Sport modality affects bradycardia level and its mechanisms of control in professional athletes.

We investigated the influence of sport modalities in resting bradycardia and its mechanisms of control in highly trained athletes. In addition, the relationships between bradycardia mechanisms and cardiac structural adaptations were tested. Professional male athletes (13 runners, 11 cyclists) were evaluated. Heart rate (HR) was recorded at rest on beat-to-beat basis (ECG). Selective pharmacological blockade was performed with atropine and esmolol. Vagal effect, intrinsic heart rate (IHR), parasympathetic (n) and sympathetic (m) modulations, autonomic influence (AI) and autonomic balance (Abal) were calculated. Plasmatic norepinephrine (high-pressure liquid chromatography) and cardiac structural adaptations (echocardiography) were evaluated. Runners presented lower resting HR, higher vagal effect, parasympathetic modulation (n), AI and IHR than cyclists (P<0.05). Abal, sympathetic modulation (m) and norepinephrine level were similar within athletes regardless of modality. The cardiac chambers were also similar between runners and cyclists (P=0.30). However, cyclists displayed higher septum and posterior wall thickness than runners (P=0.04). Further analysis showed a trend towards inverse correlation between IHR with septum wall thickness and posterior wall thickness (P=0.056). Type of sport influences the resting bradycardia level and its mechanisms of control in professional athletes. Resting bradycardia in runners is mainly dependent on an autonomic mechanism. In contrast, a cyclist's resting bradycardia relies on a non-autonomic mechanism probably associated with combined eccentric and concentric hypertrophy.

Accuracy of body mass index in diagnosing obesity in the adult general population.

BACKGROUND: Body mass index (BMI) is the most widely used measure to diagnose obesity. However, the accuracy of BMI in detecting excess body adiposity in the adult general population is largely unknown. METHODS: A cross-sectional design of 13 601 subjects (age 20-79.9 years; 49% men) from the Third National Health and Nutrition Examination Survey. Bioelectrical impedance analysis was used to estimate body fat percent (BF%). We assessed the diagnostic performance of BMI using the World Health Organization reference standard for obesity of BF%>25% in men and>35% in women. We tested the correlation between BMI and both BF% and lean mass by sex and age groups adjusted for race. RESULTS: BMI-defined obesity (> or =30 kg m(-2)) was present in 19.1% of men and 24.7% of women, while BF%-defined obesity was present in 43.9% of men and 52.3% of women. A BMI> or =30 had a high specificity (men=95%, 95% confidence interval (CI), 94-96 and women=99%, 95% CI, 98-100), but a poor sensitivity (men=36%, 95% CI, 35-37 and women=49%, 95% CI, 48-50) to detect BF%-defined obesity. The diagnostic performance of BMI diminished as age increased. In men, BMI had a better correlation with lean mass than with BF%, while in women BMI correlated better with BF% than with lean mass. However, in the intermediate range of BMI (25-29.9 kg m(-2)), BMI failed to discriminate between BF% and lean mass in both sexes. CONCLUSIONS: The accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. A BMI cutoff of> or =30 kg m(-2) has good specificity but misses more than half of people with excess fat. These results may help to explain the unexpected better survival in overweight/mild obese patients.

Dual-chamber pacing for hypertrophic cardiomyopathy: a randomized, double-blind, crossover trial.

