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

Evaluation of a new standardized ramp protocol: the BSU/Bruce Ramp protocol

BACKGROUND

Because of recent technological advances, exercise testing laboratories now have the ability to use ramp protocols with treadmill exercise tests. Since the Bruce protocol is the most widely used treadmill protocol in clinical laboratories, a standardized ramp treadmill protocol was developed that corresponds to the speed and grade settings of the Bruce protocol at each 3-minute time interval. The purpose of this study was to evaluate the utility of using subject demographic and exercise test data to predict peak oxygen uptake (VO2peak) for tests conducted with the BSU/Bruce Ramp protocol.

METHODS

Maximal exercise tests were performed by 698 men and women using the BSU/Bruce Ramp protocol. Peak oxygen uptake was measured during all tests. Stepwise multiple regression analyses were used to predict VO2peak (mL.kg-1.min-1) from maximal treadmill test time and selected variables including age, gender, physical activity habits, and body weight.

RESULTS

Maximal test time was found to be the most potent predictor of VO2peak, accounting for 86% of the variance in peak aerobic power, with a standard error of estimate of 3.4 mL kg min-1. A multiple regression equation including age, gender, physical activity habits, and body weight resulted in a slightly improved prediction (R2 = 0.88; standard error of estimates = 3.1 mL kg min-1).

CONCLUSIONS

Peak oxygen uptake values can be predicted with reasonable accuracy from the BSU/Bruce Ramp protocol. The BSU/Bruce Ramp would be an excellent choice for laboratories desiring to use a ramp treadmill protocol because of the design of the protocol with identical workloads at equivalent time periods (3, 6, 9, 12, 15, 18, 21 minutes) as the commonly used Bruce protocol.

Variation in tertiary prevention and health service utilization among the elderly: the role of urban-rural residence and supplemental insurance

OBJECTIVES

Tertiary prevention seeks to reduce chronic disease progression and illness-related dysfunction. Using the Aday-Andersen model, we evaluated the impact of predisposing, need, and enabling factors on tertiary prevention, hypothesizing that urban-rural geographic differences in delivery would be detected.

METHODS

A population-based telephone survey was conducted evaluating six common chronic indicator conditions: arthritis (n = 488), hypertension (n = 414), cardiac disease (n = 185), diabetes mellitus (n = 125), peptic ulcer disease (n = 125), and chronic obstructive pulmonary disease (n = 103). Subjects were 787 (70% women) home-dwelling elderly (age > 65 years) who had one or more of the indicator conditions and who resided in Iowa's 12 most rural and 10 most urban counties. Tertiary prevention measures included counseling for and/or treatment with: influenza and pneumococcal vaccination, smoking cessation, dietary modifications, exercise, drug side effects, chronic disease rehabilitation, aspirin/estrogen for cardiac disease, and foot/eye care for diabetes. Tertiary prevention scores were calculated to compare preventive services across disease categories and to examine relations, in particular, with enabling factors.

RESULTS

Education beyond high school, alcohol use, cigarette smoking, and medical specialist use were all significantly greater among urban residents, whereas home services use was greater among rural residents. Respondents with either health maintenance organization or fee-for-service supplemental coverage had higher tertiary prevention scores than respondents without supplemental coverage. After adjustment for the significant effects of the number of diseases, higher income, and place of residence, rural respondents having health maintenance organization supplemental coverage had higher (better) tertiary prevention scores than other respondents.

CONCLUSIONS

In this community-based study of elderly, enrollment in an health maintenance organization plan, as opposed to a fee-for-service supplement to Medicare, increased tertiary prevention quality for rural but not for urban residents. This study emphasizes that additional research is needed to evaluate the importance of specific types of insurance coverage for preventive services among the elderly.

Exercise guidelines for patients with inflammatory bowel disease

In this article, the author discusses the benefits that people with inflammatory bowel disease derive from a well-rounded exercise program that includes aerobic and resistive training. Exercise guidelines, precautions, and signs and symptoms of potential complications are reviewed.

The Sensitivity of Exercise Echocardiography Can Be Improved by Taking the Delayed Myocardial Contraction into Account

The purpose of this study was to test whether the systolic myocardial wall motion abnormalities at the early stages of ischemia are applicable to the diagnosis of coronary artery disease. Forty-four patients with suspected coronary artery disease were studied with the use of low-level exercise echocardiography. Exercise was stopped at the onset of first cardiac symptoms, and no patient exceeded 70% of the age-predicted maximal heart rate level. Forty patients had significant stenosis in at least one coronary artery on coronary angiography. Ten control subjects with a low probability of ischemic heart disease also were studied with exercise echocardiography. The first ischemic wall motion abnormality in systole, defined as delayed onset of the contraction (a regional delay of at least 100 milliseconds in a frame-by-frame analysis of echocardiograms) without any reduction in systolic movement, was regarded separately from hypokinesis (systolic wall motion excursion of less than 5 mm). When the delayed onset of the contraction also was taken into account, 37 of the 40 patients with coronary artery disease had an ischemic response after exercise. The sensitivity of the test thus was 93%. The reduction in systolic wall movement was detected in only 18 of these patients at the exercise level attained (70% or less of age-predicted maximal heart rate). There were two false-positive echocardiograms, but when the control group also was considered, the specificity of the test remained high at 86%. The sensitivity of exercise echocardiography can be increased by paying attention to the delayed onset of the systolic contraction, which occurs at the early stages of ischemia.

Sudden cardiac death in the athlete

The sudden unexpected death of an athlete is a disturbing and tragic event. Sudden cardiac death in the young athlete is caused primarily by cardiomyopathies and nonatherosclerotic coronary artery abnormalities; in the mature athlete, the most prevalent cause of sudden cardiac death is atherosclerotic coronary disease. The job of the emergency physician is to resuscitate those who succumb to ventricular dysrhythmias during exercise and to screen patients for potential risk of sudden cardiac death when they present with warning symptoms such as syncope.

