Exercise standards. A statement for health professionals from the American Heart Association

Reliability and validity of self-reported physical activity in the Nord-Trøndelag Health Study — HUNT 1

Background: A large health survey was previously conducted in 1984—86, the Nord-Trøndelag Health Study (HUNT 1), and another was conducted in 1995—97 (HUNT 2). A third, HUNT 3, started in 2006. However, the physical activity (PA) questionnaires have not yet been validated. Aims: To assess the reliability and validity of the self-reported physical activity questionnaire in the Nord-Trøndelag Health Study (HUNT 1). Methods: The HUNT 1 questionnaire was administered to a random sample of 108 healthy men aged 20—39 years. Repeatability was assessed with a repeat questionnaire after one week, and validity by comparing results with direct measurement of VO2during maximal work on a treadmill, with ActiReg, an instrument that measures PA and energy expenditure (EE) and with the International Physical Activity Questionnaire (IPAQ). ActiReg records the main body positions (stand, sit, bent forward and lie) together with the motion of the trunk and/or one leg each second. Results: The results indicated strong, significant agreement on test—retest (weighted kappa frequency, r=0.80, intensity, r=0.82, and duration, r=0.69). We found a moderate, significant correlation, r=0.48 (p≤0.01), between the index based on questionnaire responses and VO2max.Metabolic equivalent (MET) values of 6 or more from ActiReg and ``vigorous activity'' from the IPAQ most strongly correlated with the index (r=0.39, r=0.55, respectively). Associations of other measures obtained from ActiReg with questionnaire responses were weaker. Conclusions: Our results indicate that the PA questionnaire in HUNT 1 is reproducible and provides a useful measure of leisure-time PA for men. The questionnaire is very short, and compared favourably with much longer instruments for assessment of more vigorous PA. It should be an appropriate tool for use in further epidemiological studies, particularly when the interest is in aspects of PA reflected in fitness or METs greater than 6.

A comparison of treadmill scores to diagnose coronary artery disease

BACKGROUND

Recently, several treadmill scores have been proposed as means for improving the diagnostic accuracy of the exercise treadmill test (ETT). Questions remain regarding the diagnostic accuracy of treadmill scores when applied to a different patient population than that from which they were derived; furthermore, many treadmill scores have not been compared with one another in the same population.

HYPOTHESIS

The diagnostic accuracy of treadmill scores may not be the same.

METHODS

A retrospective analysis of data collected prospectively was performed on consecutive patients referred for evaluation of chest pain. All patients underwent a standard ETT followed by coronary angiography. Using angiographic evidence of coronary artery disease (CAD) as a reference, the area under the curve (AUC) of receiver operator characteristic (ROC) plots of the ST response alone, the Duke Treadmill Score (DTS), the Morise score, the Detrano score, the VA score, and a Consensus score consisting of the Morise, Detrano, and VA scores together were calculated and compared. The predictive accuracies of the DTS and the Consensus score to stratify patients for the likelihood of CAD were calculated and compared.

RESULTS

In all, 1,282 patients without a prior myocardial infarction had an ETT and coronary angiography. The AUC (+/- standard error) was 0.67+/-0.01 for the ST response, 0.73+/-0.01 for DTS, 0.76+/-0.01 for Detrano score, 0.77+/-0.01 for Morise score, 0.78+/-0.01 for VA score, and 0.78+/-0.01 for Consensus score. The AUC for each treadmill score was significantly higher (z-score > 1.96) than for the ST response alone. The AUC of DTS was significantly lower than all other treadmill scores (z-score > 1.96). The predictive accuracy (+/-95% confidence interval) of the DTS to risk stratify patients into high and low likelihood for CAD was 71 (65-77)%, versus 80 (74-86)% for the Consensus score (p < 0.0001).

CONCLUSION

In this population, the DTS remains useful for diagnosing CAD and stratifying for the likelihood of CAD, although it is less accurate than other treadmill scores.

What percent luminal stenosis should be used to define angiographic coronary artery disease for noninvasive test evaluation?

BACKGROUND

There has been controversy over what is the best angiographic luminal dimension criterion associated with ischemia for evaluating diagnostic tests. If one assumes that ST-segment depression or scores are indicators of ischemia, then whatever angiographic criteria best discriminates those with ischemic and nonischemic responses would be the best angiographic marker for ischemia. To study this, we calculated the area under the ROC curves for ST depression and scores at different angiographic cut-points in order to determine the best angiographic cut-point for defining ischemia-producing coronary disease.

METHODS

Twelve hundred and seventy-six consecutive males without prior MI with a mean age of 59 +/- 11 years who had undergone exercise testing and coronary angiography were analyzed in this study. We calculated the number of patients of this population that would be considered to have coronary artery disease at different cut-points for angiographic luminal stenosis. For example, 59% of the patients had significant CAD when disease was defined as 50% or greater coronary lumen stenosis of any coronary vessel while 49% of the patients had significant CAD when disease was defined as 70% or greater coronary lumen stenosis. Cut-points were considered between 40 to 100% coronary lumen stenosis. ROC analysis was then performed comparing ST depression and treadmill scores at each of these cut-points.

RESULTS

The cut-point for coronary lumen stenosis that returned the highest AUC for ST depression and scores was between 70 and 80% coronary luminal stenosis. However, the difference between the 50% and 75% luminal stenosis criteria was minimal.

CONCLUSION

It appears that the best cut-point for defining significant angiographic disease when evaluating diagnostic tests of ischemia is 75% or greater coronary luminal stenosis.

Barriers to Physical Activity Maintenance After Cardiac Rehabilitation

PURPOSE

Little is known about the contextual determinants for the maintenance of physical activity after cardiac rehabilitation. This study aimed to examine perceived social, psychological, and health-related barriers to the maintenance of physical activity among phase 2 cardiac rehabilitation graduates.

METHODS

Researchers using an open-ended format asked 160 participants (121 men and 39 women) 6 months after rehabilitation to identify perceived barriers to physical activity maintenance. The content of the participant responses was analyzed through categorization and coding of data, with independent review used to assess accuracy and reliability of decision rules. A social ecologic perspective was used for secondary coding and categorization. A chi analysis of categories was conducted to explore differences by gender, ethnicity, education, and employment.

RESULTS

Four categories were developed from the coded responses: intrapersonal, interpersonal, environmental, and organizational. In their responses, 93% of the participants reported intrapersonal barriers, with 24% reporting interpersonal barriers, 18% reporting environmental barriers, and 11% reporting organizational barriers. Years of education contributed significantly to acceptance of an inactive lifestyle among those less educated (chi = 32.489; P = .028). Employment status showed significant differences for work as a barrier among those employed full-time (chi = 13.570, P = .004). Barriers to physical activity by gender showed significant differences for interpersonal barriers as a whole (chi = 6.804; P = .009).

CONCLUSIONS

The open-ended format provided rich narrative data regarding barriers to the maintenance of physical activity. The acknowledgment of barriers, particularly from a social ecologic perspective, is needed to guide innovative, multilevel interventions for promoting physical activity maintenance among those with diagnosed coronary heart disease.

