Framingham Heart Study Population Research Articles

Have Long-term Benefits of Antihypertensive Therapy Been Underestimated?

The article by Sytkowski et al1 in this issue of Circulation provides an interesting analysis of secular trends of hypertension, antihypertensive therapy, cardiovascular complications, and overall mortality in the Framingham Heart Study population. Successive cohorts of men and women between the ages of 50 and 59 years were followed for a 20-year period beginning in either 1950, 1960, or 1970, thereby spanning the 40-year period during which the most important advances in the control of hypertension have been made. The authors suggest that the long-term benefits of the control of hypertension for cardiovascular disease (CVD) and total mortality may be much greater than those observed in prior shorter-term clinical trials. These secular trend data must be interpreted with caution because of the inability to control for certain variables that could have led to unknown selection bias. The treatment was not controlled, and major changes undoubtedly occurred in drug therapy during the 40 years of follow-up, during which several new classes of antihypertensive drugs became available. The diagnostic criteria for clinical end points changed as a result of new methods that provided greater specificity and earlier recognition of CVD. Secular trends occurred in other cardiovascular risk factors, such as serum cholesterol and smoking, and in overall cardiovascular mortality during the study period. The definitions used for hypertension (systolic pressure ≥160 mm Hg and/or diastolic pressure ≥95 mm Hg) and for its control (blood pressure <160/95 mm Hg) changed nationally during the period of study, and treatment was probably initiated in some of the patients at blood pressure levels <160/95 mm Hg. In addition, those who received antihypertensive therapy may have adopted healthier lifestyles. Furthermore, the attention focused on Framingham Study participants over the years may have enhanced their motivation to seek treatment for their abnormal cardiovascular risk factors. In fact, …

Prevention of embolism in atrial fibrillation

New York, NY 10029, USA. Cardiogenic thromboembolism is the mechanism responsible for upwards of 100 000 cases of ischaemic stroke annually among North Americans. Although fewer than the number caused by cerebrovascular diseases, these produce considerable disability and a cost of nearly a billion dollars annually for acute and convalescent care for stroke victims. Over half the strokes of cardiac origin occur in patients with atrial fibrillation, a relatively common cardiac rhythm disturbance with a prevalence of 21.5 per 1000 men and 17.1 per 1000 women in the Framingham Heart Study population. This and other epidemiologic studies have estimated the risk of stroke and systemic embolism associated with atrial fibrillation as five to six events per 100 patient-years, roughly five times the rate among comparable patients without this cardiac rhythm disturbance, and accumulating to a 35% lifetime risk of stroke for patients with atrial fibrillation. The risk appears related to age, such that among stroke victims over 85 years of age a history of atrial fibrillation can be found in nearly half. These strokes are typically devastating clinical events which leave survivors with lasting disability, but there is an additional incidence of subclinical ’silent’ strokes

Circadian variation in the incidence of sudden cardiac death in the framingham heart study population

To determine if sudden cardiac death shows circadian variation, the time of day of sudden cardiac deaths in the Framingham Heart Study was analyzed. Analysis was based on mortality data collected in a standardized manner for the past 38 years for each death among the 5,209 persons in the original cohort., The necessary assumptions about the cause and timing of unwitnessed deaths were made in a manner likely to diminish the possibility of detecting an increased incidence of sudden cardiac death during the morning. In the Framingham stydy, analyses using these assumptions reveal a significant circadian variation (p < 0.01) in occurrence of sudden cardiac death (n = 429), with a peak incidence from 7 to 9 Am and a decreased incidence from 9 AM to 1 PM. Risk of sudden cardiac death was at least 70% higher during the peak period than was the average risk during other times of the day. Further studies are needed to confirm this finding in other populations, to collect data regarding medications and to determine activity immediately before sudden cardiac death. Investigation of physiologic changes occurring during the period of increased incidence of sudden cardiac death may provide increased insight into its causes and suggest possible means of prevention.

Cardiovascular disease and multifactorial risk: Challenge of the 1980s

The natural history of the atherosclerotic cardiovascular diseases is reviewed in terms of the risk factor parameters in the Framingham Heart Study population over a period of 18 years. The author stresses the importance of a multifactorial approach to risk factor management. Two practical tools are offered for physician use. One is a precise number evaluation system that calculates risk by means of five parameters (total cholesterol, systolic blood pressure, absence or presence of diabetes mellitus, ECG evidence of left ventricular hypertrophy, and cigarette smoking) and a multiplier for high-density lipoprotein cholesterol. The other, a more general tool, is easily memorized and does not require attention to a set of tables, as does the number evaluation system. It is a categorical checklist that provides cutoff values for all risk factors as and aid in identifying those patients whose overall middle-value profile places them at high risk.

Obesity, very low density lipoproteins, and glucose intolerance over fourteen years: The Framingham Study.

A total of 5082 men and women in the Framingham Heart Study population who were free of any glucose abnormality and aged 33 to 67 years were followed prospectively over 14 years for the occurrence of glucose intolerance. The diagnosis of glucose intolerance was defined as developing documented hyperglycemia or being placed on justified treatment by a physician. The 14-year incidence was 6.7% in men and 5.5% in women. Multivariate analysis was used and future glucose intolerance in men and women was highly associated with casual blood glucose, Metropolitan Relative Weight and very low density lipoproteins at the baseline exam. Other factors showed only sex-specific or univariate associations. Obesity and lipoprotein abnormalities were shown to be independent markers in the prediction of future glucose intolerance.