Angina

Angina - What is angina?

Angina is a heart condition that is typically manifested as chest pain and is more of a symptom of an underlying condition than a disease in itself.

The pain in the chest is caused when the blood supply to the heart muscles of cardiac muscles falls short of the required amount. This occurs when the arteries that supply the heart become hardened and narrowed - a condition called arteriosclerosis.

Arteriosclerosis of the arteries that supply heart muscles called the coronary arteries thus gives rise to symptoms of chest pain termed angina. 1-4

What happens in angina?

Angina is manifested as a dull, aching, tightness or heavy weight like feeling over the chest. The pain may sometimes spread beyond the chest to the left arm, neck, jaw or back.

The pain more often than not is triggered by some vigorous physical activity or extreme emotional distress where in both cases the heart beats faster and the muscles require more blood supply than usual.

The arteriosclerosis of the coronary arteries restricts blood flow and there is a shortage of blood to the heart muscles leading to a pain that usually only lasts for a few minutes. This is typically called an angina attack.

Who is at risk of angina?

Angina is caused by arteriosclerosis or atherosclerosis that causes hardening and narrowing of the coronary arteries. This is seen commonly in smokers, obese and overweight individuals, those with diabetes, high blood cholesterol, advanced age etc.

In the United Kingdom, 8% men and 3% women between 55 and 64 years of age have or have had an attack of angina. Between 65 and 74 years the figures are 14% men and 8% women.

People of South Asian origin in the UK have an increased risk of this type of heart disease termed ischaemic heart disease. Black Caribbean people have a reduced risk compared with the overall UK population.

In both men and women the rate is significantly higher in lower socio-economic groups. Angina appears to be more common in men than women. Smoking in the past was significantly higher in men and this could be the reason for this gender difference in incidence.

What are different types of angina?

Angina may be of two types - stable angina and unstable angina.

Stable angina

Those with stable angina develop the symptoms gradually over time. The symptoms initially may begin after strenuous exercise or climbing stairs or running hard or even when in extreme mental stress.

Symptoms usually only last for a few minutes and can be improved by taking medication called glyceryl trinitrate. This type of angina usually does not prove to be fatal but may be a prelude to a heart attack or a stroke and mandates medical attention.

Unstable angina

This type of angina usually develops rapidly and the course is often unpredictable. Those with stable angina may go on to develop unstable angina. The symptoms of chest pain may last for around 30 minutes and may persist even when the patient is at rest. Glyceryl trinitrate may not help relieve the symptoms.

This type of angina is an emergency situation since the course of the angina is unpredictable and the heart function may rapidly deteriorate and this can increase the risk of stroke or a heart attack. This type of angina is treated with medications and surgical techniques.

How is angina treated?

Angina management aims to relieve the symptoms of an angina attack, reduce the number of angina attacks for the patient and also to prevent worsening of the condition by prevention of restricted blood supply to the heart as this could lead to a heart attack or a stroke.

Medication therapy is the first line of treatment. This includes arterial dilators that allow more blood flow like Nitrates and Calcium Channel blockers.

Surgical techniques are suggested for patients who do not respond to medications. Coronary angioplasty is one form of treatment that allows widening of a particularly narrowed section with a small tube or mesh like structure called a stent. The stent also holds the lumen of the artery open and prevents its collapse.

Another method is coronary artery bypass graft where a section of blood vessel is taken from another part of the body and this acts a as bypass to the narrowed artery to supply the heart muscles.

What could happen in angina patients?

Angina may lead to complications like stroke or heart attack. In fact, 1 in every 100 people with stable angina may go on to develop a fatal heart attack or stroke. A non-fatal heart attack or stroke may occur in 1 in 40 people with stable angina.

Causes of angina

Angina is manifested as a chest pain that may (in case of stable angina) or may not (in case of unstable type of angina) be brought about by physical exertion or mental stress. 1-5

Physiology of the heart and its blood vessels

The heart muscles work non-stop throughout life to contract and pump blood to the various organs of the body. As they are constantly in motion they require regular and adequate supply of oxygen-rich blood to function normally.

Blood to the heart muscles, called cardiac muscles, is supplied by two large blood vessels that are known as the left and right coronary arteries. These originate at the base of the largest artery that arises out of the left ventricle to supply all the organs of the body called the aorta.

Pathology of angina

When the heart beats faster or needs to pump harder like in cases of fear, emotional distress, stress, physical exertion etc. the blood supply to the heart rises along with the demand of the heart muscles for oxygen.

This increased demand thus, is usually met by the body. When this increased demand for oxygen rich blood is not met by the coronary arteries the heart muscles undergo a process called ischemic heart disease.

Types of angina

There are two types of angina – stable and unstable. In stable angina the symptoms of ischemia of the heart muscles, due to increase demand and reduced supply of blood, occurs when there coronary arteries become narrow and hardened by a process called atherosclerosis. This restricts the blood flow to the muscles of the heart.

