Effects of exercise training on progression of documented coronary arteriosclerosis in men

Patient characteristics and outcomes of cardiac rehabilitation

PURPOSE

To investigate changes in physical fitness and psychological characteristics of patients after cardiac rehabilitation, and to assess predictors of defaulting from the program.

METHODS

A prospective study of 1902 consecutive patients admitted to a community-based, hospital-linked cardiac rehabilitation program was conducted over a period of 6 years and 7 months. The cardiac rehabilitation program centered on a 2-to 6-month circuit training course with education, stress management, relaxation, and risk factor monitoring. Before and after the program, measures of physical fitness and of hospital anxiety and depression were performed.

RESULTS

The course was completed by 1443 patients (76%), with 240 patients (13%) defaulting. For those who completed the course, peak oxygen consumption per minute increased by 3.2 mL/min/kg (95% confidence interval [CI], 3.1-3.4) or 19% (95% CI, 17.7%-20.3%). According to the hospital anxiety and depression scores, anxiety fell by 1.1 (95% CI, -1.3 to -0.98) and depression by 1.3 (95% CI, -1.4 to -1.2). The main predictors of defaulting were depression (patients with depression were twice as likely to default as nondepressed patients) and diagnosis (patients who had experienced angina or percutaneous transluminal coronary angioplasty were twice as likely to default as those who had experienced infarct or coronary artery bypass graft).

CONCLUSIONS

The identification of depressed coronary patients known to be at increased risk should be a priority for cardiac rehabilitation coordinators. Every effort should be made to keep them in the cardiac rehabilitation program.

Exercise as a coronary protective factor

Exercise has multiple beneficial actions, both in normal subjects and in patients with coronary artery disease, which can be cardioprotective. Apart from reducing known risk factors and protecting against their deleterious effects, exercise also reduces the risk of coronary artery disease by increasing cardiovascular fitness. The exact contribution of each of these mechanisms in reducing coronary artery disease morbidity and mortality is unclear. Although fitness may be desirable, much of the cardioprotection can be achieved through increased leisure time and recreational physical activity. The risk-benefit ratio is very much in favor of moderate intensity exercise. Even in the absence of a controlled trial, the available evidence suggests that efforts to encourage physical activity are justified.

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.

Drug therapy and the prevention of atherosclerosis in humans

The results of the World Health Organization Cooperative Trial, the Coronary Drug Project, the Coronary Primary Prevention Trial and the Helsinki Heart Study indicate that clinical expression of coronary artery disease can be delayed with pharmacologic modification of plasma lipoproteins. Change in coronary artery disease can be semiquantitated by repeat arteriograms. Three randomized clinical trials indicate that rate of progression of atherosclerosis, as defined by arteriography, can be reduced, and existing lumen obstruction decreased. Tendon xanthomas occur in hypercholesterolemia, and reduction in xanthoma size with drug therapy suggests an improved atherosclerotic disease state. The clinician has a variety of pharmacologic therapies available. The role of bile acid-binding resins, fibric acid derivatives, hydroxymethylglutaryl coenzyme A reductase inhibitors, nicotinic acid and antioxidants is each unique. Understanding the role of lipoproteins in atherosclerosis will help in selecting the most appropriate therapy for each individual patient. Medications not designed for their lipoprotein effects can significantly alter lipoproteins. Medications, such as nonselective beta blockers, can alter low-density lipoprotein (LDL) subclass distribution with no change in LDL cholesterol content. Such changes may eradicate part of the beneficial cardiovascular effect of beta blockade therapy. In the future, therapeutic choices may depend in part on lipoprotein abnormalities such as lipoprotein (a), apolipoprotein E isoforms, hyperapobetalipoproteinemia, LDL.

Effects of exercise training on biochemical and biomechanical properties of rat aorta

The authors studied the effect of prolonged physical exercise on the mechanical properties of rat aorta in relation to the amounts and qualities of arterial connective tissue fibrous proteins. Twelve male rats were divided into two groups: 6 sedentary rats (S) and 6 training rats (T), which were forced to swim from nine weeks to twenty-five weeks of age. The ultimate tensile stress and the ultimate tensile extension ratio of ring specimens at the descending thoracic aorta were larger in T than in S (192.3 +/- 47.9 g/mm2, mean +/- SD, vs 147.8 +/- 26.0, p less than 0.05; 3.52 +/- 0.13 vs 3.18 +/- 0.27, p less than 0.05; respectively). The elasticity parameter, calculated by fitting stress-strain curves to exponential function in the stress level of 0-20 g/mm2, was lower in T than in S (1.79 +/- 0.15 vs 2.13 +/- 0.24, p less than 0.01). The contents of elastin (alkali-insoluble elastin preparation) and collagen were higher in T than in S (0.44 +/- 0.11 g/g dry aorta vs 0.30 +/- 0.06, p less than 0.05; 0.15 +/- 0.04 g/g dry aorta vs 0.11 +/- 0.04, NS, respectively). Although the aortic calcium content did not significantly change in the training rats (T 1.17 +/- 0.23 mg/g dry aorta, S 0.95 +/- 0.34), the content of calcium in elastin was lower in T than in S (1.75 +/- 0.51 mg/g dry elastin vs 2.63 +/- 1.00, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary heart disease and risk factor modification. Is there a threshold?

