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AIMS: The value of exercise electrocardiography in evaluating women with suspected coronary artery disease is limited. Conversely, stress echocardiography is effective for both diagnostic and prognostic purposes in females. The purpose of the study was to determine the relative prognostic value of exercise electrocardiography and pharmacological stress echocardiography in a cohort of women with chest pain of unknown origin, in order to verify whether criteria could be established for the daily non-invasive evaluation of such a low-risk profile population. METHODS AND RESULTS: Exercise electrocardiography and pharmacological stress echocardiography (171 dipyridamole, 73 dobutamine) were performed in 244 women (age 60+/-10 years) with chest pain and known coronary artery disease. A positive result of exercise electrocardiography (ST-segment shift > or =1 mm at 80 ms after the J point) was detected in 95 patients; a positive result of stress echocardiography (new regional wall motion abnormalities) was observed in 33 patients. During follow-up (36+/-18 months), two deaths, five infarctions, seven unstable anginas, and 11 coronary revascularizations occurred. Using Cox analysis, the positive result of stress echocardiography (odds ratio=40.1) alone, was independently related to hard cardiac events (death, infarction). With spontaneous cardiac events (death, infarction, and unstable angina) as end-points, the multivariate prognostic predictors were a positive result of stress echocardiography (odds ratio=37.0), a family history of coronary artery disease (odds ratio=4.1), typical chest pain (odds ratio=3.7), and a positive exercise electrocardiography result with a rate-pressure product < or =20 000 (odds ratio=3.5). By adopting an interactive stepwise procedure, the prognostic value of stress echocardiography was incremental to that of clinical and exercise electrocardiography data. Nevertheless, the negative result of exercise electrocardiography and pharmacological stress predicted a very high and comparable (P=ns) 24-month survival rate when both hard and spontaneous cardiac events were taken as end-points. CONCLUSIONS: In women with chest pain, stress echocardiography is a strong and independent prognostic indicator, incremental to that shown by exercise electrocardiography. However, the two tests have a similar high negative predictive value in this population. Therefore, exercise electrocardiography has to be considered the initial approach and the only test when the result is negative, whereas stress echocardiography is warranted in selected conditions, including those in women with uninterpretable electrocardiograms, those unable to exercise maximally, and those with an ambiguous or ischaemic response to exercise electrocardiography.
We examined 44 patients (pts) with hypertrophic cardiomyopathy to evaluate the prognostic value of signal-averaged electrocardiography and its possible correlations with clinical and instrumental data. All pts (31 male, 13 female, mean age 47 +/- 15) underwent clinical examination, standard electrocardiography, M-mode and two-dimensional echocardiography, 24-72 hour dynamic electrocardiography and signal-averaged electrocardiography. The mean follow-up was 14 +/- 4 months. Signal-averaged electrocardiography was performed using a 40-250 Hz bidirectional filter. An abnormal signal-averaged electrocardiography with late potentials (filtered QRS duration greater than or equal to 120 msec and root mean square voltage in terminal 40 msec less than or equal to 20 microvolts) was detected in 5 pts (group A, 11%) while 39 pts (group B, 89%) had a normal signal-averaged electrocardiography. Ventricular tachycardia runs at dynamic ECG were present in 2 pts in group A (40%), and in 8 in group B (21%, p = NS). No statistical differences were found between the two groups for any clinical or instrumental data. During our study, one group A patient died suddenly. In detecting subjects with ventricular tachycardia runs, signal-averaged electrocardiography sensitivity was 20%, and specificity was 91%. High specificity suggests that signal-averaged electrocardiography might be used to detect pts at a lower risk for ventricular tachycardia. Further investigations are required to evaluate the predictive value of signal-averaged electrocardiography for sudden death in hypertrophic cardiomyopathy.