OBJECTIVES: In a double-blind, randomized, crossover trial we sought to evaluate the effect of dual-chamber pacing in patients with severe symptoms of hypertrophic obstructive cardiomyopathy. BACKGROUND: Recently, several cohort trials showed that implantation of a dual-chamber pacemaker in patients with severely symptomatic hypertrophic obstructive cardiomyopathy can relieve symptoms and decrease the severity of the left ventricular outflow tract gradient. However, the outcome of dual-chamber pacing has not been compared with that of standard therapy in a randomized, double-blind trial. METHODS: Twenty-one patients with severely symptomatic hypertrophic obstructive cardiomyopathy were entered into this trial after baseline studies consisting of Minnesota quality-of-life assessment, two-dimensional and Doppler echocardiography and cardiopulmonary exercise tests. Nineteen patients completed the protocol and underwent double-blind randomization to either DDD pacing for 3 months followed by backup AAI pacing for 3 months, or the same study arms in reverse order. RESULTS: Left ventricular outflow tract gradient decreased significantly to 55 +/- 38 mm Hg after DDD pacing compared with the baseline gradient of 76 +/- 61 mm Hg (p < 0.05) and the gradient of 83 +/- 59 mm Hg after AAI pacing (p < 0.05). Quality-of-life score and exercise duration were significantly improved from the baseline state after the DDD arm but were not significantly different between the DDD arm and the backup AAI arm. Peak oxygen consumption did not significantly differ among the three periods. Overall, 63% of patients had symptomatic improvement during the DDD arm, but 42% also had symptomatic improvement during the AAI backup arm. In addition, 31% had no change and 5% had deterioration of symptoms during the DDD pacing arm. CONCLUSIONS: Dual-chamber pacing may relieve symptoms and decrease gradient in patients with hypertrophic obstructive cardiomyopathy. In some patients, however, symptoms do not change or even become worse with dual-chamber pacing. Subjective symptomatic improvement can also occur from implantation of the pacemaker without its hemodynamic benefit, suggesting the role of a placebo effect. Long-term follow-up of a large number of patients in randomized trials is necessary before dual-chamber pacing can be recommended for all patients with severely symptomatic hypertrophic obstructive cardiomyopathy.

Comparison of peak exercise oxygen uptake in men versus women in chronic heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

Results of exercise testing in 150 patients with chronic heart failure show that women were characterized by shorter exercise time, peak oxygen consumption, and lower peak oxygen pulse than men. There was a 4.1-ml/kg/min difference in peak oxygen uptake between genders after the adjustment of age, peak heart rate, respiratory exchange ratio, ejection fraction, and etiology of heart failure.

Sequential assessment of exercise tolerance in heart transplantation compared with coronary artery bypass surgery after phase II cardiac rehabilitation.

To investigate the improvement in exercise capacity of transplant patients after an early postoperative (phase II) cardiac rehabilitation program during the first year after surgery, we analyzed retrospectively exercise capacity within 3 months (at the completion of phase II rehabilitation) and 1 year after surgery in 17 orthotopic heart transplantation patients (15 men and 2 women) and 17 age- and gender-matched coronary artery bypass graft (CABG) patients. All patients participated in a phase II cardiac rehabilitation exercise program followed by a home-based exercise program. At the completion of phase II cardiac rehabilitation, mean peak oxygen (VO2) adjusted for body weight in heart transplant patients was not significantly different from that in CABG patients (19.7 +/- 3.7 vs 21.9 +/- 4.1 ml/kg/min), and oxygen pulse at peak exercise did not differ between the 2 groups (11.5 +/- 2.5 vs 12.6 +/- 2.4 ml/beat). Between 3 months and 1 year after surgery, CABG patients had a marked increase in exercise time, increase in heart rate from rest to peak exercise (heart rate reserve), peak VO2, and oxygen pulse. In contrast, heart transplant patients had a significant but only modest increase in peak VO2, and were much more limited in exercise capacity at 1 year than were CABG patients (21.3 +/- 3.9 vs 27.4 +/- 4.7 ml/kg/min, p <0.0001). In our limited patient population, usual phase I rehabilitation with subsequent home-based exercise training was inadequate to improve the exercise capacity of heart transplant patients, and different rehabilitation protocols, such as long-term supervised exercise training, specific to this patient group may be indicated.

Prognostic significance of exercise-induced systemic hypertension in healthy subjects.

