Does cardiac rehabilitation increase long-term survival after myocardial infarction?
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Biomedical subjects
Publications and source records attributed to A Oberman.
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The association between sedentary lifestyle and cardiovascular disease is reviewed. Hazards of exercise are discussed, and clearance procedures for participation in exercise testing are described. There is a brief section on the epidemiology of exercise participation in the United States. Implications for the practitioner are presented.
Through a multicenter registry of patients in the Coronary Artery Surgery Study, we prospectively evaluated morbidity and mortality in 4,165 smokers with angiographically proved coronary artery disease, 2,675 of whom continued to smoke and 1,490 of whom quit. At five years, mortality (adjusted by Cox analysis for baseline differences) was 22% for those who continued smoking and 15% for quitters. The relative risk (also from the Cox analysis) for mortality in continuers vs quitters was 1.55 (95% confidence interval, 1.29 to 1.85). The adverse effect of smoking mainly took the form of higher frequencies of myocardial infarction--associated death and sudden death: the frequencies of these events during follow-up in continuers vs quitters were 7.9% vs 4.4% for myocardial infarction--associated death and 2.8% vs 1.5% for sudden death. This study supports the recommendation that patients with coronary artery disease should stop smoking.
In the Dietary Intervention Study of Hypertension (DISH) we found that patients formerly treated with drugs and assigned to sodium-reduction intervention were twice as likely to remain off medication for up to 56 weeks as were the controls assigned to no-diet intervention, after adjusting for covariates. Within the sodium-restriction group approximately 60% of 131 people were Intervention Successes (IS) (urinary sodium less than or equal to 100 mmol/day at 8 weeks). The rest were classed as Non-Intervention Successes (NIS). Of the IS group, 54% were responders (drug-free for at least 56 weeks), but about 56% of the NIS group also remained drug-free. Multiple logistics showed that no one factor was able to predict response among the IS. We conclude that the IS likely to respond to sodium reduction are not readily identifiable a priori. Furthermore, since both IS and NIS showed similar blood-pressure effects from the sodium-restriction regimen compared with controls, the questions arise: whether a factor other than sodium reduction affects the blood pressure response for the sodium-restriction group; or whether the measurement of sodium intake and excretion is sufficiently precise to distinguish compliers from non-compliers.
Longitudinal population studies have consistently demonstrated an association between sedentary lifestyles and the incidence of coronary artery disease (CAD). Diverse lines of evidence from clinical and experimental studies further implicate physical inactivity as an important risk factor for CAD. The relation between physical inactivity and CAD appears to be curvilinear and independent of other major risk factors, but of lower magnitude. Several training-induced physiologic adaptations offer plausible mechanisms for the protective effects of physical activity. Extrapolation from available data indicates that exercise must be habitual, vigorous and continuous to provide protection from CAD. However, the observed association between inactivity and CAD could represent several hypotheses other than cause and effect. The need for an appropriately designed clinical trial is apparent, but such an endeavor is not feasible at present. Until more rigorous scientific data are available, judgment on the use of exercise in prevention of CAD must necessarily be based on the accumulation of evidence supporting the role of physical activity. The rationale for exercise in preventing the occurrence of CAD is reviewed.
This study asks whether prolonged antihypertensive therapy will "cure" a substantial percent of rigorously treated hypertensive patients and whether nutritional change will add an antihypertensive effect and reduce the relapse rate. Of 584 eligible patients normotensive while receiving therapy, 496 were randomized into control and discontinued-medication groups with and without dietary intervention. At 56 weeks, 50% of those who were no longer receiving medication remained normotensive by study criteria. Randomization either to weight-loss group (mean loss of 4.5 kg [10 lb]) or to sodium-restriction group (mean reduction of 40 mEq/day) increased the likelihood of remaining without drug therapy, with an adjusted odds ratio of 2.17 for the sodium group and 3.43 for the weight group. Highest success rates were in the nonoverweight mild hypertensives with sodium restriction (78%) and the overweight mild hypertensives who were reducing their weight (72%). These data demonstrate that weight loss or sodium restriction, in hypertensives controlled for five years, more than doubles success in withdrawal of drug therapy.
