischaemic myocardial segments in the Tl scintigraphy.

Diagnostic Accuracy of Exercise Thallium-201 Scintigraphy in Men With Asymptomatic Essential Hypertension

Coronary artery disease is responsible for much of the morbidity and mortality in patients with essential hypertension, and these complications have proven to be relatively resistant to antihypertensive therapy. However, the diagnosis of coronary disease in the hypertensive population has been considered problematic. In the present study, 30 asymptomatic patients with mild to moderate hypertension with positive exercise electrocardiograms (ECG) or stress thallium-201 scintigrams underwent coronary angiography to determine the accuracy of these tests for coronary artery disease. The exercise ECG was positive in 25 subjects, of whom 15 had significant coronary lesions and 10 did not. Thallium-201 scintigraphy proved more accurate: 17 of 18 patients with reversible abnormalities had significant obstructive coronary disease anatomically corresponding to the defect, one patient with a fixed defect had normal coronary arteries and was found to have an idiopathic cardiomyopathy, and 9 of 11 without defects had no significant lesions. The results were similar in populations with and without echocardiographic criteria for left ventricular hypertrophy. These findings indicate that despite previous suggestions to the contrary, thallium-201 scintigraphy can accurately diagnose coronary artery disease in most patients with asymptomatic essential hypertension, and that most asymptomatic hypertensive patients with physiologic evidence of myocardial ischemia have associated coronary artery disease.

Carotid stenosis is a powerful predictor of a positive exercise electrocardiogram in a large hyperlipidemic population

Hypercholesterolemia is a major risk factor in coronary heart disease (CHD) and ischemic stroke. However, there is no general agreement on the usefulness of systematic screening of patients with hyperlipidemia by stress exercise electrocardiogram (ECG). The feasibility of this approach would depend on selecting patients with a high risk of CHD, since the sensitivity and specificity of the test depends on the prevalence of the disease. In view of the association of CHD and ischemic stroke, we undertook a study to determine whether the presence of atherosclerosis in the carotid arteries was predictive of a positive exercise ECG in a group of 778 asymptomatic patients referred for their hyperlipidemia. We found a much higher percentage of positive exercise ECG in patients with carotid atherosclerosis in our ultrasonogaphic examinations. In a multiple regression analysis which included 13 parameters (age, sex, body mass index, arterial blood pressure, lipid parameters, serum level of glucose, smoking status and the severity of carotid lesions), the strongest predictors of a positive exercise ECG test were age ( P = 0.014) and the degree of carotid atherosclerosis ( P = 0.010). We therefore conclude that hyperlipidemic patients with atherosclerosic lesions on carotid arteries would benefit most from screening by the exercise ECG.

Effect of precision of ST-segment measurement on identification and quantification of coronary artery disease by the ST/HR index.

To assess the effect of varying precision of ST-segment depression measurement on test performance of the ST-segment/heart rate (ST/HR) index for the identification and quantification of coronary artery disease, the exercise electrocardiograms (ECGs) of 100 clinically normal subjects and 154 patients with angiographically proved coronary disease were reviewed. The ST/HR index was calculated by dividing the maximal additional ST-segment depression at end exercise by the exercise-induced change in heart rate. ST-segment depression was measured to the nearest 10 microV (ST10) at a point 60 ms after the J point on a computerized exercise ECG system, and was subsequently rounded down to the nearest 50 microV (ST50) and the nearest 100 microV (ST100) to simulate measurements to these precisions. An ST10/HR index partition of 1.60 microV/bpm with a specificity of 95% (95/100) in normal subjects identified the presence of coronary disease with a sensitivity of 94% (144/154). Precision of ST-segment measurement significantly affected sensitivity for coronary disease. At matched specificity of 95%, an ST50/HR index partition of 1.55 microV/bpm had a sensitivity of 88% (135/154, p less than 0.01) and an ST100/HR index partition of 1.22 microV/bpm had a sensitivity of 84% (130/154, p less than 0.001) for the detection of coronary obstructions. Comparison of receiver-operating characteristic curves (ROC) confirmed the superior overall performance of the ST/HR index using ST10 measurements for the identification of coronary disease. By contrast, test performance for the identification of three-vessel coronary disease was not affected by the precision of ST-segment measurement with no significant difference in test sensitivity or areas under respective ROCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise echocardiographic detection of coronary artery disease in women

The utility of exercise echocardiography for the diagnosis of coronary artery disease has been demonstrated in populations consisting largely of men with a high prevalence of disease. To determine the diagnostic value of exercise echocardiography in women, 57 women who presented with chest pain were studied with coronary cineangiography and echocardiography combined with either treadmill (n = 38) or bicycle exercise (n = 19).Significant coronary artery disease (≥50% reduction in luminal diameter) was present in 28 (49%) of 57 patients, including 16 (84%) of 19 who had typical angina, and 12 (32%) of 38 who had atypical chest pain. The overall sensitivity and specificity of echocardiography were both 86%. Exercise echocardiography correctly determined the presence or absence of coronary artery disease in 32 (84%) of 38 patients who had atypical chest pain and in 17 (89%) of 19 who had typical angina (p = NS). The exercise electrocardiogram (ECG) was nondiagnostic in 17 patients (30%) who had rest ST segment depression or ST depression with exercise that could also be induced by hyperventilation or changes in position. The correct diagnosis was made by echocardiography in 14 (82%) of 17 patients with a nondiagnostic exercise ECG.In conclusion, exercise echocardiography has a clinically useful level of sensitivity and specificity for the detection of coronary artery disease in women. The technique provides diagnostic information in women presenting with atypical chest pain and in those who have a nondiagnostic exercise ECG.

