Interpreting the exercise electrocardiogram in patients either on beta-blocking drugs or with chronotropic incompetence.
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Adrenergic beta-Antagonists↗
Biomedical subjects
A P Morise
Publications and source records attributed to A P Morise.
Are the American College of Cardiology/American Heart Association guidelines for exercise testing for suspected coronary artery disease correct?
BACKGROUND: Recently published American College of Cardiology (ACC)/American Heart Association (AHA) guidelines state that patients with suspected coronary disease and an intermediate pretest probability are appropriate candidates for exercise ECG, while those with low or high pretest probability are not. METHODS: From 5,103 consecutive patients with symptoms of suspected coronary disease, we evaluated 872 patients who underwent coronary angiography following exercise ECG. Differences in test performance were determined using receiver operating characteristic curve area analysis. A score using age, gender, symptoms, and risk factors was used to classify patients into low, intermediate, and high pretest probability groups. RESULTS: When patients with inadequate exercise tests were excluded, overall sensitivity and specificity were 70% and 66%, respectively. Only the intermediate pretest probability group demonstrated significant incremental value: pretest vs posttest intermediate, 70 +/- 3 vs 79 +/- 3 (p < 0.0001); low, 71 +/- 6 vs 76 +/- 7 (p = 0.39); and high, 69 +/- 8 vs 75 +/- 7 (p = 0.12). From the low- to the high-probability groups, there was a progressive increase in positive predictive value (21%, 62%, and 92%) and decrease in negative predictive value (94%, 72%, and 28%), respectively. The frequencies of abnormal exercise ECGs were lower in the unselected groups compared with the angiography groups (low, 13% vs 36%; intermediate, 22% vs 53%; high, 36% vs 63%). CONCLUSIONS: Based on the information added by exercise testing to clinical data, these results confirm the ACC/AHA guideline assignments for test selection. However, despite these guidelines, patients with a low pretest probability can be selected for exercise testing with the knowledge that a positive result is infrequent and a negative result carries a very high negative predictive value. Intermediate-probability patients on average carry a significant false-negative rate, suggesting that exercise ECG alone may not be a sufficient screening test in all intermediate-probability patients. Because of poor negative predictive value and a large percentage of negative tests, high-probability patients should undergo coronary angiography as the initial strategy, unless the goal of exercise testing is to assess prognosis.
American Heart Association↗
Comparison of the Diamond-Forrester method and a new score to estimate the pretest probability of coronary disease before exercise testing.
OBJECTIVE: We compared the Diamond-Forrester (DF) tabular method to assess pretest probability of coronary artery disease to a new scoring method (NS). METHODS: We evaluated 544 patients with suspected coronary disease who underwent both exercise electrocardiography and coronary angiography. The prevalence of any coronary artery disease (CAD) (>/=1 vessel with a >/=50% stenosis) within low, intermediate, and high pretest probability groups defined by the 2 methods was compared. The DF method used age, sex, and symptoms. The NS used those 3 factors plus 7 other risk factors. RESULTS: Overall prevalence of CAD was 41%. We compared the respective prevalence of CAD within pretest probability groups. Low probability: DF 27% versus NS 17% (P <.03); intermediate probability: DF 42% versus NS 47%; high probability: DF 70% versus NS 72%. We evaluated results separately in men and women. In women, no significant differences were found. However, in men, a significant difference in the low probability group was found (DF 47% versus NS 22%; P <.03). When the 47 asymptomatic patients were removed from the analysis, there were no differences between the 2 methods. Men: low probability, DF 17% versus NS 21%; intermediate probability, DF 45% versus NS 49%; high probability, DF 67% versus NS 72%. Women: low probability, DF 17% versus NS 15%; intermediate probability, DF 38% versus NS 27%; high probability, DF 83% versus NS 70%. CONCLUSION: In symptomatic patients, the accuracy of the 2 methods was the same. In asymptomatic patients, further evaluation in larger populations will be needed.
Coronary Angiography↗
Lessons learned from studies of the standard exercise ECG test.
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Coronary Disease↗
Left atrial abnormality by electrocardiogram predicts left ventricular hypertrophy by echocardiography in the presence of right bundle-branch block.