Trajectories of leg strength and gait speed among sedentary older adults: longitudinal pattern of dose response

BACKGROUND

Current theory about how an older adult's leg strength influences walking speed is based primarily on nonlinear patterns of association observed in cross-sectional data. Compared with adults with normal or high levels of leg muscle strength, weak older adults are thought to have a greater capacity for functional change in response to changes in lower extremity strength. Longitudinal data, however, have not been applied to study this putative pattern of dose response.

METHODS

Three repeated measures of leg strength, gait speed, and covariates were evaluated in a cohort of 134 sedentary, community-dwelling male and female participants (aged >64 years) of a randomized exercise intervention. Empirical Bayes methods were used to evaluate the association between trajectories of strength and gait speed during the course of the study.

RESULTS

We observed a potentially clinically important, positive linear association between strength change and gait speed change. Each additional unit increase in the monthly rate of strength change increased the rate of gait speed change by 0.29 meters/minute/month (95% CI [confidence interval] = 0.03, 0.55 m/min/mo). Absolute change in walking velocity due to strength changes in the cohort ranged from a gain of approximately 15 m/min to a loss of approximately 13 m/min over the 9-month period (changes of -18% to +20% relative to a normal walking speed of 72 m/min).

CONCLUSIONS

In this cohort, change in functional walking speed depended more on the rate of strength change observed than on the amount of muscle weakness present at baseline. These results have important implications for screening and intervention programs designed to change functional walking ability among sedentary older adults.

Treadmill scores in elderly men

OBJECTIVES

This study seeks to further characterize the role of exercise testing in the elderly for prognosis and diagnosis of coronary artery disease.

BACKGROUND

Recent exercise testing guidelines have recognized that statements regarding the elderly do not have an adequate evidence-based quality because the studies they are based on have limitations in sample size and design. The Duke Treadmill Score has been recommended for risk stratification, but recent evidence has suggested that it does not function in the elderly.

METHODS

The study population consisted of male veterans (1872 patients >or=65 years; 3798 patients <65 years) who underwent routine clinical exercise testing with a mean follow-up of six years. A subset who underwent coronary angiography as clinically indicated (elderly, n = 405; younger, n= 809) were included. The primary outcome for all subjects was cardiovascular mortality with coronary angiographic findings as the outcome in those selected for angiography.

RESULTS

In survival analysis, exercise-induced ST depression was prognostic in both age groups only when cardiovascular death was considered as the end point. Peak metabolic equivalents were the most significant predictor for both age groups only when all-cause death was considered as the end point. New age-specific prognostic scores were developed and found to be predictive for cardiovascular mortality in the elderly. Moreover, in the angiographic subset of the elderly, a specific diagnostic score provided significantly better discrimination than exercise ST measurements alone. For any new score, there is a need for validation in another elderly population.

CONCLUSIONS

The mortality end point affected the choice of prognostic variables. This study demonstrates that exercise test scores can be helpful for the diagnosis and prognosis of coronary disease in the elderly.

Is systolic blood pressure recovery after exercise a predictor of mortality?

BACKGROUND

An attenuated systolic blood pressure recovery after exercise has been associated with the severity of atherosclerotic heart disease.

METHODS

For 6 years, we observed 12,379 patients who underwent symptom-limited exercise testing. We excluded patients receiving antihypertensive medication and patients with valvular disease, emphysema, end-stage renal disease, heart failure, left ventricular systolic dysfunction, and atrial fibrillation. Blood pressure recovery ratio was defined as the ratio of systolic blood pressure at 3 minutes into recovery to systolic blood pressure at peak exercise; this has been shown to correlate with angiographic severity of coronary disease.

RESULTS

The blood pressure recovery ratios ranged from 0.36 to 1.62, with values for increasing quartiles of 0.72 +/- 0.05, 0.82 +/- 0.02, 0.88 +/- 0.02, and 0.99 +/- 0.07. During follow-up, there were 430 deaths (3%). Five-year Kaplan Meier survival rates were 0.975, 0.974, 0.969, and 0.966 in quartiles 1 to 4, respectively. Compared with patients in the lowest quartile of blood pressure recovery ratio, patients in the highest quartile were at somewhat increased risk (hazard ratio, 1.71; 95% CI, 1.31-2.24; P <.001). However, after adjusting for age, sex, body mass index, resting heart rate and blood pressure, peak systolic blood pressure, heart rate recovery, exercise chronotropic response, cardiac history, and standard risk factors, this association was no longer present (adjusted hazard ratio, 1.05; 95% CI, 0.8-1.38; P =.74).

CONCLUSIONS

In this low-risk population, abnormal systolic blood pressure recovery after exercise was not independently predictive of mortality after correcting for differences in baseline and exercise characteristics.

Exercise in hypertension. A clinical review

The current exercise prescription for the treatment of hypertension is: cardiovascular mode, for 20-60 minutes, 3-5 days per week, at 40-70% of maximum oxygen uptake (VO2(max)). Cardiovascular exercise training is the most effective mode of exercise in the prevention and treatment of hypertension. Resistance exercise is not the preferred mode of exercise treatment, but can be incorporated into an exercise regime provided the diastolic blood pressure response is within safe limits. It is inconclusive whether durations longer than 30 minutes produce significantly greater reductions in blood pressure. A frequency of three exercise sessions per week has been considered to be the minimal frequency for blood pressure reduction. Higher frequencies tended to produce greater reductions, although not significantly different. Evidence still exists that high intensity exercise (>75% VO2(max)) may not be as effective as low intensity exercise (<70% VO2(max)) in reducing elevated blood pressures. Exercise can be effective without a change in bodyweight or body fat. Bodyweight or body fat loss and anti-hypertensive medications do not have an added effect on blood pressure reduction associated with exercise. beta-blockade is not the recommended anti-hypertensive medication for effective exercise performance in non-cardiac patients. Not all hypertensive patients respond to exercise treatment. Differences in genetics and pathophysiology may be responsible for the inability of some hypertensive patients to respond to exercise. Ambulatory technology may allow advances in individualising a more effective exercise prescription for low-responders and non-responders.

Reference values for the physical work capacity on a bicycle ergometer for men -- a comparison with a previous study on women

The aim of the study was to collect new reference values for the clinical ramp exercise test on bicycle, because in our experience, the commonly used values were too low. A group of healthy men (n = 81, 20-80 years) was randomly selected from the local municipal register to achieve an even distribution in age. Data were compared with those obtained in a similar, previous study on women (n = 87). The subjects were encouraged to cycle until exhaustion (19 on the Borg scale) when maximal load, heart rate and systolic blood pressure were recorded. Maximal load (W(max)) was related to age (years) and height (m) using a non-linear function: W(max) = (244.6 x height - 92.1)/[1 + exp[0.038 x (age - 77.3)]]. Maximal heart rate (HRmax) was described by a similar function: HRmax = 203.7/[1 + exp[0.033 x (age - 104.3)]]. The maximal systolic blood pressure (BP(max)) was described by a linear function based on age: BP(max) = 0.505 x age + 192. Similar functions for the women are also given. It is suggested that 80-120% of the predicted maximal load can be taken as a reference interval for both men and women and similarly 90-110% of the maximal heart rate. In this study, 84% of the men reached a maximal load within the reference interval and 93% maximal heart rate within the reference interval. The reported values for maximal load were 104-132% of the reference values published by others.