Blood pressure and coronary heart disease in NIDDM subjects at diagnosis: prevalence and risks in a Bangladeshi population

Overall obesity and central fat distribution are frequently accompanied by hyperglycemia, hypertension (HTN) and coronary heart disease (CHD) observed in developed nations and in South Asian migrants. This study attempts to estimate the prevalence of CHD and HTN and to assess the related risks among the newly diagnosed diabetics in the developing communities. From a total of 3583 non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) subjects, the authors investigated 693 (M = 295, F = 398) randomly selected non-smokers of age 30-60 years. WHO diagnostic criteria were used for NIDDM and IGT. Systolic and diastolic hypertension (sHTN and dHTN) were defined as systolic blood pressure (SBP) > or = 140 and diastolic (DBP) > or = 90 mmHg. Diagnosis of CHD was based on electrocardiogram either on rest or on stress or both when equivocal. The overall prevalence of CHD in the NIDDM subjects was 18.6%. The prevalence rates of sHTN and dHTN were 23.2 and 13.6%, respectively. CHD and HTN did not differ significantly between male and female and between urban and rural subjects. CHD prevalence was significantly higher in the higher tertiles of age, SBP and DBP (P < 0.001, for all cases). Logistic regression showed that only the increasing age, high waist-to-hip ratio (WHR) and high BP were the independent risks for CHD. For sHTN, the independent risks were increased age and high body mass index (BMI) (kg/m2). Regardless of sex and area, increased prevalence of CHD and HTN were found in the newly diagnosed diabetic subjects. Increased age, central obesity and HTN were the independent risks for CHD while advancing age and overall obesity was related to sHTN.

Coronary heart disease risk factors of vigorously active sexagenarians and septuagenarians

OBJECTIVE

To examine the dose-response relationship between coronary heart disease risk factors and vigorous exercise in older men.

DESIGN

Physician-supplied medical data were compared with running distance and performance in a national cross-sectional survey of 175 septuagenarian, 935 sexagenarians, and 8672 younger male runners.

RESULTS

Older runners ran significantly more slowly than younger runners. Nevertheless, men 60 years of age and older who ran further had significantly higher plasma high-density lipoprotein (HDL)-cholesterol concentrations (regression slope +/- SE: 0.16 +/- 0.02 mg/dL per km/week, P < .001), and significantly lower ratios of total cholesterol to HDL-cholesterol (-0.009 +/- 0.002 per km/week, P < .001), plasma triglyceride concentrations (-0.309 +/- 0.107 mg/dL per km/week, P < or = .004), systolic and diastolic blood pressures (-0.066 +/- 0.028, and -0.042 +/- 0.016 mm Hg per km/week, respectively, P < or = .02), body mass indices (-0.039 +/- 0.004 kg/m2 per km/week, P < .001), and waist circumferences (-0.107 +/- 0.010 cm per km/week, P < .001). Better 10-kilometer race performance times were also associated (P < or = .001) with higher HDL-cholesterol levels and lower adiposity, blood pressure, triglycerides, and ratios of total cholesterol to HDL-cholesterol levels. Septuagenarians who ran faster and further also had significantly (P < or = .03) higher HDL-cholesterol, lower ratios of total cholesterol to HDL-cholesterol, and slimmer waists. Compared with those less than age sixty, older runners had significantly greater calculated reductions in waist (P = .039) and chest circumferences (P = .009) but significantly less reduction in low-density lipoprotein (LDL) cholesterol (P = .020) per kilometer run per week.

CONCLUSIONS

Age does not limit the potential for vigorous activity to increase HDL-cholesterol or to reduce blood pressure, adiposity, or triglycerides, but it may attenuate improvements in LDL-cholesterol. Sexagenarians and septuagenarians are expected to have reduced heart disease risk in proportion to their vigorous activity.

Exercise and rehabilitation in women. Indications and outcomes

Women have been shown to improve their cardiovascular risk profiles with increasing levels of physical activity and physical fitness. All-cause mortality is lower among more fit women, but reductions in cardiovascular death rates have not been established, owing to the limited number and size of existing studies. Because older women are at greater risk for cardiac events and are the least likely to engage in regular physical activity, concerted effort should be made to increase the proportion of older women who participate in regular physical activity. Attention to concerns raised by older, sedentary women and development of personalized programs that proceed gradually in intensity and duration and avoid high-impact activities should improve the likelihood of initiation and continuation of greater activity levels. Cardiac rehabilitation programs are under-used by women. Personal and social barriers have been identified as well as the potential for referral bias. Reduction in cardiovascular risk levels and improvements in exercise capacity have been demonstrated for women who do participate. Approaches that meet the needs of older women may require considerable alteration from the standard program established for middle-aged men. Yet women may have the most to gain from participation in multidisciplinary, personalized rehabilitation programs.

Sex and diagnostic evaluation of possible coronary artery disease after exercise treadmill testing at one academic teaching center

Controversy exists as to whether a sex bias exists that affects the diagnostic approach to suspected coronary artery disease: previous studies have used coronary angiography, but not other noninvasive testing, as a primary end point. This investigation examined posttest sex differences in diagnostic evaluation after exercise treadmill testing according to a broader end point than just coronary angiography alone. The design was a cohort analytic study with a 90-day follow-up. The study was done at the Cleveland Clinic Foundation, an academic group practice. Patients included consecutive adults (1023 men and 579 women) with chest pain but no documented coronary disease who were referred for symptom-limited exercise treadmill testing without adjunctive imaging; none had undergone prior invasive cardiac procedures. Main outcome measures included (1) performance of any subsequent diagnostic study (invasive or noninvasive) and (2) performance of coronary angiography as the next diagnostic study. During follow-up, 89 (8.7%) men and 48 (8.3%) women underwent a second diagnostic study (odds ratio 0.95; 95% confidence interval 0.66 to 1.37; p > 0.8), whereas 64 (6.3%) men and 21 (3.6%) women went straight to coronary angiography (odds ratio 0.56; 95% confidence interval 0.34 to 0.93; p = 0.02). In multivariable logistic regression analyses, which considered baseline clinical characteristics, the ST-segment response, and other prognostically important exercise responses, women tended to be less likely than men to be referred to any second test (adjusted odds ratio 0.70; 95% confidence interval 0.42 to 1.19; p > 0.1) but were markedly and significantly less likely to be referred straight to coronary angiography (adjusted odds ratio 0.33; 95% confidence interval 0.17 to 0.65). After exercise treadmill testing, women were only slightly less likely than men to be referred for subsequent diagnostic testing; they were, however, much less likely to be referred straight to coronary angiography as opposed to another noninvasive study.

