H. Emerson Thomas

SUDDEN CORONARY DEATH: THE FRAMINGHAM STUDY*

Sudden deaths abound in places with a high incidence of coronary heart disease. Epidemiologic studies agree that at least half of all coronary fatalities occur within 1 hour of onset of symptoms and that most occur outside the hospital. Most sudden deaths are unexpected and not preceded by symptoms of any duration or by overt coronary heart disease. The high rate of mortality from coronary heart disease can be substantially reduced only if sudden, unexpected coronary deaths can be prevented. Sudden death is now being studied seriously as an important feature of coronary heart disease. Epidemiologic studies have only recently shed some light on the natural history of this lethal manifestation of coronary heart disease.

The multiple risk factor intervention trial (MRFIT).: II. The development of the protocol

Abstract The detailed development of the MRFIT protocol is discussed, beginning with the general plan outlined by the National Heart and Lung Institute in the initial solicitation of contract proposals. The protocol is designed to test the hypothesis that lowering serum cholesterol by diet, reducing high blood pressure by diet and drugs, and cessation of cigarette smoking will result in a reduced risk of (a) death from coronary heart disease (CHD), (b) combined fatal CHD and nonfatal myocardial infarction, (c) deaths from all cardiovascular disease, and (d) death from all causes, over a period of 6 years among men aged 35–57 without initial evidence of CHD. After screening 361,662 men, from 1974 to early 1976, 12,866 from the upper end of the risk spectrum of CHD on the basis of serum cholesterol, blood pressure, and smoking habits, were randomly assigned either to a program of Special Intervention (SI) directed toward altering these risk factors or to their usual source of medical care (UC). Men in the UC group have been evaluated once each year in the clinic without direct intervention on the risk factors. Men in the SI group participated in an initial intensive series of group sessions designed to assist in modification of behavior relating to the three risk factors. The SI men have since been invited to the clinic at least three times each year to maintain and increase risk factor change. Changes in the intervention protocol have resulted mainly from difficulty in achieving the expected response in serum cholesterol. These changes have included greater emphasis on control of body weight, the recommendation of more rigorous dietary specifications for those with persistently elevated levels of serum cholesterol, and advice to increase physical activity.

Clinical-electrocardiographic correlates of newly acquired left bundle branch block: The Framingham study

To determine whether any associated electrocardiographic findings in persons with newly acquired complete left bundle branch block (LBBB) correlate with the prevalence of associated clinically apparent cardiovascular abnormalities, electrocardiograms (ECGs) from all 55 members of the Framingham Study cohort in whom LBBB developed during 18 years of routine prospective biennial examinations were reviewed. A QRS axis left of or equal to 0 degrees, left atrial conduction delay and an inverted T wave in lead V6 on the first ECG with LBBB, and an abnormal ECG in the Framingham examination preceding the appearance of LBBB each correlated with the prevalence of systemic hypertension, cardiomegaly, coronary heart disease and congestive heart failure. However, neither the PR interval nor the duration of the QRS complex on the first ECG with LBBB correlated with the prevalence of any of the associated cardiovascular abnormalities. The 8 patients with neither left atrial conduction delay nor a QRS axis left of or equal to 0 degrees on the first Framingham ECG with LBBB nor an abnormal ECG on the examination preceding the appearance of LBBB were 6 times more likely to remain free of all of the clinical cardiovascular abnormalities than the 47 patients with 1 or more of these 3 electrocardiographic findings (p less than 0.001).

Prevention of myocardial infarction

The possible methods of preventing myocardial infarction have been discussed. The desirability of prevention in the total problem of myocardial infarction is stressed. The methods consist of the prevention of the underlying coronary atherosclerosis, and the secondary prevention of myocardial ischemia contributed by other factors than those presumed to relate to atherosclerosis. In the primary prevention of coronary atherosclerosis the two major risk factors are elevation of serum lipids and of blood pressure. The benefits to be achieved by reduction of elevation of both of these abnormalities are discussed. Both require a long-term approach starting as early in life as possible. The major methods of prevention or retardation of coronary ischemia irrespective of coronary artery disease involve discontinuance of cigarette-smoking and a program of increased physical activity. In addition, prevention or correction of polycythemia, anemia or hypercoagulability should be included. The use of oxygen, in higher percentage or at higher pressure than in the atmosphere, surgical intervention to improve the myocardial blood supply and pharmacologic agents to improve myocardial metabolism are also considered. Quantitation of the benefit of preventive programs is still impossible. Benefit from lowering blood lipids and blood pressure requires long-term therapy begun early in life. Discontinuance of cigarette smoking and increasing the amount of physical activity offer reasonable assurance of immediate benefit. So also does correction of hematologic abnormalities. Pharmacologic agents and surgery to improve coronary blood flow still require further evaluation.

Clinical Evaluation in the Normative Aging Study

Life expectancy is determined by disease development and the process of aging. Much is known about the significance of control of disease to the length of life, and changes in life expectancy have largely been the result of this disease control. Further alteration in the length of life will be greatly dependent on control of the aging process. Little is known about the biochemistry, physiology, genetic, environmental and other factors involved in aging as they relate to the human subject in a clinical setting. The Normative Aging Study is attempting to improve our definition of the clinical aging process. Through the prospective evaluation of a population previously determined to be normal the various factors resulting in aging may be described. Once recognized it is hoped that alteration of these factors might allow some control of the aging process.

Precordial T wave vectors in the detection of coronary heart disease. The Framingham study

Summary An anteriorly oriented precordial T wave vector manifested by a T wave amplitude in V 1 greater than that in V 6 (TV 1 >TV 6 ) has been reported to be a useful criterion for the detection of coronary heart disease in people with otherwise normal electrocardiograms. In an effort to confirm this observation, a prospective case-control study based on 518 subjects who developed clinical coronary heart disease while under observation by the Framingham Heart Study and 518 age- and sex-matched controls free from coronary heart disease was carried out. Analysis of electrocardiograms considered to be normal and obtained at routine biennial exams revealed that on the exam prior to the onset of clinical coronary heart disease there was no significant difference in the prevalence of TV 1 >TV 6 between people who subsequently went on to develop disease and the controls. Furthermore, no significant difference in the prevalence of TV 1 >TV 6 was noted between cases and controls on the first exam following the initial clinical manifestations of coronary heart disease. When studied prospectively in the general population, the data indicate that TV 1 >TV 6 in an otherwise normal electrocardiogram is not sufficiently specific a discriminator to be utilized as a reliable criterion for the detection of coronary heart disease.