Exercise considerations in coronary artery disease, peripheral vascular disease, and diabetes mellitus

Physical inactivity is a risk factor for cardiovascular disease. Regular aerobic and resistance training increases exercise capacity and plays a role both in the primary and secondary prevention of cardiovascular disease. Patients with coronary artery disease, peripheral vascular disease, or diabetes mellitus must be considered individually when prescribing exercise because their clinical status can vary greatly. In addition, a majority of these patients have multiple comorbid disorders such as renal, neurologic, and retinal disease that may affect their ability to exercise safely. Therefore, a preparticipation medical evaluation is required. An exercise prescription should be tailored to each person's unique set of circumstances and reflect an effort to maximize the anticipated benefits while minimizing the risks.

Endothelin-1 and Nitric Oxide Concentrations and Their Response to Exercise in Patients With Slow Coronary Flow

In this study, the endothelin-1 (ET-1) and nitric oxide (NO) concentrations in slow coronary flow (SCF) patients were assessed before and at the peak of the exercise stress test and compared with the values from healthy controls. The study population was 25 patients who underwent coronary angiography and were diagnosed as SCF (11 females (44%), aged 56.7+/-9.8 years), and 20 normal subjects (9 females (45%), aged 54.3+/-9.2 years). Mean TIMI frame count in the patients was 54.1+/-13.4. Blood samples were drawn at rest and immediately at the end of exercise testing. The baseline ET-1 concentrations of the control subjects were lower than those of the patients (7.0+/-4.5 pg/ml vs 11.1+/-5.9 pg/ml p<0.0001) and this difference increased after exercise (6.2+/-4.3 pg/ml vs 20.1 +/-10.4 pg/ml, p<0.0001). Post-exercise ET-1 concentrations were significantly higher than baseline in patients with SCF (p<0.0001) and a reduction in the ET-1 concentrations was observed in control subjects (p<0.05). Baseline NO concentrations of the patients were lower than those of the control subjects (27 +/-5.1 micromol/L vs 31.2+/-4.9 micromol/L, p=0.0001). Although the NO concentrations in both groups were significantly increased after exercise (29.4 +/-5.9 micromol/L vs 33.3+/-5.6 micromol/L, p<0.05 for both), the difference was not significant. A significant negative correlation among post-exercise ET-1 concentrations and maximal heart rate, exercise duration and exercise rate - pressure product, and a significant positive correlation among post-exercise NO concentrations and maximal heart rate and exercise duration were observed in both groups. The results of this study show that endothelial function (assessed by ET-1 and NO concentrations) and its response to exercise were abnormal in SCF patients compared with healthy subjects, and this may play some pathophysiologic role.

Prognostic value of exercise tests in male veterans with chronic coronary artery disease

PURPOSE

The authors evaluate the prognostic value of treadmill testing in a large consecutive series of patients with chronic coronary artery disease. Exercise testing is widely performed, but analyses of the prognostic value of test results have largely concentrated on patients referred for the diagnosis of coronary artery disease, patients after an acute coronary event or procedure, or patients with congestive heart failure.

METHODS

All patients referred for evaluation at two university-affiliated Veterans Affairs Medical Centers who underwent exercise treadmill tests for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security Death Index after a mean 5.8-year follow-up. Patients without established heart disease and those with congestive heart failure were excluded, leaving the target population of those with a history myocardial infarction or coronary intervention. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. All-cause mortality was used as the endpoint for follow-up. Standard survival analysis was performed including Kaplan Meier curves and the Cox Hazard Model.

RESULTS

Of the 1,473 patients with coronary artery disease who had exercise testing, 273 (19%) patients had a revascularization procedure (Revascularization group); 813 (55%) had a history of myocardial infarction, diagnostic Q waves (MI group), or both; and 387 (26%) had a history of myocardial infarction or Q wave and revascularization (Combined group). Mean age of the patients was 61.8 +/- 9 years. A total of 401 deaths occurred during a mean follow-up of 5.8 years with an annual mortality rate of 4.5%. Only two variables, age and maximal exercise capacity, were independently and statistically associated with time to death in all three groups and were the strongest predictors of all cause mortality.

CONCLUSION

A simple score based on METs, age, and history of myocardial infarction or diagnostic Q waves can stratify prognosis in patients with chronic coronary artery disease. The score enabled the identification of a group at low risk (32% of the cohort) with an annual mortality rate of 2%, a group at intermediate risk (42% of the cohort) with an annual mortality rate of about 4%, and a group at high risk (26% of the cohort) with an average annual mortality rate of approximately 7%.

Modified programme of in-patient (phase I) cardiac rehabilitation after acute myocardial infarction

A group of 61 men who suffered from myocardial infarction (MI) were divided into two groups: group A (31 patients post MI, one day at intensive care unit (ICU), no beta-blockers, physical therapy according to a seven-day programme) and group B (30 patients post MI, two days at ICU, with beta-blockers, physical therapy according to a seven-day programme). Results from both groups were compared with a control group (C) (38 patients post MI, three days at ICU, physical therapy according to a longer ten-day graded programme). The objective of this study was to assess the efficacy of a proposed modified rehabilitation programme in patients after acute MI on the basis of a submaximal stress test performed on a cycle ergometer and to find out which stress test parameters might be used for the selection of an appropriate phase 2 rehabilitation programme. The performed analysis of correlation between exercise and resting parameters showed statistical relevancy with regard to systolic blood pressure in group A. Maximal load (WATs), metabolic cost (METs), maximal heart rate (beats/min), stress-test time (T-test) and time of normalization for the exercise parameters (t(n)) are the parameters of the stress test that should be taken into consideration for appropriate selection of an out-patient (phase 2) rehabilitation programme.

Anomalous Left Coronary Artery from the Pulmonary Artery

Anomalous origin of the left coronary artery from the pulmonary trunk (Bland-Garland-White syndrome) is an important congenital malformation of the coronary circulation.The anomaly occurs in ap proximately 1 in 300,000 live births.Only 10% to 15% of affected infants will reach adulthood.The usual clinical presentation is that of the infant who sustains a myocardial infarction and develops congestive heart failure.Older children or adults can present with a continuous murmur and/or mitral regurgitation resulting from dysfunction of the ischemic papillary muscle.In some cases, the coronary anomaly is unsuspected until a previously well adolescent or adult experiences chest pain, heart failure, or sudden death.

Relationship between exercise-induced ST segmental depression and myocardial ischemia assessed by technetium-99m tetrofosmin SPECT imaging in patients with inferior Q wave myocardial infarction

BACKGROUND

ST segment depression (STD) is a standard electrocardiographic sign of myocardial ischemia. Although STD may represent reciprocal changes in patients with previous myocardial infarction, studies of reciprocal changes during exercise testing are scarce.

METHODS

From December 1999 to December 2000, 160 patients (119 males, 41 females, mean age 54 +/- 8 years), undergoing, maximal or symptom-limited exercise treadmill test (Bruce-protocol), myocardial perfusion scintigraphy using technetium-99m tetrofosmin single photon emission computed tomography (SPECT) imaging, within 30 days of an uncomplicated inferior Q wave myocardial infarction. The location of STD at the electrocardiogram (ECG) was defined as anterior (V1-4), high lateral (I, aVL), and lateral (V5-6). Ischemia was defined as reversible perfusion abnormalities.

