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Value of treadmill exercise testing in patients with complete bundle branch block.

Exercise electrocardiography and selective coronary arteriography was performed in 24 consecutive patients with complete bundle branch block. The criteria for a positive exercise electrocardiogram (E-ECG) were a 1 mm depression or elevation in the J point from the control state, as well as in the ST-segment measured at 0.04 seconds from the J point. Eleven of 12 patients with complete left bundle branch block had a positive E-ECG. Nine of them had normal coronary arteriograms, except one with less than 50% lesions in two arteries. Two patients had severe three-vessel disease. Only one patient had a true negative exercise test. No patient had a false negative test. Nine of 12 patients with complete right bundle branch block had a positive E-ECG. One of these 9 had minimal nonobstructive disease, while the other 8 had severe two- or three-vessel coronary artery disease. Three of the 12 right bundle branch block patients had a negative E-ECG. Two of them had a true negative exercise test, and one a false negative test. Because of a high incidence of probably false positive results, E-ECG appears to be unreliable in detecting coronary artery disease in patients with complete left bundle branch block. But it can provide useful information in the noninvasive evaluation of coronary artery disease in patients with complete right bundle branch block.

Adult↗

Improvement in ischemic parameters during repeated exercise testing: a possible model for myocardial preconditioning.

Repeated short episodes of coronary occlusion in experimental animals, and in humans during balloon angioplasty, cause myocardial preconditioning. This study examines whether myocardial ischemia induced by repeated exercise testing can reduce the extent of ischemia induced by subsequent exercise tests. Twenty-six patients with positive stress tests underwent 3 treadmill exercise tests at 30-minute intervals. Two additional tests were performed on each of the previous 2 days in order to eliminate and/or reduce the training effect. All 3 exercise tests were of similar work load. In spite of that, total ischemic time was markedly shortened from 633 to 399 seconds (p <0.0001) as well as the recovery time from 259 to 126 seconds (p <0.0001) between the first and the second tests. There was no further improvement on the third test. Time to 1-mm ST depression was prolonged from 487 to 593 seconds (p = 0.004) and double product at 1-mm ST depression was increased in the second test from 20,322 to 22,325 mm Hg/second (p = 0.008), implying a higher ischemic threshold. An improvement of > or = 10% in < or = 1 ischemic parameter was observed in 25 of the 26 patients and in > or = 2 of the ischemic parameters in 76% of the patients. Improvement in ischemic parameters develops during repeated exercise induced ischemia in most patients. We suggest that this phenomenon, which was previously known as "warm up," is the clinical counterpart of myocardial preconditioning which develops not only during ischemia caused by reduction in coronary flow, but also during demand-induced ischemia.

Coronary Angiography↗

Ischaemic episodes detected by early exercise test and Holter monitoring after myocardial infarction: which are of most prognostic value?

BACKGROUND: The aim of this study was to assess the significance of ST-segment depressions (ST-SD) detected during exercise test or Holter monitoring and to determine which parameters of ST-SD are the most important prognostic factors in patients after myocardial infarction. METHODS: The study group consisted of 164 patients (126 men and 38 women) who survived their first uncomplicated myocardial infarction. Twenty-four-hour Holter monitoring on day 10 (+/- 2) after infarction and a treadmill exercise test 1 or 2 days later were performed. The following parameters of ST-SD were taken into consideration: amplitude, localization according to the area of infarction and presence or absence of concomitant angina. Patients were observed for 24 months to assess the occurrence of new cardiac events. RESULTS: In 78 patients (group I) ST-SD were detected in both Holter monitoring and the exercise test, and in 32 patients (group II) in the exercise test only. Fifty-four patients (group III) were without ST-SD. During follow-up there were 83 cardiac events in group I, 24 in group II and 16 in group III (P < 0.01, group I versus II; P < 0.0001, group I versus III; P < 0.05, group II versus III). In multivariate analysis the presence of ST-SD during Holter monitoring or the exercise test, or both, appeared to be of most prognostic significance (P < 0.0001). The number of new cardiac events was significantly higher in patients with painful ST-SD greater than 3 mm, detected outside the area of infarction (distant ischaemia). CONCLUSIONS: This study shows a significant prognostic value of early post-infarction ischaemia detected by Holter monitoring and an exercise test. Distant, painful ST-SD greater than 3 mm were more powerful determinants of poor prognosis than others. Electrode placement during Holter monitoring appears to be very important, particularly in post-infarction patients.