BACKGROUND: Left ventricular hypertrophy (LVH) on the electrocardiogram (ECG) may be masked in the presence of complete right bundle-branch block (RBBB). Left bundle-branch block on the ECG is associated with LVH at autopsy in 93% of hearts studied. However, RBBB does not predict LVH and the usual ECG criteria applied for LVH may not be reliable in the presence of RBBB. HYPOTHESIS: The study was undertaken to evaluate left atrial (LA) abnormality as a criterion for the diagnosis of LVH in the presence of RBBB. METHODS: Left atrial abnormality in the ECG was assessed by two independent observers as a criterion of LVH in the presence of RBBB in 100 patients, and data were compared with those of 50 patients without LA abnormality. RESULTS: Left ventricular hypertrophy was confirmed by echocardiographic determination of left ventricular (LV) mass in both groups. Observers reliably differentiated between hypertrophied and normal-sized LV in the presence of RBBB by using LA abnormality as an ECG criterion when correlated with LV mass determined by echocardiography. Observer 1 correctly detected LVH in 88% and Observer 2 in 82% of patients. False positive diagnosis was made in 12 and 18% of patients by Observers 1 and 2, respectively. Observers' performance of recognition of LA abnormality in the present study was 94%. Results showed sensitivity of 76 and 70% and specificity of 84 and 92% for Observers 1 and 2, respectively. Left ventricular mass increased significantly and was diagnostic of LVH in 92% of patients with LA abnormality. Left ventricular mass was high in 84% of patients when corrected by body surface area. LVH in the presence of RBBB by the ECG was found in only seven patients (5%) when six commonly used conventional criteria of diagnosis of LVH by ECG were employed. Regression analysis found LA abnormality to be a strong independent predictor of increased LV mass. Multiple regression analysis revealed that age, body mass index, body surface area, and frontal axis are also significant predictors of LV mass. CONCLUSION: The results obtained by the correlation of LA abnormality by ECG and LVH by echocardiography conclude that LA abnormality by ECG was significantly diagnostic of LV hypertrophy in the presence of RBBB.
Adolescent↗
The specificity of exercise electrocardiography in women grouped by estrogen status.
We compared the specificity of exercise electrocardiography in 1880 men and 1818 women with women grouped by menopausal and estrogen replacement status. Specificity for > or = 1 mm horizontal or downsloping ST-segment depression was determined using angiography in 781 patients and using two other nonangiography-based methods (a pretest probability-based method and a predictive accuracy-based method) in all patients. Using angiography, the specificities+/-SE were 84 +/- 2 for men, 79 +/- 3 for women, 81 +/- 5 for premenopausal women, 81 +/- 4 for postmenopausal women without estrogen replacement, and 77 +/- 5 for women on estrogen replacement. None of these were significantly different. For all patients, the respective specificities using the probability and predictive accuracy-based methods were 97 +/- 1 and 94 +/- 1 for men, 90 +/- 1 and 88 +/- 1 for women, 97 +/- 1 and 92 +/- 2 for premenopausal women, 92 +/- 4 and 88 +/- 3 for postmenopausal women without estrogen replacement, and 85 +/- 4 and 81 +/- 3 for women on estrogen replacement. (Men vs. all women groups except premenopausal women-P < 0.05). Therefore, the premenopausal women had significantly greater specificity than women on estrogen replacement (P < 0.001) and no difference in specificity with men. Women on estrogen replacement had a significantly lower specificity than postmenopausal women not on estrogen replacement (P < 0.05). These results suggest that estrogen replacement therapy and not naturally occurring estrogen has a role in producing false positive exercise electrocardiograms in women.
Adult↗
Accuracy of heart rate-adjusted ST segments in populations with and without posttest referral bias.