Exercise hypertension has been suggested to predict future resting hypertension, but its significance in terms of cardiovascular risk has not been defined. To assess the prognostic significance of exercise hypertension, 150 healthy, asymptomatic subjects with normal resting blood pressures and exercise systolic blood pressures > or =214 mm Hg (i.e., >90th percentile) on Bruce treadmill tests were identified retrospectively and age- and gender-matched with subjects with exercise systolic blood pressures of 170 to 192 mm Hg (40th to 70th percentiles). Subjects were contacted by survey a mean of 7.7+/-2.9 years after the index treadmill test. The survey response rate was 93%. There were 12 deaths, including 8 in the exercise hypertension group. A major cardiovascular event, defined as cardiovascular death, myocardial infarction, stroke, coronary angioplasty, or coronary bypass graft surgery occurred in 5 controls and 10 subjects with exercise hypertension. At follow-up, 13 controls and 37 subjects with exercise hypertension were now diagnosed as having resting hypertension. In multivariate analysis, exercise hypertension was not a significant predictor for death or any individual cardiovascular event, but was for total cardiovascular events and new resting hypertension. The multivariate risk ratio for exercise hypertension was 3.62 (p = 0.03) in predicting a major cardiovascular event. Other significant predictors included body mass index and age. For predicting new resting hypertension, the multivariate odds ratio for exercise hypertension was 2.41 (p = 0.02). These data suggest that exercise hypertension carries a small but significant risk for major cardiovascular events in healthy, asymptomatic persons with normal resting blood pressures.

Management of coronary risk factors by registered nurses versus usual care in patients with unstable angina pectoris (a chest pain evaluation in the emergency room [CHEER] substudy).

This study examined whether nurses could manage coronary risk factors in patients with unstable angina more effectively than physicians practicing usual care. Three hundred twenty-six patients were randomized in the emergency room to a 6-month program of risk factor management by a registered nurse versus participation in usual care. The nurse intervention consisted of a 30-minute counseling visit at 6 to 10 days after the chest pain episode and a second 30-minute session 1 month later. Multiple risk factors were assessed and addressed: smoking, blood lipids, blood pressure, blood glucose, physical inactivity, weight, psychological stress, and social isolation. Compared with usual care, nurse intervention patients significantly reduced both triglycerides (-29 +/- 8 vs 5 +/- 6 mg/dl; p <0.0004) and weight (-0.9 +/- 3.3 vs +0.1 +/- 2.1 kg; p = 0.0071), and had corresponding improvements in self-reported diet compliance and exercise (+34 +/- 106 vs +9 +/- 98 minutes, p = 0.0491). No significant differences between groups were observed in terms of 6-month changes in total, high-density lipoprotein, or low-density lipoprotein cholesterol, blood pressure, fasting blood glucose, percent body fat or waist-hip ratio, or psychological distress scores. The 6-month rate of recurrent events (cardiac death, out-of-hospital cardiac arrest, myocardial infarction) and/or revascularizations (coronary artery bypass surgery or coronary angioplasty) was lower in the nurse intervention group (1% vs 9%; p = 0.002). We conclude that a nurse-delivered risk factor intervention program for patients with chest pain is feasible and more effective than usual care in terms of fostering lifestyle changes that may lower coronary risk.

Vitamin E supplementation in the prevention of coronary heart disease.

Vitamin E consists of a number of compounds, tocopherols and tocotrienols, that function as lipid-soluble antioxidants. A hypothesis is that vitamin E may slow the progression of atherosclerosis by blocking the oxidative modification of low-density lipoprotein cholesterol and thus decrease its uptake into the arterial lumen. Basic science and animal studies have generally supported this hypothesis. Observational studies have primarily assessed patients with no established coronary heart disease (CHD), and results have generally supported a protective role of vitamin E in CHD. Early primary and secondary prevention clinical trials (Alpha-Tocopherol, Beta-Carotene Cancer Protection study and Cambridge Heart Antioxidant Study) showed mixed results. Despite years of encouraging evidence from basic science and observational studies, 3 large randomized clinical trials (Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico, Heart Outcomes Prevention Evaluation, and Primary Prevention Project) with a combined total of more than 25,000 patients failed to show a significant benefit with vitamin E taken as a dietary supplement for the prevention of CHD. Four large randomized primary prevention trials currently under way should add to our knowledge. The American Heart Association has recommended consumption of a balanced diet with emphasis on antioxidant-rich fruits and vegetables but has made no recommendations regarding vitamin E supplementation for the general population. Although vitamin E supplementation seems to be safe for most people, recommendations from health care professionals should reflect the uncertainty of established benefit as demonstrated in clinical trials.

Cardiovascular responses in a whirlpool bath at 40 degrees C versus user-controlled water temperatures.

