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Prognostic value of treadmill exercise testing in elderly persons.

BACKGROUND: Recent exercise testing guidelines recognized a gap in knowledge about the prognostic value of treadmill exercise testing in elderly persons. OBJECTIVE: To test the hypothesis that treadmill exercise testing has equal prognostic value among elderly (> or =65 years of age) and younger (<65 years of age) persons and to examine the incremental value of this testing over clinical data. DESIGN: Inception cohort with a median follow-up of 6 years. SETTING: Olmsted County, Minnesota. PATIENTS: All elderly (n = 514) and younger (n = 2593) residents of Olmsted County who underwent treadmill exercise testing between 1987 and 1989. MEASUREMENTS: Overall mortality and cardiac events (cardiac death, nonfatal myocardial infarction, and congestive heart failure). RESULTS: Compared with younger patients, elderly patients had more comorbid conditions, achieved a lower workload (6.0 and 10.7 metabolic equivalents; P < 0.001), and had a greater likelihood of a positive exercise electrocardiogram (28% and 9%; P < 0.001). With median follow-up of 6 years, overall survival (63% and 92%; P < 0.001) and cardiac event-free survival (66% and 95%; P < 0.001) were worse among elderly persons than among younger persons. Workload was the only treadmill exercise testing variable associated with all-cause mortality in both age groups, and the strength of association was similar. Workload and angina with exercise testing were associated with cardiac events in both age groups, whereas a positive exercise electrocardiogram was associated with cardiac events only in younger persons (P < 0.05 for all comparisons). After adjustment for clinical variables, workload was the only additional treadmill exercise testing variable that was predictive of death (P < 0.001) and cardiac events (P < 0.05); the strength of the association was similar in both age groups. Each 1-metabolic equivalent increase in exercise capacity was associated with a 14% and 18% reduction in cardiac events among younger and elderly persons, respectively. CONCLUSIONS: In elderly persons, treadmill exercise testing provided prognostic information that is incremental to clinical data. After adjustment for clinical factors, work-load was the only treadmill exercise testing variable that was strongly associated with outcome, and its prognostic effect was of the same magnitude in elderly and younger persons.

Age Factors↗

The anaerobic threshold measurement in exercise testing.

The exercise intensity (VO2) above which aerobic energy production starts to be supplemented by anaerobic mechanisms is termed the anaerobic threshold (AT). Lactic acid is produced at an increased rate above this work level. Since this acid is almost completely buffered by HCO-3, the rate of CO2 production increases in excess of that being derived from oxidative metabolism. Thus measurement of this excess CO2, or some reflection of it, can be used during exercise to measure the AT noninvasively. The AT has great physiologic significance, as it demarcates the work rate that the subject can perform for a prolonged period and above which a metabolic acid occurs.

Acid-Base Equilibrium↗

Can primary care doctors prescribe exercise to improve fitness? The Step Test Exercise Prescription (STEP) project.

BACKGROUND: Sedentary lifestyle is associated with adverse health outcomes. Available evidence suggests that, despite positive attitudes toward regular exercise in promoting a healthy lifestyle, few physicians actually prescribe exercise for their patients. Barriers include lack of skills and standard office instruments. Because primary care physicians have regular contact with a large proportion of the population, the impact of preventive health interventions may be great. OBJECTIVES: To determine the effect of an exercise prescription instrument (i.e., Step Test Exercise Prescription [STEP]), compared to usual-care exercise counseling delivered by primary care doctors on fitness and exercise self-efficacy among elderly community-dwelling patients. DESIGN: Randomized controlled trial; baseline assessment and intervention delivery with postintervention follow-up at 3, 6, and 12 months. SETTING: Four large (>5000 active patient files) academic, primary care practices: three in urban settings and one in a rural setting, each with four primary care physicians; two clinics provided the STEP intervention and two provided usual care control. PARTICIPANTS: A total of 284 healthy community-dwelling patients (72 per clinic) aged >65 years were recruited in 1998-1999. INTERVENTION: STEP included exercise counseling and prescription of an exercise training heart rate. MAIN OUTCOME MEASURES: The primary outcome measure was aerobic fitness (VO(2max)). Secondary outcomes included predicted VO(2max) from the STEP test, exercise self-efficacy (ESE), and clinical anthropometric parameters. RESULTS: A total of 241 subjects (131 intervention, 110 control) completed the trial. VO(2max) was significantly increased in the STEP intervention group (11%; 21.3 to 24ml/kg/min) compared to the control group (4%; 22 to 23ml/kg/min) over 6 months (p <0.001), and 14% (21.3 to 24.9ml/kg/min) and 3% (22.1 to 22.8ml/kg/min), respectively, at 12 months (p <0.001). A similar significant increase in ESE (32%; 4.6 vs 6.8) was observed for the STEP group compared to the control group (22%; 4.2 vs 5.4) at 12 months (p < 0.001). Systolic blood pressure decreased 7.3% and body mass index decreased 7.4% in the STEP group, with no significant change in the control group (p <0.05). Exercise counseling time was significantly (p <0.02) longer in the STEP (11.7+/-3.0 min) compared to the control group (7.1+/-7.0 min), but more (p <0.05) subjects completed > or =80% of available exercise opportunities in the STEP group. CONCLUSIONS: Primary care physicians can improve fitness and exercise confidence of their elderly patients using a tailored exercise prescription (e.g., STEP). Further, STEP appears to maintain benefits to 12 months and may improve exercise adherence. Future study should determine the impact of combining cognitive/behavior change strategies with STEP.