We compared the accuracy of the ST segment/heart rate (STHR) index and slope to standard criteria (> or =1 mm horizontal/downsloping ST-segment depression at J + 60 msec) in 1358 patients (152 underwent angiography). All exercise tests used the Cornell protocol and computer measurements of maximum ST-segment depression at J + 60 msec. Test accuracy was determined for the entire group with a probability-based method. Thresholds with equal specificity to standard criteria were determined. By using only patients who underwent angiography, neither STHR index nor slope was more accurate than standard criteria (maximum sensitivity: standard criteria, 42%; STHR index, 51%; STHR slope, 40%). However, by using the entire group, both STHR index and slope were more accurate than standard criteria, but only STHR index achieved statistical significance (maximum sensitivity: standard criteria, 31%; STHR index, 60%; STHR slope, 47%). We conclude that heart rate-adjusted ST-segment criteria are more accurate than standard ST-segment criteria. A lack of demonstration of improved accuracy of STHR index and slope only occurs in patients affected by posttest referral bias.
Adult↗
Development and validation of a clinical score to estimate the probability of coronary artery disease in men and women presenting with suspected coronary disease.
PURPOSE: Guidelines for the management of patients with suspected coronary disease have emphasized stratification into groups with low, intermediate, and high probability of significant coronary disease. Previously derived clinical prediction rules have been difficult to apply in clinical settings. The purpose of this study was to develop and validate a clinical score that facilitates this stratification process. PATIENTS AND METHODS: We performed a retrospective analysis of prospectively acquired data from 915 patients with suspected coronary disease and normal resting electrocardiograms who presented for exercise testing at a university hospital. All patients subsequently underwent coronary angiography. Analysis included logistic regression with significant coronary disease (> or = 1 vessel with a > or = 50% lesion) presence as the dependent variable and clinical variables as independent variables. From this analysis, a coronary disease score was developed to estimate prevalence of coronary disease from clinical variables. Validation of this score was performed in a separate prospectively acquired cohort of 348 patients. RESULTS: For the entire validation group, the prevalence of significant coronary disease was 16% (10/63) in the low probability group, 44% (86/195) in the intermediate probability group, and 69% (62/90) in the high probability group. Both men and women were stratified equally well into the 3 probability groups. CONCLUSION: The clinical score is an easily memorized and accurate method for categorizing patients with suspected but not proven coronary disease and normal resting electrocardiograms into clinically meaningful probability groups upon which decisions concerning appropriate diagnostic test selection could potentially be based.
Aged↗
Statistical, epidemiological and fiscal issues in the evaluation of patients with coronary artery disease.
The application of myocardial perfusion scintigraphy to patient care in the era of health care cost containment is a difficult issue. The traditional diagnosis based approach to testing, although effective, is incompletely applied, as evidenced by the number of low likelihood of coronary artery disease patients referred for testing. A prognosis- or risk-based testing approach may be applied to both patients with or without known coronary artery disease by utilizing clinical and scan information to estimate the projected risk of adverse outcomes (cardiac death or myocardial infarction) and planning subsequent patient strategy based upon this estimate. Patients at high risk for these events are more likely to benefit from referral to catheterization while those patients at lower risk may benefit from medical therapy alone. Irrespective of the approach utilized to evaluate testing, consideration of patient population selection and its implications must be considered when reviewing the results of testing or published literature. Further, scrutiny of both the statistical methods used for evaluation of the value of testing and the economic implications of testing in particular patient subgroups are of importance.
Coronary Disease↗
Validation of estrogen status as an independent predictor of coronary artery disease presence and extent in women.
OBJECTIVE: To validate the independent nature and incremental value of estrogen status concerning the diagnostic evaluation of women with suspected coronary artery disease. DESIGN AND METHODS: The study comprised a total of 1,168 patients, the first 915 of whom served as a training or derivation population. Data from the subsequent 253 patients were prospectively collected and used to validate observations from the derivation group. We performed logistic regression analysis of age, sex, symptoms, smoking habits, diabetes, hypertension, and other variables with and without estrogen status (defined according to menopausal and estrogen replacement status). Diagnostic outcomes were assessed by receiver-operating characteristic curve area analysis. RESULTS: Within the derivation group, estrogen status was an independent predictor of both significant (> or = 1 lesion > or = 50% stenosis) and serve (at least two vessels with > or = 70% stenosis) coronary disease on angiography. Receiver-operating characteristic curve areas for models applied to the validation group were as follows: women without estrogen status, 77 +/- 4 for significant disease and 76 +/- 5 for severe disease; women with estrogen status, 80 +/- 4 for significant disease and 80 +/- 5 for severe disease; men, 72 +/- 4 for significant disease and 74 +/- 4 for severe disease (women with versus women without estrogen status; P < 0.05). CONCLUSION: Estrogen status has significant incremental value for enhancing the diagnostic discrimination of significant and severe coronary disease in women. Estrogen status, as defined in this study, is an important and independent diagnostic clinical variable in women with suspected coronary disease.