When the heart is back at rest or if the person who has developed the attack of angina rests, the symptoms of chest pain gradually recede. This means that the relative discrepancy between supply and demand is met and removed at rest.

In patients with unstable angina the underlying cause is still atherosclerosis. Atherosclerosis leads to deposits of fatty tissues called plaques in the walls of the coronary arteries. These may break open or rupture and lead to clots of blood within the artery. This leads to obstruction of blood flow and symptoms of angina.

This type of angina may rapidly progress into a heart attack that is caused due to death of a large part of heart muscles due to ischemia and lack of oxygen rich blood supply.

Who is at risk of angina?

Angina (both Stable and Unstable types) are caused when any cause leads to narrowing of the coronary arteries. These may include hypertension, high blood cholesterol and so forth.

Hypertension or high blood pressure

Risk factors for high blood pressure include:

  • stress
  • obesity
  • lack of exercise
  • family history of high blood pressure
  • smoking

Hypertension is more common in people of Afro-Caribbean and south Asian (Indian, Pakistani and Bangladeshi) descent. This could be a genetic link. High blood pressure raises the risk of getting angina.

High blood cholesterol or dyslipidemia

Cholesterol is normally is needed for the functions of the body. There are two main types of cholesterol – LDL and HDL.

Low density lipoprotein (LDL) often referred to as ‘bad cholesterol’ as it blocks the arteries when in excess. Another type is high density lipoprotein (HDL) that helps remove the fat deposits from within the arteries and is thus called ‘good cholesterol’.

People with high levels of LDL and low levels of HDL are at risk of atherosclerosis and development of angina.

Obesity and overweight individuals

A diet high in fat and lack of exercise predisposes to heart disease, hypertension and high blood cholesterol and raises risk of angina.

Smoking

Smoking damages the arterial walls and also helps form platelet clots, clumps and plaques that may obstruct blood flow and lead to angina. In addition smoking decreases the oxygen carrying capacity of blood and leads to a raised risk of angina.

High alcohol consumption

This leads to risk of high blood pressure and high blood cholesterol and is interlinked with risk of angina.

Other risk factors for angina

Other risk factors for angina include:

  • Diabetes mellitus
  • Advancing age – Arterial walls thicken and harden with age and the arteries tend to get narrow.
  • Those with a family history of angina – Those with a first degree relative (mother, father, brother or sister) who has high blood pressure, high blood cholesterol, heart disease or angina carry a higher risk of angina.
  • Other conditions include arrhythmias (abnormal heart rhythms), disease of the heart valves, aortic stenosis, structural or anatomical defects of the coronary arteries, severe anemia, hypertrophic obstructive cardiomyopathy, etc.

Symptoms of angina

Angina is commonly manifested as chest pain or discomfort in the chest.

Angina is of two classical types – stable and unstable angina. Stable angina results from atherosclerosis and narrowing of the coronary arteries while unstable angina results from breakage of plaques or fatty deposits on the inside walls of the coronary arteries leading to formation of clots and obstructions.

All symptoms of angina arise due to ischemia or lack of oxygen rich blood supply to the heart muscles. The muscles develop fatigue, and increase in levels of toxic chemicals giving rise to the pain.

The symptoms of angina may be outlined as 1-7 –

  • A dull, aching, tightness or heaviness in the chest.
  • The pain may spread from the chest to the insides of the left arm, neck, jaw and back.
  • Breathlessness or shortness of breath
  • Nausea or feeling sick. There may be a general feeling of unwell
  • Fatigue or tiredness unrelated to present level of activity
  • Patients may complain of dizziness
  • There is usually severe anxiety along with the symptoms
  • There may be restlessness and need for fresh air due to feeling of breathless or constriction in the chest
  • Some patients may manifest with belching or burping

Symptoms of stable angina

In patients with stable angina the dull, aching chest pain is usually brought upon by a bout of physical activity like climbing stairs, having sex or running or even mental upsets or stress.

An attack of angina may be precipitated after a bout of laughing, eating a heavy meal, or going out in particularly cold weather. These factors that lead to an angina attack are termed angina triggers.

The symptoms of stable angina usually last for a few minutes and ease up upon resting for a while as the heart rate slows down and requirement of oxygen of the heart muscles goes down

The symptoms of stable angina are also relieved when the patient is given a medication called Glyceryl trinitrate. This may be applied as a patch over the skin or the pill may be kept underneath the tongue for absorption. The drug leads to dilatation of the arteries and thus relieves the obstruction and eases the chest pain.

Symptoms of unstable angina

Those with unstable angina may not have a specific angina trigger before the onset of the attack.

Unstable angina symptoms persist despite the patient being at rest

Unlike stable angina, unstable angina patients may have symptoms persisting for over 30 minutes and is usually longer than 5 minutes in duration.