RESULTS

STD occurred in anterior leads in 29 patients (18.1%), in the lateral leads in 41 patients (25.6%), in the high lateral leads in 20 patients (12.5%). In 70 patients (43.8%) no significant STD occurred during the exercise test. ST segment elevation occurred in 28 patients (17.5%) in inferior leads. High lateral STD was associated with inferior ST elevation in 16 patients (80%), whereas only eight patients (19.5%) with lateral STD and nine patients (31%) with anterior STD were associated with inferior ST elevation. Ischemia was detected in 63 of 90 patients (70%) with and in 10 of 70 patients (14.3%) without STD (p < 0.0001). Patients with high lateral STD had a higher prevalence of fixed perfusion defects in the inferior wall (95 vs. 27.8%) and in posterolateral wall (75 vs. 18.9%) compared with other patients (p = 0.003 and 0.002, respectively). Ischemia was more prevalent in patients with lateral STD than without (87.8 vs. 14.3%, p < 0.0001).

CONCLUSION

In patients with inferior Q wave, the presence of exercise-induced STD in lateral and anterior leads appears to be a sign of myocardial ischemia, and may require invasive evaluation; on the other hand, the presence of STD in high lateral leads should be recognized as a reciprocal change for ST elevation in the inferior leads, and may not be an indication for invasive evaluation.

Influence of aerobic exercise with an intermission, using a bicycle ergometer, on fat metabolism in obese patients with gonarthrosis

Our study was conducted to acquire essential information on the fat metabolism of obese patients with gonarthrosis during aerobic exercise, with a bicycle ergometer, with an intermission and without an intermission. Two experiments were conducted. Six women with gonarthrosis participated in the first experiment and another six women with gonarthrosis participated in the second experiment. The first experiment was conducted to investigate the influence of the total programmed workload on fat metabolism during bicycle aerobic exercise, and the second was conducted to investigate the effect of an intermission on fat metabolism when exercise consisted of an equally distributed total 50-W workload. During the experiment three exercise patterns were tested (six training sessions, each with 5 min of aerobic bicycle exercise with of 5 min, three training sessions each with 10 min of exercise with intermissions of 5 min, and 30 min of continuous exercise). The first experiment revealed that there was a significant relationship between the increase in free fatty acids (FFA) after exercise and the workload (P < 0.05). The second experiment revealed that there was no significant difference in the increase of FFA among the three exercise patterns. Exercise that was undertaken at a 50-W workload had a negligible effect on the women's vital signs. The bicycle ergometer aerobic exercise with an intermission actually led to an increase in FFA values compared with the effects of the continuous aerobic exercise.

Performance tests and disability: developing an objective index of mobility-related limitation in older populations

BACKGROUND

Disability reflects physiological limitations, social and environmental barriers, and "sickness" behavior. Being able to measure these influences separately would greatly assist interpretation of disability comparisons over time or between populations. This study aimed to identify an index of mobility-related limitations composed of physiological measures that are most closely associated with reported mobility disability in elders.

METHODS

Data from the Third National Health and Nutrition Examination Survey (NHANES III) were used. Participants aged 60 and older were included in this analysis. Participants included 6596 respondents who were interviewed in their homes, and 5724 (87%) of these attended a further examination. Domains of measurements included body measurements, bone densitometry, physical examination, spirometry, fundus photography, and physical performance measures. Multivariate models were developed on a random half subsample of the data and were validated on the other half. Receiver operating characteristic (ROC) areas and logit rank slopes were used to evaluate sets of measures.

RESULTS

In weighted logistic regression models, six and five measures were significantly associated with difficulty and inability in walking a quarter of a mile, respectively. These mainly included measures of lower extremity and lung function. A relatively minimal loss of sensitivity and specificity occurred from using more economical models, employing a subset of the identified measures.

CONCLUSIONS

Subsets of measures associated with reported mobility disability could provide objective indices of mobility-related limitation for comparing populations or long-term population health monitoring.

Exercise prescription for the elderly: current recommendations

The benefits for elderly individuals of regular participation in both cardiovascular and resistance-training programmes are great. Health benefits include a significant reduction in risk of coronary heart disease, diabetes mellitus and insulin resistance, hypertension and obesity as well as improvements in bone density, muscle mass, arterial compliance and energy metabolism. Additionally, increases in cardiovascular fitness (maximal oxygen consumption and endurance), muscle strength and overall functional capacity are forthcoming allowing elderly individuals to maintain their independence, increase levels of spontaneous physical activity and freely participate in activities associated with daily living. Taken together, these benefits associated with involvement in regular exercise can significantly improve the quality of life in elderly populations. It is noteworthy that the quality and quantity of exercise necessary to elicit important health benefits will differ from that needed to produce significant gains in fitness. This review describes the current recommendations for exercise prescriptions for the elderly for both cardiovascular and strength/resistance-training programmes. However, it must be noted that the benefits described are of little value if elderly individuals do not become involved in regular exercise regimens. Consequently, the major challenges facing healthcare professionals today concern: (i) the implementation of educational programmes designed to inform elderly individuals of the health and functional benefits associated with regular physical activity as well as how safe and effective such programmes can be; and (ii) design interventions that will both increase involvement in regular exercise as well as improve adherence and compliance to such programmes.

Quantification of cardiac stress during EGD without sedation

BACKGROUND

Although the complication rate of endoscopy is low, EGD may induce cardiac stress. The aim of this study was to quantify cardiac stress during EGD.

METHODS

Heart rate, blood pressure, cardiac output, and peripheral oxygen saturation were measured during endoscopy without sedation in 7 volunteers. Cardiac output was measured with an automated echocardiographic technique. Cardiac index, left ventricular work index, and rate-pressure product were calculated. Serum catecholamine concentrations were measured before and after the examination.

RESULTS

Heart rate increased significantly when the endoscope was located in the esophagus compared with the rate before insertion (p < 0.05). No significant changes in cardiac index and left ventricular work index were observed during endoscopy. Rate-pressure product increased significantly at the point of esophageal observation compared with that before insertion (p < 0.05). The rate-pressure product was maximally increased during esophageal observation at 66% over baseline (95% CI [45%, 86%]). Serum concentration of norepinephrine rose significantly after the examination (p < 0.05).

CONCLUSIONS

Cardiac output did not increase during EGD without sedation in healthy male volunteers. Cardiac stress increased during EGD as indicated by a 66% increase in rate-pressure product. The cardiac stress was approximately equal to that observed in 3.3 to 5 metabolic equivalents of treadmill exercises.

Reference values for the physical work capacity on a bicycle ergometer for women between 20 and 80 years of age

A sample of women (n=87) uniformly distributed in age (20-80 years) was randomly selected from the municipal population register and conventional clinical exercise tests were performed on a bicycle. The load started at 30 W and increased (5 W/30 s) until exhaustion. Care was taken to perform a maximum exercise test. The women were required to be cardiovascularly healthy and not on regular medication to be included in the study. The maximum work load was found to be dependent on age and height. The following equation described the maximum load. Max load (W)=(137.7 * Height (m) - 23.1)/(1 + exp (0.064 * (Age (years) - 75.9))). The upper and lower limits of the reference interval were 120 and 80% of the predicted load, respectively. The upper and lower limits for maximum heart rate were 110 and 90% of the maximum heart rate given by 190.2/(1 + exp (0.0453 * (Age - 107.5))). The reference value for maximum systolic blood pressure was taken as the interval between the two lines 153.3 + 0.281 * Age and 172.0 + 1.13 * Age. The reference values presented for work capacity are higher than those normally used in Sweden.