Coronary Disease↗
Diagnostic accuracy of heart rate-adjusted ST segments compared with standard ST-segment criteria.
We compared the accuracy of ST segment/heart rate (ST/HR) index with that of standard criteria (> or = 0.1 mV horizontal/downsloping ST depression 80 ms after the J point) in 121 patients who had undergone angiography (49 with > or = 1 lesion with > or = 50% stenosis) and 50 clinically normal subjects. All exercise tests used the Cornell protocol and computer measurements of maximal ST depression 80 ms after the J point. Thresholds with equal specificity to standard criteria were determined for ST/HR index using each of the 2 normal groups (those who were normal by angiography and those who were clinically normal). In using only patients who underwent angiography, we found that the ST/HR index had a sensitivity that was not significantly greater than that of standard criteria (standard criteria 51%, ST/HR index 59%; p = 0.21). However, the receiver-operating characteristic curve area increased from 64 +/- 4 to 68 +/- 4 (p < 0.02). When clinically normal subjects were used instead of patients without angiographic disease, there was a clearly discernible improvement in sensitivity of ST/HR index over standard criteria (standard criteria 51%, ST/HR index 69%; p < 0.05). The associated curve areas were 69 +/- 4 and 79 +/- 3 (p < 0.001). Therefore, accuracy of the ST/HR index was marginally better than standard criteria only in patients who underwent angiography. When clinically normal subjects were used, the accuracy of the ST/HR index was definitely better than standard criteria. We conclude that the demonstration of improved accuracy of the ST/HR index depends on the population being tested.
Adult↗
Correlation of reported exercise test results with recommendation for coronary angiography in men and women with suspected coronary artery disease.
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Coronary Angiography↗
Comparison of the sensitivity and specificity of exercise electrocardiography in biased and unbiased populations of men and women.
To assess for sex-related differences in posttest referral bias, we compared the accuracy of exercise electrocardiography in biased (coronary angiography only) and unbiased (all unselected) populations with possible coronary disease. A retrospective analysis of clinical and exercise test data from 4467 patients (788 who underwent angiography) was performed (2824 men and 1643 women). The accuracy of a positive exercise test result was assessed in the entire unbiased group with a method that used disease probability (derived with a logistic algorithm) rather than angiography results. We found that the sensitivity and specificity were significantly greater in men than in women with use of the biased or unbiased groups. When the results for the unbiased and biased groups were compared, the sensitivities for the unbiased group were significantly lower and the specificities were significantly higher than those of the biased group. These differences reflect the effects of posttest referral bias. The amounts that sensitivity decreased and specificity increased, however, was not different for men and women. Therefore, we conclude that the accuracy of exercise electrocardiography is lower in women than men irrespective of whether a biased or an unbiased group is used. However, these differences cannot be explained on the basis of sex-related differences in posttest referral bias.
Adult↗
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.
Adult↗
Afterimages: integration of diagnostic information through Bayesian enhancement of scintigraphic images.