In the Hypertension Detection and Follow-up Program (HDFP), elevated blood pressure (BP) was treated by rigorous, stepped care (SC) therapy among half the participants, while the other half were referred to usual sources of care (referred care, RC). There was no program to reduce weight, however, some participants changed weight voluntarily over the first 2 yr, providing an opportunity to examine the role of weight change in the development of diuretic-induced hyperuricemia, hyperglycemia and hypercholesterolemia. There was a stepwise progression from decreased glucose, uric acid and cholesterol concentrations, and BP associated with maximum weight loss to increased values with maximum weight gain. In SC, systolic BP declined by 22.4% among weight-losers and by 17.1% among weight-gainers; in RC, it was 14.4 and 8.1%, respectively. The pattern in diastolic blood pressure and weight change was similar but not as marked. These findings suggest the potential importance of weight loss in enhancing effectiveness of antihypertensive drug treatment and attenuating increases in glucose, uric acid, and cholesterol associated with diuretic treatment of hypertension. The weight change analyses are based on postrandomization observations and do not reflect experimental changes.
Late survival and freedom from myocardial infarction were determined for 192 patients with coronary artery disease and depressed left ventricular ejection fraction at rest (less than or equal to 35%) determined by biplane angiography who were evaluated between 1970 and 1977. Seventy-seven patients had coronary artery bypass grafting and 115 patients were treated medically and were considered surgical candidates. The medical and surgical groups were comparable in all baseline characteristics examined except frequency of three vessel disease and angina pectoris, which occurred in a significantly greater percent of the surgically treated patients (p less than 0.01). Only three medically treated patients (2.6%) underwent coronary bypass grafting in the follow-up period. Seven year actuarial survival was 63% in the surgical and 34% in the medical group (p less than 0.001). Ninety-three percent of patients in the surgical group and 81% of those in the medical group were free of nonfatal myocardial infarction (p = 0.01), and 62 and 33%, respectively, were alive and free of myocardial infarction (p less than 0.001) at 7 years. Significant differences in survival favoring surgical treatment were observed for the subsets of patients with an ejection fraction of 25% or less (p = 0.0002) and 26 to 35% (p = 0.01), and for the subsets with three vessel coronary disease (p less than 0.001), normal left ventricular end-diastolic volume (less than or equal to 100 ml/m2) (p = 0.005) and elevated end-diastolic volume (greater than 100 ml/m2)(p = 0.001). After adjustment for other important prognostic variables, the type of treatment remained significant in predicting the relative risk (medical to surgical) of mortality at 5 and 7 years (2.58 and 2.12, respectively). These data corroborate the trends observed in several randomized trials of medical and surgical therapy in patients with abnormal left ventricular function. If hospital mortality for coronary artery bypass grafting is less than 5%, substantial benefit can be anticipated for the majority of patients with depressed ventricular function.
A Dietary Intervention Study of Hypertension (DISH) was undertaken to determine whether patients whose high blood pressure had been controlled pharmacologically for a period of more than 5 years could maintain that control with sodium restriction or weight reduction instead of drugs. Four hundred ninety-six patients, classified by degree of overweight, were randomly assigned into one of seven groups. Included were those who would be withdrawn from antihypertensive medication and receive intervention for either sodium restriction or weight reduction. After 8 weeks of intervention, an average reduction of 24-hour urinary sodium output from a baseline of 158 mEq to 106 mEq (p less than .001) and from 130 mEq to 96 mEq (p less than .01) was achieved for the overweight and nonoverweight groups, respectively. That decline was still maintained at 56 weeks. Dietary estimates, obtained by analysis of 3-day food records, underestimated urinary output by an average of 12%, with blacks more likely to underestimate than whites, and the overweight more likely to underestimate than the nonoverweight. An average 10-lb weight loss was achieved, with no difference between men and women. Weight declined for 32 weeks, then leveled off and was maintained up to 56 weeks, indicating that sodium intake modification can be accomplished faster than weight reduction. Modest sodium restriction and weight reduction are feasible and achievable in a free-living population and have a positive effect on control of hypertension.
