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PubMed1995

Ventricular tachycardia during exercise testing as a predictor of sudden death in patients with chronic chagasic cardiomyopathy and ventricular arrhythmias.

OBJECTIVE: To verify the prognostic value of exercise induced ventricular arrhythmias in patients with chagasic cardiomyopathy. METHODS: 69 consecutive patients (37 male, 32 female; age range 21-67 years) with chronic chagasic cardiomyopathy and ventricular arrhythmias (more than 10 ventricular premature complexes per hour) were evaluated during treadmill exercise testing, using the Bruce protocol. Protocol end points were peak heart rate or presence of sustained ventricular tachycardia. MAIN OUTCOME MEASURE: Sudden cardiac death. RESULTS: 44 patients (group I) developed ventricular tachycardia during exercise testing (five sustained and 39 non-sustained), and 25 did not (group II). After a follow up of 24 (SD 15) months sudden cardiac death occurred in seven patients in group I and in none in group II (P < 0.05). CONCLUSIONS: Ventricular tachycardia on exercise testing is significantly associated with sudden cardiac death in patients with chronic chagasic cardiomyopathy and ventricular arrhythmias.

Adult↗
PubMed1981

Present status of exercise testing in the evaluation of coronary artery disease.

The present status of exercise testing in coronary artery disease (CAD) was discussed in respect to test protocols, ECG criteria and lead systems, and hemodynamic responses. Advantages of modern multistage protocols over single-stage ones such as Master two-step tests are obvious in diagnostic accuracy and patient's safety. Clinical significance of horizontal and downsloping ST depression has already been established. Diagnostic significance of other exercise-induced ECG alterations such as slow upsloping ST depression, ST elevation, U-wave inversion, and R-wave amplitude changes was discussed. The latter parameter is still controversial as to its clinical significance. Use of an inadequate ECG lead system is one of major causes of false negative tests. Necessity of multiple lead systems was emphasized for higher diagnostic accuracy. From the view point of cost-efficacy relation, we will recommend simultaneous recording of CC5 or CM5, V3 and CL or III in routine exercise testing for screening of CAD. Test results such as exercise time, and heart rate and systolic blood pressure responses are also useful parameters for the evaluation of the severity and prognosis of CAD. It was emphasized that in exercise monitoring of ECG and blood pressure is indispensible in multistage exercise testing for improvement of diagnostic accuracy as well as patient's safety.

Angina Pectoris↗
PubMed2004

Variations in lymphocyte activation during exercise testing in patients with coronary artery disease.

BACKGROUND: Several studies have shown that strenuous exercise induces changes in the immune system. Soluble interleukin-2 receptor (sIL-2R) is a marker of immune system activation and is known to increase in association with cardiac disease. The aim of the present study was to assess sIL-2R levels in patients with coronary artery disease (CAD) in conjunction with exercise testing. METHODS: Blood levels of sIL-2R were determined in 10 healthy control individuals and 21 patients with CAD before exercising, at maximal exercise testing (Bruce) and at 0.5 h and 3-4 h after exercise (T1-T4). The study group had stable angina and normal or near-normal left ventricular function. Patients at risk of abnormal cytokine levels were excluded. RESULTS: The patients were divided into two groups: those with mild to moderate ischemia (according to a thallium scan) (n = 14, group 1a) and those with severe exercise-induced ischemia (n = 7, group 1b). The prevalence of anginal pain at exercise and mean ST depression were similar in both groups, however, signs of left ventricular dysfunction during exercise were significantly more frequent in group 1b. Mean sIL-2R levels (units per ml) showed no significant difference between group 1a and the control group at all time points (503 +/- 122, 518 +/- 140, 489 +/- 164, 461 +/- 131 mu/ml compared with 505 +/- 135, 509 +/- 112, 469 +/- 126, 416 +/- 103 mu/ml, respectively, P = NS), while a significant increase in group 1b compared with the control group was found at 0.5-h after exercise (T3) (1147 +/- 510 mu/ml, P = 0.03). DISCUSSION: This study demonstrated immunological involvement in some patients with severe exercise-induced ischemia shortly after exercise, suggesting an association with heart failure.

Aged↗
PubMed1985

Value of arm exercise testing in detecting coronary artery disease.