Aged↗

The uses and limits of standard exercise tests.

Standard exercise electrocardiography to detect coronary artery disease involves limitations of accuracy in a population of apparently healthy persons, to the extent that its value for counseling such individuals is doubtful. Among subjects being examined for chest pain, however, the accuracy of the exercise ECG in predicting coronary obstructive disease is better. In addition, the presence of more severe coronary obstructive disease tends to be associated with more distinctly abnormal tests at low levels of exercise. This tendency of association between marked ST-segment displacement at low exertion levels and more severe obstructive disease adds a measure of prognostic value to the standard exercise ECG in persons with chest pain or after myocardial infarction. The addition of either isotopic cardiac imaging or coronary arteriography to exercise ECG will be appropriate for situations in which either the ECG is known to be nonspecific or inadequate exercise is achieved.

Angina Pectoris↗

Exercise testing for functional evaluation and exercise prescription.

Although radionuclide tests, despite their high cost, are being used with ever-increasing frequency in diagnostic testing, the ECG exercise stress test remains the best method for providing inexpensive, noninvasive information on how patients will function in vocational and recreational pursuits. This article explains the usefulness of respiratory gas analysis measurements in evaluating performance as well as providing some substitutes when direct measurement is not available. Various exercise test modifications that help in prescribing exercise for athletes, able-bodied cardiac patients, or the disabled are also described.

Adaptation, Physiological↗

[Exercise tests in pneumology. C.R.E.D.O].

Exercise tests have proved very useful in numerous areas such as sports medicine, research, clinical medicine and rehabilitation to exercise and therapeutic trials. It is not always easy for a pneumologist to decide what sort of effort and which protocol to use. There is also the question of which parameter to use and the relationship between parameters and which are the most pertinent as a function of the aim of the research. Above all the exercise test should be adaptable in view of the diversity of the objectives. In routine pneumology the exercise test using a bicycle ergometer and a triangular type of protocol are recommended for numerous reasons. The usual parameters (ventilation, oxygen consumption, production of carbonic dioxide, cardiac rate and blood gases) and their derivatives all have a value in the domain of cardiorespiratory physiology. It is important in clinical practice not to give too great an emphasis to the exact relationship expressed as a function of the workload, because the cycloergometer is practically never calibrated or even checked by the user. Dyspnoea was the major symptom leading the patient to seek a consultation and it is of primary importance that all effort tests include an estimation of the sensation of breathlessness.

Blood Gas Analysis↗

A non-ischemic forearm exercise test for the screening of patients with exercise intolerance.

BACKGROUND: The forearm exercise test is a common investigation that allows detection of some metabolic myopathies. It is not completely standardized and, when performed in ischemic conditions, may induce rhabdomyolysis in patients with glycogenosis. OBJECTIVE: To develop a standardized non-ischemic exercise test for a safe screening of patients with exercise intolerance. METHODS: Twenty-six healthy subjects and 32 patients with exercise intolerance performed an isometric exercise at 70% of the maximal voluntary contraction during 30 seconds in non-ischemic conditions. Blood concentrations of creatine kinase, lactate, and ammonia were analyzed. RESULTS: A nearly fourfold lactate rise was induced by exercise in healthy subjects. All patients with normal muscle biopsy showed values similar to those of healthy subjects. No significant lactate increase was observed in six patients with a myophosphorylase defect and one with a debrancher defect. Disparate lactate responses were observed in 14 patients with a mitochondrial myopathy. The blood lactate level at rest was abnormally high in four of these patients. The lactate surface normalized by the mechanical energy production was above the normal range in eight patients. CONCLUSIONS: The authors propose a standardized non-ischemic grip test that overcomes the main drawbacks of the classic ischemic forearm exercise test. It provides a specific, efficient, and safe screening test for patients with exercise intolerance. Its sensitivity was very good for patients with a glycogenolysis defect but remains partial in patients with a mitochondrial disorder.