Coronary heart disease morbidity and mortality in hypercholesterolemic men predicted from an exercise test: The lipid research clinics coronary primary prevention trial

A positive exercise electrocardiogram (ECG) has been proved to predict cardiovascular events in asymptomatic normolipidemic men. To study whether it is also predictive for hypercholesterolemic men, data from 3,806 asymptomatic hypercholesterolemic men in the Lipid Research Clinics Coronary Primary Prevention Trial were analyzed. All the men had performed a submaximal treadmill exercise test at baseline, before they were assigned to the cholestyramine or placebo treatment group. Because of missing or inconclusive data, 31 men were excluded from the analyses. A test was positive if the ST segment was displaced by ≥1 mm (visual code) or there was ≥10 μV-s change in the ST integral (computer code), or both. The prevalence of a positive test was 8.3%.During the 7 to 10 year (mean 7.4) follow-up period, the mortality rate from coronary heart disease was 6.7% (21 of 315) in men with a positive test and 1.3% (46 of 3,460) in men with a negative test (placebo and cholestyramine groups combined). The age-adjusted rate ratio for a positive test, compared with a negative test, was 6.7 in the placebo group and 4.8 in the cholestyramine group. With use of Cox's proportional hazards models, it was found that the risk of death from coronary heart disease associated with a positive test was 5.7 times higher in the placebo group and 4.9 times higher in the cholestyramine group after adjustment for age, smoking history, systolic blood pressure, high density lipoprotein cholesterol and low density lipoprotein cholesterol. A positive test was not significantly associated with nonfatal myocardial infarction.Thus, the results indicate that the exercise ECG response is a valuable and independent predictor of the risk of death from coronary heart disease in hypercholesterolemic men.

Early detection of restenosis after successful percutaneous transluminal coronary angioplasty by exercise-redistribution thallium scintigraphy

The value of exercise testing and thallium scintigraphy in predicting recurrence of angina pectoris and restenosis after a primary successful transluminal coronary angioplasty (PTCA) was prospectively evaluated. In 89 patients, a symptom-limited exercise electrocardiogram (ECG) and thallium scintigraphy were performed 4 weeks after they had undergone successful PTCA. Thereafter, the patients were followed for 6.4 ± 2.5 months (mean ± standard deviation) or until recurrence of angina. They all underwent a repeat coronary angiography at 6 months or earlier if symptoms recurred. PTCA was considered successful if the patients had no symptoms and if the stenosis was reduced to less than 50% of the luminal diameter. Restenosis was defined as an increase of the stenosis to more than 50% luminal diameter. The ability of the thallium scintigram (presence of a reversible defect) to predict recurrence of angina was 66%, vs 38% for the exercise ECG (ST-segment depression or angina at peak workload). Restenosis was predicted in 74% of patients by thallium scintigraphy, but only in 50% of patients by the exercise ECG. Thus, thallium scintigraphy was highly predictive but the exercise ECG was not (p < 0.005). These results suggest that restenosis had occurred to some extent already at 4 weeks after the PTCA in most patients in whom it was going to occur.

The effect of validation group bias on screening tests for coronary artery disease.

The exercise electrocardiogram (ECG) is frequently used as a screening tool for coronary artery disease (CAD) in epidemiological studies and routine health evaluation. Estimates of the validity of this diagnostic test have usually been obtained by correlating the exercise ECG with the results of coronary angiography. However, coronary angiography is usually performed only on selected individuals with symptomatic CAD. If symptomatic subjects are more likely to respond positively to the exercise ECG than asymptomatic individuals with comparable severity of disease, then biased estimates of the test validity for an unselected population may be obtained. In this paper the validation group bias is shown to be a function both of the proportion of the population with symptomatic CAD and of the relative validity of the test for the symptomatic and asymptomatic subjects. The extent of this bias is examined.

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 < 0.001) and in patients with left anterior descending disease than in those without (85% versus 26%, respectively; p < 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 < 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.

Reliability of stress thallium-201 scanning in the clinical evaluation of coronary artery disease.

Stress thallium-201 scanning proved to be a highly sensitive and specific screening procedure for myocardial ischemia in 52 consecutive cases with coronary arteriograms. Stress thallium-201 scanning was considerably more accurate and more specific than the exercise electrocardiogram (ECG) as evidenced by a sensitivity of 83% compared to 55%, and a specificity of 94% compared to 82%. When submaximal stress tests were excluded, improved sensitivity of thallium scan to exercise ECG was 95% to 64% with no change in specificity. Factors producing negative thallium scans in the presence of coronary artery disease were: delay in obtaining the first post-exercise scan, positioning and observing variability, severe three-vessel disease uniformly affecting all myocardial segments, and failure to achieve maximal stress testing due to attenuation of the heart-rate response by propranolol or somatic complaints.

Two-step electrocardiogram for chest pain reported on multiphasic screening

Among 264 consecutive persons (142 men, 122 women) greater than or equal to 35 years of age presenting for multiphasic screening examination, 85 (54 men, 31 women) reported chest pain. In most, the pain was not typical of coronary artery disease. The two-step exercise electrocardiogram (ECG) was positive (greater than or equal to 0.5-mm ischemic ST depression) in 21% of the patients who reported pain and in 19.5% of 66 randomly selected, similarly examined controls without chest pain (36 men, 30 women) (difference not significant). Females with positive ECGs (5-mm or 1-mm depression) predominated over males greater than or equal to 5:1 in the chest pain group and greater than 3:1 in controls. This study indicates that the routine two-step exercise ECG is not helpful in detecting ischemic heart disease in persons reporting chest pain during their multiphasic screening examination.