Clinical utility of the exercise ECG in patients with diabetes and chest pain

OBJECTIVE

The purpose of this study was to determine the characteristics of exercise treadmill testing in diabetic patients presenting with chest pain.

BACKGROUND

The diagnosis of coronary artery disease (CAD) in diabetic patients is confounded by different manifestations of coronary disease than are seen in the general population. Because of the association of diabetes with accelerated CAD, it is critical to assess the diagnostic utility of the standard exercise test in diabetic patients with chest pain.

METHODS

This study was a retrospective analysis of standard exercise test results in 1,282 male patients without prior myocardial infarction who had undergone coronary angiography and were being evaluated for possible CAD at two Veterans' Administration institutions.

RESULTS

In patients with diabetes, 38% had an abnormal exercise test result, and the prevalence of angiographic CAD was 69%; the sensitivity of the exercise test was 47% (95% confidence interval [CI], 41 to 58), and specificity was 81% (95% CI, 68 to 89). In patients without diabetes, 38% had an abnormal exercise test result, and the prevalence of angiographic CAD was 58%; the sensitivity of the exercise test was 52% (95% CI, 48 to 56), and specificity was 80% (95% CI, 76 to 83). The receiver operating characteristic curves were also similar in both diabetic and nondiabetic patients (0.67 and 0.68, respectively).

CONCLUSION

These data demonstrate that the standard exercise test has similar diagnostic characteristics in diabetic as in nondiabetic patients.

Simple treadmill score to diagnose coronary disease

OBJECTIVE

Our aim was to derive and validate a simplified treadmill score for predicting the probability of angiographically confirmed coronary artery disease (CAD).

BACKGROUND

The American College of Cardiology/American Heart Association guidelines for exercise testing recommend the use of multivariable equations to enhance the diagnostic characteristics of the standard treadmill test. Most of these equations use complicated statistical techniques to provide diagnostic estimates of CAD. Simplified scores derived from such equations that require physicians only to add points have been developed for pretest estimates of disease and for prognosis. However, no simplified score has been developed specifically for the diagnosis of CAD using exercise test results.

METHODS

Consecutive patients referred for evaluation of chest pain who underwent standard treadmill testing followed by coronary angiography were studied. A logistic regression model was used to predict clinically significant (> or = 50% stenosis) CAD and then the variables and coefficients were used to derive a simplified score. The simplified score was calculated as follows: (6 x maximal heart rate code) + (5 x ST-segment depression code) + (4 x age code) + angina pectoris code + hypercholesterolemia code + diabetes code + treadmill angina index code. The simplified score had a range from 6 to 95, with < 40 designated as low probability, between 40 and 60 was intermediate probability, and > 60 was high probability for CAD.

RESULTS

A total of 1,282 male patients without a prior myocardial infarction underwent exercise treadmill testing and coronary angiography in the derivation group, and there were 476 male patients in the validation group from another institution. The area under the receiver operating characteristic curve (+/- SE) for the ST-segment response alone was 0.67 as compared to 0.79 +/- 0.01 for the diagnostic score (p > 0.001). The prevalence of significant disease for the men was 27% in the low-probability group, 62% in the intermediate-probability group, and 92% in the high-probability group, which was similar to the prevalence in the validation group, with 22%, 58%, and 92% in low-, intermediate-, and high-probability groups, respectively. The low-probability group had < 4% prevalence of severe disease. In both populations, 7 more patients out of 100 were correctly classified than with the use of ST-segment criteria. When used as a clinical management strategy, the score has a sensitivity of 88% and a specificity of 96%.

CONCLUSION

This simplified exercise score that estimates the probability of CAD can be easily applied without a calculator and is a useful and valid tool that can help physicians manage patients presenting with chest pain.

Performing the exercise test

Exercise testing is useful in assessing physical fitness, determining functional capacity, diagnosing ischemic heart disease, defining the prognosis of ischemic heart disease, developing an exercise prescription, and guiding cardiac rehabilitation. This article outlines the current indications, contraindications, and special considerations for exercise testing. Specific protocols are discussed along with physician responsibilities for performing this procedure. A summary of current testing equipment is included.

Using the exercise test to create the exercise prescription

Exercise testing can provide valuable information to aid the primary care physician in developing a safe and effective exercise program for his or her patients. This review presents the most recent recommendations for the components of an exercise program as well as methods to accomplish appropriate prescription writing for the various subsets of individuals from the healthy patient to the patient with chronic disease. In addition, a plea is made for physicians to encourage all patients to engage in at least some kind of regular exercise activity in an attempt to counteract the increasingly sedentary lifestyles found in our culture.

Effect of physical activity during teenage years, based on type of sport and duration of exercise, on bone mineral density of young, premenopausal Japanese women

In this cross-sectional study, 91 healthy premenopausal women aged 20-39 years were investigated to determine the effect of physical activities during their teenage years on their current bone mineral densities (BMD). We measured whole-body BMD (WBMD), lumbar BMD (LBMD), and radial BMD (RBMD) with dual energy X-ray absorptiometry (DXA). Using a questionnaire, we asked the women about their physical activities during junior and senior high school and at present. We also asked about their current nutritional status and past and current milk intake. After adjusting for age, body mass index (BMI), current total calorie and calcium (Ca) intake, and milk intake when they were teenagers and at present, we determined that subjects who exercised during extracurricular activities at each of the three periods (during junior and senior high school and at present) had significantly higher WBMD and LBMD (P <0.01, respectively) than did those who did not exercise at those times. Subjects who played high-impact sports at each period had significantly higher WBMD and LBMD than did subjects who played low-impact sports (P <0.05, respectively). Subjects who had exercised regularly from their teenage years to the present had significantly higher BMD at all sites than BMD in other subjects after adjusting for the potential confounders described above (P <0.05, respectively). Our data suggest that continuous exercise beginning in junior high school, especially high-impact sports, may be associated with greater current bone mass. It is important to incorporate adequate exercise beginning in the teenage years to lower one's future risk for osteoporosis.

Re-evaluation of exercise prescription for Japanese type 2 diabetic patients by ventilatory threshold

Prescription of aerobic exercise for Type 2 diabetes mellitus (Type 2 DM) in clinical practice is frequently based on exercise intensity at maximum heart rate (60<HR(max)<79%), heart rate reserve (50<HR(reserve)<74%), and rating of perceived exertion (12<RPE<13). We examined these parameters in Japanese males with Type 2 DM at ventilatory threshold (VT) to investigate the exercise capacity of Type 2 DM patients and re-evaluate the exercise prescription. Fifty-six Japanese Type 2 DM males without autonomic neuropathy [age, 53.5+/-7.7 years; body mass index (BMI), 23.7+/-3.6 kg/m(2)] were enrolled and compared with 56 age- and BMI-matched healthy Japanese males. VT was determined breath by breath during exercise test using a ramp protocol and rates of oxygen consumption (VO(2)), work rate (WR), HR, DeltaHR, %HR(max), %HR(reserve), and RPE were measured at VT. Type 2 DM patients had significantly lower VO(2) (3.6+/-0.4 metabolic equivalents (METs)) and WR (62+/-14 W) than controls (VO(2), 3.9+/-0.6 METs; WR, 74+/-13 W). %HR(reserve), (32.6+/-7.7%) was also significantly lower compared with controls (37.6+/-8.3%), while %HR(max), was not different. RPE was also similar in diabetics (12.4+/-1.5) and controls (12.9+/-1.2), however, it was significantly lower in diabetic patients aged 60-69 years (11.8+/-2.0) and those with distal symmetric sensory neuropathy (12.2+/-1.0). Our results indicate reduced exercise capacity in Japanese Type 2 DM males and the exercise intensity of 60%HR(max), 30%HR(reserve), and RPE 12 is recommended in elderly diabetics and those with diabetic sensory neuropathy.