Unstable angina is not relieved by glyceryl trinitrate

Unstable angina is a medical emergency and may progress to a myocardial infarction (heart attack) rapidly.

Diagnosis of angina

Angina is a symptom of an underlying heart disease and is manifested as chest pain that may or may not be brought about by physical exertion or by emotional stress.

Diagnosis of this condition and early management is vital in order to prevent the underlying disease process from progressing into a heart attack or stroke.

Angina is basically caused by narrowing of the coronary arteries that leads to lack of blood supply to the heart muscles leading to ischemic symptoms.

Diagnosis of angina includes asking questions about the patient’s history, physical examination, blood tests and so forth. 1-6

Patient’s medical history

History of similar condition, high blood pressure, high cholesterol, diabetes, smoking, alcohol intake, obesity etc. in the patient is important as these are important risk factors for angina.

Someone in the family may have heart disease or angina as these conditions may run in families.

Physical examination

A complete physical examination includes assessment of weight, waist size, height (to assess Body mass index – BMI with respect to weight) and features of high blood cholesterol like spots over the eye lids or a hardened feel of the arteries at the wrist etc.

Blood tests

Routine blood tests are prescribed to detect anemia (that may raise the risk of angina), cholesterol and glucose in blood as well as liver and kidney functions.

Urine examination is also advised to check on the kidneys. Liver and kidney function tests may guide medication to be used as some medications may not be used in patients with disorders of these organs.

Electrocardiogram (ECG or EKG)

This is a record of the rhythms and electrical activity of the heart. The test is a painless one where small electrodes or patches are stuck on various parts of the chest of the patient and the electrical activity of the heart is recorded onto a strip of paper.

Each heart beat has typical wave patterns and abnormalities of these waves (P, Q, R, S, T and U) may detect ischemia of the heart muscles in angina patients.

Echocardiography

Echocardiography may be required to assess cardiac function, detect valve disease or cardiomyopathy as cause of angina.

Exercise tolerance test (ETT)

This is a similar test to ECG or EKG and is carried out while the patient is made to exercise under supervision. This may be with a treadmill or an exercise bike. This is also called a treadmill test.

This measures the amount of exercise that is required for the heart to develop symptoms of angina.

Myocardial perfusion scintigraphy (MPS)

This test is performed alternatively to ETT when ETT results are not diagnostic. This test involves injection of a small amount of radioactive substance into the patient’s blood.

This is then viewed using a gamma camera. This camera tracks the movement of the dye as it passes through the blood vessels of the heart and helps detects narrowing and obstructions.

It is performed when the patient is at rest and also when he or she is on the exercise bike or treadmill.

Coronary angiography

This is a more invasive test and may require a day of stay at the hospital. A thin flexible tube or catheter is threaded into a vein or artery at the groin (Femoral vein or artery) or at the arm (Brachial artery or vein). X rays are used to guide the catheter into the heart and coronary arteries.

A dye is injected into the catheter to highlight the coronary arteries. Repeated X rays and films show up the site of blockages.

Other tests for angina

Other tests include Stress echocardiography, Multi slice CT scan, first-pass contrast-enhanced magnetic resonance (MR) perfusion (MRI) and MR imaging for stress-induced wall motion abnormalities. These tests show the heart function as well as detect the area of calcified or hardened arteries that is leading to symptoms of angina.

Emergency diagnosis

For patients with unstable angina, treatment is a medical emergency. An immediate EKG or ECG is prescribed upon admission.

Blood tests like Troponin T levels and Creatinine K –MB levels are tested to look for damage to the heart muscles. A coronary angiography may also be performed to assess the size and site of blockage.

Ruling out other conditions

Angina symptoms may be confused with other conditions as well. These need to be ruled out for accurate diagnosis. These include:

  • indigestion
  • gastroesophageal reflux disorder
  • heart attack or acute myocardial infarction
  • acute pericarditis
  • muscle pain or sprains or chest muscles or back muscles
  • pleural pain
  • pleuritis
  • pulmonary embolism
  • aortic dissection
  • gallstones
  • acute cholecystitis etc.

Treatment of angina

Treatment of angina aims at three basic targets:

  1. reduction of symptom severity of the angina attacks
  2. reduction of frequency of attacks
  3. 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:

  1. Treatment that aims at immediate relief – Mainly drugs are used for this target achievement
  2. Treatment that reduces the frequency of attacks – Medications are the mainstay for this target as well
  3. 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.

  • Beta-blockers

    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.

  • Long-acting nitrates

    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.

  • Ivabradine

    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.

  • Nicorandil

    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.

  • Ranolazine

    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:

  • Cholesterol-lowering drugs

    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.

  • Antiplatelet agents

    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.

  • Surgical therapy

    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.

  • Preventive measures

    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.