Coronary Angiography↗

Ventricular arrhythmias during exercise testing: mechanism, response to coronary bypass surgery and prognostic significance.

To investigate the determinants and prognostic significance of ventricular arrhythmias during exercise testing, 86 patients with such arrhythmias were identified from a consecutive series of 446 patients who underwent treadmill exercise testing and cardiac catheterization. The prevalence of these arrhythmias was 19% in the total group but increased to 30% in the 120 patients with 3-vessel or left main coronary artery disease. Patients with exercise-induced arrhythmias were more likely to have 3-vessel or left main coronary artery disease, a lower resting ejection fraction, greater than or equal to 2 mm of ischemic ST depression and more severe segmental wall motion abnormalities than patients without this finding (p less than 0.05). Repeat exercise testing in 22 patients with exercise-induced arrhythmias after coronary bypass surgery revealed that persistence of these arrhythmias was associated with either severe wall motion abnormalities preoperatively or residual ischemic ST depression during the post-operative exercise testing. At a mean follow-up period of 5.3 years, the presence of exercise-induced ventricular arrhythmias was not associated with increased cardiac mortality in the medically treated patients.

Arrhythmias, Cardiac↗

[Platelet activation and endothelial factors in standard exercise test before and after menopause].

OBJECTIVES: Postmenopausal lack of estrogens may accelerate cardiovascular atheromatic changes. Standard exercise test (SET) challenges hidden signs of the vascular involvement. Although the test is known not to carry a risk of thromboembolic complications, it may influence plasma concentrations of endothelial and platelet factors. The question is if and to what extend the menopause aggravates the SET induced changes. AIM: Plasma concentrations of nitric oxide, endothelin-1, beta-thromboglobulin and von Willebrand factor activity before, at the maximum exercise and 15 minutes after the SET referred to, as a recovery time were estimated. METHOD: SET was performed according to Bruce protocol in group of 31 premenopausal and 57 postmenopausal women. Standard RIA kits for plasma beta-thromboglobulin (beta-TG) (Boehringer Mannheim) and endothelin-1 (Et-1) (Blotrack) concentration were used. The von Willebrand factor (vWF) activity was assayed by ELISA system (Boehringer Manheim). Plasma nitric oxide (NO) concentration was calculated from nitrides/nitrates levels, by Griess reaction, modified by use of NADPH reductase. RESULTS: Mean plasma levels of beta-TG, Et-1, NO and vWF activity do not differ between pre and postmenopausal women. The standard exercise test significantly increases both beta-TG plasma concentration and vWF activity (p < 0.00001). During the 15 minutes rest period the changed values do not return to preexercise levels. Neither plasma NO nor Et-1 plasma concentrations change during the exercise test. There was a similar increase in beta-TG plasma levels and vWF activity during the SET in pre- and postmenopausal women and a slighter increase of plasma Et-1 levels in postmenopausal women (p < 0.04). The close relationships between NO plasma concentration and both vWF activity (p < 0.002) and vascular endothelial growth factor (VEGF) level (p < 0.04) were observed in postmenopausal women. The vWF activity in postmenopausal; women inversely correlates with insulin-like growth factor-I (IGF-I) concentration (p < 0.001). In premenopausal women the important modulators of vWF activity were: body mass (p < 0.04), serum total cholesterol (p < 0.02) and sex hormone binding globulin (SHBG) levels (p < 0.04). The postmenopausal beta-TG increase during SET depends on body mass (p < 0.02), whereas the preexercise levels seem to be related to VEGF level (p < 0.03) and inversely to Et-1 (p < 0.007) and dehydroepiandrosterone sulfate (DHEAS) concentration (p < 0.03) Both the basal and stimulated by exercise vWF activity are higher in obese women (p < 0.003), but the net increase is larger in lean group (BMI < 30 kg/m2). In premenopausal women plasma NO concentration depends on 17 beta-estradiol serum level (p < 0.02). The higher VEGF (p < 0.01) levels as well as vWF activity was observed (p < 0.03) in hypercholesterolemic women. CONCLUSION: The standard exercise test increases the procoagulatory von Willebrand factor activity so as the platelets activity (beta-thromboglobulin concentration) in both pre and postmenopausal women. The slight endothelin-1 rise has been found at the maximum exercise in postmenopausal women. The close relation between plasma nitric oxide and endothelin-1 levels was found in postmenopausal women. Obesity and hypercholesterolemia may contribute to the observed changes.

