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Sudden death in men with increased risk of myocardial infarction. The MRFIT Programme
Insights
The Multiple Risk Factor Intervention Trial (MRFIT) found no overall difference in heart attack deaths between special intervention and usual care groups. However, high-risk men with electrocardiogram abnormalities saw more heart attack deaths with special intervention.
Area of Science:
- Cardiovascular Disease Prevention
- Clinical Trials
- Public Health
Background:
- Coronary Heart Disease (CHD) poses a significant risk to middle-aged men.
- Identifying and intervening in high-risk populations is crucial for cardiovascular health.
- The Multiple Risk Factor Intervention Trial (MRFIT) aimed to assess CHD prevention strategies.
Purpose of the Study:
- To evaluate the effectiveness of a special intervention (SI) program compared to usual care (UC) in preventing fatal first heart attacks.
- To determine if intensive risk factor modification reduces coronary heart disease mortality.
- To investigate differential effects of intervention based on baseline risk factors.
Main Methods:
- Randomized clinical trial involving screening of 361,662 men aged 35-57.
- 12,866 high-risk men (elevated cholesterol, blood pressure, smoking) randomized to SI or UC.
- SI group received intensive risk factor management, including pharmacological treatment for hypertension; UC group received standard medical care.
Main Results:
- No significant differences in overall CHD or all-cause mortality between SI and UC groups after 6-8 years.
- A subgroup of men with both diastolic blood pressure ≥ 90mm Hg and baseline electrocardiogram abnormalities showed an excess of CHD deaths in the SI group (36 vs 21).
- Sudden cardiac deaths were notably higher in the SI subgroup with these combined risk factors (20 vs 8).
Conclusions:
- Intensive multifactorial risk factor intervention did not reduce overall CHD mortality in high-risk men.
- The intervention may have been harmful in a specific subgroup with high blood pressure and electrocardiogram abnormalities.
- Further research is needed to understand the risks and benefits of intensive interventions in heterogeneous high-risk populations.
Abstract:
The Multiple Risk Factor Intervention Trial (MRFIT) was a randomised clinical trial of the preventability of fatal first heart attacks among middle-aged men at high risk of coronary heart disease (CHD). After screening 361,662 men aged 35 to 57 years, 12,866 men currently free of CHD at the upper end of the risk spectrum on the basis of their levels of serum cholesterol, diastolic blood pressure and cigarette smoking were randomised either to 'special intervention' (SI) or to 'usual care' (UC). Those SI men with a sustained diastolic blood pressure greater than or equal to 90mm Hg (following attempted weight loss, if indicated) received pharmacological treatment in the form of a protocol of 'stepped care'. UC men were referred to their usual source of medical care. At the termination of the study - after 6 to 8 years of intervention - no significant differences in overall deaths from CHD or from all causes were observed between the SI and UC groups. However, among the subgroup of individuals who had both a diastolic blood pressure greater than or equal to 90mm Hg and abnormalities of the resting electrocardiogram at baseline there was an excess of deaths from CHD in the SI group compared with the UC group (36 vs 21), and most of the excess deaths were sudden (20 vs 8).