Long-term mortality with multiple treadmill exercise test abnormalities: comparison between patients with and without cardiovascular disease

Exercise, Physical Activity, and Cardiometabolic Health: Pathophysiologic Insights

Physical activity and its sustained and purposeful performance-exercise-promote a broad and diverse set of metabolic and cardiovascular health benefits. Regular exercise is the most effective way to improve cardiorespiratory fitness, a measure of one's global cardiovascular, pulmonary and metabolic health, and one of the strongest predictors of future health risk. Here, we describe how exercise affects individual organ systems related to cardiometabolic health, including the promotion of insulin and glucose homeostasis through improved efficiency in skeletal muscle glucose utilization and enhanced insulin sensitivity; beneficial changes in body composition and adiposity; and improved cardiac mechanics and vascular health. We subsequently identify knowledge gaps that remain in exercise science, including heterogeneity in exercise responsiveness. While the application of molecular profiling technologies in exercise science has begun to illuminate the biochemical pathways that govern exercise-induced health promotion, much of this work has focused on individual organ systems and applied single platforms. New insights into exercise-induced secreted small molecules and proteins that impart their effects in distant organs ("exerkines") highlight the need for an integrated approach towards the study of exercise and its global effects; efforts that are ongoing.

Aerobic Fitness is a Predictor of Body Composition in Women With Breast Cancer at Diagnosis

BACKGROUND

The objective of this study was to investigate the relationship of aerobic fitness (AF) at diagnosis, before treatment and its relationship with body composition, physical function, lipidic profile, comorbidities, tumor characteristics, and quality of life of women with breast cancer (BC) PATIENTS AND METHODS: This cross-sectional cohort study included 78 women with BC that were assessed before treatment. A 6-minute walk test was used to evaluate the subjects' AF, estimating the maximum oxygen consumption (VO_2max) to classify the women with BC into 2 groups: good/excellent AF or fair/weak/very weak AF. Dual-energy x-ray absorptiometry was performed to assess body composition. The International Global Physical Activity Questionnaire and the Functional Assessment of Cancer Therapy - Fatigue questionnaires were applied to assess the level of physical activity and the quality of life, respectively.

RESULTS

Among the women included, the majority (81%) had the luminal subtype of BC. Most of the women were diagnosed with T1/T2 tumors and with negative axillary lymph nodes. We found that women with BC with good/excellent AF (VO_2max = 32.9 ± 6.0 mL/kg/min^-1) presented significantly lower weight, body mass index, abdominal circumference, percentual and total body fat, and bone mineral density compared with women with fair/weak/very weak AF (VO_2max = 21.8 ± 6.9 mL/kg/min^-1). Also, women with BC with good/excellent AF showed better performance on physical functional tests. No relationship between estimated VO_2max and comorbidities, tumor characteristics, or quality of life was found.

CONCLUSION

AF is a predictor of body composition and physical function in women with BC. These data suggest that women with BC with higher AF can decrease the chance of adverse effects during BC treatment.

False-positive stress testing: Does endothelial vascular dysfunction contribute to ST-segment depression in women? A pilot study

BACKGROUND

The utility of exercise-induced ST-segment depression for diagnosing ischemic heart disease (IHD) in women is unclear.

HYPOTHESIS

Based on evidence that IHD pathophysiology in women involves coronary vascular dysfunction, we hypothesized that coronary vascular dysfunction contributes to exercise electrocardiography (Ex-ECG) ST-depression in the absence of obstructive coronary artery disease, so-called false positive results. We tested our hypothesis in a pilot study evaluating the relationship between peripheral vascular endothelial function and Ex-ECG.

METHODS

Twenty-nine asymptomatic women without cardiac risk factors underwent maximal Bruce protocol exercise treadmill testing and peripheral endothelial function assessment using peripheral arterial tonometry (Itamar EndoPAT 2000) to measure reactive hyperemia index (RHI). The relationship between RHI and Ex-ECG ST-segment depression was evaluated using logistic regression and differences in subgroups using 2-tailed t tests.