Effects of aerobic physical exercise in the elderly with type 2 diabetes mellitus

The objective of this study was to determine the impact of an aerobic physical exercise program in the treatment of a group of elderly patients with type 2 diabetes mellitus (DM) in relation to metabolic control, physical capacity, quality of life (QOL) and attitudes toward diabetes. Patients were randomly assigned to either an experimental (n=19) or a control (n=20) group. The following measurements were conducted at baseline and after week 16: glycosylated hemoglobin (hbA1c), fructosamine, 3 h oral glucose tolerance test, treadmill test (Balke-Naughton), and a questionnaire on QOL and attitudes toward DM. After the intervention, the experimental group showed a significant decrease of glucose excursion during the oral glucose tolerance test (OGTT) (area under the curve) (16.6+/-3.8 vs. 15.3+/-3.1, P<0.05) and an increase in total time on the treadmill (s) (423+/-207 vs. 471+/-230, P<0.05). An improvement in the attitudes toward DM was observed in the experimental group (P=0.01) but not in the control group. Female gender, higher body mass index and hbA1c were factors associated with a response to the intervention. This study suggests that physical exercise has significant effects on glucose excursion during an OGTT and exercise tolerance in elderly patients with type 2 DM.

Diagnostic testing

The results of cardiac tests must always be interpreted through the lens of pretest probabilities created by the history and the physical examination. Tests should be chosen with a clear diagnostic and prognostic purpose in mind. A clear understanding of the relationship between the history and physical examination and more technologic diagnostic testing improves the primary care physician's ability to evaluate potential cardiac disease in an efficient and cost-effective manner.

A survey of exercise testing: methods, utilization, interpretation, and safety in the VAHCS

BACKGROUND

Healthcare organizations are being graded in terms of their adherence to practice guidelines. The authors sought information on practice patterns of exercise testing within the Veterans Affairs Health Care System (VAHCS) to determine how well current practice patterns adhere to current guidelines. In addition, we sought to update past surveys to determine methods, indications, utilization of alternative diagnostic modalities, criteria for interpretation, safety, and physician supervision of exercise testing within the VAHCS.

METHODS

Questionnaires were sent to 72 of the largest Veterans Affairs Medical Centers with cardiology divisions. The centers were queried regarding volume and type of exercise testing (standard, nuclear, and echocardiographic), indications, safety, protocols used, and criteria for interpretation.

RESULTS

Seventy-one questionnaires were returned, comprising a total of 75,828 exercise tests performed within the last year. Virtually all indications for exercise testing fit the American Heart Association/American College of Cardiology (AHA/ACC) guidelines Class I criteria; 46% of patients were tested for the evaluation of chest pain; 14% were tested to evaluate patients at high risk for coronary artery disease; 10% were preoperative evaluations; and 8% were post-myocardial infarction evaluations. The most commonly used diagnostic test was the standard exercise electrocardiogram; a patient was five times more likely to undergo a standard exercise electrocardiogram or nuclear exercise test than an exercise or pharmacologic echocardiogram. The largest proportion of centers (49%) used 1.0-mm horizontal or downsloping ST depression as a criterion for an abnormal test, although 22% considered 1.5-mm upsloping ST depression to be abnormal, and 25% relied on a treadmill score. Seventy-eight percent of respondents used the treadmill, and of these, 82% used the Bruce or modified Bruce protocol. Four major cardiac events were reported (three myocardial infarctions, one sustained ventricular tachycardia) representing an event rate of 1.2/10,000. A physician was present during 73% of all standard exercise tests; 21% of respondents reported that a physician was required to be present "only for high-risk patients."

CONCLUSION

Indications for exercise testing are in close agreement with the AHA/ACC guidelines; thus, the test continues to have an important role in diagnosis and prognosis among patients with or suspected of having coronary artery disease. The exercise test is an extremely safe procedure, with an event rate similar to other recent surveys. However, a great deal of variation exists in terms of criteria for abnormal results and whether physician presence is required during exercise testing.

Wavelet analysis and time-frequency distributions of the body surface ECG before and after angioplasty

In a pilot study, electrocardiographic (ECG) recordings of patients with left and right coronary stenosis taken before and after angioplasty were analyzed using the continuous wavelet transform. Time-frequency distributions were obtained for different leads in order to examine the dynamics of the QRS-spectrum and establish features specific of ischemia in the time-frequency domain. We found relevant changes in the mid-frequency range, reflecting the ECG's response to percutaneous transluminal coronary angioplasty (PTCA). The changes appeared in ECG leads close to ischemic zones of the myocardium. Time-frequency distributions of the ECG during the QRS may thus become another electrocardiographic indicator of ischemia, alternative to ST-level in standard ECG or body surface mapping. The paper demonstrates the ability of the continuous wavelet transform to detect short lasting events of low amplitude superimposed on large signal deflections.

Exercise following myocardial infarction. Current recommendations

Cardiac rehabilitation services are comprehensive long term programmes designed to limit the physiological and psychological effects of cardiovascular disease (CVD), control cardiac symptoms and reduce the risk of subsequent CVD events by stabilising or partially reversing the underlying atherosclerosis process through risk factor modification. Exercise training is the cornerstone of such programmes. Ideally, exercise conditioning or training for the stable cardiac patient should include a combination of cardiorespiratory endurance (aerobic) training, arm exercises and muscular conditioning resistance (strength) training. Flexibility exercises should also be performed, usually as part of the warm-up and cool-down routines preceding and following endurance and strength training. This review discusses the potential physiological, psychological and health benefits of regular exercise and provides guidelines for exercise training for the rehabilitation of post-myocardial infarction patients following hospitalisation.

How silent is perioperative myocardial ischemia? A hemodynamic, electrocardiographic, and biochemical study in patients undergoing coronary artery bypass graft surgery

OBJECTIVE

To analyze the relationship among Holter electrocardiogram (ECG) recordings, hemodynamic measurements indicative of global myocardial oxygen balance, and serum cardiac troponin I concentrations (cTnI) in the early postoperative period after coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

PARTICIPANTS

Thirty patients undergoing CABG surgery.

INTERVENTIONS

ECG measurements consisted of Holter and standard ECG recordings. Hemodynamic measurements included heart rate, systolic and diastolic blood pressure (SBP, DBP), pulmonary capillary wedge pressure, and cardiac index (CI). Derived indices included tension time index (TTI), rate-pressure product, pressure work index (PWI), and endocardial viability ratio (EVR). Serial measurements of cTnI concentrations were measured postoperatively; the area under the cTnI concentration time curve was calculated for each patient (AUC cTnI).

