Angina refers to the chest pain resulting from the decrease in blood flow to the heart. Angina is the major symptom of coronary artery disease. The chest pain felt is usually described as a squeezing, pressure, heaviness or tightness on the chest. It can be an acute or a recurring condition. Chest pain due to angina can be confused with chest pains due to other conditions such as indigestion.
The worst complication due to angina is heart attack. It is important to seek medical attention when chest pain is not relieved within a few minutes or after taking antianginal medications.
Forms of angina:
- Stable angina or angina pectoris is the most common form of angina. It usually manifests during physical exertion so the occurrence of pain can be predicted. The heart needs a greater supply of blood during an activity, but the narrowed arteries restrict blood flow. It can also be triggered by emotional stress, cold temperature, heavy meals and smoking. The pain has similar characteristics to previous chest pains. It lasts for around five minutes or less and disappears with antianginal medication or rest.
- Unstable angina is a medical emergency that occurs even at rest. It happens unexpectedly and differently from the usual chest pains felt. It has a longer duration that can last even for 30 minutes and does not resolve with medications. This can lead to a heart attack if the blood flow remains blocked.
- Variant angina or Prinzmetal’s angina is due to a spasm in the coronary artery instead of a narrowing or blockage. This occurs even at rest, but can be relieved by antianginal medications.
- Microvascular angina occurs when there are spasms in smallest coronary artery blood vessels. The chest pain lasts for more than 10 minutes. It is felt during routine daily activities and mental stress.
- Angina decubitus occurs when a person is lying down. The fluids in the body are redistributed due to the gravity so there is extra effort on the heart.
Women typically have different symptoms from the usual angina symptoms. They can experience extreme fatigue or a stabbing pain instead of the chest pressure. The differences in symptoms lead to delay in seeking treatment.
Diagnosis of angina relies on the patient’s signs and symptoms and possible risk factors. Several tests confirm if the patient has angina. An electrocardiogram during or before a stress test is used to determine if the heart has changes in its electrical signals. An echocardiogram, coronary angiography or CT scan is done to determine the presence of narrowing or blockage of arteries and presence of heart damage.
Commonly Prescribed Drugs
- Nitrates are the major class of antianginal drugs. These drugs dilate the blood vessels which decreases the pressure and oxygen requirements of the heart. The absorption is fastest and most complete when administered sublingually. Nitroglycerin is given to relieve and prevent angina. It can be given 5 minutes before an activity that might cause angina. If angina is not relieved by rest and at most 3 tablets of nitroglycerin, the patient should immediately consult a physician. Other examples include isosorbide mononitrate and dinitrate. Use the minimum effective dose and allow the body to be kept free of nitrates for at least 8 hours daily. This will minimize the effects of tolerance or the reduced response with the drug. Side effects: pulsating feeling in the head, headache, dizziness upon standing up
- Beta blockers have greater effects on the heart during exercise than at rest. These agents inhibit increases in heart rate, blood pressure and contractility. It reduces the risk of heart attack and sudden death. Beta blockers should not be given to asthma patients and patients with history of mental depression. Usual examples include acebutolol, bisoprolol and metoprolol. Side effects: fatigue, slow heart rate, reduced ability to exercise
- Calcium channel blockers (CCBs) have similar effects with beta blockers during an angina attack. These are prescribed when beta blockers cannot be given, or have reduced or no effect. Variant or Prinzmetal’s angina benefits the most from CCBs. Examples include verapamil, diltiazem and amlodipine. Side effects: hypotension, headache, slow heart rate
- Antiplatelet drugs block platelets from sticking together. Aspirin reduces angina attacks even in patients with no symptoms of heart disease. However, long-term use of aspirin can lead to bleeding. Clopidogrel is used as a substitute if side effects from aspirin manifest.
- Potassium channel activators such as nicorandil dilates the coronary arteries to increase blood flow. These agents are considered as an alternative for CCBs. Side effects: dizziness, headache
- Ivabradine has the same effect as beta blockers, but its mechanism of action is different. This is considered an alternative for patient who cannot take beta blockers. Side effects: temporary flashes of brightness
- Ranolazine is given to patients that do not improve with any other medications. It relaxes the heart muscles to improve blood flow. Side effects: constipation, dizziness, weakness