RESULTS

Mean age was 54 ± 7 years, body mass index 25 ± 4 kg/m² , and RHI 2.51 ± 0.66. Three women (10%) had RHI <1.68, consistent with abnormal peripheral endothelial function, whereas 18 women (62%) met criteria for positive Ex-ECG based on ST-segment depression in contiguous leads. Women with and without ST-segment depression had similar baseline and exercise vital signs, metabolic equivalents achieved, and RHI (all P > 0.05). RHI did not predict ST-segment depression.

CONCLUSIONS

Our pilot study demonstrates high prevalence of exercise-induced ST-segment depression in asymptomatic, middle-aged, overweight women. Peripheral vascular endothelial dysfunction did not predict Ex-ECG ST-segment depression. Further work is needed to investigate the utility of vascular endothelial testing and Ex-ECG for IHD diagnostic and management purposes in women.

Inherent aerobic capacity-dependent differences in breast carcinogenesis

Although regular physical activity is associated with improvement in aerobic capacity and lower breast cancer risk, there are heritable sets of traits that affect improvement in aerobic capacity in response to physical activity. Although aerobic capacity segregates risk for a number of chronic diseases, the effect of the heritable component on cancer risk has not been evaluated. Therefore, we investigated breast carcinogenesis in rodent models of heritable fitness in the absence of induced physical activity. Female offspring of N:NIH rats selectively bred for low (LIAC) or high (HIAC) inherent aerobic capacity were injected intraperitoneally with 1-methyl-1-nitrosurea (70 mg/kg body wt). At study termination 33 weeks post-carcinogen, cancer incidence (14.0 versus 47.3%; P < 0.001) and multiplicity (0.18 versus 0.85 cancers per rat; P < 0.0001) were significantly decreased in HIAC versus LIAC rats, respectively. HIAC had smaller visceral and subcutaneous body fat depots than LIAC and activity of two proteins that regulated the mammalian target of rapamycin, protein kinase B (Akt), and adenosine monophosphate-activated protein kinase were suppressed and activated, respectively, in HIAC. Although many factors distinguish between HIAC and LIAC, it appears that the protective effect of HIAC against breast carcinogenesis is mediated, at least in part, via alterations in core metabolic signaling pathways deregulated in the majority of human breast cancers.

Resting heart rate and measures of effort-related cardiac autonomic dysfunction predict cardiovascular events in asymptomatic type 2 diabetes

BACKGROUND

Autonomic control of the cardiovascular system may be impaired in type 2 diabetes and is associated with increased morbidity and mortality. Parameters obtained during stress testing may reflect early stages of cardiac autonomic dysfunction and provide prognostic information in asymptomatic type 2 diabetes.

METHODS

We performed maximal exercise treadmill testing in 594 patients with type 2 diabetes without known coronary heart disease. The prognostic significance of physiological parameters associated with autonomic dysfunction was assessed, including chronotropic incompetence (<80% heart rate reserve), abnormal heart rate recovery at 1 minute <18 beats/minute, and resting tachycardia >100 beats/minute. Cox proportional hazards analysis was used to determine the association of exercise parameters with a composite outcome of all-cause mortality, myocardial infarction or stroke.

RESULTS

Resting heart rate >100 beats/minute was observed in 18% of patients, chronotropic incompetence in 30% and heart rate recovery at 1 minute <18 beats/minute in 35%. Over 79 ± 16 months, there were 72 (12%) events. Each parameter was significantly associated with event risk in an adjusted multivariate analysis: chronotropic incompetence (hazard ratio 1.89, 95% confidence interval 1.18-3.01; P = 0.008), resting heart rate ≥100 beats/minute (hazard ratio 1.97, 95% confidence interval 1.19-3.26; P = 0.008) and heart rate recovery at 1 minute <18 beats (hazard ratio 1.77, 95% confidence interval 1.12-2.81; P = 0.015). A progressive relationship between the number of abnormal parameters and event risk was observed (log rank P < 0.001).

CONCLUSIONS

Chronotropic incompetence, resting tachycardia and reduced heart rate recovery are independently and additively associated with long-term mortality, myocardial infarction or stroke in type 2 diabetes without known coronary heart disease.

Fitness level and body composition indices: cross-sectional study among Malaysian adolescent

BACKGROUND

The importance of fitness level on the well-being of children and adolescent has long been recognised. The aim of this study was to investigate the fitness level of school-going Malaysian adolescent, and its association with body composition indices.