Endothelial Growth Factors↗

[The exercise test in congenital aortic stenosis].

Exercise tests can be carried out without risk in a child or young adult with asymptomatic congenital aortic stenosis. In such a case, the ECG at rest gives only a very poor indication of the severity of the stenosis, which often becomes worse with age. The only sinister findings is that of repolarisation defects, which are almost always absent at rest. Exercise, by causing an imbalance between myocardial oxygen consumption and oxygen transport, will cause "ischaemic" signs to appear on the ECG. At the same time, the absence of compensation of pressure is a very important sign of poor tolerance; the test can usefully be concluded by using a floating catheter to measure the pulmonary capillary pressure. The correlation between a positive test and the stenotic pressure gradient, measured on catheterisation at rest, is good; but "negative" tests may be found in certain cases with a tight stenosis, especially if maximal rate could not be reached. In cases of stenoses which were initially mild or moderate, this test is very useful as a follow-up procedure, as such stenoses may become worse with age and require surgical correction. It is also useful for assessing the results of surgery, and of rehabilitation.

Adolescent↗

[Unstable coronary disease--clinical course and significance of exercise tests in patients with left coronary artery stenosis].

This study aimed at evaluating predictive value of exercise tests in case of left coronary artery stenosis. The study involved 57 patients with left coronary artery stenosis, including 10 patients with isolated left main stenosis (group X), and 47 patients with left coronary artery stenosis and multivessel involvement (group Y). Unstable angina was staged according to Booth et al. classification as type I or II. Exercise tests were performed according to Bruce's protocol. Unstable angina of type I was diagnosed in 51 (89%) patients, and type II in 6 (11%) patients. Electrocardiographic evidence of myocardial ischemia both et rest and anginal pain was seen in 46 (80%) patients. Electrocardiographic recording was within normal limits in 11 (20%) patients at rest. Clinical and ECG improvement was seen in 38 (66%) patients. Exercise tests in all of these patients were positive at low load work--mean 50 W. The obtained results suggest that patients with left coronary stenosis constitute heterogenous group. Therefore, prediction of the left main stenosis on the clinical ground alone is impossible. Exercise tests producing positive results at low load indicate with high probability critical multivessel lesions and/or left main stenosis in such patients.

Adult↗

Design of exercise test, with special reference to heart patients.

Estimation of exercise tolerance in patients with heart disease and significant symptoms can usually not be expressed in terms of maximal oxygen uptake or power at a fixed heart rate calculated from a 'steady state' exercise test. The exercise tolerance can be expressed only by the maximal power developed, when limited by symptoms. For this purpose the level of tolerance is better assessed by a test with small increments and short duration of each work load. In clinical practice this type of almost continuous increase in load was found to be particularly useful in patients with ischaemic heart disease. Comparative studies showed that the work per heart beat at equal loads is significantly higher in the test with continuous increase in load than in the test with steps of 6 minutes duration, both in normal subjects and in heart patients. The difference, however, is small (7%) and for practical purposes these tests have equal validity as a measure of the circulatory capacity.

Adult↗

Exercise testing in patients with chest pain to sumatriptan.

OBJECTIVES: In order to assess whether chest pain attributed to sumatriptan is associated with abnormalities on cardiac exercise testing, we performed a case-control study. SUBJECTS: Cases were selected as consumers of sumatriptan who reported sumatriptan associated chest pain. A reference group was selected randomly from consumers of sumatriptan with the same GP as the case, who reported no chest pain after use of sumatriptan. If possible, controls were matched for age (within 5-year groups) and gender. OUTCOMES: In a total of 74 cases and 55 controls symptom-limited exercise tests were performed. Besides a small difference in age, there were no differences in basic characteristics between cases and controls. Three cases had ST-depression on ECG during exercise. However, none of the variables measured during exercise testing differed significantly between cases and controls. CONCLUSIONS: The prevalence of abnormal exercise tests in patients with sumatriptan-induced chest pain is low, and not statistically different from patients without chest pain after intake of sumatriptan. Routine performance of exercise testing in patients with sumatriptan-associated chest pain is not recommended.