OBJECTIVES: Studies on the diagnostic value of exercise electrocardiography in right bundle branch block produced controversial results, and data on the accuracy of stress echo are still lacking. The aim of the study was to compare the diagnostic value of exercise electrocardiography and dipyridamole stress echo in chest pain patients with right bundle branch block, and to verify whether stress testing accuracy is affected by history of hypertension. METHODS: The study group was made up of 71 patients (56 men, aged 63 +/- 8 years) with chest pain of unknown origin and complete right bundle branch block. Of them, 35 were hypertensives and 36 normotensives. Patients performed, on different days and in random order, exercise electrocardiography and dipyridamole stress echo and underwent coronary angiography. RESULTS: Significant (> or = 70% diameter stenosis) coronary artery disease was found in 34 patients (17 hypertensives and 17 normotensives). Positive exercise electrocardiography (ST-segment shift > 1 mm at 80 ms after the J point in leads V5 and V6 or leads II and Vf) and dipyridamole stress echo (new wall motion abnormalities) were observed in 38 and 30 patients, respectively. The result of tests was concordant in 69% of hypertensives and 92% of normotensives. The two tests shared the same sensitivity in hypertensives (82%) and normotensives (71%). Of 37 patients without coronary artery disease, 12 had a false-positive result during exercise electrocardiography and four during stress echo. The specificity was lower for exercise electrocardiography than for stress echo in hypertensives (50 versus 89%, P = 0.0006), while no difference was evidenced in normotensives (84 versus 89%, P = 0.4). In hypertensives, the accuracy, positive, and negative predictive values were 66, 61, and 75% for exercise electrocardiography, and 86, 87, and 84% for stress echo. Corresponding figures in normotensives were 78, 80, and 76% for exercise electrocardiography, and 81, 86, and 77% for stress echo. CONCLUSIONS: In chest-pain patients with right bundle branch block, dipyridamole stress echo was effective to diagnose coronary artery disease in both normotensives and hypertensives. Moreover, it exhibited superior diagnostic information than exercise electrocardiography in hypertensives, due to significantly higher specificity. However, the two tests had similar diagnostic value in normotensives.
The year 1987 marks the centennial of electrocardiography. As Beamish reminds us, it was the first and foremost technical aid to the cardiologist. During the history of cardiovascular epidemiology, which dates back roughly forty years, electrocardiography has played a central role as a relatively specific marker for coronary and hypertensive heart disease. The lack of sensitivity of electrocardiography and the advent of new technologies such as ultrasonography for assessment of such heart disease in cardiology and cardiovascular epidemiology has raised questions as to whether electrocardiography might be replaced in the next century. Recent developments in computer electrocardiography have rendered suggestions of the decreased importance of electrocardiography premature. Use of computer analysis of electrocardiograms in epidemiologic studies, which dates back less than three decades, has renewed interest in and expanded the role of electrocardiography in cardiology in general and cardiovascular epidemiology in particular. The computer analysis of electrocardiograms has allowed the processing and analysis of large numbers of electrocardiograms in a rapid, efficient, systematic and consistent manner. This has led to new, more sensitive criteria for detection of left ventricular hypertrophy as a discrete variable. In addition, the numerous waveform amplitude and duration measurements by computer have allowed the development of mathematical models to express the likelihood of coronary heart disease (myocardial infarction) and degree of left ventricular hypertrophy (estimates of left ventricular mass) on continuous scales. These developments have contributed substantially to the potential of electrocardiography (and particularly computer electrocardiography) in future studies and clinical applications.