METHODS

1071 healthy secondary school students participated in the fitness assessment for the Malaysian Health and Adolescents Longitudinal Research Team (MyHEART) study. Body composition indices such as body mass index for age, waist circumference and waist height ratio were measured. Fitness level was assessed with Modified Harvard Step Test. Physical Fitness Score was calculated using total time of step test exercise and resting heart rates. Fitness levels were divided into 3 categories - unacceptable, marginally acceptable, and acceptable. Partial correlation analysis was used to determine the association between fitness score and body composition, by controlling age, gender, locality, ethnicity, smoking status and sexual maturation. Multiple regression analysis was conducted to determine which body composition was the strongest predictor for fitness.

RESULTS

43.3% of the participants were categorised into the unacceptable fitness group, 47.1% were considered marginally acceptable, and 9.6% were acceptable. There was a significant moderate inverse association (p < 0.001) between body composition with fitness score (r = -0.360, -0.413 and -0.403 for body mass index for age, waist circumference and waist height ratio, respectively). Waist circumference was the strongest and significant predictor for fitness (ß = -0.318, p = 0.002).

CONCLUSION

Only 9.6% of the students were fit. There was also an inverse association between body composition and fitness score among apparently healthy adolescents, with waist circumference indicated as the strongest predictor. The low fitness level among the Malaysian adolescent should necessitate the value of healthy lifestyle starting at a young age.

Cardiopulmonary fitness and heart rate recovery as predictors of mortality in a referral population

BACKGROUND

Exercise testing provides valuable information in addition to ST-segment changes. The present study evaluated the associations among exercise test parameters and all-cause mortality in a referral population.

METHODS AND RESULTS

We examined conventional cardiovascular risk factors and exercise test parameters in 6546 individuals (mean age 49 years, 58% men) with no known cardiovascular disease who were referred to our clinic for exercise stress testing between 1993 and 2003. The association of exercise parameters with mortality was assessed during a follow-up of 8.1±3.7 years. A total of 285 patients died during the follow-up period. Adjusting for age and sex, the variables associated with mortality were: smoking, diabetes, functional aerobic capacity (FAC), heart rate recovery (HRR), chronotropic incompetence, and angina during the exercise. Adjusting for cardiovascular risk factors (diabetes, smoking, body mass index, blood pressure, serum total, HDL, LDL cholesterol, and triglycerides) and other exercise variables in a multivariable model, the only exercise parameters independently associated with mortality were lower FAC (adjusted hazard ratio [HR] per 10% decrease in FAC, 1.21; 95% confidence interval [CI], 1.13 to 1.29; P<0.001), and abnormal HRR, defined as failure to decrease heart rate by 12 beats at 1 minute recovery (adjusted HR per 1-beat decrease, 1.05; 95% CI, 1.03 to 1.07; P<0.001). The additive effects of FAC and HRR on mortality were also highly significant when considered as categorical variables.

CONCLUSION

In this cohort of patients with no known cardiovascular disease who were referred for exercise electrocardiography, FAC and HRR were independently associated with all-cause mortality.

Role of Endogenous Estrogen on the Incidence of Coronary Heart Disease in Men

Estrogens protect the vascular system in women, but its effect in men is unclear. We evaluated the impact of estrogen on the male cardiovascular system. Of 140 Chinese males, 55 (aged 61.2 ± 3.5) were cases and 60 (aged 59.5 ± 4.6) were controls. Compared with the control group, only serum estradiol ([E2]; P < .01) levels but not testosterone ([T]; P = .21) were significantly lower in the cases. Linear and multiple regression analysis showed that serum T was positively associated with triglycerides ([TG]; r = .439, P < .01) and d-dimer ( r = .258, P < .05) but negatively associated with high-density lipoprotein cholesterol (HDL-C) levels ( r = −.267, P < .05) and C-reactive protein (CRP; r = −.214, P < .05). Estradiol was highly associated with TG ( r = .783, P < .01) and HDL-C ( r = .515, P < .01) but was negatively related with low-density lipoprotein cholesterol (LDL-C; P < .05), total cholesterol/HDL-C ( P < .05), CRP ( P < .01), and d-dimer ( P < .01). In conclusion, serum E2 and T levels affect coronary heart disease risk factors in males.

