What is Unstable Angina?
Unstable angina is a type of condition that falls under the broader category of acute coronary syndrome, which is a serious health problem affecting a vast number of people every day and is the primary cause of death globally. It is important to identify unstable angina separately from other causes of chest pain, such as stable angina, as it helps in deciding the right course of treatment for the patient.
Healthcare professionals should have a clear idea of signs and symptoms of acute coronary syndrome (heart conditions like heart attacks or unstable angina that happen when the heart doesn’t get enough blood), because patients depend on them to differentiate this from other sources of chest pain. Many patients might arrive at the emergency room with these symptoms, while others might show up at regular health check-ups.
A lot of research over the years has focused on determining the best treatments as well as diagnostic tools (methods to identify a disease) for evaluating unstable angina and other types of acute coronary syndrome.
What Causes Unstable Angina?
Coronary atherosclerotic disease is usually what causes unstable angina in almost all patients experiencing acute myocardial ischemia. To put it simply, unstable angina is chest pain caused by an irregular blood flow to the heart. This irregular blood flow is often due to a blockage or narrowing of the coronary artery, which is a blood vessel supplying your heart with blood and oxygen.
The most common cause of unstable angina is a clot, or thrombus, that forms on a broken atherosclerotic plaque, but doesn’t completely block the artery. An atherosclerotic plaque is a fatty deposit build-up inside the arteries, that can disrupt the blood flow to the heart when it’s damaged or ruptured.
A less common cause is a sudden tightening, or vasospasm, of a coronary artery, often referred to as Prinzmetal angina. This spasming can happen because of an issue with the lining of the blood vessel or the muscle layer in the wall of the blood vessel not working properly.
Risk Factors and Frequency for Unstable Angina
Coronary artery disease is a health issue affecting many people. It’s responsible for over a third of deaths in individuals over 35, making it the top cause of death for this age group. About 18 million people in the United States are believed to have this disease. It’s more common in men, but the rates become similar for both men and women past the age of 75. Risk factors for coronary artery disease can vary and might include things like obesity, high blood pressure, and a family history of the disease. The average age that people are diagnosed is 62, although this can vary depending on factors like sex and ethnicity.
- Coronary artery disease affects many people, especially those over 35 years old.
- It is the leading cause of death for this age group.
- About 18 million people in the United States are estimated to have this disease.
- Men are typically more affected, but the incidence becomes similar in both genders after 75 years of age.
- The average age of diagnosis is 62 years old.
- Women are usually diagnosed at an older age than men.
- African Americans are typically diagnosed at a younger age.
- Obesity
- Diabetes
- High blood pressure
- High cholesterol
- Smoking history
- Abuse of cocaine or amphetamines
- Family history of the disease
- Chronic kidney disease
- HIV infection
- Autoimmune disorders
- Anemia
These are some known risk factors for coronary artery disease.
Signs and Symptoms of Unstable Angina
People often experience chest pain and difficulty breathing when they have unstable angina. The chest pain may feel like pressure, tightness, or burning sensation, and it can be severe enough to be described as discomfort rather than just pain. It’s also common for the pain to spread to the jaw or arms, impacting both sides. They may also experience symptoms like nausea, vomiting, sweating, dizziness, and rapid heart rate. Actions such as physical exertion can worsen the pain, while resting or taking medicines like nitroglycerin and aspirin can often provide some relief.
However, in the case of unstable angina, the pain might not go away completely even with these treatments. In addition, many patients with unstable angina may have already been diagnosed with coronary artery disease or have been suffering from its symptoms for some time. These individuals are likely already familiar with their symptoms. They might notice that their chest pain episodes are becoming more frequent and the pain more severe, taking longer to go away.
This pattern of symptoms suggests that they may have unstable angina rather than stable angina or other causes of chest pain. This is a crucial distinction because unstable angina could indicate an impending heart attack and needs urgent assessment, as it carries higher health risks compared to stable angina.
During a physical exam, patients might clutch their chest, seem sweaty, or show signs of difficulty in breathing; their heart might be beating faster than normal; and there might be unusual sounds when listening to their lungs due to fluid build-up. Certain findings during the examination may suggest a serious situation:
- A dyskinetic apex, where the tip of the heart has abnormal motion
- Increased pressure in the neck veins
- The presence of third or fourth heart sounds
- A new heart murmur audible at the apex of the heart
- The presence of unusual lung sounds
- Low blood pressure
Testing for Unstable Angina
When you arrive at the hospital with symptoms like chest pain or feeling out of breath, the doctors aim to evaluate and treat you as quickly as possible. This would typically start with a test called an electrocardiogram (ECG), which is used to check your heart’s activity for any signs of distress or a severe condition called STEMI (where a part of the heart isn’t getting a sufficient blood supply). Signs of these conditions can include unusual waves on your ECG readout, which are referred to as changes in things like T-waves and ST sections.
Those who show a ST elevation, which indicates a STEMI, would usually receive treatments to help restore blood flow to the heart. This could involve procedures such as percutaneous coronary intervention (a procedure to open up blocked coronary arteries), or medications that break down blood clots (known as thrombolytics). It’s also possible for heart rhythm disorders, known as arrhythmias, to be present but most patients will have a normal rhythm particularly if they’re suffering from unstable angina (chest pain that can occur at rest and is not associated with heart tissue damage).
In addition to an ECG, blood tests would also typically be done. These would include a complete blood count to look at various components of your blood, checking for conditions like anemia (low red blood cell count) or abnormal platelet count (which could affect clotting), and general checks for any irregularities with your body’s electrolyte balance. There’ll be a focus on a protein called troponin, as its levels can indicate if the heart muscle has been damaged. In some circumstances, they may also check for probrain natriuretic peptide (proBNP), a substance that can suggest a heart issue when its levels are high. If there’s a possibility that blood thinners might be used, coagulation studies could also be performed to see how quickly your blood clots.
