Coronary Artery Disease: Early Detection and Early Prevention

12 July 2019

Dr Kim Tan, Consultant Cardiologist

 

The heart’s major role is to deliver oxygen filled blood to all the organs of the body to ensure their survival and normal function. The heart is an organ that is made up of muscle cells and therefore also requires oxygen filled blood for it to function normally. The heart is made up of many components and disease processes can affect each of them e.g. disease affecting the valves, muscle, electrical rhythm, and coronary arteries. The most devastating of these conditions is unquestionably coronary artery disease, which is now the leading cause of mortality in Malaysia.

Coronary artery disease is caused by narrowing of the arteries that supply oxygen filled blood to the heart, of which there are three, namely left anterior descending artery, circumflex artery, and right coronary artery. The disease process begins by damage of the inner lining of the arteries resulting in deposition of cholesterol, white cells, and other material in the wall. Damage of the inner lining of the arteries is initiated by the presence of multiple predisposing risk factors such as hypertension, high cholesterol, diabetes, smoking, obesity, sedentary lifestyle, stress, and genetic predisposition.

Prevention of heart disease can be achieved by:-

  • understanding the symptoms and what they indicate so that prompt action can be taken, and
  • ensuring a regular checkup and prompt treatment.

Mild to moderate blockage of the arteries produce no symptoms. More severe blockage (>70%) causes angina pectoris (chest pain) and breathlessness usually brought on by exertion and relieved by rest. Sudden complete occlusion of the arteries cause a heart attack, the most feared presentation of coronary artery disease. Heart attack can result in sudden death, heart failure, irregularity of heart rhythm, perforation of the heart muscle, and formation of aneurysm.

Regular checkups can allow the disease to be diagnosed early before any of the above complications can have a chance to manifest. One cannot rely on symptoms to indicate the presence or absence of coronary artery disease since the onset of angina pectoris signifies the presence of a severe blockage whereas mild to moderate blockage produces no symptoms. However, most of the investigations performed in hospital to diagnose coronary artery disease have their limitations in that they only become positive or abnormal if damage of the heart muscle has already occurred (ECG, CXR, Echocardiogram) or if the blockage is already >70% (stress test, nuclear scan, or stress echocardiogram). In a sense, these non-invasive investigations can only detect coronary artery disease when it is already at an advanced stage. To make matters worse, the catastrophic complications of coronary artery disease, namely sudden death and heart attack frequently occur in the very early stages of the disease process. In fact ¾ of all heart attacks occur in arteries that have a blockage that is <50%. Even invasive investigations such as coronary angiography do not allow one to detect these early collections of cholesterol plaques in the walls of the arteries.

In recent years, a major focus of the medical community has been to discover means to identify coronary artery disease at the earliest stages of development. One such technological breakthrough is the introduction of the Multidetector Computerized Tomography (MDCT) Scanner. This is the fastest scanner in the world with the ability to visualize the structure of the heart as if it is standing still. It is also the most accurate scanner with a resolution of 0.3mm. Using this technology, one is able to visualize early deposition of plaques in the walls of the arteries well before they are detectable by conventional non-invasive methods thus allowing early intervention and treatment. It also allows angiography to be performed non-invasively as an alternative to the invasive method to assess coronary blockages, bypass grafts and congenital abnormalities.

Management of coronary artery disease involves modifying the risk factors and taking medication to improve symptoms and reduce risk of heart attacks. Once arterial blockages have already become severe, coronary angioplasty and coronary artery bypass grafting should be performed to alleviate symptoms and to improve prognosis.

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