The value of treadmill exercise test parameters together in patients with known or suspected peripheral arterial disease

BACKGROUND

Exercise test parameters (exercise ankle brachial index (ABI), walking distance and blood pressure response) separately are associated with long-term outcome in patients with known or suspected peripheral arterial disease (PAD). However, the clinical value of the combination of these parameters together is unknown.

METHODS

2165 patients performed a treadmill exercise test to diagnose or to evaluate their PAD. Resting ABI, exercise ABI, abnormal blood pressure response (hypotensive and hypertensive) and walking distance (impairment <150 m) were measured. The study population was divided into patients with a resting ABI ≥ 0.90 and patients with PAD (resting ABI < 0.90).

RESULTS

The mean follow-up period was 5 years (0.5-14 years). Long-term mortality rate and risks increases when more exercise parameters became abnormal (p-value = 0.001). Patients with a normal resting ABI but with an abnormal exercise test had a higher mortality risk--HR 1.90 (1.32-2.73)--than patients with a normal exercise test. The highest mortality risk and cardiac death was observed in PAD patients with a walking impairment together with an abnormal blood pressure response--HR 3.48 (2.22-5.46).

CONCLUSION

Exercise tests give multiple parameters, which together provide important prognostic information on long-term outcome in both patients with normal resting ABI and PAD.

Maximal exercise electrocardiographic responses and coronary heart disease mortality among men with metabolic syndrome

OBJECTIVE

To examine the association between abnormal exercise electrocardiographic (E-ECG) test results and mortality (all-cause and that resulting from coronary heart disease [CHD] or cardiovascular disease [CVD]) in a large population of asymptomatic men with metabolic syndrome (MetS).

PATIENTS AND METHODS

A total of 9191 men (mean age, 46.9 years) met the criteria of having MetS. All completed a maximal E-ECG treadmill test (May 14, 1979, through April 9, 2001) and were without a previous CVD event or diabetes at baseline. Main outcomes were all-cause mortality, mortality due to CHD, and mortality due to CVD. Cox regression analysis was used to quantify the mortality risk according to E-ECG responses.

RESULTS

During a follow-up of 14 years, 633 deaths (242 CVD and 150 CHD) were identified. Mortality rates and hazard ratios (HRs) across E-ECG responses were the following: for all-cause mortality: HR, 1.36; 95% confidence interval (CI), 1.09-1.70 for equivocal responses and HR, 1.41; 95% CI, 1.12-1.77 for abnormal responses (P(trend)<.001); for mortality due to CVD: HR, 1.29; 95% CI, 0.88-1.88 for equivocal responses and HR, 2.04; 95% CI, 1.46-2.84 for abnormal responses (P(trend)<.001); and for mortality due to CHD: HR, 1.62; 95% CI, 1.02-2.56 for equivocal responses and HR, 2.45; 95% CI, 1.62-3.69 for abnormal responses (P(trend)<.001). A positive gradient for CHD, CVD, and all-cause mortality rates across E-ECG categories within 3, 4, or 5 MetS components was observed (P<.001 for all).

CONCLUSION

Among men with MetS, an abnormal E-ECG response was associated with higher risk of all-cause, CVD, and CHD mortality. These findings underscore the importance of E-ECG tests to identify men with MetS who are at risk of dying.

Exercise training and cardiac rehabilitation in primary and secondary prevention of coronary heart disease

Substantial data have established a sedentary lifestyle as a major modifiable risk factor for coronary heart disease (CHD). Increased levels of physical activity, exercise training, and overall cardiorespiratory fitness have provided protection in the primary and secondary prevention of CHD. This review surveys data from observational studies supporting the benefits of physical activity, exercise training, and overall cardiorespiratory fitness in primary prevention. Clearly, cardiac rehabilitation/secondary prevention (CRSP) programs have been greatly underused by patients with CHD. We review the benefits of CRSP programs on CHD risk factors, psychological factors, and overall CHD morbidity and mortality. These data support the routine referral of patients with CHD to CRSP programs. Patients should be vigorously encouraged to attend these programs.