Alternative methods of exercise testing are needed for patients with vascular, orthopedic or neurologic conditions who cannot perform leg exercise. To determine the sensitivity of arm exercise in detecting coronary artery disease (CAD), 30 patients with angina pectoris performed both arm ergometry and treadmill testing before coronary angiography. All patients had at least 70% diameter reduction in 1 or more major coronary arteries. Ischemic ST depression (greater than or equal to 1 mm) or angina occurred more frequently (86%, 26 patients) with leg exercise than with arm exercise (40%, 12 patients). There was no significant difference in peak rate-pressure product achieved with either test, although the peak oxygen consumption was greater during leg exercise than during arm exercise (18 vs 13 ml/kg/min, respectively, p less than 0.001). For concordantly positive tests, the oxygen consumption at onset of ischemia was significantly lower during arm testing than during leg testing (12 vs 17 ml/kg/min, respectively, p less than 0.001). There was no significant difference in heart rate during either test at onset ischemia. Thus, arm exercise testing is a reasonable, but not equivalent, alternative to leg exercise testing in patients who cannot perform leg exercise.

Aged↗
PubMed1988

Methodologic problems in exercise testing research. Are we solving them?

To evaluate the comparative effects of methodologic factors on the reported accuracies of two standard exercise tests, 56 publications comparing the exercise thallium scintigram with the coronary angiogram were analyzed for conformation to five methodologic standards. Analyzed were adequate definition of study group, avoidance of a limited challenge group, avoidance of workup bias, and blinded analysis of the coronary angiogram and myocardial scintigram. Study group characteristics and technical factors were also reviewed. Better conformation with methodologic standards was found than has been reported previously for treadmill exercise testing. Furthermore, study group characteristics and technical factors were better predictors of sensitivity and specificity than were methodologic deficiencies. Only workup bias and test blinding were significantly associated with test accuracy. The percentage of patients with previous myocardial infarction had the highest correlation and was independently and directly related to sensitivity and inversely related to specificity.

Coronary Angiography↗
PubMed1992

Exercise testing, 6-min walk, and stair climb in the evaluation of patients at high risk for pulmonary resection.

To evaluate three types of exercise testing in prediction of death or prolonged mechanical ventilation after lung resection in high-risk patients, 16 patients underwent evaluation prior to resection. Eleven patients (group 1) had minor or no complications (arrhythmia, atelectasis, pneumonia) and five patients (group 2) died within 90 days of surgery. Exercise testing showed that group 1 had a longer 6-min walk distance and a higher stair climb than group 2. The maximum oxygen uptake on a cycle ergometer was not significantly different between groups, although only ten patients completed this test. Group 1 had a significantly greater calculated oxygen uptake with stair climbing than group 2. A 6-min walk distance of greater than 1,000 feet and a stair climb of greater than 44 steps were predictive of successful surgical outcome. Preoperative exercise testing is a useful adjunct to traditional spirometric testing in evaluation of the high-risk surgical patients.

Aged↗
PubMed2003

Ability of exercise testing to predict cardiovascular and all-cause death in asymptomatic women: a 20-year follow-up of the lipid research clinics prevalence study.

CONTEXT: The value of exercise testing in women has been questioned. OBJECTIVE: To determine the prognostic value of exercise testing in a population-based cohort of asymptomatic women followed up for 20 years. DESIGN AND SETTING: Near-maximal Bruce-protocol treadmill test data from the Lipid Research Clinics Prevalence Study (1972-1976) with follow-up through 1995. PARTICIPANTS: A total of 2994 asymptomatic North American women, aged 30 to 80 years, without known cardiovascular disease. MAIN OUTCOME MEASURES: Cardiovascular and all-cause mortality. RESULTS: There were 427 (14%) deaths during 20 years of follow-up, of which 147 were due to cardiovascular causes. Low exercise capacity, low heart rate recovery (HRR), and not achieving target heart rate were independently associated with increased all-cause and cardiovascular mortality. There was no increased cardiovascular death risk for exercise-induced ST-segment depression (age-adjusted hazard ratio, 1.02; 95% confidence interval [CI], 0.57-1.80; P =.96). The age-adjusted hazard ratio for cardiovascular death for every metabolic equivalent (MET) decrement in exercise capacity was 1.20 (95% CI, 1.18-1.30; P<.001); for every 10 beats per minute decrement in HRR, the hazard ratio was 1.36 (95% CI, 1.19-1.55; P<.001). After adjusting for multiple other risk factors, women who were below the median for both exercise capacity and HRR had a 3.5-fold increased risk of cardiovascular death (95% CI, 1.57-7.86; P =.002) compared with those above the median for both variables. Among women with low risk Framingham scores, those with below median levels of both exercise capacity and HRR had significantly increased risk compared with women who had above median levels of these 2 exercise variables, 44.5 and 3.5 cardiovascular deaths per 10 000 person-years, respectively (hazard ratio for cardiovascular death, 12.93; 95% CI, 5.62-29.73; P<.001). CONCLUSION: The prognostic value of exercise testing in asymptomatic women derives not from electrocardiographic ischemia but from fitness-related variables.