OBJECTIVE: To compare cardiovascular responses in a whirlpool bath at 40 degrees C versus user-controlled water temperature (UCT). MATERIAL AND METHODS: In an experimental study, six healthy men, 36 to 43 years of age, participated in two randomly assigned trials of whirlpool bath use for 25 minutes at 40 degrees C and UCT. Water temperature, esophageal temperature (Tes) heart rate (HR), systolic blood pressure (SBP), and perceived comfort were monitored before immersion and at 5-minute intervals during immersion. RESULTS: Although the mean water temperature during the UCT trial was slightly below 40 degrees C (39.4 +/- 2.0 degrees C), it varied considerably among subjects (from 36.5 +/- 2.1 degrees C to 42.5 +/- 1.7 degrees C). Peak Tes9 HR, and SBP were not significantly different between the two trials, although the UCT trial had greater variability. No adverse effects were observed. Mild or moderate overheating was reported by four subjects in the 40 degrees C trial and two subjects in the UCT trial, and mild chest pain, light-headedness, dyspnea, and nausea were reported by one subject during the UCT trial. A trend toward higher comfort ratings was noted in the UCT than in the 40 degrees C trial, especially during the final 10 minutes of immersion. CONCLUSION: These data show that cardiovascular responses to whirlpool bathing for 25 minutes at 40 degrees C are mild. In comparison with the 40 degrees C trial, peak Tes9, HR, and SBP under UCT conditions were not, on the average, significantly higher, although more variability existed among the subjects.

Cardiovascular rehabilitation: status, 1990.

Cardiovascular rehabilitation is defined as the process of development and maintenance of a desirable level of physical, social, and psychologic functioning after the onset of a cardiovascular illness. Patient education, counseling, nutritional guidance, and exercise training play prominent roles in the process of rehabilitation. Benefits from cardiac rehabilitation include improved exercise capacity and decreased symptoms of angina pectoris, dyspnea, claudication, and fatigue. Recent pooled data regarding exercise training after myocardial infarction demonstrated a 20 to 25% reduction in mortality and major cardiac events. Exercise training may result in an improvement in systemic oxygen transport, a reduction in the myocardial oxygen requirement for a given amount of external work, and a decrease in the extent of myocardial ischemia during physical activity. The efficacy of modification of risk factors in reducing the progression of coronary artery disease and future morbidity and mortality has been established. Herein we review the history, current practice and results, and future challenges of cardiovascular rehabilitation.

Low-dose, time-release nicotinic acid: effects in selected patients with low concentrations of high-density lipoprotein cholesterol.

In a retrospective analysis, 63 participants in a cardiac rehabilitation-preventive cardiology program were identified as having low blood concentrations (mean, 34 mg/dl) of high-density lipoprotein cholesterol (HDL-C) and a mean total cholesterol level of 223 mg/dl after 3 months of hygienic measures (aerobic exercise, avoidance of tobacco, diet, and weight loss) designed to increase the HDL-C level. These patients (treatment group) were treated with low-dose, time-release nicotinic acid (mean, 1,297 mg/day) for a mean duration of 7.4 months. All subjects were able to take the drug without intolerable side effects. Fifty-four patients similar to those in the treatment group participated in the same program but were not treated with nicotinic acid (control group). Exercise, diet, body weight, and smoking remained stable throughout the period of observation. For the treatment group, HDL-C levels increased a mean of 18% (+6 mg/dl), total cholesterol concentrations decreased 9% (-20 mg/dl), the ratio of total cholesterol to HDL-C decreased 25% (from 6.8 to 5.1), low-density lipoprotein cholesterol levels decreased 13% (-20 mg/dl), and triglyceride levels decreased 20% (from 165 mg/dl to 132 mg/dl). Aspartate aminotransferase and uric acid concentrations were minimally increased after treatment, and the blood glucose level was unchanged. In the control group, HDL-C levels increased a mean of 8% (+3 mg/dl) and the other blood lipid variables were not improved after a mean of 8.3 additional months of diet and exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Peak exercise blood pressure stratified by age and gender in apparently healthy subjects.