Adult↗

Anxiety responses to maximal exercise testing.

The influence of maximal exercise testing on state anxiety was examined in three separate studies. Highly trained male distance runners (Study 1, n = 12) as well as college students with average (Study 2, n = 16) and below average (Study 3, n = 32) physical fitness levels completed graded maximal exercise tests. This last group was also randomly assigned to either a control or an 8 week training programme in order to determine the effect of increased fitness on the psychological responses to maximal exercise testing. Physical fitness was determined by the measurement of maximal oxygen uptake. State anxiety (State-Trait Anxiety Inventory) was assessed before and from 2-15 min following exercise. It was found that the state anxiety responses to maximal exercise testing were not influenced by re-testing or by 8 weeks of endurance training. Across the three study groups, the anxiety response was variable during the first 5 min following exercise testing; increases, decreases and no changes in anxiety were observed when compared to pre-exercise levels. The anxiety response to maximal exercise appeared to be dependent on the pre-exercise anxiety levels as well as the timing of the post-exercise assessments. It is concluded that maximal exercise testing can be associated with negative mood shifts during the first 5 min after exercise; however, this response is transitory and followed by positive mood shifts 10-15 min following such tests.

Adult↗

[Early exercise test after myocardial infarction].

Exercise tests of coronary function at the tenth day of an uncomplicated myocardial infarction offer objective evaluation of short-term benefits of an early accelerated physical retraining program. They also allow better individual adaptation of exercises prescribed at the start of convalescence at home. Exercise test results show significant correlation with clinical data and bicycle ergometer tests carried out two months after infarction, with respect to physical aptitude, reasons for discontinuation of test and lethality risk two months after infarction. This suggests that exercise tests performed after the acute phase of myocardial infarction are of diagnostic and prognostic value.

Aged↗

Current review of exercise testing: application and interpretation.

Exercise testing has changed dramatically in scope over the past 50 years. While initially used to assess functional capacity, it is now also utilized to detect the presence and severity of coronary artery disease (CAD), to evaluate postmyocardial infarction patients at risk for future cardiac events, to screen certain asymptomatic populations for CAD, and to evaluate dysrhythmias, peripheral vascular disease, and lung disease. Dynamic exercise in continuous multistage protocols is most popularly employed because of the more easily measured workload. The safety of exercise testing, its contraindications and termination end points are summarized. The sensitivity of exercise testing ranges between 60 and 70% while specificity has been reported between 85 and 90%. Both sensitivity and specificity are enhanced through use of radionuclide exercise thallium imaging and ventricular angiography.

Coronary Disease↗

Differentiating syndrome X from coronary artery disease by treadmill exercise test in patients with chest pain and exercise-induced myocardial ischemia.

Even though the underlying mechanisms of myocardial ischemia may be different, it is difficult to differentiate syndrome X from coronary artery disease (CAD) by means of the treadmill exercise test in elderly patients with chest pain and exercise-induced myocardial ischemia. One hundred sex- and age-matched patients-42 with syndrome X and 58 with CAD-were studied. Another 10 subjects with atypical chest pain, negative treadmill exercise test, and normal-appearing coronary angiograms served as controls. We evaluated the difference in exercise performance between patients with syndrome X and CAD, and the treadmill exercise test was undertaken with modified Bruce protocol within 2 weeks before coronary angiography. Parameters including time to 1 mm ST segment depression (STD), exercise duration (ED), heart rate (HR), systolic blood pressure, rate-pressure product (RPP), and percentage of age-predicted maximum HR (% HR) at different stages of the test were measured and then compared among the three groups of patients. Compared with CAD patients, syndrome X patients had significantly higher HR, % HR, and RPP at the time of 1 mm STD and at peak exercise. The time to 1 mm STD and ED were longer in syndrome X than in CAD patients. However, ED was shorter and HR, % HR, and RPP at peak exercise were similar in syndrome X patients as compared with control subjects. The new criterion of combined ED (> or =315 seconds) and RPP at peak exercise (> or =24,000 beats x mmHg/min) was found to be highly specific (86%) and moderately sensitive (64%) in differentiating syndrome X from CAD patients. The positive likelihood ratio for this criterion was 4.57 and negative likelihood ratio was 0.42. In conclusion, syndrome X patients had better exercise performance than CAD patients, but less ED and similar workload when compared with control subjects. The new criterion proposed in this study may provide a quick and simple way to differentiate syndrome X from CAD in a group of aged and predominantly male patients with chest pain and positive treadmill exercise test.