Modification of coronary heart disease risk factors may play an important role in the control and alteration of the atherosclerotic process. The amount of modification necessary to obtain beneficial results is a controversial issue. Review of epidemiologic studies and recent arteriographic investigations allows for the approach to the issue of threshold levels of modification that may be required prior to obtaining some benefit. Serum lipoproteins appear to play a central role in the atherosclerotic risk factor relationship. On the basis of current evidence, clinical aims are suggested for coronary heart disease risk factor modification in order to assist in obtaining optimal health goals.

Role of exercise training in secondary prevention of ischemic heart disease

A review of recent studies indicates that: (1) Physiological characteristics, e.g., left ventricular performance and exercise tolerance, are important prognostic determinants; (2) the natural history of acute myocardial infarction includes a significant degree of spontaneous functional improvement during the early recovery phase; (3) short-term programs of physical training are likely to produce significant functional and symptomatic improvement at no cost in terms of excess mortality or morbidity--the mechanisms of improvement are largely peripheral and regulatory; (4) recent scintigraphic studies suggest that prolonged physical training produces improvement in left ventricular function and myocardial perfusion; (5) long-term studies of the effect of physical training on mortality and morbidity have failed to demonstrate conclusively the efficacy of exercise as a single agent, but provide support for the continued use of physical training as a component of multiple interventions.

Reduction of coronary atherosclerosis by moderate conditioning exercise in monkeys on an atherogenic diet

All available evidence that exercise may protect against coronary heart disease is circumstantial, and direct evidence is difficult to obtain in human beings. Therefore, we studied the effect of moderate conditioning with treadmill exercise on developing coronary-artery disease in monkeys on an atherogenic diet. Physical training was demonstrated by slow heart rates. Serum total cholesterol was the same (approximately 600 mg per deciliter or 15.5 mmol per liter) in exercising and non-exercising monkeys, with significantly higher high-density-lipoprotein (HDL) cholesterol and much lower triglyceride and low-density-lipoprotein (LDL) plus very-low-density-lipoprotein (VLDL) triglyceride in the exercise group. Ischemic electrocardiographic changes, angiographic signs of coronary-artery narrowing, and sudden death were observed only in non-conditioned monkeys, in which post-mortem examination revealed marked coronary atherosclerosis and stenoses. Exercise was associated with substantially reduced overall atherosclerotic involvement, lesion size, and collagen accumulation; it also produced much larger hearts and wider coronary arteries, further reducing the degree of luminal narrowing. Our data suggest that moderate exercise may prevent or retard coronary heart disease in primates.

Serumlipoprotein cholesterol in sedentary and trained male patients with coronary heart disease

To demonstrate the influence of exercise training on the lipoprotein cholesterol fractions (high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) cholesterol) in patients with coronary heart disease (CHD), 65 male patients were examined for cardiovascular function and lipid metabolism, before starting or after having participated in a coronary training group for more than one year. There were notable improvements not only in the physical performance data of the trained patients in reference to the tested maximal performance capacity per body weight (MPC/W) as well as the calculated heart volume performance ratio (HVPR) (MPC/W, + 26.0%; HVPR, -18.0%), but also in the lipoprotein cholesterol values and the calculated risk quotient of HDL and total cholesterol (HDL cholesterol, +5.1 mg/dl; LDL cholesterol, -23.3 mg/dl; VLDL cholesterol, -12.5 mg/dl; HDL/total cholesterol, +0.038). The results indicate the positive effect of physical training on lipoprotein cholesterol concentrations, and also in CHD patients in coronary training groups.

Long-term effects of physical training on coronary patients with impaired ventricular function

Eighteen patients with coronary heart disease and an ejection fraction of 0.40 or less were entered into an individualized exercise training program. Maximal symptom-limited exercise stress test and cardiac catheterization studies were performed initially and 12--42 months (average 18.5 months) after exercise training. At the time of the follow-up study, the mean functional aerobic impairment (FAI) improved from 32.1 to 23.4% (p less than or equal to 0.01); resting and submaximal heart rates were significantly lower (p less than 0.01 and 0.05, respectively). There was no significant change in the pulmonary artery or left ventricular end-diastolic pressure, cardiac index, stroke index, left ventricular end-diastolic volume or ejection fraction. Exercise training, therefore, can be beneficial even for patients with impaired ventricular function. Increase in physical work capacity was not correlated with improvement of ventricular function; on the other hand, exercise training did not cause deterioration of ventricular function.