Validity of rating of perceived exertion during graded exercise testing in apparently healthy adults and cardiac patients

PURPOSE

Recent exercise guidelines recommend a generalized rating of perceived exertion (RPE) range of 12 to 16 (15-point Borg scale) as the perceptual range associated with a physiological training effect. However, whether an individual who selects an RPE within the generalized range during an graded exercise test or exercise training, is actually within the correlated physiological range (50 to 85% maximum oxygen consumption [VO2max]) has not been studied in large samples of apparently healthy individuals or cardiac patients. The purpose of the present study was to assess the validity of the generalized RPE recommendations in a large heterogeneous group of apparently healthy subjects and cardiac patients.

METHODS

Subjects included apparently healthy adults (N = 463) and cardiac patients (N = 217) who presented for a sign-symptom limited maximal graded exercise test (SSLMGXT). Ratings of perceived exertion associated with relative exercise intensities of 60 and 80% of maximal heart rate reserve (MHRR) and peak exercise were selected for analyses.

RESULTS

Significant interindividual variability in RPE was observed at both relative exercise intensities (6 to 20 RPE range at 60% MHRR; 8 to 20 RPE range at 80% MHRR) for both populations. Thirty-nine percent of healthy subjects and 32% of cardiac patients reported an RPE outside an 11 to 14 range at 60% of MHRR, whereas 32% of healthy subjects and 52% of cardiac patients reported an RPE outside of a 14 to 17 range at 80% of MHRR. Peak RPE was higher for the apparently healthy subjects compared with the cardiac patients (18.8 +/- 1.2 versus 16.5 +/- 1.8; P < 0.01).

CONCLUSIONS

These results challenge the applicability of the generalized RPE recommendations described in recent exercise guidelines under typical clinical exercise testing conditions. The basis for the generalized RPE recommendations warrant further investigation. Those who desire to use RPE as a marker of relative exercise intensity during SSLMGXT should take into consideration the large interindividual variability in these measures.

Age and referral to coronary angiography after an abnormal treadmill thallium test

This study investigated the association between age and referral to coronary angiography among ambulatory adults with an abnormal treadmill thallium scan. The subjects studied were 416 consecutive adults who were > or = 30 years old, under the care of cardiologists, and had an abnormal treadmill thallium scan between 1990 and 1993 at the Cleveland Clinic Foundation. The primary end point was performance of coronary angiography within 90 days of the treadmill test. Coronary angiography was performed in 163 subjects. Coronary angiography was performed in 46% of patients aged 30-49 years, in 53% of those aged 50 to 64 years, in 33% of those aged 65 to 74 years, and in only 18% of those aged > or = 75 years (chi2 test for trend, p < 0.0001). After adjustment for potential confounders, age remained associated with a lower rate of referral to angiography (p < 0.0001). During 2 years of follow-up 34 deaths occurred (14 cardiac), with particularly high mortality rates among those aged >74 years (cumulative rate 31%, 95% confidence interval 16% to 47%). The number of abnormal thallium scan segments was predictive of death (p = 0.02). These data suggest that increasing age is associated with a lower rate of referral to coronary angiography after an abnormal treadmill thallium test.

Prevalence of unrecognized silent myocardial ischemia and its association with atherosclerotic risk factors in noninsulin-dependent diabetes mellitus. Milan Study on Atherosclerosis and Diabetes (MiSAD) Group

To determine the prevalence of unrecognized silent myocardial ischemia, 925 noninsulin-dependent diabetic outpatients (333 women and 592 men), aged 40 to 65 years, asymptomatic, free from known coronary artery disease (CAD), advanced diabetic retinopathy, and nephropathy, severe hypertension, and poor prognosis disease, underwent exercise electrocardiogram (ECG), followed, if abnormal, by an exercise thallium scintigraphy. The exercise ECG tests were abnormal in 112 patients (12.1%, 31 women, 81 men), of whom 59 (6.4%, 12 women, 47 men) had perfusion defects at thallium scintigraphy. Adopting the more restrictive criteria (positive response to both tests) the prevalence of silent CAD resulted in 6.4%. Multivariate analysis showed that in the whole population and in the men, the associated independent risk factors were age, total cholesterol, proteinuria, and ST-T abnormalities at ECG at rest. This last factor had the highest odds ratio (9.27, confidence interval [CI] 4.44 to 19.38) and was the only one identified also in women. The relevance of ST-T abnormalities at ECG at rest as a predicting factor for silent CAD outlines the importance of a periodical ECG at rest in noninsulin-dependent diabetic patients and suggests an indication of performance of further investigations in presence of these abnormalities.

[I. Usefulness of the exertion test and other methods based on the electrocardiogram in chronic ischemic disease]

Exercise testing still plays an important role in the management of patients with chronic ischemic heart disease, not only in the diagnosis but also in their prognostic and functional evaluation, and in the assessment of effects of the therapy. Moreover, ambulatory electrocardiography, signal averaged electrocardiography and heart rate variability provide useful information for certain groups of patients. This paper reviews the rationale, methodology and indications of the above mentioned procedures applied to chronic ischemic heart disease, with special reference to exercise testing. Recommendations for their use in clinical practice are also made.

Spontaneous changes of heart rate, blood pressure, and ischemia-type ST-segment depressions in patients with hypertension without significant coronary artery disease: beneficial effects of beta-blockade

In hypertensives, a reduced coronary flow reserve is observed and may contribute to angina pectoris and silent (painless) myocardial ischemia, which frequently occur in these patients even in the absence of coronary artery disease (CAD). To assess the frequency of ischemia-type ST-segment depressions in these patients and the influence of heart rate (HR) and blood pressure (BP) as major determinants of myocardial oxygen demand and to test the effects of beta-blocker therapy (10-20 mg betaxolol/day for 4 weeks) on these variables, simultaneous 24-h Holter and 24-h ambulatory BP monitoring was performed in 19 patients with hypertension (age, 43-71 years; nine women, 10 men) without CAD (stenosis < 50% in angiography). Before treatment, 25 periods of significant ST-segment depressions with a total duration of 470 min were observed in nine patients. ST-segment depressions were significantly correlated with preceding increases in HR and the rate-pressure product. The majority (79%) of episodes with ST-segment depression were clinically painless. In this open study, beta-blockade significantly decreased the number of episodes with ST-segment depressions to six in four of 15 patients and the total duration to 38 min (p < 0.05). The data demonstrate that HR seems to be associated with the development of ischemic ST-segment deviations in patients with hypertension without CAD. Antihypertensive therapy in these patients should target not only sufficient BP control, but also reduction of ischemic events.