Adult↗

Combining low-intensity and maximal exercise test results improves prognostic prediction in chronic heart failure.

OBJECTIVES: This study investigated the combination of maximal and low-intensity exercise testing in predicting prognosis in chronic heart failure (CHF), using one single exercise test (two-step protocol). BACKGROUND: Risk assessment based on any single factor has limited accuracy and reproducibility. METHODS: Treadmill exercise testing was performed in 202 consecutive CHF patients (174 male; mean age 52 +/- 11 years) using "breath-by-breath" gas exchange monitoring. Oxygen uptake (VO(2)) kinetics were defined as oxygen deficit (DeltaVO(2) x time [rest to steady state] - Sigma VO(2) [rest to steady state]) and mean response time (MRT = oxygen-deficit/DeltaVO(2)). Peak VO(2) (VO(2)max) was defined as the highest VO(2). Mean follow-up was 873 +/- 628 days. The primary end point was cardiac mortality and the need for urgent heart transplantation. RESULTS: Forty-four patients (22%) died and 15 (7%) were urgently transplanted. In both univariate and multivariate analyses, MRT >50 s was the most powerful predictor of the primary end point (hazard ratio [HR] 4.44), followed by predicted VO(2)max <50% (HR 3.50) and resting systolic blood pressure <105 mm Hg (HR 2.49, all p < 0.001). A majority (n = 130 [64%]) had one or none of these risk factors, with a one-year event rate of only 3%. Patients with two risk factors (n = 45 [22%]) were at medium risk (one-year event rate of 33%). Twenty-seven patients (13%) had all three risk factors, with a one-year event rate of 59%. The area under the curve, using the number of risk factors, was 0.86 +/- 0.04 for the primary end point at one year. These results were independent of medication, in particular, beta-blockade. CONCLUSIONS: A combination of low-intensity and maximal exercise test results improves assessment of prognosis in patients with CHF.

Adult↗

Comparison of oxygen saturation by pulse oximetry and co-oximetry during exercise testing in patients with COPD.

INTRODUCTION: Measurement of oxygen saturation by pulse oximetry (SpO2) is frequently performed during exercise testing of patients with COPD to monitor for hypoxemia. The purpose of this study was to assess the accuracy and precision of pulse oximetry during exercise. We hypothesized that the SpO2 would more closely reflect oxygen saturation as measured by co-oximetry (SaO2) when it was corrected for carboxyhemoglobin (COHb). We also hypothesized that SpO2 would more closely reflect SaO2 when the pulse rate by oximeter was equivalent to the heart rate by ECG. Finally, we hypothesized that SpO2 would be a better measure of SaO2 at maximal workloads than at rest or submaximal workloads. METHODS: Eight white men with severe COPD (mean +/- SD FEV1, 0.91 +/- 0.37) underwent progressive, symptom-limited exercise testing by cycle ergometry. SaO2 was measured from arterial blood at each workload using a co-oximeter. SpO2 and pulse rate were obtained by a pulse oximeter (Ohmeda 3700). Heart rate was continuously monitored by ECG. RESULTS: Reliable oximetric values as determined by a dicrotic notch in each waveform and adequate signal intensity were obtained in all eight patients. SpO2 was a moderately accurate measure of SaO2 (bias, 1.7%; precision, 2.9). The bias actually increased (4.1%) when SpO2 was corrected for COHb. Accuracy of SpO2 was not improved when pulse rate by oximetry and heart rate by ECG were equivalent, nor was the accuracy improved at maximal workloads relative to submaximal workloads during the exercise test. CONCLUSION: Oxygen saturation as measured by pulse oximetry (SpO2) in patients with COPD undergoing exercise testing is not sufficiently accurate to replace SaO2 as the gold standard for oxygen saturation.

Carboxyhemoglobin↗

Prognosis of patients with unstable angina and low-risk exercise test: significance of ST-segment depression on the admission ECG.