MEASUREMENTS AND MAIN RESULTS

Episodes of myocardial ischemia were associated with small but significant rises in SBP (p = 0.01), DBP (p = 0.001), and TTI (p = 0.005) compared with periods without ischemia in the same patients. Serum cTnI concentrations 24 hours after cardiopulmonary bypass (p = 0.03) and AUCcTnI (p = 0.01) values were greater in patients who developed ECG myocardial ischemia compared with patients who did not.

CONCLUSIONS

The small changes in hemodynamics seen, although statistically significant, are unlikely to be the primary cause of the ischemia. They more likely reflect an independent process that causes or occurs as a result of ischemic episodes. Ischemic episodes detected by the Holter monitor are associated with significant release of cardiac troponin from the myocardium.

The effect of resting ST segment depression on the diagnostic characteristics of the exercise treadmill test

OBJECTIVES

The aim of this study is to demonstrate the effect of resting ST segment depression on the diagnostic characteristics of the exercise treadmill test.

BACKGROUND

Previous studies evaluating the effect of resting ST segment depression on the diagnostic characteristics of exercise treadmill test have been conducted on relatively small patient groups and based only on visual electrocardiogram (ECG) analysis.

METHODS

A retrospective analysis of data collected prospectively was performed on consecutive patients referred for evaluation of chest pain. One thousand two hundred eighty-two patients without a prior myocardial infarction underwent standard exercise treadmill tests followed by coronary angiography, with coronary artery disease defined as a 50% narrowing in at least one major epicardial coronary artery. Sensitivity, specificity, predictive accuracy and area under the curve of the receiver operating characteristic (ROC) plots were calculated for patients with and without resting ST segment depression as determined by visual or computerized analysis of the baseline ECG.

RESULTS

Sensitivity of the exercise treadmill test increased in 206 patients with resting ST segment depression determined by visual ECG analysis compared with patients without resting ST segment depression (77 +/- 7% vs. 45 +/- 4%) and specificity decreased (48 +/- 12% vs. 84 +/- 3%). With computerized analysis, sensitivity of the treadmill test increased in 349 patients with resting ST segment depression compared with patients without resting ST segment depression (71 +/- 6% vs. 42 +/- 4%) and specificity decreased (52 +/- 9% vs. 87 +/- 3%) (p < 0.0001 for all comparisons). There was no significant difference in the area under the curve of the ROC plots (0.66-0.69) or the predictive accuracy (62-68%) between the four subgroups.

CONCLUSIONS

The diagnostic accuracy and high sensitivity of the exercise treadmill test in a large cohort of patients with resting ST segment depression and no prior myocardial infarction support the initial use of the test for diagnosis of coronary artery disease. The classification of resting ST segment depression by method of analysis (visual vs. computerized) did not affect the results.

Determinants of exercise tolerance after acute myocardial infarction in older persons

OBJECTIVES

Exercise tolerance is reduced with advancing age. Identification of potentially reversible determinants of the age-related decrement in exercise tolerance, which remain largely unexplored in older subjects and in patients recovering from a recent myocardial infarction (MI), may have useful therapeutic implications. The objective of this study was to identify the independent determinants of exercise tolerance in older patients with a recent MI.

DESIGN, SETTING, AND PARTICIPANTS

Data is from baseline assessment of 265 post-MI patients (age range 45-85 years) enrolled in the Cardiac Rehabilitation in Advanced Age randomized, controlled trial. Patients with major comorbidities or severe MI complications were excluded from the trial. Exercise tolerance was determined from symptom-limited exercise testing and expressed as total work capacity (TWC, kg.m) or peak oxygen consumption (VO2peak, mL/kg/min). The associations between both TWC and VO2peak and baseline demographic, social, clinical, and neuropsychological variables and an index of health-related quality of life were determined with univariate and multivariate analysis.

RESULTS

With univariate analysis, TWC decreased by 1285 kg.m per decade of increasing age between 45 and 85 years of age. With multivariate analysis, TWC decreased by 922 kg.m per decade. Increasing age (P < .001), female gender (P < .001), a small body surface area (P < .001), a low level of usual physical exercise before MI (P < .002), and the presence of post-MI depressive symptoms (P < .024) were independently associated with a lower TWC. The same factors, in addition to a small arm muscle area (P < .002), were also independently associated with a lower VO2peak.

CONCLUSIONS

Age per se accounts for approximately 70% of the age-related decay in TWC or VO2peak. However, the inclusion of modifiable factors such as physical exercise and depression in the prediction model reinforces the importance of a multidimensional approach to the evaluation and treatment of older patients with a recent MI.

Aerobic capacity in adult dermatomyositis/polymyositis patients and healthy controls

OBJECTIVE

Assessment of myositis patients has relied on symptoms, strength testing, and serum muscle enzyme activity. Recently, functional assessments and evaluation of strength by dynamometry and of disease activity by magnetic resonance imaging have also been added. Aerobic testing in selected patients has been considered useful.

DESIGN

Case-control study.

SETTING

University Hospital, Vienna, Austria.

PATIENTS

Twenty-two subjects (8 outpatients with chronic dermatomyositis and 3 outpatients with chronic polymyositis, and 11 healthy controls) participated, allowing the identification of 11 case-control pairs matched by age (+/-3 years) and gender (mean age, 48+/-14 yrs; ratio of women to men, 18/4).

MAIN OUTCOME MEASURES

Target parameters were peak oxygen uptake (peak VO2) to estimate aerobic exercise capacity and peak isometric torque for muscle strength. Creatine phosphokinase (CPK) was measured to assess elevation of muscle enzymes.

RESULTS

The mean peak VO2 in patients with dermatomyositis/polymyositis was 15.3 mL/min/kg (SD = 5.8) and in the healthy controls 28.7 mL/min/kg (SD = 7.8). Cardiorespiratory capacity expressed as peak VO2 was thus significantly reduced at 53% (p = .0001) of the control value. Muscle strength expressed as peak isometric torque was significantly lower (p = .01) in patients (mean 148+/-73 Nm) when compared to the control group (mean 261+/-99 Nm). In myositis patients peak VO2 and peak isometric torque correlate well with each other (r = .7631; p = .0001), but not at all with serum CPK levels (r = .056; p = .869).

CONCLUSION

Peak VO2 is significantly diminished in patients with dermatomyositis/polymyositis, compared with age- and sex-matched controls. Serum CPK did not significantly correlate with VO2. Aerobic exercise testing may be a useful assessment parameter in selected patients with dermatomyositis/ polymyositis.

Ischemia-induced changes of the signal-averaged electrocardiogram: experimental investigation during percutaneous transluminal coronary angioplasty balloon-occluded coronary artery

INTRODUCTION

The influence of myocardial ischemia on the detection of an arrhythmogenic substrate with the signal-averaged ECG is unclear.