Complications of pharmacologic stress echocardiography in coronary artery disease

In the last few years, pharmacologic stress echocardiography is emerging as a promising diagnostic tool with a favorable cost/benefit ratio. Its main clinical applications include the assessment of coronary artery disease, the identification of viable myocardium, and risk stratification before major vascular surgery. However, cardiac (arrhythmic, ischemic, or hemodynamic) as well as noncardiac complications have been reported, so that a risk/benefit analysis is advisable in view of the extensive introduction of this technique in the clinical arena. The most popular pharmacologic agents employed for stress echocardiography are dipyridamole, dobutamine, and adenosine. A comparative analysis with exercise stress testing, the classical standard a reference of all ischemia-provoking tests, confirms that in terms of safety and tolerability pharmacologic stress echocardiography may be considered a good alternative in patients unable to exercise maximally. No appreciable difference among the safety profiles of the most common pharmacologic agents has been found, but a careful evaluation of the risk/benefit ratio is advisable for any stressor in the individual patient by considering the relative importance of the expected diagnostic contribution and the pharmacodynamic impact of the test. Finally, adequate training of the operator and monitoring of the patient during stress and recovery are essential for getting optimal safety conditions.

"Lifestyle" interventions for promoting physical activity: a kilocalorie expenditure-based home feasibility study

The Centers for Disease Control and Prevention and the American College of Sports Medicine in cooperation with the President's Council of Physical Fitness and Sports recommended short periods of daily kilocalorie (calorie) expenditure with moderate-intensity physical activities to complement the currently existing recommendations. In this study the feasibility (adherence and safety) of employing calorie expenditure as the basis for prescribing a home-based walking program to healthy, community-dwelling men and women was examined. This was a 16-week pretest-posttest feasibility study of a home-based calorie-expenditure walking program conducted in an outpatient clinic in an academic medical center. Participants included 20 healthy, elderly, community-dwelling men and women. A 16-week home-based walking program was individually prescribed as a weekly amount of calorie expenditure increasing from an initial 300 calories per week to 1,200 calories per week (approximately 30 minutes of walking daily) during the final 6 weeks of the study. Adherence to the program was recorded individually in a diary (kept daily and reviewed at each visit), body weight, and walking pace. All but one participant were able to complete this 16-week program (95 percent adherence). That a calorie-based approach to promote physical activity among the elderly has a high adherence rate is suggested by these findings. Additional studies are necessary to define the potential role for this approach in promoting physical activity and improving health outcomes among the elderly.

Gender and referral for coronary angiography after treadmill thallium testing

Considerable controversy exists regarding whether women are less likely than men to be referred to coronary angiography after an abnormal noninvasive test. This prospective cohort study analyzed consecutive subjects (2,351 men and 1,318 women) with no prior history of invasive cardiac procedures who were referred for treadmill thallium testing at the Cleveland Clinic Foundation. The primary end point was performance of coronary angiography within 90 days of treadmill thallium testing. A secondary end point was all-cause mortality during 1.8 years of follow-up. Women were less likely than men to undergo coronary angiography (6% vs 14%, odds ratio [OR] 0.42, 95% confidence interval [Cl] 0.33 to 0.54, p < 0.001), but were also less likely to have an abnormal thallium scan (8% vs 29%, p < 0.001). In logistic regression analyses with adjustment for thallium result and age, women were as likely as men to be referred for coronary angiography (adjusted OR 1.00, 95% Cl 0.75 to 1.34, p > 0.9). Women were less likely to have severe coronary disease on angiography (15% vs 30%, p = 0.006). During 1.8 years of follow-up there were 26 deaths (2%) among women and 84 deaths (4%) among men. After adjusting for age, thallium abnormalities, and clinical characteristics in Cox regression analyses, women had a lower mortality rate than men (relative risk 0.58, 95% Cl 0.36 to 0.94, p = 0.03). Thus, gender-related differences in referral for coronary angiography after treadmill thallium testing can be explained by a higher rate of abnormal tests in men. No evidence of a post-test gender bias was detected, but a pretest bias affecting referral to nuclear testing cannot be excluded. Furthermore, women have a lower prevalence of severe coronary disease and a lower adjusted mortality rate.

Dobutamine stress echocardiography for noninvasive diagnosis of cardiac allograft vasculopathy: a comparison with angiography and intravascular ultrasound

This study was performed to assess the value of dobutamine stress echocardiography for noninvasive diagnosis of cardiac allograft vasculopathy (CAV) compared with coronary angiography and intravascular ultrasound (IVUS) in 50 consecutive orthotopic heart transplant recipients. In 46 of 50 patients, a technically adequate echocardiogram could be obtained. Using a 16-segment model, a total of 675 segments were analyzed. At rest, wall motion abnormalities were found in 61 of 675 (9.0%) left ventricular segments in 15 of 46 patients. At maximal dobutamine stress, 103 of 675 segments (15.3%) had wall motion abnormalities (25 of 46 patients). Based on IVUS and angiographic findings, patients were allocated to 2 groups. Group I (n=18) had absent or only mild intimal hyperplasia (mean IVUS grade < or = 3.0 on a 6-grade scale). Group II (n=28) had moderate to severe intimal hyperplasia (mean grade > 3.0 with or without angiographic evidence of CAV. The prevalence of wall motion abnormalities was significantly higher in group II than in group I, both at rest (50 of 415 vs 11 of 270 coronary segments in 13 of 28 vs 2 of 18 patients) and during maximal stress (88 of 415 vs 15 of 270 coronary segments in 22 of 28 vs 3 of 18 patients). Quantitative M-mode echocardiography demonstrated decreased wall thickening in group II versus group I patients at maximal dobutamine dosage in the septum (48 +/- 18% vs 61 +/- 17%; p < 0.01) as well as in the left ventricular posterior wall (77 +/- 21% vs 96 +/- 21%; p <0.005). Regional myocardial dysfunction as assessed by dobutamine stress echocardiography was associated with IVUS evidence of moderate to severe intimal hyperplasia. Dobutamine stress echocardiography appears to be a feasible noninvasive method for detection of CAV in heart transplant recipients, which may reduce the need for routine coronary angiography.

