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Beta-blockers: primary and secondary prevention
1Royal Brompton, National Heart and Chest Hospital, Cheshire, England.
Insights
Beta-blockers are highly effective for secondary prevention of myocardial infarction and moderately effective for primary prevention in hypertensive men under 65. Early and later interventions with beta-blockers significantly reduce cardiovascular mortality.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Coronary heart disease is a leading cause of death in industrialized nations.
- Syndrome X, characterized by hypertension, obesity, lipid disturbances, and insulin resistance, is common.
- Beta-blockers show significant efficacy in secondary myocardial infarction prevention, unlike calcium antagonists.
Purpose of the Study:
- To evaluate the effectiveness of beta-blockers in secondary and primary prevention of myocardial infarction.
- To compare beta-blocker efficacy with other drug classes like calcium antagonists and diuretics.
- To assess the impact of timing, formulation, and patient demographics on beta-blocker outcomes.
Main Methods:
- Review of studies on beta-blocker use in myocardial infarction and hypertension.
- Analysis of early (intravenous) and late (oral) beta-blocker interventions.
- Comparison of beta-blockers with calcium antagonists, diuretics, and ISA-containing beta-blockers.
- Examination of hydrophilicity/lipophilicity and effects in different age groups and risk profiles.
Main Results:
- Early intravenous beta-blockers reduced cardiovascular mortality by 15% at 1 week.
- Late oral non-ISA beta-blockers reduced mortality by 30% at 1 year.
- Beta-blockers are first-line for hypertensive patients <65, especially men, reducing Q-wave MI.
- In elderly hypertensives, diuretics were more effective for MI prevention than beta-blockers, though beta-blockers are indicated for overt ischemia.
Conclusions:
- Beta-blockers are crucial for secondary myocardial infarction prevention.
- They offer moderate primary prevention benefits in younger hypertensive men.
- Treatment strategies should be tailored based on patient age, risk factors, and presence of ischemia.
Abstract:
Coronary heart disease is the most frequent cause of death in Western, industrialized countries. Coronary risk factors are prevalent in such countries and sometimes combine to constitute the so-called syndrome X--hypertension, central obesity, serum lipid and clotting disturbances, and insulin resistance. beta-Blockers, unlike calcium antagonists, have proved highly effective in secondary prevention of myocardial infarction. If present at the time of the myocardial infarction, beta-blockers (unlike calcium antagonists and diuretics) probably decrease mortality 1 month later. Early intervention (within 12 h) of chest pain with intravenous beta-blockers results in a 15% reduction in cardiovascular mortality at 1 week. Later intervention (3-28 days) with oral non-ISA beta-blockers results in a 30% reduction in mortality after 1 year; ISA-containing beta-blockers are probably less effective (less decrease in heart rate). Hydrophilicity/lipophilicity of beta-blockers is unimportant in terms of decreased mortality. Primary prevention of myocardial infarction, unlike stroke, in hypertensive patients has been disappointing, possibly due to treatment-induced biochemical/lipid changes or inappropriate lowering of diastolic blood pressure in high-risk subjects (J-curve effect). beta-Blockers should be first-line therapy for hypertensive patients up to the age of 65 years, particularly men (and nonsmokers) as Q-wave myocardial infarction is significantly decreased by beta-blockers and significantly increased by diuretics. However, in elderly hypertensive subjects, beta-blockers have not significantly decreased myocardial infarction (unlike stroke), whereas diuretics have. The effects of beta-blockers and diuretics on heart size (and thus coronary flow reserve) in the elderly may be important. Thus, beta-blockers should be second-line therapy for the elderly hypertensive individual but first-line if overt ischemia (e.g., angina or recent myocardial infarction) also is present. In patients with angina but normal blood pressure, beta-blockers tend to decrease and calcium antagonists increase cardiovascular events. Thus, beta-blockers are highly effective agents in the secondary prevention of myocardial infarction and are moderately effective in primary prevention of myocardial infarction in hypertensive patients (particularly men) under the age of 65 years.