OBJECTIVE: To determine the peak blood pressure responses during symptom-limited exercise in a large sample of apparently healthy subjects, including both men and women over a wide range of ages. DESIGN: We retrospectively studied the blood pressure response during maximal treadmill exercise testing with use of the Bruce protocol in apparently healthy subjects. MATERIAL AND METHODS: Peak exercise blood pressures in 7,863 male and 2,406 female apparently healthy subjects who underwent a screening treadmill exercise test with the Bruce protocol between 1988 and 1992 were analyzed by age and gender. RESULTS: In this large referral population of apparently healthy subjects, peak exercise systolic and diastolic blood pressures and delta systolic blood pressure (rest to peak exercise) were higher in men than in women and were positively associated with age. In men, the 90th percentile of systolic blood pressure increased from 210 mm Hg for the age decade 20 to 29 years to 234 mm Hg for ages 70 to 79 years; the corresponding increase among women was from 180 mm Hg to 220 mm Hg. Delta diastolic blood pressure also increased with advancing age. The difference in peak and delta systolic blood pressures between men and women seemed to decrease after age 40 to 49 years. Exercise hypotension, defined as peak exercise systolic pressure less than rest systolic pressure, occurred in 0.23% of men and 1.45% of women and was not significantly related to age. CONCLUSION: Overall, peak exercise systolic and diastolic, as well as delta systolic, blood pressures were higher in men than in women and increased with advancing age. The reported data will enable clinicians to interpret more accurately the significance of peak exercise blood pressure response in a subject of a specific age and gender and will allow investigators to define exercise hypertension in statistical terms stratified by age and gender.

Achieving National Cholesterol Education Program goals for low-density lipoprotein cholesterol in cardiac patients: importance of diet, exercise, weight control, and drug therapy.

OBJECTIVE: To determine how frequently the National Cholesterol Education Program (NCEP) goal of a low-density lipoprotein (LDL) cholesterol level of 100 mg/dL or less is achieved in clinical practice in patients with coronary artery disease and what fraction of patients can achieve this goal without drug therapy. DESIGN: We examined the results of lipid management in 152 consecutive patients who had completed cardiac rehabilitation after an acute coronary event. Patients were randomized to follow-up by specially trained nurses or by preventive cardiologists, and they were not receiving lipid-lowering drugs at the start of the study. MATERIAL AND METHODS: Patients were given aggressive diet and exercise recommendations and lipid-lowering drugs in accordance with NCEP guidelines. Follow-up was continued for a mean of 526 days after the first lipid assessment subsequent to the coronary event. Multiple logistic regression analysis was used to identify independent predictors of a final LDL cholesterol level of 100 mg/dL or less. RESULTS: Of the study group, 39% achieved the NCEP goal LDL cholesterol level of 100 mg/dL or less. Characteristics of the patients with LDL cholesterol levels of 100 mg/dL or less in comparison with those with LDL cholesterol levels of more than 100 mg/dL included a greater frequency of drug therapy (65% versus 38%), more rigorous dietary compliance, longer follow-up (586 +/- 317 days versus 493 +/- 264 days), more favorable weight change (-0.3 +/- 4.9 kg versus +1.7 +/- 5.0 kg), and more extensive weekly exercise (183 +/- 118 minutes versus 127 +/- 107 minutes). CONCLUSION: The registered nurses managed the lipids of these patients as effectively as did the preventive cardiologists. Appropriate drug therapy was the most important factor in achieving an LDL cholesterol level of 100 mg/dL or less, but 35% of patients attaining this NCEP goal were not receiving drug therapy. Exercise, dietary compliance, and weight loss were also important factors.

Cardiovascular responses to immersion in a hot tub in comparison with exercise in male subjects with coronary artery disease.

In order to test the safety of hot tub use for persons with heart disease, 15 men with clinically stable coronary artery disease underwent 15 minutes of immersion in a hot tube at 40 degrees C. On another day, they exercised on a cycle ergometer for 15 minutes; target heart rate was determined by standard methods. Tympanic temperature, skin temperature, electrocardiographic findings, blood pressure, plasma catecholamines, subjective comfort, and cardiovascular symptoms were monitored. The peak heart rate was significantly lower during the hot tub session versus the exercise session (85 +/- 14 versus 112 +/- 19 beats/min), as were the systolic (106 +/- 15 versus 170 +/- 21 mm Hg) and diastolic (61 +/- 6 versus 83 +/- 8 mm Hg) blood pressure measurements (P < 0.01). Tympanic temperature increased by a mean of 0.6 +/- 0.3 degrees C during immersion and 0.1 +/- 0.1 degrees C during exercise. No ischemic electrocardiographic changes or clinical complications occurred. Simple ventricular ectopic activity and "just noticeable" chest pain were more frequent during exercise than during immersion. Plasma norepinephrine increased during exercise but not during immersion. These data suggest that hot tub use within these time and temperature constraints should be safe for men with stable heart disease who can follow an exercise regimen at home.