Training level comparison study. Effect of high and low intensity exercise on ventilatory threshold in men with coronary artery disease

PURPOSE

To determine whether exercise at low intensity (LO; 50% of peak VO2) or high intensity (HI; 85% of peak VO2) results in improvement of the ventilatory threshold (VT), 186 men with coronary artery disease (CAD) were enrolled in an exercise study for 1 year.

METHODS

A symptom-limited exercise test was performed at baseline and the heart rate corresponding to 50% and 85% of peak VO2 was determined. Subjects were randomized to LO or HI intensity exercise. Exercise sessions included 45 minutes of walking/jogging and/or stationary cycling at the appropriate target heart rate and were conducted 3 days per week. The exercise test was repeated at 3 and 6 months. Target heart rates were revised to adjust for training.

RESULTS

Both LO and HI resulted in improved VO2 at VT and peak. However, HI resulted in greater improvement than LO.

CONCLUSION

Among this population, both HI and LO improve the VO2 at VT and peak, but the improvement is greater with HI. The VT can be a useful adjunct to heart rate and peak oxygen uptake when prescribing exercise.

Exercise echocardiography in the diagnosis of coronary artery disease

The purpose of this study was to test the applicability of exercise echocardiography in the diagnosis of coronary artery disease. The results were compared to findings of coronary angiography. 118 patients, 100 males and 18 females, who were all referred to coronary angiography for suspected ischaemic heart disease, underwent exercise echocardiography using a cycle ergometer. At coronary angiography 108 patients had significant stenosis in at least one coronary artery. Ten patients had angiographically normal coronary arteries. A new or increased wall motion abnormality detected by echocardiography after the exercise was considered an ischaemic response. Of the 108 patients with coronary artery disease, 101 had abnormal exercise echocardiograms, and the overall sensitivity of exercise echocardiography in detecting ischaemic heart disease was 94%. Among the 10 patients without coronary artery disease, seven had normal and three had abnormal exercise echocardiograms, and the specificity of the test was 70%. In conclusion, exercise echocardiography is a reliable diagnostic method in screening of ischaemic heart disease, and it can be combined relatively easily with the exercise examinations.

Angiographic and prognostic implications of an exaggerated exercise systolic blood pressure response and rest systolic blood pressure in adults undergoing evaluation for suspected coronary artery disease

OBJECTIVES

This study was designed to assess the angiographic and prognostic implications of an exaggerated systolic blood pressure response to exercise ("exercise hypertension") in adults undergoing evaluation for suspected coronary artery disease.

BACKGROUND

The clinical implications of exercise hypertension are unclear.

METHODS

Subjects for this prospective cohort study were derived from a consecutive sample of 9,608 adults who were referred for treadmill testing and who augmented their systolic blood pressure by at least 10 mm Hg. There were 594 subjects who underwent coronary angiography within 90 days of treadmill testing. Exercise hypertension was defined as a peak exercise systolic blood pressure > or = 210 mm Hg in men and > or = 190 mm Hg in women. Severe angiographic coronary disease was defined as left main coronary artery disease (> or = 50% diameter stenosis), three-vessel disease (> or = 70% diameter stenosis) or two-vessel disease with > or = 70% diameter stenosis of the proximal left anterior descending coronary artery. All-cause mortality was assessed during a follow-up period of approximately 2 years.

RESULTS

Exercise hypertension was present in 196 subjects (33%). Severe coronary disease was less common in subjects with exercise hypertension (14% vs. 25%, odds ratio 0.51, 95% confidence interval [CI] 0.32 to 0.81, p = 0.004). Exercise hypertension remained associated with a lower rate of severe coronary disease even after adjusting for rest hypertension, age, gender, exercise capacity and other possible confounders. During the follow-up period, there were 23 deaths; only 2 occurred in the group with exercise hypertension. After adjusting for severity of coronary disease, exercise hypertension remained associated with a lower mortality rate (adjusted relative risk 0.20, 95% CI 0.05 to 0.84, p = 0.03).

CONCLUSIONS

In adults evaluated for coronary artery disease, exercise hypertension is associated with a lower likelihood of angiographically severe disease and a lower adjusted mortality rate.

Impact of echocardiographic left ventricular mass on mechanistic implications of exercise testing parameters

Electrocardiographic left ventricular (LV) hypertrophy has long been known to be associated with an abnormal ST-segment response to exercise; this association has been considered to represent a false-positive finding. There is a paucity of data relating echocardiographic LV mass to exercise ST-segment responses and other exercise parameters. As part of a routine evaluation, 1,408 men and 1,618 women from the Framingham Heart Study who were free of clinical cardiac disease underwent echocardiography and exercise treadmill testing according to the Bruce protocol at the same clinic visit. Abnormal ST-segment responses were defined both by standard criteria and the delta ST/heart rate index. LV mass was calculated from M-mode echocardiography. Echocardiographic LV hypertrophy was associated with an abnormal delta ST/heart rate index (in men, odds ratio [OR] 1.78, 95% confidence interval [CI] 1.05 to 3.01, p = 0.03; in women, OR 2.13, 95% CI 1.31 to 3.44, p = 0.002) but not with an abnormal response according to standard criteria. Echocardiographic LV hypertrophy was also associated with a lower likelihood of achieving an age-predicted target heart rate (in men, OR 0.45, 95% CI 0.31 to 0.65, p < 0.001; in women, OR 0.53, 95% CI 0.37 to 0.76, p < 0.001) and with a lower exercise capacity. Despite these associations, echocardiographic LV hypertrophy was associated with a higher peak heart rate-systolic blood pressure double product. In conclusion, echocardiographic LV hypertrophy is associated with an abnormal ST-segment response, a lower likelihood of achieving target heart rate, decreased exercise capacity, and an increased double product, which is a reflection of myocardial oxygen demand.

