I. Drug Treatment
Anti anginal drugs – These drugs are used to relieve symptoms of angina and to minimise the frequency of anginal attacks. Four groups of drugs are being used for this purpose – nitrates, beta receptor blockers, calcium channel blockers and potassium channel openers.
A. Treatment of acute episodes – Sublingual glyceryl trinitrate (GTN ) or nitroglycerin is the drug of choice to relieve the symptoms. Sublingual isosorbide dinitrate can also be used for this purpose. It usually relieves the symptoms within 2 to 3 minutes, and if it fails the drug may be repeated after 5 minutes (maximum three doses). This drug can be taken as tablet or oral spray. Headache or pulsatile feeling in the head is the most common side-effect of this drug and can be avoided by spitting the undisolved tablet as soon as symptom is relieved. It may also cause lowering of blood pressure. Nitroglycerine tablets deteriorate rapidly as soon as they come in contact with the atmosphere and sunlight. Therefore, the opened bottle should be replaced every two months. An effective drug produces a slight burning sensation at the sublingual site (below the tongue).
Intravenous nitroglycerine is useful in treatment of unstable angina.
B. Prevention of anginal episodes – Long acting drugs are used for prevention of angina. Sublingual nitroglycerine can be taken before events which is likely to precipitate anginal attacks.
- These drugs causes systemic vasodilatation and reduce the workload of the heart, leading to decreased oxygen demand of the heart muscles as well as dilatation of coronary arteries. This leads to improved blood flow and oxygen supply.
- A Nitroglycerine transdermal patch, oral isosorbide dinitrate and oral isosorbide mononitrate may also be used. Sustained release oral preparations have a longer-lasting effectivity.
- Side-effects – Headache (may diminish with continuous use), flushing, dizziness, palpitation, sweating and fainting.
Beta blocker drugs
- Beta blocker drugs decrease the oxygen demand by reducing the heart rate, myocardial (heart muscle) contractility and blood pressure.
- Propranolol and nadolol are nonselective (acting on various parts of body) beta blockers whereas atenolol, metoprolol, bisoprolol are cardio selective (acting selectively on the heart) and are better tolerated.
- These drugs can precipitate asthma in susceptible individuals and can mask hypoglycemic (low blood sugar) symptoms in diabetics.
- These drugs may aggravate or precipitate heart failure in patients with left ventricular dysfunction.
- When beta blocker drugs are to be stopped, they should be withdrawn gradually. Abrupt withdrawal can lead to cardiac arrhythmia (disturbed heart rhythm), worsening of angina or heart attack.
- Side effects – Bradycardia (decreased heart rate), fatigue, cold hands and feet, impotency.
Calcium channel blockers
- Nifedipine, amlodipine, diltiazem, verapamil cause coronary vasodilatation (improved blood flow) and reduce oxygen demand of the heart by reducing the blood pressure and myocardial (heart muscle) contractility. Diltiazem and verapamil decrease the heart rate as well.
- Like beta blockers, these drugs may aggravate or precipitate heart failure in patients with left ventricular dysfunction.
- Nifedipine, amlodipine can produce reflex increase in heart rate (tachycardia) and is best used in combination with beta blockers. They are unlike diltiazem and verapamil which cause brady- cardia (decreased heart rate) and make it necesary for this combination to be avoided.
- Side-effects – Flushing, headache, nausea (with all calcium channel blockers), tachycardia and ankle edema or swelling (with nifedipine, amlodipine), constipation, liver dysfunction and disturbed heart rhythm (with verapamil and diltiazem).
Potassium channel openers
- Nicorandil, pinacidil causes coronary as well as systemic vasodilatation (dilates blood vessels in various parts of the body) without having significant effect on cardiac contractility or conduction.
- Side-effects – Nausea, vomiting, flushing, headache, dizziness.
Low dose aspirin
- Low dose aspirin (75-300mg) prevents the formation of clot in the coronary artery which is responsible for acute events such as heart attack.
- Side-effects include dyspepsia (hyperacidity), allergy or gastrointestinal bleeding and precipitation of asthmatic attacks.
- Patients who can not take aspirin, may be recommended alternatives like ticlopidine and clopidogrel.
C. Treatment of unstable Angina – As the chances of heart attack is more in cases of unstable angina, affected patients should be hospitalised and kept on heparin or low molecular weight heparin in addition. Intravenous nitroglycerine is required for persistent chest pain.
II. Coronary revascularisation (reestablishment of obstructed blood flow): Coronary revascularization is an invasive procedure that is employed in a selected group of patients with angina. It is important to note that this is not a permanent cure for the basic problem (i.e. atherosclerosis) and one needs to take care of risk factors associated with atherosclerosis. However, the option of going through this procedure depends on the severity of the symptoms, the site of the block and ventricular function (ability to eject blood). Coronary revascularization is generally advocated in the following cases:
- Persistent symptoms in spite of adequate medical treatment.
- Unstable angina, with positive exercise ECG testing.
- Angina or severe ischemia in exercise testing after myocardial infarction (heart attack)
- Significant left main coronary artery block with or without symptoms.
- Significant obstruction of two vessels with compromised ventricular function (i.e. decreased ability to eject blood).
- When all the three main coronary arteries are involved and left ventricular function is compromised.
III. Taking Care Of Risk Factors
By taking care of risk factors one can reduce the chances of development and progression of coronary heart disease. Risk factors include:
- Smoking – It accelerates the process of atherosclerosis. Cessation of smoking leads to significant reduction in chances of heart attack and death in persons having coronary heart disease. The risk of coronary disease decreases substantially within one year of stopping smoking.
- Obesity – Obesity alone may increase the risk of adverse events substantially. It is also associated with other risk factors like hypertension and abnormal lipid profile (hyperlipidemia). So appropriate body weight needs to be maintained.
- Hyperlipidemia – Maintaining safe levels of lipids especially LDL (low density lipoproteins) and HDL (high density lipoproteins) cholesterol is very important in patients with coronary artery disease. Drugs known as statins (lovastatin, simvastatin, atorvastatin) are particularly effective in lowering LDL cholesterol level when combined with saturated fat restricted diet.
- Hypertension – Uncontrolled hypertension not only increases the risk of adverse incidents but also increases the oxygen demand of heart muscles by increasing the thickness of the heart muscle wall. Hypertension can be treated effectively by salt restriction, avoiding high alcohol intake, regular physical exercise, weight control and suitable antihypertensive drugs.
- Diabetes – Strict control of diabetes not only decreases the risk of angina and heart attack but also helps in lowering LDL cholesterol and triglyceride level (associated with diabetes).
- Sedentary life style – An individualised physical exercise programme not only reduces the body weight and blood pressure but also improves exercise tolerance to angina. It also increases the HDL cholesterol level.