Alcohol and coronary artery disease

Alcohol Health & Research World,  Summer, 1990  by Arthur L. Klatsky

• E-mail
• Print
• Link

To many people, admonished by their physicians to lose weight, stop smoking, or give up favorite foods to reduce the risk of heart attack, the saying that "everything one might enjoy in life is illegal, immoral, or bad for the heart" can seem all too true. Thus, when population studies in the 1970s and 1980s suggested that moderate drinkers were at lower risk for developing coronary artery disease (CAD) than abstainers and heavy drinkers, the notion that consuming light to moderate quantities of alcoholic beverages might provide some protection against heart attack came as surprising ness to the general public. Some people were pleased; others were dismayed at the possibility that a substance with many obviously harmful effects might have some beneficial effects, as well.

Although plausible hypothetical mechanisms through which alcohol might protect against coronary artery disease have surfaced (these are discussed below), the interpretation of the data from the population studies remains controversial. Some researchers believe that appearance of a lower risk of coronary artery disease among lighter drinkers results from statistical artifacts (results produced by the methods used to analyze the data rather than by the data themselves) and that it does not represent a protective effect of alcohol (Sahper et al. 1988).

Coronary artery disease is the most frequent cause of death in developed countries; as such, it has a great impact on public health. Although coronary artery disease is the most common form of carrdiovascular disease (it accounts for approximately two-thirds of the total cases of cardiovascular disease), the two are not synonymous. Heavier drinking is associated with forms of cardiovascular disease such as cardiomyopathy (Damage to the heart muscle) (Klastsky 1982; Regan 1984); hypertension (high blood pressure) (Klatsky 1990); hemorrhagic strokes (rupturing of blood vessels which leads to brain damage) (Donahue et al. 1986a; Stampfer et al. 1988a); and heart rhythm disturbances (Ettinger et al. 1978; Cohen et al. 1988). Lighter drinking is not associated clearly with these conditions (Klatsky et al. 1990), although it has been associated with a lower risk of coronary artery disease and of occlusive stroke (stroke due to blocked blood vessels, leading to brain damage) (Stampfer et al. 1988a; Klatsky et al. 1989). Thus, it cannot be stated that alcohol generally is "good for the heart" or "bad for the heart." Specific conditions and individual factors related to the risks of drinking must be considered for each person.

DEFINING CORONARY ARTERY

DISEASE

Coronary artery disease develops when lesions (areas of abnormal tissue) form in the major coronary arteries and impair the flow of blood to the heart muscle. The usual process is known as atherosclerotic narrowing, and it is characterized by a particular type of thickening and hardening of the medium-sized and large-sized arteries. The name of the lesion is derived from the Greek word "athera," meaning gruel or porridge. Atherosclerotic lesions are characterized by lipid (fat) deposits that develop into plaques that have soft cores. The arteries supplying blood to the heart muscle, brain, and lower extremities are especially prone to these lesions.

The clinical effects of atherosclerotic lesions derive from two characteristics of the plaques. First, plaques occupy space in the vessel, which can lead to narrowing of the blood vessels and chronically decreased blood flow to heart muscle cells. Second, plaques have thrombogenic (clotting) qualities, which can lead to acute occlusion of the involved arteries with correspondingly sudden clinical events, such as heart attack or death.

Risk Factors and Possible Predictors

Largely as a result of epidemiologic observations of large populations, researchers have established interrelated risk factors, believed to be causal, or traits that predispose individuals to develop coronary artery disease (Kannel et al. 1976). The risk factors are hypertension, unfavorable blood lipid levels (increased low-density lipoprotein and diminished high-density lipoprotein cholesterol), cigarette smoking, and hyperglycemia (high blood sugar). Other predictors--factors that predispose an individual to coronary artery disease--include male gender, a family history of coronary artery disease, and excess weight. These predictors may affect the development of coronary artery diseae independently, or they may operate substantially through interactions with the (presumed) causal risk factors. Thus, the causes of coronary artery disease are multiple, and the prevalence of coronary artery disease varies considerably among different population groups.

Clinical Aspects of Coronary Artery

Disease

There are three major clinical expressions of coronary artery disease. The first is a symptom of the disease known as angina pectoris; the second is acute myocardial infarction or "heart attack"; and the third is sudden death.