Stress echocardiographic results predict risk of reinfarction early after uncomplicated acute myocardial infarction: large-scale multicenter study. Echo Persantine International Cooperative (EPIC) Study Group

OBJECTIVES

This study sought to assess the value of dipyridamole echocardiography in predicting reinfarction in patients evaluated early after uncomplicated acute myocardial infarction.

BACKGROUND

The identification of future nonfatal reinfarction seems an elusive target for physiologic testing. However, a large sample population is needed to detect minor differences in phenomena with a low event rate.

METHODS

We assessed the value of dipyridamole echocardiography in predicting reinfarction in 1,080 patients (mean [+/- SD] age 56 +/- 9 years; 926 men, 154 women) evaluated early (10 +/- 5 days) after uncomplicated acute myocardial infarction and followed up for 14 +/- 10 months.

RESULTS

Submaximal studies due to limiting side effects occurred in 14 patients (1.3%); these test results were included in the analysis. Results of dipyridamole echocardiography were positive in 475 patients (44%). During follow-up, there were 50 reinfarctions: 45 nonfatal, 5 fatal (followed by cardiac death < or = 4 days after reinfarction). Reinfarction (either nonfatal or fatal) occurred in 30 patients with positive and 20 with negative results (6.3% vs. 3.3%, p < 0.01). Nonfatal reinfarction occurred in 25 patients with positive and 20 with negative results (5% vs. 3.3%, p < 0.05). Reinfarction was fatal in 5 of 30 patients with positive and in none of 20 with negative results (16.6% vs. 0%, p = 0.07). The relative risk of reinfarction was 1.9.

CONCLUSIONS

Dipyridamole echocardiographic positivity identifies patients evaluated early after uncomplicated acute myocardial infarction at higher risk of reinfarction, especially fatal reinfarction.

Comparison of the sensitivity and specificity of exercise electrocardiography in biased and unbiased populations of men and women

To assess for sex-related differences in posttest referral bias, we compared the accuracy of exercise electrocardiography in biased (coronary angiography only) and unbiased (all unselected) populations with possible coronary disease. A retrospective analysis of clinical and exercise test data from 4467 patients (788 who underwent angiography) was performed (2824 men and 1643 women). The accuracy of a positive exercise test result was assessed in the entire unbiased group with a method that used disease probability (derived with a logistic algorithm) rather than angiography results. We found that the sensitivity and specificity were significantly greater in men than in women with use of the biased or unbiased groups. When the results for the unbiased and biased groups were compared, the sensitivities for the unbiased group were significantly lower and the specificities were significantly higher than those of the biased group. These differences reflect the effects of posttest referral bias. The amounts that sensitivity decreased and specificity increased, however, was not different for men and women. Therefore, we conclude that the accuracy of exercise electrocardiography is lower in women than men irrespective of whether a biased or an unbiased group is used. However, these differences cannot be explained on the basis of sex-related differences in posttest referral bias.

Multiresolution wavelet analysis of the body surface ECG before and after angioplasty

Electrocardiographic recordings of patients with coronary artery stenosis, made before and after angioplasty, were analyzed by the multiresolution wavelet transform (MRWT) technique. The MRWT decomposes the signal of interest into its coarse and detail components at successively finer scales. MRWT was carried out on different leads in order to compare the P-QRS-T complex from recordings made before with those made after percutaneous transluminal coronary angioplasty (PTCA). ECG signals before and after successful PTCA procedures show distinctive changes at certain scales, thus helping to identify whether the procedure has been successful. In six patients who underwent right coronary artery PTCA, varying levels of reperfusion were achieved, and the changes in the detail components of ECG were shown to correlate with the successful reperfusion. The detail components at scales 5 and 6, corresponding approximately to the frequencies in the range of 2.3-8.3 Hz, are shown to be the most sensitive to ischemia-reperfusion changes (p < 0.05). The same conclusion was reached by synthesizing the post-PTCA signals from pre-PTCA signals with the help of these detail components. For on-line monitoring a vector plot, analogous to vector cardiogram, of the two most sensitive MRWT detail components is proposed. Thus, multiresolution analysis of ECG may be useful as a monitoring and diagnostic tool during angioplasty procedures.

Multislice first-pass myocardial perfusion imaging on a conventional clinical scanner

A technique is demonstrated for the acquisition and processing of multislice, first-pass contrast-enhanced perfusion images in the myocardium. The acquisition is a modification of "keyhole" imaging in which time series images are acquired by sampling a limited segment of k-space, corresponding to the low spatial frequencies. In the modification demonstrated here, keyhole samples are divided into two groups that are sampled on alternate cardiac cycles. The alternate "missing" k-space portions are synthesized by Fourier interpolation. Visualization of contrast agent accumulation by image subtraction is demonstrated. A motion artifact reduction process using time domain Fourier filtering is used to reduce artifacts from respiration. Studies were performed on 46 patients at 1.5 T using gadoteridol (0.05-0.1 mmol/kg) injected into the right antecubital vein in conjunction with radionuclide imaging. Fully concordant studies were noted in 27 of these patients. Remaining studies were either partially or completely discordant for reasons relating to the differing natures of radionuclide versus MR contrast agent characteristics.

Assessment and significance of ST-segment changes detected by ambulatory electrocardiography after acute myocardial infarction

This study assessed the prognostic value of ST-segment changes detected by ambulatory electrocardiographic monitoring during the early in-hospital period after acute myocardial infarction. New methods for defining the ST-segment reference level and for measuring ST-segment elevation were used. ST-segment depression was defined as a change in ST level by > or = 0.1 mV 80 ms after the J point, elapsing > or = 1 minute. ST-segment elevation was defined as a deviation by > or = 0.15 mV, elapsing > or = 1 minute, and measured at the J point. An interval of > or = 2 minutes was required before another discrete episode was counted. Four ST-segment reference levels were automatically calculated: (1) "isoelectric," (2) "nearest to normal," (3) "24-hour median," and (4) "first-hour median." During a mean follow-up period of 3 years (mean 36 +/- 15 months), 47 cardiac events occurred in 38 patients: 18 deaths, 9 nonfatal reinfarctions, and 20 revascularization procedures. More deaths occurred in patients with than without ST elevation-24-hour median (22% vs 5%, p = 0.03), and in patients with than without ST depression-isoelectric (61% vs 32%, p = 0.02), and in patients with than without ST-depression-24-hour median (61% vs 23%, p = 0.003). "All cardiac events" (deaths, infarctions, or revascularization procedures) occurred more often in patients with than without ST depression-isoelectric (55% vs 22%, p = 0.003), and in patients with than without ST-depression-24-hour median (47% vs 17%, p = 0.004). Sensitivity, specificity, and accuracy of ST depression/elevation-24-hour median to assess mortality were 78%, 71%, and 73%, respectively.

