Management of Coronary Artery Disease

Coronary artery disease is the leading cause of morbidity and mortality in the world, accounting for nearly 1 million of deaths each year in the United States. It is also the second commonest killer in Singapore accounting for nearly 25 per cent of annual mortality.

The disease is a result of progressive deposit of cholesterol and fatty deposits within the coronary arteries with resultant impairment in blood flow. When the fatty deposits, also called atherosclerotic plaque, rupture or have superficial erosions, blood clot form immediately and occlude the coronary blood flow, causing heart attack or acute myocardial infarction.

There are several risk factors for coronary artery disease and these can be broadly divided into modifiable and non-modifiable ones. The former include age, gender (males have higher incidence of heart attacks) and family history of coronary artery disease.

The non-modifiable risk factors include chronic smoking, high cholesterol level, diabetes mellitus and hypertension. Other causative risk factors include obesity, sedentary lifestyle and stress.

Presentation of Coronary Artery Disease

The early warning symptom of coronary artery disease is angina pectoris. Angina pectoris is described as a discomfort in the chest or adjacent areas associated with myocardial ischemia (insufficient oxygen delivery to the heart muscle).

It is generally precipitated by exertion or emotional stress and commonly relieved by rest. Angina is most commonly felt in front of the chest but can manifest exclusively in the jaw or neck, the left shoulder or arm.

However not all chest pain arises from myocardial ischemia. There are other conditions that may mimic angina.

These include musculoskeletal chest pain, reflux esophagitis and emotional stress. Hence cardiac investigations may need to be performed to provide an accurate diagnosis.

Cardiac Investigations

Electrocardiogram (ECG) at rest should be recorded in all patients with symptoms suggestive of angina pectoris. However, a normal resting ECG does not exclude severe coronary artery disease.

An ECG obtained during chest pain is only abnormal in about 50 per cent of patients with angina who have a normal rest ECG.

Exercise treadmill testing (Figure 1) is a well-established diagnostic tool for detecting the presence of coronary artery disease. It provides information on patient's symptomatic response, exercise capacity, hemodynamic and ECG response. The most important ECG findings are ST-segment depression and elevation. However, the overall sensitivity of treadmill exercise stress testing is 68 per cent and its predictability depends on the prevalence of the disease in the population under study.

Myocardial perfusion imaging (Figure 2) tests using radioactive isotopes such as thallium-201 and technetium-99m can be used as an alternative noninvasive test for assessing coronary reperfusion. In this technique, the radionuclide is injected at peak exercise and images of perfusion pattern are obtained at rest in comparison with those during stress. Defects detected on scintigraphy can represent either stress-induced impairment of blood flow or infarction.

Echocardiography allows visualisation of the left ventricle and serial recordings may detect wall motion abnormalities and enhance the yield of a treadmill exercise test. Stress echocardiography may be carried out by exercise on the treadmill or bicycle, or by infusion of dobutamine. The advantages of stress echocardiography compared to myocardial stress perfusion are higher specificity, more versatility in evaluating cardiac anatomy and function, and lower cost.

Stress perfusion imaging, on the other hand, has a higher technical success rate, higher sensitivity for single-vessel coronary disease and has more extensive published data on prognostication.

Selective coronary angiography (Figure 3), the invasive technique for imaging the arteries, remains the most definitive diagnostic investigation to define the anatomic extent and severity of coronary narrowings. It should be performed to establish the diagnosis of coronary artery disease in high-risk subjects or those in whom noninvasive tests are inconclusive.

Management of Coronary Artery Disease

The management strategy can be broadly divided into four aspects: (1) modification of specific risk factors; (2) lifestyle change; (3) specific pharmacologic therapy and (4) revascularisation by percutaneous transluminal angioplasty and coronary bypass operation.

Modification of risk factors must include smoking cessation, treatment of hypertension and diabetes mellitus and lowering of LDL-cholesterol.

The goals of pharmacologic therapy in the treatment of angina are relief of symptoms and improvement of exercise tolerance; and prolongation of survival. Symptomatic therapy will include nitrates, beta-blockers, calcium antagonists and metabolically active agents.

Drugs, which have been shown to prevent death or myocardial infarction, are antiplatelets, lipid-lowering drugs and angiotensin converting enzyme (ACE) inhibitors Coronary revascularisation refers to the reestablishment of blood flow in the coronary arteries and remains the mainstay of therapy.

There are two established approaches of coronary revascularisation, namely percutaneous coronary intervention with stent implantation, and coronary artery bypass grafting (CABG) in which segments of chest wall arteries or veins are used to reroute blood around the narrowed segment.

Percutaneous coronary intervention (PCI) remains the lesser invasive strategy with the procedure performed either via the femoral (groin) or radial (wrist) artery. It is performed under local anaesthesia with excellent safety and long-term efficacy outcomes. Most procedures of PCI are now performed with the implantation of coronary stents (Figure 4) which provide good 'scaffolding effect' and which are also able to deliver drugs locally to prevent 'renarrowing' of the vessel.

These drug-eluting stents have nearly completely eliminated the problem of restenosis associated with this procedure. In addition, there are effective drugs such as glycoprotein IIb/IIIa platelet receptor inhibitors that may be administered periprocedurally to improve the safety of the procedure. Intravascular ultrasound imaging is also available to check that the lesions are adequately covered and the stent properly deployed.

