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CORONARY ARTERY DISEASE


What is Coronary Artery Disease (CAD)?

Coronary artery disease (CAD) is the end result of the accumulation of atheromatous plaques within the walls of the coronary arteries (blood vessels) that supply the myocardium (the muscle of the heart) with oxygen and nutrients.


Coronary artery disease remains the leading cause of death in the developed world and is ranked second most common cause of mortality in Singapore. CAD is also the most common cause of sudden death in adults over 20 years of age.


While the symptoms and signs of coronary artery disease are noted in the advanced state of disease, most individuals with coronary artery disease show no evidence of disease for decades as the disease progresses before the first onset of symptoms, often in the form of a “sudden” heart attack, finally arises.


After decades of progression, some of these atheromatous plaques may rupture and (along with the activation of the blood clotting system) start limiting blood flow to the heart muscle.


Management of Coronary Artery Disease

The management of coronary artery disease can be divided into

(1) primary prevention of coronary artery disease.

(2) secondary prevention(definitive treatment of established coronary artery disease).


What is primary prevention of Coronary Artery Disease?

Primary prevention is the process to reduce cardiovascular risk factors before coronary artery disease develops.


Prevent/delay the onset of atherosclerosis (deposition of cholesterol) in the coronary arteries before it happens. (via healthy lifestyles). Slow the progression of atherosclerosis in the coronary arteries (if it is present sub-clinically as confirmed by carotid intimal thickness measurement by ultrasound or cardiac computer tomography). Stabilise cholesterol plaques in the coronary arteries so as to prevent the rupture of the plaques leading to heart attack and potential sudden death.


What is secondary prevention of Coronary Artery Disease?Secondary prevention is the process to reduce future risk of CAD exacerbation after clinically significant coronary artery disease has already been diagnosed. Definitive treatment of existing coronary artery disease (either via lifestyle changes, medications or coronary artery treatment such as angioplasty or bypass operation)


Aggressive cardiovascular risk factors control (More intensive control of various risk factors is required in view of higher risk of future disease occurrence)


What are the common risk factors that contribute towards development of coronary artery disease?

  • Age

  • Male

  • Family History Modifiable Hypertension

  • Hyperlipidaemia (especially ↑ cholesterol)

  • Diabetes Mellitus

  • Smoking

  • Type A personality

  • Obesity


How to control the coronary artery disease risk factors?

1) Cholesterol control

If a person had never had coronary artery disease, the goal (primary prevention) is to try to achieve a total blood cholesterol level of below 200 mg/dL or an LDL level (the bad cholesterol) of between 100 – 130 mg/dL.

Once there is confirmation of coronary artery disease and especially with other added risk factors (secondary prevention), then the total cholesterol level should drop below 180 mg/dL and preferably below 160 mg/dL and a surrogate LDL level of below 100 mg/dL and preferably below 80 mg/dL in the very high risk groups. (Based on the Singapore Lipid guidelines). This can be achieved with a combination use of dietary therapy and lipid-lowering drugs (eg. statins).


2) Dietary therapy

Basically a healthy diet would include the following:- Consume a diet rich in vegetables and fruits, whole grains, low-fat and non-fat dairy products, legumes, fish (at least 2 times per week) and lean meat, coupled with food choices that minimize in-takes of excess energy, saturated fat, trans fat, cholesterol and salt.Note the importance of focusing on the overall diet quality (dietary pattern) rather than individual foods and nutrients, balancing energy intake and expenditure, engaging in regular physical activity and increasing the importance of selecting a healthy diet program when eating outside of home is of paramount importance if one’s wish is to be successful in reducing his or her blood cholesterol through diet modification.


Overweight / Obesity

The next risk factor to modify is the weight. Obviously if one is overweight or is obese, there will be a need to reduce weight. The key to weight reduction is to reduce the number of calories taken to match the physical activity of the individual. One also needs to engage in regular physical exercise to try and burn off the excess calories and reach an ideal body weight.


Aim to keep BMI (body mass index) below 23 kg/m² (healthy range 18.5 – 22.9 kg/m² – source; Health Promotion Board).


3) High blood pressureBlood pressure is another important risk factor that should be controlled to prevent coronary artery disease. Blood pressure should be kept below 130/80 mmHg and again a diet low in salt will be a good start. This couple with increased regular physical activities can reduce your blood pressure. Controlling the amount of work stress, alcohol intake and smoking, all contribute towards successful control of high blood pressure.


Diabetes Mellitus

Aim to avoid diet high in carbohydrates and a HBA1C ≤ 6.0%.4) SmokingIf one is smoking then one should stop smoking and also avoid the use and exposure of tobacco products. To summarize, the American Heart Association had come up with a summary of the diet and lifestyle goals for cardiovascular disease risk reduction in 2006. These are very good points to note and to try and achieve a heart healthy lifestyle and nutrition pattern and also would result in minimizing the development of obesity and diabetes mellitus as well as establishing life long healthy dietary habits.


AHA 2006 Diet and Lifestyle Goals for Cardiovascular Disease Risk Reduction

  • Consume on overall healthy diet

  • Aim for a healthy body weightAim for recommended levels of low-density lipoprotein cholesterol, high-density lipoprotein, and triglycerides

  • Aim for a normal blood pressureAim for a normal glucose level

  • Be physically active

  • Avoid use of and exposure to tobacco products.


Definitive Treatment of Coronary Artery Disease

The definitive treatment of established coronary artery disease would include initially cardiac medications that will improve the blood flow to the muscles of the heart and also to stabilize the cholesterol plaques within the coronary arteries.


Cardiac medications

The recommendations for primary prevention (risk factors control) will apply as the back bone of the treatment. Then comes the use of cardiovascular medications and this will usually include the use of:Anti-platelet agents (either Aspirin or Clopidogrel) to prevent platelet adhesion (in other words to ‘thin the blood’).


Beta-blockers (to slow the heart rate thereby reducing oxygen requirement by the heart muscle)Nitrates (to dilate the coronary arteries so as to maximize the blood flow to myocardium i.e muscles of the heart)Statins (to achieve the targeted LDL level of below 100 mg/dL and preferably below 80 mg/dL in very high risk patients. ACE inhibitor or Angiotensin Receptor Blocker (ARB) (to normalize the blood pressure and confer protection to the brain, heart and kidneys by blocking the action of an adverse hormone in the blood which is called angiotensin II which when in excess, can cause high blood pressure and heart failure. It also prevents new onset diabetes mellitus). The definitive treatment for coronary artery disease if it is shown to be severe and patient has symptomatic chest pain (angina) despite medications would be either to undergo a coronary artery bypass surgery or angioplasty / stent.


Prevention is better than Cure

One would have to understand that the treatment of coronary artery disease is a life long treatment and cannot be stopped as the process of coronary artery disease is a progressive disease life long and has to be managed therefore on a long term basis. However once treatment has been instituted and the patient has been stabilized the lifestyle modifications and the oral medications would in most instances be sufficient to prolong the life of the patient as well as to keep the patient symptom free from angina.


Although improved treatment for heart disease is saving more lives, about half of all deaths occur before there is time to start treatment. Thus treatment no matter how sophisticated it may become, it is not the ideal solution of reducing deaths from heart disease.


Preventing heart attacks by reducing coronary risk factors undoubtly can save lives and therefore modifying your risk factors can be thought of as preventive maintenance.



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