The presence of ST-segment depression on the admission electrocardiogram (ECG) is an important predictor of poor outcome in patients with unstable angina. On the other hand, patients with unstable angina who undergo a low-risk exercise test are supposed to have a favorable prognosis. The objective of the study was to determine the prognostic significance of ST-segment depression on the admission ECG in patients with unstable angina who undergo an exercise test that indicates a low risk of events. An interpretable exercise test was performed in 257 patients with primary unstable angina. A low-risk exercise test was completed by 156 (60%) patients and medical therapy was planned for all these patients. A multivariate analysis was performed in order to determine the independent predictors of events (cardiac death, nonfatal acute myocardial infarction, or admission for unstable angina) during a 12-month follow-up. Among patients with a low-risk exercise test, there were no significant differences between patients with and without ST-segment depression on the presenting ECG with regard to event rate (34 vs. 29%, P=NS). In multivariate analysis, ST-segment depression was not related to a higher incidence of events. Our findings appear to indicate that the presence of ST-segment depression on the admission ECG loses its prognostic significance in patients with primary unstable angina if they complete a low-risk exercise test.

Aged↗

An agreement approach to predict severe angiographic coronary artery disease with clinical and exercise test data.

OBJECTIVE: To demonstrate that an agreement approach to applying equations on the basis of clinical and exercise test variables is an accurate, self-calibrating, and cost-efficient method for predicting severe coronary artery disease in clinical populations. DESIGN: Retrospective analysis of consecutive patients with complete data from exercise testing and coronary angiography referred for evaluation of possible coronary artery disease. After developing an equation in a training set, this equation and two other equations developed by other investigators were validated in a test set. The study was performed at two university-affiliated Veteran's Affairs medical centers. PATIENTS: 1080 consecutive men studied between 1985 and 1995 who had coronary angiography within 3 months of the treadmill test. The population was randomly divided into a training set of 701 patients and a test set of 379 patients. Patients with previous coronary artery bypass surgery, valvular heart disease, marked degrees of resting ST depression, and left bundle branch block were excluded. MEASUREMENTS: Recording of clinical and exercise test data along with visual interpretation of the electrocardiogram recordings on standardized forms and abstraction of visually interpreted angiographic data from clinical catheterization reports. RESULTS: Simple clinical and exercise test variables improved the standard application of exercise-induced ST criteria for predicting severe coronary artery disease. By setting probability thresholds for severe disease of <20% and >40% for the three prediction equations, the agreement approach divided the test set into three groups: low risk (patients with all three equations predicting <21% probability of severe coronary disease), no agreement, and high risk (all three equations with >39% probability) for severe coronary artery disease. Because the patients in the no agreement group would be sent for further testing and would eventually be correctly classified, the sensitivity of the agreement approach was 89% and the specificity was 96%. The agreement approach appeared to be unaffected by disease prevalence, missing data, variable definitions, or even angiographic criteria. CONCLUSIONS: Requiring diagnosis of severe coronary disease to be dependent on agreement between these three equations has made them likely to function in all clinical populations. The agreement approach should be an efficient method for the evaluation of populations with varying prevalence of coronary artery disease, limiting the use of more expensive noninvasive and invasive testing to patients with a higher probability of left main or triple-vessel coronary artery disease. This approach provides a strategy that can be applied by inputting the results of basic clinical assessment into a programmable calculator or a computer to assist the practitioner in deciding when further evaluation is appropriate, thus assuring patients access to subspecialty care.

Confounding Factors, Epidemiologic↗

Use of the exercise test to predict prognosis after coronary artery bypass grafting.

The objective of this study was to predict the prognosis of patients who become symptomatic after having undergone coronary artery bypass grafting (CABG) using clinical and exercise test responses. A retrospective analysis was performed of all veterans referred for clinical indications to a Veterans Administration Medical Center for a treadmill test after having undergone CABG. Of 2,044 patients who were exercise tested from April 1984 to May 1987, 296 had previously undergone CABG. Clinical data considered included age, sex, medication and symptom status, history of myocardial infarction, type of myocardial infarction and time from CABG. The exercise test responses considered were MET level, maximal heart rate, maximal systolic blood pressure, chest pain pattern and ST-segment response. During a 2-year follow-up after exercise testing, there were 15 deaths, 11 nonfatal myocardial infarctions, 6 repeat CABGs and 3 percutaneous transluminal coronary angioplasties. Although MET level and maximal heart rate were significantly related to prognosis and no patient who exceeded 8 METs died, the predictive power of these exercise test responses was low and ST-segment depression was not predictive at all. The inability of the exercise electrocardiogram to predict cardiac events in patients after CABG requires the use of other methods of testing to identify those who need invasive studies and intervention.