Assessment of a circuit of exercises through heart rate response

OBJECTIVE

A circuit of seven exercises was designed for a cardiac population. This study evaluated whether the patients achieved their training heart rate during the circuit, recommended to be 70-85% of the maximum heart rate achieved during an exercise test.

DESIGN

Patients were randomly allocated to a starting exercise to balance any order effect from performing the exercises in a given sequence. Each of the seven exercises was performed for 30 s, so one circuit lasted 3.5 min. The circuit was repeated five times.

PATIENTS

Twenty patients who had had myocardial infarctions within 6 weeks of the study participated.

OUTCOME

Heart rate was measured to assess the stress placed on the cardiorespiratory system during the circuit. Measurements were taken at 10 and 20 s following the termination of each exercise and over two repetitions of the circuit (a total of 14 exercise periods).

RESULTS AND CONCLUSION

Comparisons of the readings taken at 10 and 20 s indicated, contrary to previously published findings, that no significant heart rate deceleration occurred within this period. Every exercise maintained the mean heart rate within the specified band of 70-85% of the maximum heart rate achieved during the exercise test. The study has shown that the selected exercises were suitable for use during a cardiac rehabilitation programme.

Diagnostic accuracy of heart rate-adjusted ST segments compared with standard ST-segment criteria

We compared the accuracy of ST segment/heart rate (ST/HR) index with that of standard criteria (> or = 0.1 mV horizontal/downsloping ST depression 80 ms after the J point) in 121 patients who had undergone angiography (49 with > or = 1 lesion with > or = 50% stenosis) and 50 clinically normal subjects. All exercise tests used the Cornell protocol and computer measurements of maximal ST depression 80 ms after the J point. Thresholds with equal specificity to standard criteria were determined for ST/HR index using each of the 2 normal groups (those who were normal by angiography and those who were clinically normal). In using only patients who underwent angiography, we found that the ST/HR index had a sensitivity that was not significantly greater than that of standard criteria (standard criteria 51%, ST/HR index 59%; p = 0.21). However, the receiver-operating characteristic curve area increased from 64 +/- 4 to 68 +/- 4 (p < 0.02). When clinically normal subjects were used instead of patients without angiographic disease, there was a clearly discernible improvement in sensitivity of ST/HR index over standard criteria (standard criteria 51%, ST/HR index 69%; p < 0.05). The associated curve areas were 69 +/- 4 and 79 +/- 3 (p < 0.001). Therefore, accuracy of the ST/HR index was marginally better than standard criteria only in patients who underwent angiography. When clinically normal subjects were used, the accuracy of the ST/HR index was definitely better than standard criteria. We conclude that the demonstration of improved accuracy of the ST/HR index depends on the population being tested.

Patients with high baseline exercise capacity benefit from cardiac rehabilitation and exercise training programs

Despite the well-proven benefits of cardiac rehabilitation and exercise training, no data are available on the benefits of this therapy in patients with preserved baseline exercise capacity. Therefore we assessed data before and after phase II cardiac rehabilitation and exercise programs at two large teaching institutions to determine the benefits in 163 patients with high baseline exercise capacity (> or = 6 estimated [mean 8.8 +/- 2.4] metabolic equivalents [METs]) compared with 125 patients with low baseline functional capacity (< 6 estimated [mean 4.6 +/- 0.8] METs). After cardiac rehabilitation and exercise training, patients with high baseline exercise capacity had significant improvements in triglyceride (-10%; p < 0.05), high-density lipoprotein cholesterol (+7%; p < 0.001), and low-density lipoprotein cholesterol (-4%; p = 0.09) levels; low-density lipoprotein/high-density lipoprotein ratio (-10%; p < 0.01); body mass index (-1.5%; (p < 0.001); percent body fat (-6%; p < 0.0001); and exercise capacity (+22%; p < 0.0001). Patients with high baseline exercise capacity had less relative improvement in exercise capacity (p < 0.0001) after cardiac rehabilitation but had greater relative improvement in low-density lipoprotein cholesterol level (p < 0.05) and low-density lipoprotein/high-density lipoprotein ratio (p < 0.05) than did patients with low baseline exercise capacity. These data demonstrate the benefits of cardiac rehabilitation and exercise training in patients with preserved exercise capacity and support routine referral of these patients to these programs after major cardiac events.

Nonpharmacologic therapy improves functional and emotional status in congestive heart failure

PURPOSE

To compare the effects of a multimodal nonpharmacologic intervention to digoxin and to placebo in patients with congestive heart failure receiving background therapy with angiotensin-converting enzyme inhibitors.

DESIGN

Randomized, parallel assignment to three treatment groups of 20 patients with congestive heart failure (New York Heart Association Class II and III).

INTERVENTION

Nonpharmacologic treatment program included the following: (1) graduated exercise training, three to five times per week; (2) structured cognitive therapy and stress management; and (3) dietary intervention aimed at salt reduction and weight reduction in the overweight. Digoxin was titrated to achieve a blood level between 0.8 and 2.0 ng/ml. Placebo and digoxin were administered in a randomized, double-blind fashion.

RESULTS

Echocardiographic ejection fraction improved (p < 0.05) in the digitalis group (change = +4.4 +/- 6.5) compared with both placebo (change = -3.2 +/- 3.9) and nonpharmacologic therapy (change = -3.2 +/- 3.9). The nonpharmacologic treatment program was well tolerated by all patients and resulted in significant improvement (p < 0.05) in exercise tolerance (digoxin = +51 +/- 50 s, placebo = +91 +/- 76, nonpharmacologic therapy = +182 +/- 139), as well as Beck Depression Inventory score (digoxin = +1.2 +/- 4.4, placebo = +2.0 +/- 4.2, nonpharmacologic therapy = -5.0 +/- 4.2), Hamilton Scale scores of anxiety (digoxin = +3.0 +/- 6.8, placebo = +6.0 +/- 2.6, nondrug therapy = -5.2 +/- 5.4), and depression (digoxin = +1.0 +/- 4.9, placebo = +5.0 +/- 5.0, nonpharmacologic therapy = -6.6 +/- 10.1). In addition, weight loss was significantly greater with nonpharmacologic therapy (digoxin = +0.32 +/- 1.76 kg; placebo = -1.35 +/- 1.44 kg; nonpharmacologic therapy = -4.37 +/- 4.50 kg) compared with both digoxin and placebo.

