What Causes CAD

A number of different conditions have been recognized as contributing to the development and progression of CAD, and are considered risk factors. A risk factor is a condition or situation that increases the likelihood of a certain outcome, such as developing a particular disease or condition. For example, cigarette smoking is a well-known risk factor for the development of lung cancer. Risk factors for the development of CAD include:

Hyperlipidemia: The term hyperlipidemia refers to elevated fat, or lipid, levels in the blood. The term lipid primarily refers to triglycerides and cholesterol. Different types of cholesterol are known, including low-density lipoproteins (LDL) and high-density lipoproteins (HDL), among other types. LDL is often referred to as "bad cholesterol," and higher LDL levels have been associated with development and progression of CAD when levels equal to or greater than 130 mg/dl. In contrast, HDL is often referred to as "good cholesterol," because HDL levels greater than 40 mg/dl (men) or 50 mg/dl (women) are associated with a decreased risk of CAD. Total cholesterol and triglyceride levels less than 200 mg/dl are considered desirable for decreasing the risk for CAD.

Hypertension: Hypertension, or high blood pressure, represents elevated blood pressure, usually measured in millimeters of mercury. Hypertension is often considered present when the systolic/diastolic blood pressure is greater than 140/90. However, it is known that increased rates of development of and complications related to CAD occur at blood pressures lower than 140/90, and therefore CAD treatment and prevention strategies often target decreasing the blood pressure well below this level.

Diabetes Mellitus: Diabetes mellitus (DM) is a metabolic disorder characterized by elevated blood sugar levels which result from either low levels of the hormone insulin or resistance to the effects of insulin. The classic symptoms of DM include excessive thirst and fluid intake (polydipsia), excessive urine production (polyuria), and blurry vision. DM results in accelerated coronary artery atherosclerosis.

Tobacco Use: Use of tobacco increases the risk for development of CAD, but cessation of tobacco use results in a rapid decrease in this elevated risk. Smoking is known to increase processes that promote blood clotting and also decreases HDL levels.

Family History of Heart Disease: A family history of heart disease is considered present if a close relative has been diagnosed with "early" heart disease. For example, if your father or brother was diagnosed before age 55 or your mother or sister was diagnosed with heart disease before age 65, then your family history would be considered positive for early heart disease and place you at higher risk for CAD.

Advancing Age: Age is a major risk factor for the development of CAD, probably the strongest of all CAD risk factors. Also, older patients with CAD tend to have higher rates of death from CAD than younger patients, and also tend to have more problems with interventions used to treat CAD.

Other Risk Factors: Other risk factors include obesity and sedentary lifestyle. Stress is also considered a risk factor for CAD. Men tend to have greater rates of CAD than women, although women "catch up" to men about 10 years after menopause.

Newly Recognized Risk Factors: A number of blood laboratory values are now recognized as risk factors for the development of CAD. These include C-reactive protein, homocysteine, fibrinogen, high iron levels, and possibly lipoprotein (a) levels. Whether or not these risk factors are potentially modifiable is unclear.