Coronary bypass surgery is an effective alternative treatment strategy for patients with coronary artery disease. It is best suited for patients with multi-vessel coronary artery disease, patients who are diabetes mellitus and have poor left ventricular function. The long-term patency of internal mammary artery graft may be up to 90 per cent in 10 years.


The management of patients with coronary artery disease depends upon a careful overall strategy of good history taking and physical examination, judicious choice of noninvasive tests and combined optimal medical and revascularisation therapies.

Q1. Who are The People Likely to Develop Coronary Artery Disease?

The typical patients who have coronary artery disease are middle-aged to elderly obese males with risk factors of smoking, high cholesterol level, diabetes mellitus and hypertension. Women are less likely to develop the condition until they reach menopause when they no longer enjoy the protection of their female hormones. However, young women who smoke and have diabetes mellitus are at equally high risk.

Q2. Are All Chest Pain From The Heart?

Angina pectoris, a symptom arising from inadequate blood supply to the heart muscles, is a unique experience frequently described as a 'choking' or 'suffocating' sensation which comes on whenever the patient exerts himself. The symptom is vague in location in the anterior chest and may spread to the jaw and upper limbs. It usually disappears when the patients rests himself. There are many other causes of chest pain such as muscle and bone aches, 'gastric' pains and emotional stress.

Patients who have symptoms of focal sharp chest pain lasting briefly for few seconds do not have angina pectoris.

Q3. What should I Do If I Have Chest Pain?

You should seek a medical consult with a doctor who will then assess your medical history and conduct a physical examination. He may then go on to order some tests to make sure you have no coronary artery disease, which is the most dangerous cause of all chest pain. These investigations may include a simple resting electrocardiogram (ECG) or a treadmill exercise stress. If these tests are inconclusive, he may go on to order a myocardial perfusion scan or stress echocardiographic examination. If he is very concerned with the possibility of coronary artery disease in you, he may perform a cardiac catheterisation procedure, called coronary angiography. This is the most accurate of all the cardiac investigations in determining the presence of coronary artery disease.

Q4. What Treatment Can I Expect If I Have Coronary Artery Disease?

This is a disease of bad lifestyle that requires a multi-pronged approach. Your doctor is likely to prescribe you medicine to prevent the occurrence of your symptom and possible heart attacks. He will also advise you to control your risk factors such as weight control, smoking cessation, exercise and control of your high blood cholesterol level, diabetes mellitus and hypertension. In the event that you have significant narrowing of your heart arteries, he may ask that you go for 'revascularisation treatment' which is to either open the blocked arteries by stenting or bypass the blockages in an operation called coronary bypass graft surgery (CABG).

Q5. What is Coronary Stenting?

In this procedure, the doctor will insert a small tube into your groin or wrist artery and tread to your heart arteries under X-ray guidance. A guidewire is first used to cross the narrowing and a coronary stent is then loaded onto the guidewire and deployed across the narrowing. The stents are metal scaffold that work by supporting the inner structure of the arteries hence preventing collapse of the vessel. This allows for normal blood flow to be established. However there is a risk of renarrowing of the vessel in 20 per cent to 30 per cent of patients within six months of the procedure, a phenomenon termed restenosis. This problem has however been overcome in recent times with the advent of drug-eluting stents, in which the stent surface is coated with drugs that can specifically prevent restenosis.

Q6. When Do I Need To Go For Coronary Bypass Surgery?

Coronary bypass surgery is reserved for patients with very severe coronary artery disease involving more than two or three vessels, diabetic patients and those with poor heart function. The surgery is safe with less than 1 per cent mortality risk in modern times and is associated with good long-term outcomes.

Diabetes has everything to do with Cardiovascular Health

Do you know that diabetes dramatically ups the likelihood of cardiovascular disease (CVD)? The facts are pretty startling: People with diabetes are two to four times more likely to have heart attacks, strokes and peripheral vascular disease-caused by fat build-up in arteries in the legs and arms.

Diabetes also causes nerve damage in the heart, making painless heart attacks more likely and harder to diagnose. These problems develop in both type 1 and type 2, because high glucose levels inflame the blood vessel walls, increase deposits of plaque, increase the tendency to form blood clots, raise blood pressure and trigger a range of problems in the arteries and in the smallest blood vessels. In addition, in type 2 diabetes, insulin resistance causes problems that lead to vascular and heart disease.

Fortunately, there is good news. According to the American Heart Association, making significant lifestyle changes can make a big difference in the development of cardiovascular complications.

Better Glucose Control

"One way to avoid diabetes-related heart disease is to maintain long term blood glucose control," says Kathy Berkowitz, CDE, past president of the American Association of Diabetes Education's. A new approach to glucose control is known as DAFNE (dose adjustment for normal eating). This allows you to match your insulin dosing to what you eat, instead of the other way around. The result is more control and better quality of life, according to a study in the British Medical Journal.

Rx for Cholesterol

Another way to reduce the risk of heart disease is to keep cholesterol levels under control. Drugs known as stations have been shown to work effectively and appear to be helpful to those with diabetes.

The five-year Heart Protection Study (HPS) round that people with diabetes who took 40 milligrams a day of the cholesterol-lowering drug simvastatin, cut the incidence of heart disease by about one-quarter to one-third.

Look to the Future

"Managing diabetes can be overwhelming," says Berkowitz, "but never give up. Ask for help from friends, family, your physicians and a diabetes educator. Your life and happiness depend on it."

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