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVES: This study sought to assess the relative prognostic power of dobutamine echocardiography and exercise electrocardiography after acute myocardial infarction. BACKGROUND: The prognostic value of dobutamine echocardiography early after acute myocardial infarction has not yet been reported. METHODS: One hundred seventy-eight patients (mean age 58 +/- 9 years) with a first uncomplicated acute myocardial infarction underwent predischarge dobutamine echocardiography (5 to 40 micrograms/kg body weight per min, plus atropine if needed) and symptom-limited bicycle exercise electrocardiography and were followed up for 17 +/- 13 months. Stress-induced dyssynergy and ST segment depression > 1 mm were considered criteria of positivity for dobutamine echocardiography and exercise electrocardiography, respectively. RESULTS: Dobutamine echocardiography was positive in 83 patients and exercise electrocardiography in 60. At follow-up there were 5 deaths, 6 nonfatal myocardial infarctions (11 hard events) and 20 cases of unstable angina. Dobutamine echocardiography and exercise electrocardiography had similar negative predictive values both for all events (88% and 86%, respectively) and for hard events (98% and 95%, respectively). The hard events rate was significantly higher in patients with positive rather than negative dobutamine echocardiography (relative risk [RR] 5.15, 95% confidence interval [CI] 1.14 to 23.16), although there was no difference between patients with positive and negative exercise electrocardiograms. When Cox analysis was performed, dobutamine echocardiography had an independent prognostic value both for all events (RR 2.88, 95% CI 1.37 to 6.08) and for hard events (RR 6.56, 95% CI 1.42 to 30.46). CONCLUSIONS: After uncomplicated acute myocardial infarction, dobutamine echocardiography and exercise electrocardiography have a similar high negative predictive value for both all events and hard events only. Positive dobutamine echocardiography, but not positive exercise electrocardiography, identifies a group of patients at higher risk of subsequent cardiac events.
The development of the electrocardiograph was the culmination of a scientific effort aimed at perfection of a device conceived for the elucidation of a physiologic phenomenon. The development of the digital computer was the culmination of a scientific effort aimed at perfection of warfare. Both of these fairly recent innovations of modern technology have been moderately successful in their initial objectives. Electrocardiography has had a profound influence on the practice of medicine. On the global scene, computers have so far had an insignificant influence on the practice of electrocardiography. In North America, however, computer interpretation of ECGs has already made a modest impact, perhaps more in terms of commercial gains rather than producing a substantial benefits to health care. The introduction of computers into clinical electrocardiography has not resulted in any widespread application of improved diagnostic criteria. The automation of ECG interpretation has not resulted in reduction of the cost of health care, on the contrary, in general it has increased the cost. Perhaps the most dismal failure has been the negligible use of computers in epidemiologic studies and heart disease prevention efforts. Palmistry, astrology, the art of palpation of the pulse, auscultation and acupuncture have had a more profound influence on the practice of medicine than computer analysis of the electrocardiogram. On the positive side, one of the beneficial effects of the use of computers has been the increasing awareness of the limited diagnostic accuracy of currently used ECG criteria, and the recognition of the fact that a substantial improvement is warranted; if such improvement can not be achieved in the foreseeable future, electrocardiography will lose much of its current clinical utility. Computers have had a profound influence on research in electrocardiology, and although a very few tangible concrete results have thus far diffused into clinical electrocardiography, their impact can be expected during the last two decades of this century. Computers will produce at least containment of costs if not actual net cost reduction in clinical electrocardiography. Computer analysis will rapidly antiquate the present primitive visual ECG classification in epidemiologic studies and clinical heart disease intervention trials. Computer analysis will enhance the diagnostic accuracy of the electrocardiogram. However, a radical departure from the current ECG display and interpretation practice will be mandatory before any substantial breakthrough can be materialized. All these anticipated evolutionary and perhaps even revolutionary changes will require a continuing intensive research effort, a change in the professional attitude of practicing electrocardiographers and a considerable effort in professional education. Finally, the elucidation and exploration of the full diagnostic and predictive value of the ECG remains the challenge of first magnitude in electrocardiography...