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Patient characteristics, treatment choices, and long-term survival were examined to seek possible explanations for marked differences in the racial distribution among 6594 consecutive patients who underwent arteriography or coronary artery bypass grafting (CABG) from 1970 to 1978. Overall, the percentage of whites undergoing coronary arteriography was 96% compared with 4% of the blacks; only black females showed a secular increase in the relative percentage. Clinical manifestations and predisposing factors for coronary atherosclerosis differed little between the blacks and the whites in this population. Angina, as measured by the Rose Questionnaire, had the same clinical significance in blacks as in whites. Findings indicated that similar covariates of comparable strength appeared to be operative as indices for severity of coronary heart disease in both blacks and whites. On the basis of regression analyses, whites had approximately a three times greater chance of having two or more diseased vessels than did blacks after adjustment for multiple clinical characteristics and risk factors. After adjusting for pertinent variables, whites with three-vessel disease were two and a half times more likely to have CABG than blacks (42.5% vs 16.2%). However, differences in choice of initial therapy for whites and blacks with multiple-vessel disease were significant only in those older than 50 years. Except for older blacks who demonstrated a decreased survival rate when managed surgically, survival rates were similar for blacks and whites. Trends in the evaluation and clinical management of black populations with suspect coronary heart disease should further clarify these preliminary findings.
As part of the initial examination of individuals enrolled in the Hypertension Detection and Follow-Up Program, a standardized questionnaire to elicit symptoms of angina pectoris and myocardial infarction and to inquire about the clinical diagnosis of myocardial infarction was administered. Angina pectoris was more prevalent in black males than white males and more prevalent in black females than white females. In white and black males and in white females, baseline prevalence of angina was associated with an approximate doubling of the 5-year mortality. A positive Rose Questionnaire for myocardial infarction, a positive clinical history of myocardial infarction, or a positive ECG for myocardial infarction was also associated with increased mortality in all of the race-sex groups, with the exception of black females, in whom the ECG evidence of myocardial infarction at baseline was only modestly associated with mortality. The Rose Questionnaire evidence of myocardial infarction was actually associated with a lesser 5-year mortality. The higher prevalence of angina pectoris in black hypertensive males in the face of a high prevalence of hypertension in blacks suggests that the combination of coronary artery disease and hypertension is more of a health problem in black males than in white males. The situation in black females, however, is less clear. The 5-year incidence of myocardial infarction, positive ECG or history, or positive Rose Questionnaire was approximately equal in blacks and whites among the treated hypertensive patients.
To test the hypothesis that subtle changes in the resting electrocardiogram can have predictive value for subsequent cardiovascular disease, the authors evaluated serial electrocardiograms from a cohort of initially healthy men and related these to later development of ischemic heart disease. The cohort of 1056 men originally physically qualified for naval aviation were followed from 24-61 years of age between 1940 and 1977. Resting electrocardiograms were obtained at 24, 36, 42, and 54 years of age. Particular emphasis was directed to measurement of electrocardiographic intervals, amplitudes, and vectorial orientation. The potential effects of weight, blood pressure, and other major risk factors on electrocardiographic changes were controlled in analysis. At younger ages, the amplitude of the T wave in lead 2 and the change in P-R interval were predictive of cardiovascular disease. With aging of the cohort, more leftward orientation of the frontal plane QRS and T forces were predictive, as were the serial changes in the angle between QRS and T. When major risk factors (smoking, blood pressures, and serum cholesterol) were included in a predictive model, addition of electrocardiographic changes significantly improved prediction of ischemic heart disease. These subtle serial changes may be helpful to epidemiologists and clinical investigators in assessing risk of subsequent cardiovascular disease.
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Persons at any age can substantially improve their fitness for work and play through appropriate exercise training. Considerable evidence indicates that physical activity is valuable for weight control, modifying lipids and improving carbohydrate tolerance. Less rigorous scientific data are available for associated long-term blood pressure and psychological changes with habitual exercise. Strenuous physical activity most likely reduces the incidence of coronary heart disease and the detrimental impact of certain chronic diseases on health. Adverse effects may result from a training program, but the major concern is the susceptibility to cardiovascular events during and immediately after exertion. To achieve optimal benefits with minimal risk, exercise must be carefully prescribed within the context of overall health and training objectives. Taken altogether, a distinct rationale exists for regular vigorous exercise as an integral part of a personal health maintenance program.
The effect of dietary modification on continued blood pressure control after discontinuation of antihypertensive therapy has been studied. Participants who had been treated for 5 years in the Hypertension Detection and Follow-up Program were enrolled and randomly assigned to continue medication, discontinue medication with no dietary intervention, discontinue medication and reduce weight, discontinue medication and reduce sodium groups. Relapse of hypertension was slow, even without dietary modification. Both weight loss and sodium restriction slowed relapse. The severity of the hypertension and the number of drugs required for hypertension control had a marked effect on the rate of relapse. Relapse was slowest in the participants who had attained the lowest blood pressure on therapy.