METHODS AND RESULTS

In 80 patients with single vessel coronary artery disease and a critical stenosis of the left anterior descending vessel selected after coronary angiography in whom percutaneous transluminal coronary angioplasty (PTCA) was planned, we retrospectively investigated the signal-averaged ECGs in the time domain before, during, and after occlusion of the coronary artery by the PTCA balloon. Forty patients were resuscitated from ventricular fibrillation (VF group), and 40 patients had no ventricular arrhythmia (non-VF group). Late potentials were seen at rest in 26 of 40 patients in the VF group. During ischemia, the duration of the filtered QRS complex and the duration of low-amplitude signals < 40 microV increased significantly. In another 14 patients in the VF group, late potentials were observed only during ischemia. In 4 of 26 patients in the VF group without prior infarction but with severe ischemia present at rest, successful PTCA eliminated preexistent late potentials. In the non-VF group, one patient had late potentials present at rest. In two patients with prior infarction, late potentials were provokable only during transmural ischemia.

CONCLUSION

Myocardial ischemia is able to modify detection of an arrhythmogenic substrate with the signal-averaged ECG.

Effect of myocardial ischaemia on left ventricular function and adaptability to exercise training

PURPOSE

We evaluated the possible interaction between exercise-induced myocardial ischemia and abnormalities in left ventricular function in 72 patients with coronary artery disease at entry and upon discharge from a 6-month exercise training program.

METHODS

Twenty-two patients with myocardial ischemia (MIS) defined by electrocardiographic and radionuclide imaging criteria constituted our experimental group (EG). Fifty patients without MIS were assigned to the control group for exercise training (CG-ET) and 31 healthy subjects to the control group for measures of left ventricular function (CG-LV).

RESULTS

Both groups EG and CG-ET showed significant and comparable increases in peak oxygen uptake (EG: 25.2 +/- 5.1 to 26.9 +/- 5.4 mL x kg(-1) x min(-1), P < 0.02; CG-ET: 25.1 +/- 0.6 to 27.4 +/- 0.7 mL x kg(-1) x min(-1), P < 0.001) after exercise training, but only CG-ET showed significant reductions in heart rate, systolic blood pressure, and rate-pressure product during submaximal exercise. A significant increase in end-diastolic volume contributed to the increase in cardiac output during exercise in patients with MIS. Heart rate or treadmill time at onset of ST segment depression failed to increase as a result of training, and stroke counts and the product of stroke counts and heart rate showed a trend toward a decrease in response to exercise, suggesting progression of disease.

CONCLUSIONS

Patients with myocardial ischemia showed improvements in maximal exercise capacity but failed to elicit physiologic adaptations during submaximal exercise or to increase the threshold for ischemia after exercise training. It is possible that the main emphasis in the management of this type of patient in a cardiac rehabilitation setting should be placed more on coronary risk factor modification to slow progression of disease than on improving cardiovascular efficiency.

P, Shinzato GT, Cardoso MA, Carnevali N, Battistella LR. Perfil de aptidão cardiorrespiratória e metabólica em bailarinos profissionais

O principal objetivo deste estudo foi analisar aspectos cardiorrespiratórios e metabólicos e as alterações provocadas pelo treinamento específico de dança em um grupo de 16 bailarinos de balé profissional, modalidade clássico, sendo oito mulheres e oito homens, com média de idade de 18,2 ± 3,8 anos e 26,2 ± 4,5 anos, respectivamente. Todos foram submetidos a teste máximo em esteira rolante utilizando-se o protocolo de Bruce. Foi utilizado, na análise das respostas respiratórias e metabólicas, o sistema computadorizado Metabolic Measurement Cart da Beckman. Os seguintes resultados foram obtidos entre o grupo de balé vs. o grupo controle masculino: VO2 máx. - 46 ± 4 vs. 43 ± 6mlO2.kg.-1min-1; FC máx. - 194 ± 12 vs. 202 ± 11bpm; V E máx. - 112 ± 16 vs. 123 ± 18L.min-1; VO2-LA - 35 ± 4 vs. 26 ± 4mlO2.kg.-1min-1 (p < 0,01); FC-LA - 169 ± 18 vs. 163 ± 15 bpm. Grupo de balé vs. grupo controle feminino: VO2 máx. - 39 ± 6 vs. 35 ± 6mlO2.kg.-1min-1; FC máx. - 197 ± 10 vs. 201 ± 6bpm; V E máx. - 72 ± 9 vs. 81 ± 6L.min-1; VO2-LA - 26 ± 4 vs. 27 ± 4mlO2.kg.-1min-1; FC-LA - 164 ± 10 vs. 176 ± 17bpm. Conclusões: 1) a rotina específica de dança parece não gerar estímulo suficiente para aprimorar a aptidão cardiorrespiratória e metabólica dos bailarinos e 2) sugere-se condicionamento físico adicional ao treinamento de balé.

Risk stratification for exercise training in cardiac patients: do the proposed guidelines work?

PURPOSE

Four authoritative organizations (American Association of Cardiovascular and Pulmonary Rehabilitation [AACVPR], the American College of Cardiology [ACC], the American College of Physicians [ACP], and the American Heart Association [AHA]) have risk stratification guidelines for supervised exercise in patients with cardiovascular disease. The ability of the guidelines to predict exercise complications is untested.

METHODS

A prospective sample was evaluated that included 239 patients enrolled for a total of 5720 patient exercise hours in a phase II supervised outpatient cardiac rehabilitation exercise program between December 1, 1992, and June 16, 1995, who had had preprogram stress testing and/or left ventricular ejection fraction determination. Complications during supervised exercise were measured.

RESULTS

Overall, 12 patients experienced complications during supervised exercise. None of the guidelines was predictive of complications (positive predictive values, 3-7%). Regression analyses demonstrated that current cigarette smoking was the only predictor of complications. There was reasonable correlation of patient risk stratification among the four guidelines (r = 0.19-0.47; P < 0.0001).

CONCLUSIONS

Currently proposed exercise risk stratification guidelines are not predictive of complications during supervised exercise. Further work is needed before exercise risk stratification guidelines are used to adjudicate use of supervised services.

Value of exercise treadmill testing in women

OBJECTIVES

We sought to determine the ability of a treadmill score to provide accurate diagnostic and prognostic risk estimates in women.

BACKGROUND

Treadmill testing has been reported to have a lower accuracy for diagnosis of chest pain in women. The diagnostic and prognostic value of the Duke Treadmill Score (DTS) in women is unknown.

METHODS

We determined the diagnostic and prognostic value of the DTS in 976 women and 2,249 men who underwent both treadmill testing and cardiac catheterization in a single institution from 1984 to 1994.

RESULTS

Women and men differed significantly in DTS (1.6 vs. -0.3, p < 0.0001), disease prevalence (32% vs. 72% significant coronary artery disease [CAD], p < 0.001), and 2-year mortality (1.9% vs. 4.9%, p < 0.0001). The DTS provided information beyond clinical predictors of both coronary disease and survival in women and men. Although overall women had better survival, the DTS performed equally well in stratifying both genders into prognostic categories. The DTS actually performed better in women than in men for excluding disease, with fewer low risk women having any significant coronary disease (> or = 1 vessel with > or =75% stenosis) (20% vs. 47%, p < 0.001), or severe disease (3-vessel disease or > or =75% left main stenosis) (3.5% vs. 11.4%, p < 0.001).

CONCLUSIONS

By combining several aspects of treadmill testing, the DTS effectively stratifies women into diagnostic and prognostic risk categories.