Adult↗
PubMedDate not supplied

Cardiopulmonary exercise testing in the pre-operative assessment of patients for repair of abdominal aortic aneurysm.

We have investigated the value of cardiopulmonary exercise testing in the pre-operative assessment to patients for abdominal aortic aneurysm repair. Thirty-six patients were entered into the study. All had a pre-operative clinical assessment and investigations including chest radiograph, electrocardiograph, spirometry and echocardiogram with measurement of left ventricular ejection fraction. Each patient performed a symptom limited treadmill exercise test using a STEEP protocol with on-line measurement of respiratory gas exchange. Patients were followed up for 12 months post-operatively by review of casenotes. Thirty out of 36 patients had surgical repair of abdominal aortic aneurysm. There was 1 death in the perioperative period and 2 deaths in the following 12 months. Seven other patients suffered post-operative complications. There were no significant differences in left ventricular ejection fraction, spirometry and peak achieved oxygen consumption (PVO2) between those patients who died or who had post-operative complications and those who had not. However, PVO2 < 20 ml/min/kg was found in 70 per cent of patients who had complications compared with 50 per cent of those who had not. Also 4 patients considered medically unfit for surgery all had PVO2 < 20 ml/min/kg. Cardiopulmonary exercise testing with measurement of PVO2 may be helpful in identifying patients more at risk of post-operative complications but should not be used in isolation without through clinical assessment.

Aged↗
PubMed1984

Evaluation of a microprocessor-controlled exercise testing system.

We evaluated a new exercise-testing system (Beckman Horizon MMC), incorporating a microprocessor that controls the acquisition of data, corrects for time delays, applies calibration factors, ensures quality control, and presents results in a variety of formats. Precision of measurements of ventilation (VE) and mixed expired gas concentrations was high. In steady-state exercise (n = 100) VO2 was measured with a precision (+/- SD) of 66 ml/min (4.3%), (r = 0.991); there was a small (4.62%) systematic underestimation of VCO2, but precision was comparable with VO2, with SD being 67 ml/min (4.55%) (r = 0.993). Good agreement was obtained between measurements made in progressive incremental exercise in healthy subjects with correlation coefficients of 0.997 for VE, 0.995 for VO2, and 0.994 for VCO2. Agreement in patients with cardiorespiratory disorders (n = 10) was similar, except in three patients in whom a variable pattern of breathing limited strict comparisons. Comparison with a breath-by-breath analysis system (n = 5) showed that rapid changes in VE, VCO2, and VO2 were followed accurately; the half time for a change in VO2 was not systematically different between the two systems (SD, 3.34 s, r = 0.951). The incorporation of microprocessor-controlled calibration procedures, which are simple to carry out frequently, was judged to be an important feature of this system.

Exercise Test↗
PubMed1999

Coronary dissection and thrombosis associated with exercise testing three months after successful coronary stenting.

Exercise testing is commonly performed to assess the functional result of coronary revascularization procedures and is usually not associated with any complications. However, this report documents a rare case of coronary dissection and thrombosis, which resulted in an acute myocardial infarction, in a patient who underwent stress testing 3 months following successful coronary stent implantation.

Aged↗
PubMed1977

Electrocardiographic exercise test in patients with abnormal T waves at rest.

The results of submaximal ECG exercise test were evaluated in six leads recorded simultaneously in two groups of patients with T-wave abnormalities in one or more of Leads I, II, and V4-6. Group I included 185 patients with documented ischemic heart disease (IHD) and Group II 28 patients in whom IHD appeared unlikely. The test was positive in 88 per cent of patients in Group I and in 4 per cent of patients in Group II. In the majority of patients in both groups the T wave either did not change or became more positive or less negative after exercise. The pattern of exercise-induced T-wave changes was similar in patients with and without IHD, and was influenced predominantly by the physiologic effects of exercise. T-wave normalization after exercise occurred frequently in patients with and without IHD, and in patients with positive and negative exercise tests. Our results suggest that T-wave abnormalities, not caused by hypertrophy, conduction disturbances, drugs, or electrolyte imbalance, do not modify the results of submaximal ECG stress test, and that behavior of T wave after exercise does not alter the interpretation of the postexercise ECG. The independent behavior of the S-T segment and T wave after exercise in consistent with the theory that the S-T segment and the T wave are generated by different components of the ventricular action potential.

Adult↗
PubMed1998

[An aggressive exercise test is suitable for myocardial scintigraphy].