Angiography↗

Comparison of free range and graded exercise testing.

Previous studies with athletes have demonstrated greater physiologic responses during free range (FR) compared with graded (GXT) exercise testing. Since the sensitivity of clinical exercise testing depends upon the magnitude of physiologic responses, we sought to determine whether FR might provoke greater responses than GXT in nonathletic individuals and patients. Healthy, physically active nonathletes and clinically stable CHD patients (N = 12) performed GXT on cycle ergometer (15 W + 15 W.min-1) and FR (minimal time for 75 kJ task) on a cycle ergometer. A starting power output was recommended for FR, but the patients were free to pedal at their own rates. During FR, VO2max (36.5 +/- 10.1 vs 34.1 +/- 9.4 mL.min-1.kg-1), HRmax (156 +/- 25 vs 144 +/- 27 beats.min-1), double product (31.4 +/- 4.9 vs 29.1 +/- 5.9) and VEmax (111 +/- 26 vs 94 +/- 17 L.min-1) were all significantly greater than during cycle GXT. The mean peak power output during GXT (180 +/- 45 W) was not significantly different than the mean power output during FR (204 +/- 45 W). During FR, successive "0.5 mile laps" (approximately 12.5 kJ) were accomplished at power outputs of 217 +/- 45, 217 +/- 52, 192 +/- 60, 194 +/- 65, 199 +/- 63, and 207 +/- 63 W. No patient experienced angina or ECG changes during either FR or GXT. The patients uniformly reported that FR felt like "hurrying" in the real world. Some patients had to make large reductions in their power output in mid ride to allow recovery from a too aggressive start, much as they would in the real world. We conclude that FR exercise provides a clinically useful method of exercise testing that is not only more like real world exercise patterns but also provokes greater physiologic responses than are achievable during conventional GXT.

Adult↗

Strenuous physical activity, treadmill exercise test performance and plasma high-density lipoprotein cholesterol. The Lipid Research Clinics Program Prevalence Study.

During the Lipid Research Clinics North American Prevalence Study, plasma lipoprotien determinations and treadmill exercise testing were performed on 2319 white men and 2067 white women ages 20 years or older randomly selected from population surveys by nine clinics in the U.S. and Canada. Before exercise testing, participants were asked if they performed any strenuous physical activity on a regular basis. Data were analyzed to determine the relationship of plasma high-density lipoprotein (HDL) cholesterol to treadmill exercise test performance and a self-report of strenuous activity. Neither treadmill exercise test duration nor heart rate response to submaximal exercise was significantly related to HDL cholesterol levels for either men or women. However, participants who reported some strenuous physical activity generally had higher HDL cholesterol levels than those who reported none, and the more active men ages 30-49 years and active women ages 20-39 had significantly higher values (p < 0.05). When HDL cholesterol was adjusted for age, body mass index, alcohol use, cigarette smoking and interclinic population variation, more active men (47.1 vs 45.2 mg/dl; p = 0.0001) and more active women (59.6 vs 57.7 mg/dl; p = 0.02) had higher HDL cholesterol levels than their sedentary counterparts. Thus, the association between HDL cholesterol and reported physical activity was, at least in part, independent of other factors that influence HDL cholesterol concentration, but was not associated with exercise tolerance as determined by treadmill exercise testing.

Adult↗

Exercise testing in the new millennium.

In the changing economic times, internists and family physicians are becoming the main performers of the standard exercise test. The education of those noncardiologists who wish to perform exercise testing is quite important. In the new millennium, the American College of Cardiology/American Heart Association evidence-based guidelines on exercise testing continue to have a large impact. Used for diagnosis or prognosis, exercise scores such as the Duke exercise score will be applied to each test. Increased computerization and the internet will bring inexpensive web-enabled devices for sophisticated exercise testing into the doctor's office and allow remote over-reading services.

Cardiovascular Diseases↗