Niacin-induced hepatitis: a potential side effect with low-dose time-release niacin.

Hepatitis developed in five patients who were taking low dosages (3 g/day or less) of time-release niacin. In four of the five patients, clinical symptoms of hepatitis developed after the medication had been taken for a relatively short time (2 days to 7 weeks). This manifestation of hepatotoxicity seems to differ from that previously reported in association with use of crystalline niacin, which occurred with high dosage and prolonged usage of the medication. In view of the recent increased frequency of prescribing niacin for the treatment of hyperlipidemia, physicians should be aware of the potential for hepatotoxicity with even low-dose and short-term use of time-release niacin.

Medical and economic costs of psychologic distress in patients with coronary artery disease.

OBJECTIVE: To determine the effect of psychologic distress, measured with a commonly used screening questionnaire, on 6-month morbidity and rehospitalization costs in coronary patients. DESIGN: Psychologic distress was determined by screening with the Symptom Checklist-90--Revised (SCL-90-R) self-report inventory during the second week of cardiac rehabilitation. Costs associated with cardiovascular rehospitalization during a 6-month follow-up period were recorded, and differences between "distressed" and "nondistressed" patients were analyzed statistically. MATERIAL AND METHODS: The study cohort consisted of 381 patients (311 men and 70 women) referred for cardiac rehabilitation after an index hospitalization for unstable angina, myocardial infarction, coronary angioplasty, or coronary bypass procedure. Patients with SCL-90-R scores above the 90th percentile for outpatient adults were considered distressed (N = 41); patients with scores below this level were considered nondistressed (N = 340). RESULTS: The 6-month follow-up was complete in all but 1 of the 381 patients. Distressed patients had significantly higher rates of cardiovascular rehospitalization, any recurrent events, and recurrent "hard events" (cardiac death, myocardial infarction, or cardiac arrest and resuscitation) within 6 months after dismissal from their index hospitalization in comparison with nondistressed patients. Adjustment for other factors associated with a risk of early rehospitalization and recurrent events did not reduce the strength or significance of the association between psychologic distress and early cardiovascular rehospitalization or recurrent events. The mean rehospitalization costs were significantly higher in the distressed than in the nondistressed patients ($9,504 versus $2,146). CONCLUSION: These data add support to the hypothesis that psychologic distress adversely affects the prognosis in coronary patients, confirm the added morbidity and rehospitalization costs attributable to psychologic distress, and suggest the potential for improving the prognosis in selected coronary patients by identification and appropriate treatment of psychologic distress.

Further increase in oxygen uptake during early active recovery following maximal exercise in chronic heart failure.

STUDY OBJECTIVE: Some patients with chronic heart failure manifest a further increase in oxygen uptake (VO2) after maximal exercise whereas others do not. The purpose of this study was to determine the characteristics of chronic heart failure patients with further increase in VO2 in early active recovery following maximal exercise. DESIGN: Retrospective analysis of clinical and exercise testing characteristics in patients with or without a further increase in VO2 during early active recovery. PATIENTS: One hundred forty-two patients with a history of congestive heart failure and left ventricular ejection fraction of 45%, or less who performed a symptom-limited graded treadmill exercise test. MEASUREMENTS AND RESULTS: Expired gases were monitored breath by breath from rest throughout exercise and during 1 min of active recovery. Patients were defined as having a further increase in VO2 if the average VO2 during the initial 30 s of active recovery was greater than or equal to VO2 during the final 30 s of graded exercise and the instantaneous VO2 (from the breath-by-breath plot) at 30 s of active recovery was greater than or equal to the instantaneous VO2 at peak exercise. Thirty patients (21%) showed a further increase in VO2 following peak exercise (group 1), and 112 had decreased VO2 at 30 s after peak exercise (group 2). In group 1, treadmill time was significantly shorter, peak VO2 was significantly lower (16.6 +/- 3.6 vs 21.6 +/- 6.4 mL/kg/min), and peak ventilatory equivalent for carbon dioxide (VE/VCO2) was significantly higher than those in group 2. There was no difference in etiology of heart failure or functional class and medication status. CONCLUSION: A further increase in VO2 during early active recovery was associated with poorer exercise tolerance, lower peak VO2, and higher peak VE/VCO2 in chronic heart failure patients. This sign may be a new functional variable for assessment of chronic heart failure. Further investigations are warranted to clarify the mechanisms and clinical implications of this phenomenon.