Exercise myocardial scintigraphy is frequently used as a second step tool in the assessment of coronary artery disease. Little attention has been paid on the exercise protocol used as a stress during scintigraphy. However, the diagnostic accuracy of the test is better if higher heart rate is achieved. The aim of this study was to evaluate if an aggressive exercise protocol was safe and more effective than a standard protocol in achieving higher heart rate. Eighty-four patients (64 men and 20 women, mean age 56 +/- 10 years, range 34-78 years) underwent a standard exercise test (cycloergometry; SET: 25 W increments every 2 min starting from 25 W load) and an aggressive exercise test (AET: 50 W increments every 2 min starting from 50 W load); during AET a myocardial scintigraphy (Tc-99m sestamibi; SPECT) was performed. Heart rate and blood pressure were monitored during the tests and the rate-pressure product was calculated. No patients had major adverse events during either tests. During AET with respect to the SET, higher maximal heart rate (142 +/- 15 vs 134 +/- 16 b/min; p < 0.01) and rate-pressure product (27,293 +/- 4341 vs 25,773 +/- 6690 b/min x mmHg; p < 0.05) were obtained. During AET higher number of maximal (55/84 vs 34/84; p < 0.05) and positive tests (45/84 vs 29/84; p < 0.05) were detected with respect to the SET. Using myocardial scintigraphy as a reference test, the diagnostic accuracy of the SET and AET was 54 and 73% respectively. In conclusion, an aggressive protocol during exercise stress test can safely be used to obtain a greater number of maximal and positive exercise tests.

Adult↗
PubMed1985

The use of exercise testing in children to evaluate abnormalities of pacemaker function not apparent at rest.

The purpose of this study was to evaluate the use of exercise testing in identifying abnormalities of pacemaker function and in confirming set parameters not apparent at rest in children with implanted atrial synchronous physiologic pacemakers. Maximal exercise tests were performed on 24 children (15 boys, 9 girls) from 4.5 to 18 years of age (median = 15) with physiologic pacemakers. The lower rate limit was observed before or following testing in 19 of 24 cases. In each case this correlated with the set lower rate limit. The upper rate limit was reached in 10 of 24 cases and was found to be lower than that programmed in one case in which a long atrial refractory period had limited the upper rate limit. Six children reached the maximum upper rate limit to which their pacemaker could be programmed. No abnormalities of atrial capture or ventricular capture occurred during exercise testing. Ventricular sensing was normal in each case. Atrial sensing was observed to be normal in 15 of the 24 cases. Two patients had decreased atrial sensing with exercise. Reversion to the "noise rate" due to myopotential inhibition was found in seven other cases. Subsequent tests on two of these children showed normal sensing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Behavior of different activity-based pacemakers during treadmill exercise testing with variable slopes: a comparison of three activity-based pacing systems.

A new generation of activity-based pacemakers incorporates an accelerometer sensitive to low frequency acceleration signals in the anteroposterior direction for sensing of bodily stress. The purpose of our investigation was to test a representative model of these new activity-based pacemakers (Relay) and compare it with current vibration- and housing pressure-sensing systems. We tested ten pacemaker patients with implanted Activitrax, Sensolog, and Relay systems during treadmill exercise testing with variable slopes. Devices from the three systems were also strapped externally to the chest of each patient and to ten normal test subjects in the control group. Exercise tests were conducted with changes of treadmill speed and/or treadmill slope. For comparable workloads during constant speed/variable slope and constant slope/variable speed, Relay had similar rate responses (difference not significant). Significant differences (P < 0.05) in rate adaptation attributable to the kind of treadmill exercise (change in treadmill speed or slopes) were observed in the housing pressure- and vibration-based pacemakers. Activity-based pacemakers with an acceleration sensor adapt pacing rates during treadmill exercises independent of treadmill speed or slope better than those controlled by a conventional housing pressure or vibration sensor.

Acceleration↗
PubMed2006

Brain natriuretic peptide is a reliable indicator of ventilatory abnormalities during cardiopulmonary exercise test in heart failure patients.