CONCLUSIONS

Nonpharmacologic therapy improved functional capacity, body weight, and mood state in patients with congestive heart failure. In contrast, digoxin improved ejection fraction without corresponding changes in exercise tolerance or quality of life.

Usefulness of exercise testing shortly after acute myocardial infarction for predicting 10-year mortality

Previous studies on the prognostic value of exercise test variables after acute myocardial infarction (AMI) are limited methodologically and have yielded inconsistent results. This study determined whether 6 exercise test variables (systolic blood pressure, ST-segment depression or elevation, exercise capacity, arrhythmias, and angina pectoris) after controlling for age and sex, enhance 6 clinical variables (digoxin, previous AMI, history of systemic hypertension and angina, Killip class, and stress) as predictors of cardiovascular death and act as independent predictors as well. The present study followed 258 patients for 10.6 years, each of whom had AMI between 1977 and 1980 and an exercise test before hospital discharge. By 1988, 71 of the 258 patients had died, 56 of cardiovascular causes. This study is unique because exposure and outcome variables are clearly defined and follow-up was complete and longer than in previous studies. Multivariate survival analysis using an exponential model was tested to evaluate the conditional effects of the exercise test and clinical variables and to control for confounders. The model combined the exercise test and clinical variables. Results are reported with hazard ratios (HR) and 95% confidence intervals (CI). For important clinical risk predictors, the HRs with CIs are: digoxin use, HR 4.0 (CI 1.8, 8.5); history of prior AMI, HR 2.4 (CI 1.2, 4.7); history of systemic hypertension, HR 2.5 (CI 1.3, 4.5); angina, HR 2.4 (CI 1.3, 4.5); and stress, HR 4.2 (CI 2.2, 7.9).(ABSTRACT TRUNCATED AT 250 WORDS)

Relation of leisure-time physical activity and cardiorespiratory fitness to the risk of acute myocardial infarction

BACKGROUND

Previous studies have suggested that higher levels of regular physical activity and cardiorespiratory fitness are associated with a reduced risk of coronary heart disease. We investigated the independent associations of physical activity during leisure time and maximal oxygen uptake (a measure of cardiorespiratory fitness) with the risk of acute myocardial infarction.

METHODS

During the period 1984 to 1989, we performed base-line examinations in 1453 men 42 to 60 years old who did not report having cardiovascular disease or cancer. Physical activity was assessed quantitatively with a detailed questionnaire, and maximal oxygen uptake was measured directly by exercise testing. During an average follow-up of 4.9 years, 42 of the 1166 men with normal electrocardiograms at base line had a first acute myocardial infarction.

RESULTS

After adjustment for age and the year of examination, the relative hazard (risk) of myocardial infarction in the third of subjects with the highest level of physical activity (> 2.2 hours per week) was 0.31 (95 percent confidence interval, 0.12 to 0.85; P = 0.02), as compared with the third with the lowest level (P = 0.04 for linear trend over all three groups). The relative hazard in the third with the highest maximal oxygen uptake (> 2.7 liters per minute) was 0.26 (95 percent confidence interval, 0.10 to 0.68; P = 0.006) (P = 0.006 for linear trend), after adjustment for age, the year and season when the examination was performed, weight, height, and the type of respiratory-gas analyzer used. After up to 17 confounding variables were controlled for, the relative hazards for the third of subjects with the highest level of physical activity (0.34; 95 percent confidence interval, 0.12 to 0.94; P = 0.04) and maximal oxygen uptake (0.35; 95 percent confidence interval, 0.13 to 0.92; P = 0.03), as compared with the values in the lowest third, were significantly (P < 0.05) less than 1.0.

CONCLUSIONS

Higher levels of both leisure-time physical activity and cardiorespiratory fitness had a strong, graded, inverse association with the risk of acute myocardial infarction, supporting the idea that lower levels of physical activity and cardiorespiratory fitness are independent risk factors for coronary heart disease.

Diagnostic and prognostic accuracy of the exercise electrocardiogram in patients with preexisting right bundle branch block

The value of exercise testing in patients with right bundle branch block (RBBB) is uncertain. A retrospective review of 3609 patients who underwent exercise testing identified 163 (4.5%) with preexisting RBBB. After excluding those with coronary artery bypass graft(s), 133 patients remained and 48 (36%) had a prior myocardial infarction. Angiograms were available for 30 (23%) patients. After a mean follow-up of 33 +/- 23 months, seven patients had a fatal or nonfatal myocardial infarction. Twenty five (19%) patients had > or = 1 mm of non-upsloping ST depression in leads V5 or V6. With angiographic disease or previous myocardial infarction used as endpoints of coronary artery disease, the exercise test had a sensitivity of 27% (15/56), a specificity of 87% (67/77), and a predictive accuracy of 62% (82/133), (chi 2 = 4.04, p = 0.04). There were 24 deaths, a 10% annual mortality rate. Univariate analysis of clinical, exercise, and angiographic data revealed that nonsurvivors had a lower peak systolic blood pressure, a lower exercise capacity in METS, and a higher prevalence of coronary artery disease (p = 0.0001, p = 0.02, p = 0.03, respectively). Left ventricular ejection fraction and the amount of additional ST depression during exercise did not differ significantly (p = NS). Receiver operating characteristic curve analysis revealed that systolic blood pressure (area = 0.741, z = 5.22, p < 0.001) and exercise capacity (area = 0.66, z = 3.12, p = 0.009) were predictive of mortality, whereas additional ST depression during exercise (area = 0.588, z = 0.70, p = 0.24) was not.(ABSTRACT TRUNCATED AT 250 WORDS)