Coronary artery disease affects almost 40% of the American population but only 1 out of 4 people experience any complications with symptoms. A large number of people do not even know they have coronary artery disease and are at risk of complications like a heart attack. Fortunately routine screening in high risk groups has been able to make many people aware of their coronary artery disease well before such complications arise. Unfortunately there is still millions of people who have no idea that they are walking around with a ticking time bomb that can be fatal.
What is coronary artery disease?
Coronary artery disease (CAD) is a condition where the arteries supplying the heart (coronary arteries) becomes narrow. The term coronary artery disease does not clearly indicate the problem of the underlying disease and therefore the term coronary artery atherosclerosis is a better choice. Atherosclerosis is a condition that can affect any artery by causing it to narrow due to the build up of fatty plaques in the artery wall. Due to this narrowing, less blood can reach the target organ. With regards to the coronary arteries, less blood is reaching the heart muscle.
Across the globe, coronary artery disease remains the number one cause of heart attacks. In the United States alone, coronary artery disease coronary artery disease is the number one cause of death among both men and women. It is responsible for 20% of all deaths among Americans. While it usually causes complications in people older than 40 years, the condition may start as early as childhood. Early lesions start shortly after birth, increase significantly between the age of 8 to 18 years and advanced lesions begin to appear around 25 years of age.
Coronary artery disease is also referred to at time as ischemic heart disease (IHD). The latter is where there is insufficient oxygen reaching the heart tissue leading to tissue damage. Therefore ischemic heart disease is the consequence of coronary artery disease. Both terms are often used interchangeably.
Causes of Coronary Artery Disease
The inner lining of the arteries is composed of a smooth endothelium. There are various factors that prevent blood cells from sticking to it unless there is an injury and a blood clot has to form to seal off the broken artery. In atherosclerosis some injury to this endothelium precipitates the process whereby the fatty plaques will form. Often it is factors such as hypertension (high blood pressure) which cause fluid sheer to this endothelium thereby injuring it.
Fat particles along with blood cells and other particles in the blood then aggregate at the site and an atherosclerotic plaque (atheroma) gradually forms in the wall of the artery. It grows in size over time taking about 10 to 15 years to reach full development. The larger the plaque the more the lumen of the artery is narrowed. In the early stages the narrowing is minor and does not restrict blood sufficiently to cause any symptoms. As the narrowing worsens, symptoms may not become evident during times of increased blood flow demand.
Even with major narrowing there may be no significant symptoms for people with an otherwise sedentary lifestyle. However there is a risk that a blood clot formed elsewhere in the body (embolus) may attempt to pass through this narrowed artery and block it. Alternatively the fatty plaque may rupture and a blood clot may then form at the site (thrombus). Whether it is a thrombus or an embolus, this cause sudden and severe occlusion of the artery thereby preventing blood from flowing to the target organ.
Without an adequate blood flow, the tissue requiring the oxygen and nutrients is injured. Eventually it dies off (infarction). In coronary artery disease this injury and eventual tissue death involves a portion of the heart. This condition is known as a heart attack or myocardial infarction.
Who is at risk?
Coronary artery disease can affect any person but it is more likely to occur in people with one or more of these risk factors.
The risk of coronary artery increases significantly with age. Older people are therefore at a much higher risk of complications. There is significant risk after the age of 40 years these days.
Men are at a significantly higher risk than women. However, after menopause and especially around 70 years of age the risk between men and women is somewhat equal.
A family history of coronary artery disease significantly increases the chance of first relatives developing it. Any person with either a parent or sibling with coronary artery disease is therefore considered to be high risk.
High Blood Pressure
Hypertension (high blood pressure) is one the main risk factors for coronary artery disease. The risk is significantly greater if hypertension is uncontrolled usually due to poor management.
High Blood Cholesterol
High blood cholesterol is another major risk factor for coronary artery disease. It is people with high levels of LDL cholesterol, also known as the “bad cholesterol”, that are significantly at risk.
Diabetes is a growing problem across the globe. It is known to increase he risk of many conditions, such as coronary artery disease. It may also be associated with high blood pressure, another major risk factor.
People who are overweight or obese are also at risk of coronary artery disease. Obesity also contributes to hypertension or diabetes which in turn increases the risk of coronary artery disease.
It is now well known that cigarette smoking can increase the risk of coronary artery disease. Cigarette smoking increases the risk between three and six times when comparing smokers to non-smokers.
The benefits of a proper exercise regimen is well known when it comes to cardiovascular health. Conversely a sedentary lifestyle can also contribute to coronary artery disease because it contributes to obesity and other conditions that increase the risk.
Another important factor is psychological stress. The exact mechanism by which it contributes to coronary artery disease is not fully understood although it is believed to be associated with the “stress hormones”.