Information About Angina and Lab Testing

 Angina is the term used for a type of chest pain, which is mainly caused by a lack of supply of oxygen and blood flow to the individual’s heart. Over 7 million residents in the U.S. are believed to have this condition. It is typically linked with arteries that have started to narrow, which is typical in coronary artery diseases. The narrowing occurs when plaques begin to accumulate (thickening of the linings) inside the arteries, which is caused by the process known as atherosclerosis. When a person has angina, their heart might be getting an adequate supply of blood to accommodate daily activities, but these arteries are usually unable to deliver enough oxygen and blood during the stages of increasing demands, such as physical or emotional stress, exercise, and temperature extremes.  

Angina comes in 3 main types: 

1. Stable Angina 

This condition is typically characterized by patterns of common symptoms and stages of discomfort or pain that usually happen during exercise or when the affected person is stressed. This type of discomfort typically subsides with rest or/and treatment using nitroglycerin of other appropriate medications. Most people that suffer from this angina type can generally live a normal life over several years, yet others will progress gradually or rapidly onto unstable angina. Stable angina is the type that is linked to the gradual accumulation of plaque, which is mainly made up of fibrosis (scar tissue).  

2. Unstable Angina 

With this condition, an acute coronary syndrome that goes along with it can include a heart attack. This type is characterized by pattern changes in the angina episodes. This typically means that the episodes occur more frequently even at rest, or/and are no longer responding to medications or treatments. This is typically the sign that the individual’s condition has gotten worse. The pain and discomfort that the person experiences with this type of angina are often more prolonged and severe when compared to stable angina. The individuals that have unstable angina are also at an increased risk when it comes to cardiac arrest, critical cardiac arrhythmia, and heart attacks. This condition is classified as one of the acute emergencies that should always be treated and evaluated as soon as possible. Unstable angina is also characterized by plaques that contain higher amounts of debris and lipids when compared to the plaque found in the people diagnosed with stable angina. If these materials start leaking into the surrounding vessels, clots will form. 

3. Prinzmetal’s Angina (Variant Angina) 

This condition typically occurs at night, almost always during rest periods. The main cause is linked to when the coronary artery spasms. Most people that have variant angina will also have critical atherosclerosis in one or more of the main blood vessels on their hearts. It also occurs but a lot less frequently in individuals with hypertension (uncontrolled high blood pressure) or heart valve disease. It may also be seen in people that abuse methamphetamines and cocaine. This angina type occurs when the arteries spasm, which briefly narrows them without causing any permanent damages.  

Symptoms and Signs 

The symptoms associated with angina often appear, followed by either disappearing or not disappearing when at rest. The person might experience chest pain, pressure, and/or discomfort, or experience what is known as referred pain. This type of pain is usually felt in areas such as the jaw, back, arm, or left shoulder.  

Angina can be more complicated to identify in older people when they are suffering from a symptom like abdominal pain directly after eating (caused by an increase in blood demand to accommodate digestion) or when they have shoulder or back pain (that might be caused by arthritis).  

The level of activities that are needed to trigger angina episodes and the symptoms that are involved vary from one person to the next and can also vary over time and between each episode. Coronary artery disease is usually progressive, which means that angina can worsen overtime when it comes to symptoms that are more severe, episodes that become more frequent, or/and less responsive when it comes to treatment and rest.  

Tests for Angina 

The main aim when it comes to testing for this condition is to differentiate between: 

  • Chest pains that are not related to the heart, like the type that is caused by skeletal muscle injuries.  
  • Chest pain that is caused by angina that is treatable and not by heart damage. 
  • When a person lands up in an ER (emergency room) with a coronary syndrome that is acute, which is a symptom group that suggests that the heart is injured.  
  • Chest pain caused by a heart attack. 

All the above symptoms result in evaluating the person with different types of non-laboratory and laboratory tests. These are typically used to establish what is causing the pain, along with how severe the condition is. Since certain treatments for heart attacks must be administered very quickly to lower damage to the heart, a precise diagnose must be confirmed as fast as possible.  

Laboratory Tests for Angina 

Cardiac biomarkers are the proteins that release when the muscle cells become damaged are usually ordered in order to help distinguish heart attacks from angina. These will include: 

This is the most common cardiac-specific ordered marker. The levels of troponin in the blood will remain elevated after the first few hours of damage to the heart and stay raised for as long as two weeks. Troponin tests are typically ordered in the ER when the person is presenting with symptoms linked to unstable angina, followed by more tests over the following hours to detect concentration changes. If the levels remain normal, then the chest pain and symptoms are less likely from damaged heart muscles and more from pain caused by stable angina. An elevation or/and fall in troponin level results is usually an indication of a heart attack.  

The test known as high-sensitivity troponin is used to detect the same proteins that standard tests do but at far lower levels. This test is much more sensitive, which means it shows a positive result much sooner and can help to establish acute coronary syndrome and heart injury a lot earlier than the standard tests. The hs-troponin test can also show positive results in individuals that have stable angina as well as in individuals that are showing no symptoms.  

When the levels are raised in these people, it is an indication of increased risks for a future heart event, such as a heart attack. This test is not approved currently in the United States, yet research continues, which means it might soon become available. This test is routinely used in Canada, Europe, along with other countries as the cardiac biomarker across many clinical practices.  

A specific type of enzyme, creatine kinase, which is mainly found in the heart muscle, will rise when damages have occurred to the cells in the heart muscle. This is a test that is now used a lot less frequently.  

Other tests that are commonly performed include: 

  • Myoglobin This is a protein that releases into the bloodstream when the skeletal muscle or the heart is injured. This is also a test that is not used as often anymore.  
  • Nt-proBNP or BNP The body releases BNP in response to a condition such as heart failure. When BNP levels increase, while it is not diagnostic for heart attacks, it does indicate increased risks of cardiac issues in people that have acute coronary syndrome.  

Other screening tests that are more general are also commonly ordered to assist with evaluating the main organs in the person’s body, blood glucose, electrolyte balance, white and red blood cells to establish if there is any deficiencies, excesses, or dysfunction that could be contributing to making the individual’s symptoms worse.

These can include: 

This typically includes a group of 14 tests used as a type screening tool to establish the current state of the person’s electrolyte and base/acid balance, blood proteins, liver, kidneys, and blood glucose.  

This test is typically used for screening for several disorders that may affect the blood cells, like an infection or anemia.