Adult↗

Comparison of exercise-positive with recovery-positive treadmill graded exercise tests.

A treadmill exercise test response may become positive because a diagnostic electrocardiographic ST-segment shift occurred during exercise, or, less often, because it occurred only during the recovery period after exercise had been completed. Factors that may be related to these 2 different responses in subjects enrolled in the Program of Surgical Control of Hyperlipidemia were investigated. No differences were found with regard to age, sex, level or location of Minnesota electrocardiographic Q-QS codes, number of narrowed coronary arteries, presence of collateral coronary artery circulation, ejection fraction, number of abnormally moving left ventricular wall segments, heart rate, systolic and diastolic blood pressure, double product, total exercise time, exercise-induced angina, or maximally achieved exercise heart rate or double product. Thus, the same significance should be attributed to a recovery-positive as to an exercise-positive treadmill test, and electrocardiographic, hemodynamic and angiocardiographic variables do not distinguish between subjects who exhibit these 2 different responses.

Adult↗

[The integrative cardiorespiratory exercise test: 2. Response to maximal exercise in heart and lung diseases].

Physiological measurements during integrative cardiorespiratory progressive exercise in different cardiovascular and respiratory disorders help discern and describe the characteristic exercise response patterns of different disorders. Cardiovascular limitation to exercise is characterized by reduced maximal exercise capacity and reduced anaerobic threshold and oxygen utilization. On the other hand, respiratory limitation of exercise is characterized by reduced breathing reserve with high ventilatory equivalents for a given metabolic load but with a normal cardiovascular response. Combined cardiovascular and respiratory disorders demonstrate both cardiovascular and respiratory types of limitation of exercise. We present 2 patients with cardiovascular disorders, 2 with respiratory, and 2 with combined cardiovascular and respiratory disorders. The interpretation of the physiological data of the progressive cardiorespiratory exercise test increased the accuracy of clinical evaluation and treatment. We therefore think the test will gain wide use in the clinical evaluation of patients with cardiovascular and respiratory disorders.

Cardiovascular Diseases↗

Exercise testing in suspected coronary artery disease.

The interpretation and selection of exercise tests depends on the pretest probability of CAD. Imperfect tests (like exercise tests) provide probability estimates, not definite statements (such as "the patient has CAD" or "the patient does not have CAD"). In patients with a low pretest probability of CAD (asymptomatic persons or men and women with nonanginal chest pain), abnormal exercise test results provide probability estimates that are much too low to conclude that the patient has CAD. In patients with anginal pain and normal exercise tests, the probability of CAD is too high to conclude that the patient has a normal coronary circulation. Exercise tests are not useful for trying to rule out CAD in patients with anginal pain. In patients with an intermediate pretest probability of CAD (men and women with atypical angina and women with typical angina), abnormal exercise tests (particularly the myocardial scintiscan) provide probability estimates that are high enough to justify starting treatment for CAD. Exercise tests are most useful in this group, a conclusion that has been reached by other methods of analysis. The myocardial scintiscan is much more useful than the exercise ECG in women. When CAD is strongly suspected, exercise tests have relatively little diagnostic value but may be useful for prognosis. However, clinical evidence of poor ventricular function may alone suffice to select patients with angina pectoris for coronary arteriography. Conversely, when clinical indicators of congestive heart failure are absent, the prognosis in chronic stable angina is so favorable that any further testing may be unnecessary. Screening asymptomatic persons for CAD is a very low yield practice. Patients who have no cardiac risk factors (hypercholesterolemia, family history of CAD, cigarette smoking, and hypertension) are at especially low risk of a primary cardiac event. Older men with stable typical angina are particularly likely to have left main coronary artery stenosis or three-vessel disease with poor ventricular function. The exercise ECG can identify groups of older men with a relatively high risk of having left main coronary artery stenosis. Physicians should be cautious when applying these recommendations to a primary care practice. The foregoing analysis is based on data obtained from patients who had been selected for coronary arteriography. There are two principal effects of biased selection of study patients: The pretest probability of CAD in clinical subgroups is probably lower than as shown here.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