By Dr Ananya Mandal, MD
Treatment of angina aims at three basic targets:
- reduction of symptom severity of the angina attacks
- reduction of frequency of attacks
- improving the underlying pathology to improve blood flow to the heart muscles
The third target aims at reducing the risk of fatal or non-fatal but severely debilitating heart attacks or strokes. 1-6
Three basic groups of treatment
Treatment may be outlined into three basic groups:
- Treatment that aims at immediate relief – Mainly drugs are used for this target achievement
- Treatment that reduces the frequency of attacks – Medications are the mainstay for this target as well
- Treatment that reduces the risk of heart attacks and strokes – Both medication and surgery may be sued to achieve this target
Treatment that aims at immediate relief
Glyceryl trinitrate (GTN) is the most common drug used for this purpose. It belongs to the class of Nitrates. There are various Nitrate preparations. These act by increasing the blood vessel diameter by relaxing the muscles of the vessel walls and relieve the obstruction reducing the symptoms of angina.
GTN may be given as a patch to be applied over the skin. Alternatively they are administered as a pill which is placed underneath the tongue for rapid absorption.
GTN usually eases the pain within two to three minutes. If the first dose does not work, a second dose can be taken after five minutes and a third dose after a further five minutes.
If GTN fails to relieve pain after 15 minutes, unstable angina should be suspected and patient should be moved for urgent medical help.
GTN may cause some headaches and dizziness. This occurs due to a fall in blood pressure due to widening of blood vessels of the head and whole body. Driving and operating heavy machinery should be avoided when GTN is taken.
Treatment that reduces the frequency of attacks
Several medications are available for this purpose. These include:
Calcium Channel Blockers (CCBs)
These act by relaxing the muscles that line the blood vessels of the heart and the body. In the heart they lead to easing up of the narrowed coronary arteries and thus reduce the frequency of attacks of angina. Drugs include Amlodipine, Nifedipine etc.
They may lead to side effects like dizziness (due to fall in blood pressure), edema of the feet, flushed face, headaches, and tiredness and skin rashes (due to allergies). These usually are relieved with use and do not require therapy.
These drugs are important for treatment of high blood pressure. They include drugs like Atenolol, Metoprolol etc. These act by reducing the blood pressure and heart rate. Both of these mechanisms reduce the oxygen requirement of the heart muscles and thus reduce the frequency of the angina attacks.
Common side effects include dizziness, tiredness, cold feet and hands, nausea etc. These are usually resolved with time. Older beta blockers like Propranolol may lead to exacerbation of symptoms of asthma and are not prescribed in angina.
These include drugs like Isosorbide mononitrate and Isosorbide dinitrate. These drugs also relax the blood vessels and improve blood flow to the heart and reduce the frequency of attacks. Their side effects are similar to GTN.
This is a newer agent used in angina routinely these days. This acts like beta blockers by slowing down the speed of the heart and reducing cardiac muscle oxygen demand.
Ivabradine may be used in patients who cannot use beta blockers. A common side effect of ivabradine is vision difficulties.
This drug acts by opening up tiny channels within the cells that transmit Potassium. This falls under a group Potassium channel activators. These have similar effects as CCBs and increase the blood flow to the heart.
These drugs may be used as an alternative to CCBs. Side effects include dizziness and headaches that are resolved with long term usage.
This relaxes the heart muscles and improves the blood flow to reduce the frequency of angina attacks. Ranolazine use is associated with weakness, dizziness and constipation.
Many patients are managed with single drugs while some may require combination therapy for better efficacy. When symptoms fail to ease with two drug groups, patient may be recommended for surgery.
Treatment that reduces the risk of heart attacks and strokes
Treatments that reduce the risk of heart attacks and strokes include:
Drugs that lower the bad cholesterol include statins. Over long term these drugs like Atorvastatin, Pravastatin, Lovastatin, Rosuvastatin etc. help prevent atherosclerosis of the coronary arteries. These act by blocking an enzyme in the liver that is essential for production of cholesterol.
Side effects of statin use are liver damage, muscle aches and pains etc.
These include Aspirin in low doses. These agents reduce the propensity of platelets to form clots and obstruct the arteries as the atherosclerotic plaques rupture.
Aspirin in low dose (75 mg per day) reduces the risk of a heart attack in susceptible individuals. All angina patients especially those with unstable angina are prescribed low dose Aspirin.
Common side effects include stomach ulcer and indigestion. Patients who are unable to take Aspirin may be given other Antiplatelet agents like Clopidogrel.
Angiotensin-converting enzyme (ACE) inhibitors
These drugs are commonly used in high blood pressure patients and those with diabetes and high blood pressure. Over long term these drugs including Enalapril, Captopril, Lisinopril etc. help in reduction of cardiac muscle damage by the angina and reduce the risk of heart attacks.
Side effects include allergic reactions and cough. Pregnant women cannot take these drugs as they may damage the kidneys of the unborn fetus.
The two main types of surgical therapy include Coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI).
CABG involves taking a part of the blood vessels from the leg or another part of the body and creating a diversion channel for the blood to flow to the heart muscles.
PCI involves placing a tiny tube or mesh within the narrowed part of the artery to hold it open. This is called a stent.
Both PCI and CAGB are broadly similar in their effectiveness in treating angina and may prevent complications of angina. PCI, however, allows for shorter hospital stay and rapid recovery. However, PCI may increase the risk of a recurrence of obstruction.
CABG is thus preferred in diabetics, those over 65 and those with more than three blockage sites.
These include lifestyle changes like eating a healthy balanced diet with adequate fruits and vegetables and avoidance of smoking and excess alcohol.
Avoidance of red meat and fatty foods is important to lower bad cholesterol in blood. Keeping weight in control, regular physical exercise also keeps the heart healthy. Stress relief and relaxation is important as well.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)