Atherosclerosis (Main cause of Coronary Artery Disease)

The most common cause of coronary artery disease is atherosclerosis, sometimes referred to as “hardening of the arteries.” This is a disease of the inner lining of the heart’s arteries characterized by an accumulation of fatty or waxy substances such as cholesterol, proteins, carbohydrates, and a variety of other cellular and blood—related components (such as smooth muscle cells, white blood cells, and other blood constituents).

The build up of material is often referred to as atherosclerotic plaque. Close inspection of diseased arteries reveal a prominent “cap” covering the plaque. Over time, the plaque may increase in size as well as undergo structural changes. This buildup of plaque can eventually restrict the flow of blood to the heart muscle causing pain upon exertion (angina) or the plaque may contribute to the formation of a fresh blood clot blocking blood flow, leading to a heart attack.

If a portion of the cap cracks or ruptures, the plaque material underneath the cap begins to leak out into the blood flowing within the artery. Blood constituents especially platelets then begin to react to this exposed plaque material and eventually a fresh blot clot can form. The new blood clot obstructs or blocks the flow of oxygen-rich blood to the heart muscle, leading to angina and a possible heart attack.

Smaller plaques occupying a small percentage of the total arterial diameter (e.g., less than 30%) may be less stable than larger, older plaques (e.g., 90% of the arterial diameter), and these smaller plaques may be more likely to rupture, leading to the formation of a fresh blood clot. This may explain why a person who successfully completes a maximal exercise test without any signs of heart blockage (no symptoms or electrocardiographic changes) may experience a heart attack a few days or weeks later. This kind of patient likely had small coronary artery blockage but the unstable plaque for some reason has cracked or ruptured.

Fortunately, if medical intervention such as the use of clot busters is initiated shortly after the formation of a new coronary artery blood clot, the clot can be dissolved, restoring the flow of blood and oxygen to the heart muscle and largely preventing permanent heart muscle damage. The sooner the treatment for a heart attack is started, the less the heart muscle damage.

Keep in mind coronary heart disease is the result of a number of lifestyle and environmental factors superimposed on a genetic predisposition. Even though genetic tendencies for coronary heart disease may exist in an individual, the control of environmental and lifestyle influences can significantly slow or even reverse coronary heart disease. In addition, positive lifestyle habits such as regular physical activity and a healthy diet may have a favorable influence on plaque stability.

Risk Factors for Coronary artery disease (CAD) “Who is At Risk?”

Risk factors for CAD can be divided into irreversible factors (those cannot be changed or modified) or reversible factors (Can be modified, changed or treated).

Irreversible Risk factors (cannot be modified):

1. Heredity: lot of complex genes share in the development of CAD as well as associated diseases as hypertension and obesity.
2. Aging: the risk of CAD and heart attacks increases with age especially after 65 years.
3. Male Sex: Unfortunately, this cannot be modified.
4. Ethnic background: African Americans and Hispanics are more prone to CAD than white Americans.

Reversible Risk factors (can be modified):

1. Smoking: 2 packs of cigarettes per day double the risk of having a heart attack compared to non smokers.
2. High blood pressure or hypertension.
3. Physical inactivity and sedentary life.
4. High cholesterol level: an optimal LDL level is below 100 mg/dl. High risk level is between 160 and 189 mg/dl.
5. Obesity: risk of death from CAD in an obese patient is double or triple the normal.
6. Diabetes.
7. Alcohol and drugs
8. High triglycerides levels.