BACKGROUND: Whether brain natriuretic peptide (BNP), a neurohormone marker of ventricular dysfunction, correlates with an enhanced ventilatory response (EVR) during cardiopulmonary exercise test, a well-known predictor of prognosis, in systolic heart failure (HF) is currently unknown. MATERIAL/METHODS: Resting BNP was measured in 134 consecutive stable outpatients aged 69 +/- 11 years with mild to moderate HF and LV ejection fraction (LVEF) < 40% who performed a maximal exercise test. EVR was assessed as the slope of the relation between minute ventilation and carbon dioxide production (VE/VCO2 slope) > or = 35. RESULTS: LVEF averaged 33 +/- 7%, BNP 350 +/- 396 pg/ml, and the VE/VCO2 slope 36 +/- 8. Fifty-six of 123 patients (45%) had EVR. BNP correlated with VE/VCO2 slope (r = 0.453; p < 0.01). By multivariate logistic regression, plasma BNP was the only independent predictor of EVR (RR: 1.004 per unit increment, 95% CI: 1.002-1.006, p < 0.0001). A BNP > or = 160 pg/ml had 86% sensitivity, 67% specificity, and 76% overall accuracy for the prediction of EVR (chi square: 37.4, RR 12.2, 95% CI: 4.96-30.3, p < 0.0001, AUC 0.815 (95%CI. 0.738-0.892)). CONCLUSIONS: In systolic HF, plasma BNP is related to an enhanced ventilatory response to exercise and offers a simple and reliable alternative to the cardiopulmonary exercise test in patients with inability or contraindications to exercise.

Aged↗
PubMed1996

Clinical evaluation of algorithms for ST measurement during exercise test.

HYPOTHESIS: Computer processing of the exercise electrocardiogram (ECG) has many advantages, but the reliability of the analysis algorithms is not easily evaluable. No standard annotated database, nor recommended practice for testing and reporting performance results is available: thus, performance evaluation of such devices can be accomplished only by using a set of unannotated recordings, obtained in clinical practice. We evaluated the accuracy of an original microcomputer-based exercise test analyzer comparing the ST computer output with the measurements obtained by two experienced cardiologists. METHODS: Six hundred ECG strips were randomly selected from the exercise test recordings of 60 patients. The ST shift (at J + 80 ms) was blindly assessed by two observers (with the aid of a calibrated lens) and compared with computer measurements. Correlation coefficients, linear regression equations, percent of discrepant measurements, and 95% confidence limits of the mean error were calculated for all leads, peripheral leads, precordial leads, and "stress-test" leads (II, III, aVF, V4, V5, V6). RESULTS: The computer did not analyze five samples on a total of 600 (0.83%) ECG strips because of excessive noise or signal loss, while 51 (8.5%) were considered unreadable by both observers and 67 (11.2%) were rejected by at least one observer. Correlation between the measurements taken by computer and observer(s) measurements was statistically significant (p < 0.001 for all lead groups), no systematic measurement bias was found, and the mean difference was lower than human eye resolution. CONCLUSIONS: Our algorithms provide results as good as those provided by trained cardiologists in measuring ST changes occurring during exercise test. However, this study did not evaluate whether computer improvement of the signal-to-noise ratio would allow accurate measurements even on cardiologists' uninterpretable ECG. This potential advantage of computer-assisted analysis could be assessed only by using a dedicated exercise test database, in which different patterns of noise are superimposed on noise-free recordings previously annotated for ST level.

Adult↗
PubMed1984

Interpretation of clinical exercise testing in respiratory disease.

The usefulness of exercise tests is considerably enhanced if the treating physician becomes involved in interpretation of their results. Interpretation is facilitated through the use of a graphic approach that can be implemented with inexpensive desk-top computers. The relevant relations and the clinical and pathophysiologic significance of abnormalities in these graphs are discussed.

Adult↗
PubMed1998

Interpretive algorithms for the symptom-limited exercise test: assessing dyspnea in Persian Gulf war veterans.

Interpretation of symptom-limited exercise testing requires analysis of a large body of simultaneously recorded cardiopulmonary data. Karlman Wasserman has recommended an algorithmic approach to interpretation (WA) that leads to a dichotomous choice between pulmonary and cardiovascular impairment. An alternative algorithm published by William Eschenbacher (EA) provides for concurrent assessment of cardiovascular and pulmonary exercise impairment. We analyzed a group of 29 individuals referred to the Pulmonary Physiology Laboratory at the Washington Veterans Affairs Medical Center for evaluation of dyspnea following service in the Persian Gulf War to assess the concordance of the two algorithms in determining the cause of dyspnea and exercise impairment in these individuals. They each performed a progressive, ramped, symptom-limited exercise test on a bike for a minimum of 6 min. Exercise measurements were analyzed by both interpretive algorithms. Concordance was found in 28% of tests. The greatest discordance occurred in identifying pulmonary limitation. Eleven had pulmonary limitation by EA; of these, WA found 1 to have pulmonary limitation, 5 to be normal, 4 indeterminate, and 1 musculoskeletal limitation. Of the 11 with pulmonary limitation by EA, but not by WA, 5 had abnormal resting pulmonary function measurements. Analysis of the differences between these two interpretive approaches is given. The EA algorithm may be more sensitive for detecting exercise impairment of pulmonary origin, but its specificity remains to be determined.

Adult↗