The ability of supine exercise electrocardiography and exercise radionuclide angiography to predict time to subsequent cardiac events (cardiac death, nonfatal myocardial infarction or late coronary bypass grafting or angioplasty) were compared in 265 patients with normal resting electrocardiograms who were not taking digoxin. All patients had undergone coronary catheterization and were initially treated medically. Follow-up study was performed at a median of 51 months. Separate logistic regression models, which had been previously developed to predict 3-vessel or left main coronary artery disease (CAD), were compared using a Cox regression analysis to predict time to a subsequent cardiac event. The exercise electrocardiography model, consisting of the magnitude of ST depression, exercise heart rate and patient gender, was a powerful predictor (chi-square = 30.8, p less than 0.0001) of subsequent events. The exercise radionuclide angiography model, which included the exercise response of the pressure-volume ratio in addition to the exercise electrocardiography variables, had similar prognostic power (chi-square = 31.8, p less than 0.0001). In a separate analysis considering only cardiac death and nonfatal myocardial infarction, the exercise electrocardiography model remained a significant predictor of events (chi-square = 12.2, p less than 0.001). None of the radionuclide angiography variables added significantly to the prognostic power of the exercise electrocardiography model. Thus, in patients with a normal resting electrocardiogram who are not taking digoxin, the supine exercise electrocardiography model that predicts 3-vessel or left main CAD also predicts future cardiac events. Exercise radionuclide angiography does not provide any additional prognostic information in such patients.
BACKGROUND: Patients with stroke commonly undergo investigations to determine the underlying cause of stroke. These investigations often include ambulatory electrocardiography to detect paroxysmal atrial fibrillation. There is conflicting evidence in the literature regarding whether routine ambulatory electrocardiography should be performed in all or selected stroke patients. This paper reviews the available evidence on (1) the yield of ambulatory electrocardiography in detecting paroxysmal atrial fibrillation in patients with stroke or transient ischemic attack and (2) the effectiveness of anticoagulation in preventing recurrent stroke in patients with paroxysmal atrial fibrillation. METHODS: A MEDLINE search for primary articles was performed, and the references were reviewed manually. In addition, citations were obtained from experts. The evidence was systematically reviewed using the evidence-based methodology of the Canadian Task Force on Preventive Health Care. RESULTS: Ambulatory electrocardiography can detect atrial fibrillation not found on initial electrocardiogram in between 1% and 5% of people with stroke. Ambulatory electrocardiography is generally safe. The risk of recurrent stroke in the setting of paroxysmal atrial fibrillation is uncertain, but appears to be similar to that seen with chronic atrial fibrillation (about 12% per year). Therapy with warfarin may reduce this risk by about two-thirds as compared to placebo. The annual risk of major bleeding with warfarin therapy is between 1% and 3% but rates for individual patients depend on various specific risk factors. INTERPRETATION: There is insufficient evidence to recommend for or against the use of ambulatory electrocardiography for the detection of paroxysmal atrial fibrillation in either selected or unselected patients with stroke (C Recommendation). There is fair evidence to recommend therapy with warfarin for patients with stroke and paroxysmal atrial fibrillation (B Recommendation).
BACKGROUND: Opportunities for interactive learning in electrocardiography are limited--particularly at postgraduate level. In medical education, increasing use is being made of the electronic medium and various materials have been developed to improve clinicians' skills. AIMS: To test and evaluate the learning of electrocardiography among health professionals. METHODS: A software package, containing a tutorial on electrocardiography and a self-assessment programme of 140 electrocardiograms (ECGs) was constructed. Seventy-two health professionals were recruited into the study and tested before and after the study period. Participants were randomly allocated to one of three groups: control (no study material), tutorial or computer. The tutorial group participated in a series of tutorials and the computer group were provided with a CD-ROM containing study material for them to use in their own time. The results were assessed for statistical significance between all groups using analysis of variance techniques. RESULTS: Sixty-one individuals completed the study. Each of the three groups was pre and post tested on their knowledge of electrocardiography and their ability to interpret ECGs. The computer group was the only group to achieve a significant increase in performance in their knowledge on electrocardiography and in their ability to interpret ECGs. CONCLUSIONS: Suitably structured computer programmes are effective in helping clinicians understand electrocardiography and interpret ECGs.