Pulmonary function in patients with reduced left ventricular function: influence of smoking and cardiac surgery.

STUDY OBJECTIVE: The impact of stable, chronic heart failure on baseline pulmonary function remains controversial. Confounding influences include previous coronary artery bypass or valve surgery (CABG), history of obesity, stability of disease, and smoking history. DESIGN: To control for some of the variables affecting pulmonary function in patients with chronic heart failure, we analyzed data in four patient groups, all with left ventricular (LV) dysfunction (LV ejection fraction [LVEF] < or =35%): (1) chronic heart failure, nonsmokers, no CABG (n = 78); (2) chronic heart failure, nonsmokers, CABG (n = 46); (3) chronic heart failure, smokers, no CABG (n = 40); and (4) chronic heart failure, smokers, CABG (n = 48). Comparisons were made with age- and gender-matched patients with a history of coronary disease but no LV dysfunction or smoking history (control subjects, n = 112) and to age-predicted norms. RESULTS: Relative to control subjects and percent-predicted values, all groups with chronic heart failure had reduced lung volumes (total lung capacity [TLC] and vital capacity [VC]) and expiratory flows (p < 0.05). CABG had no influence on lung volumes and expiratory flows in smokers, but resulted in a tendency toward a reduced TLC and VC in nonsmokers. Smokers with chronic heart failure had reduced expiratory flows compared to nonsmokers (p < 0.05), indicating an additive effect of smoking. Diffusion capacity of the lung for carbon monoxide (DLCO) was reduced in smokers and in subjects who underwent CABG, but not in patients with chronic heart failure alone. There was no relationship between LV size and pulmonary function in this population, although LV function (cardiac index and stroke volume) was weakly associated with lung volumes and DLCO. CONCLUSIONS: We conclude that patients with chronic heart failure have primarily restrictive lung changes with smoking causing a further reduction in expiratory flows.

Is rest or exercise hypertension a cause of a false-positive exercise test?

STUDY OBJECTIVES: To determine if a history of hypertension or an exaggerated rise in exercise systolic BP is associated with a false-positive exercise ECG. DESIGN, SETTING, AND PATIENTS: Retrospective analysis of the associations between exercise-induced ST-segment depression and a history of hypertension, exercise systolic BP, and several other clinical and exercise test variables. Among 20,097 patients referred for exercise tomographic thallium imaging in a nuclear cardiology laboratory at a tertiary care center, 1,873 patients met inclusion criteria for this study, which included no history of myocardial infarction or coronary artery revascularization, a normal resting ECG, and normal exercise thallium images. RESULTS: False-positive ST-segment depression occurred in 20% of the population. A history of hypertension was actually associated with a lower likelihood of ST-segment depression (odds ratio, 0.70; 95% confidence interval [CI], 0.55 to 0.89; p = 0. 004). A higher peak exercise systolic BP was associated with a higher likelihood of ST-segment depression (odds ratio, 1.08 for each 10-mm Hg increase in systolic BP; 95% CI, 1.03 to 1.14; p < 0. 001). However, the association between peak exercise systolic BP and ST-segment depression was so weak that this measurement could not be predictive in the individual patient (R(2) = 0.2%). For every 20-mm Hg increase in peak exercise systolic BP, the percentage of patients with ST-segment depression increased by only 3%. CONCLUSIONS: In patients with normal resting ECGs, we conclude the following: (1) a history of hypertension is not a cause of a false-positive exercise test, and (2) higher exercise systolic BP is a significant but weak predictor of ST-segment depression.