Although the diagnostic accuracy of myocardial perfusion scintigraphy can be improved by additional consideration of clinical and exercise information, multivariate prediction models are infrequently used for this purpose in the clinical setting. We therefore developed a Bayesian algorithm that instead transforms the scintigraphic image itself, modifying defect contrast as a function of the pretest likelihood of coronary artery disease. The algorithm was tested in computer simulations of myocardial perfusion scintigraphy with data from 378 patients (166 from California and 212 from West Virginia) who underwent planar exercise thallium-201 scintigraphy and coronary angiography. Images were interpreted before and after enhancement by eight readers (four at each medical center) with different training orientations (internist, radiologist, cardiologist, nuclear cardiologist, and nuclear medicine technologist) who used a four-point score (from 0, normal to 3, severe defect). Accuracy was quantified as area under a receiver-operating characteristic (ROC) curve. Improvements in accuracy obtained by the algorithm were compared to those provided by multiple logistic regression. Overall, Bayesian enhancement increased ROC area from 0.63 +/- 0.04 to 0.71 +/- 0.04 (p < 0.01). The improvement was consistent for all 16 reading sets (eight readers multiplied by two patient populations; p < 0.05). In comparison, multiple logistic regression increased ROC area from 0.63 +/- 0.04 to 0.79 +/- 0.03 (p < 0.01), outperforming interpretation of the enhanced images in 13 of the 16 reading sets. Bayesian enhancement improves diagnostic accuracy of conventional scintigraphic image interpretation. The improvement is stable across individuals, training orientations, and patient populations. Although this approach is not as accurate as multiple logistic regression, it may be more practical for widespread clinical application.
Algorithms↗
Incremental evaluation of exercise capacity as an independent predictor of coronary artery disease presence and extent.
To determine the independent incremental value of exercise capacity (METS) concerning the presence and extent of coronary artery disease, we analyzed data from 800 patients with suspected coronary disease who underwent both exercise testing and coronary angiography. We performed logistic regression analysis of clinical and exercise test data with an incremental design to mimic the usual flow of data acquisition. Separate analyses were performed concerning coronary disease presence (> or = 1 vessel with a > or = 50% lesion) and extent (three-vessel/left main disease). Diagnostic accuracy was determined by calculating receiver operating characteristic (ROC) curve areas. When considered alone, METS was a significant predictor of both presence and extent of disease. Multivariate analysis revealed that METS was an independent predictor of disease extent but not presence. However, comparison of ROC curve areas failed to show any loss of accuracy when METS was removed from the coronary disease extent analysis. Despite the strong univariate relationship between exercise capacity and coronary disease presence and extent and the independence of exercise capacity as a predictor of coronary disease extent, the lack of an additional incremental accuracy attributed to its consideration virtually cancels its value as a diagnostic variable for assessing both coronary disease presence and extent.
Adult↗
Frequency of oral estrogen replacement therapy in women with normal and abnormal exercise electrocardiograms and normal coronary arteries by angiogram.
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Adult↗
Development and validation of a logistic regression-derived algorithm for estimating the incremental probability of coronary artery disease before and after exercise testing.
OBJECTIVES: Our goals were to develop and validate a multivariate algorithm for estimating the incremental probability of the presence of coronary artery disease. BACKGROUND: Multivariate methods, including logistic regression analysis, have been extensively applied to diagnostic exercise testing. However, few previous studies have included both an incremental design and external validation. METHODS: A retrospective collection of clinical, exercise test and catheterization data was performed involving four U.S. referral medical centers. All patients had no prior history of coronary disease and had undergone coronary angiography < or = 3 months after exercise stress testing. An algorithm was developed in one center (590 patients with a 41% prevalence of coronary artery disease) with the use of logistic regression analysis and was validated in the other three centers (1,234 patients, 70% prevalence). The algorithm incorporated pretest variables (age, gender, symptoms, diabetes, cholesterol), exercise electrocardiographic (ECG) variables (mm of ST segment depression, ST slope, peak heart rate, metabolic equivalents [METs], exercise angina) and one thallium variable. Discrimination was measured with receiver operating characteristic curve analysis. Calibration (that is, reliability) was assessed from a comparison of probability estimates and the actual prevalence of disease. RESULTS: The overall incremental receiver operating characteristic curve areas for the validation group were pretest, -0.738 +/- 0.016; postexercise ECG, 0.78 (SE 0.017); and postthallium, 0.82 (SE 0.016); p < 0.01 for both increments. Within the three validation institutions, the institution with a disease prevalence closest to that of the derivation institution had the best incremental receiver operating characteristic curve areas. There was a stepwise incremental improvement in calibration especially from exercise ECG to thallium testing. CONCLUSIONS: An incremental multivariate algorithm derived in one center reliably estimated disease probability in patients from three other centers. The incremental value of testing was best demonstrated when the derivation and validation groups had a similar disease prevalence. This algorithm may be useful in decision making that relates to the diagnosis of coronary disease.
Algorithms↗