In addition, a chest X-ray is often done to study the size of your heart and the area in the middle of your chest known as the mediastinum. This helps doctors check for other potential reasons for your chest pain. Remember that it’s also important for doctors to consider whether your symptoms might be caused by conditions other than heart issues, such as blood clots in the lungs (pulmonary embolism), tears in the aorta (aortic dissection), tearing of the esophagus, lung infections (pneumonia), and lung collapse (pneumothorax).
To monitor your condition, you would typically be connected to a device that keeps track of your heart rhythm. Depending on your symptoms and the results of your tests, a variety of further examinations might be arranged. This could include stress tests that observe how your heart responds to exertion, or even a procedure called a cardiac catheterization, where a long thin tube (catheter) is threaded through your blood vessels to your heart for direct evaluation.
Your doctors would also take a close look at your medical history, as prior conditions like heart attacks or cases of coronary artery disease greatly increase the risk of acute coronary syndrome. Temporary changes in your heart activity or symptoms like chest, arm, or neck pain during periods of chest pain can also warn of this syndrome. This is in addition to abnormally appearing heart rhythms like more than a 1mm shift in the ST sections or unusual ‘inverted’ T-waves.
Treatment Options for Unstable Angina
The key to treating heart conditions like Unstable Angina involves improving the flow of blood through the arteries leading to the heart, a process known as perfusion. There are several ways to do this.
Aspirin is often given to patients for its ability to prevent blood clots by stopping blood cells from sticking together, a function known as antiplatelet therapy. It’s usually taken as a quick-acting oral or rectal dose.
Another medication, nitroglycerin, may be administered in various forms, including intravenously, under the tongue, through the skin, or orally. Nitroglycerin works by widening the arteries, leading to better blood flow and helping to reduce blood pressure. This makes it easier for your heart to work, lowering its energy needs.
For those who can’t tolerate aspirin, clopidogrel is available. There’s also prasugrel, which is more effective than clopidogrel but has a higher risk of causing bleeding. In addition, a medication named ticagrelor has been recently approved to be used alongside aspirin to reduce the chances of clot-related heart events.
It’s also common to provide extra oxygen to patients via a small tube that sits just below the nostrils known as a nasal cannula. This helps to ensure that the patient maintains good oxygen levels in their blood. These three steps – aspirin, nitroglycerin, and supplemental oxygen – are crucial initial treatments in Unstable Angina. Regularly checking the patient’s response, especially if they continue to experience chest pain or recovery is prolonged, is equally important as it may indicate a higher risk of a heart attack.
Additional treatments can include:
* Heparin: a medication that prevents clots, available in low or high versions.
* Beta-blockers: can lower the energy demands of the heart by reducing blood pressure and heart rate.
* Ranolazine: studied in patients with Unstable Angina; it significantly reduced the recurrence of insufficient blood supply to the heart.
* Statins: cholesterol-lowering drugs, the use of which has been widely supported by research in treating patients with Unstable Angina.
In severe cases of Unstable Angina, cardiac angiography – a procedure that assesses how well the heart’s blood vessels are working – may be needed. This procedure is typically indicated if the patient has severely low blood pressure, reduced heart function, chest pain that doesn’t respond well to medications, a new heart valve issue, or unstable heart rhythms.
An urgent procedure to open blocked arteries, known as percutaneous coronary intervention, has been shown to reduce deaths in people with a specific type of heart attack (non-STEMI) when performed within 6 hours of the heart attack.
What else can Unstable Angina be?
When a doctor is trying to diagnose unstable angina, which is a condition where your heart doesn’t get enough blood flow and oxygen, they might consider these conditions as other possible reasons for your symptoms:
- Aortic dissection: a serious condition involving a tear in the heart’s main artery
- Pericarditis: inflammation of the lining around the heart
- Pneumothorax: a collapsed lung
- Pulmonary embolism: a blockage in one of the pulmonary arteries in your lungs
- Peptic ulcer disease: sores that develop on the inside lining of your stomach and upper portion of your small intestine
What to expect with Unstable Angina
Unstable angina can lead to serious complications such as a heart attack, stroke, and even death. Research has proven that patients who show new signs of ST-segment elevation (a specific change in your heart rhythm, as seen on an ECG), have a 12-month rate of a heart attack or death of about 11%. This is compared to a 7% rate for patients who only have a specific different kind of ECG change known as an isolated inversion of the T-wave.
There are also factors that could make unstable angina more dangerous or hard to manage. This includes a low ejection fraction, which means your heart doesn’t pump blood as well as it should. Another factor is ongoing congestive heart failure, which is a condition where your heart can’t pump enough blood to meet the body’s needs. New or worsening mitral regurgitation (a condition where the blood flows back into your heart due to improper closing of heart valves), blood pressure that drops dangerously low (called, hemodynamic instability), a rapid and irregular heart rhythm (known as sustained ventricular tachycardia), and recurrent episodes of chest pain despite taking maximum treatment, are also significant factors that raise concern.
Preventing Unstable Angina
To prevent any further heart-related issues, the main goals are to help you get back to your daily activities, protect your heart’s ability to pump blood, and stop future heart problems. Most healthcare centers that specialize in heart health have a team ready to offer helpful advice and support.
In regards to lifestyle, quitting smoking is essential to prevent additional heart issues, and this applies to everyone living in the same home. Also, keeping your cholesterol levels in check is crucial. Ideally, your low-density cholesterol (bad cholesterol) should be 70 mg/dL or lower, high-density cholesterol (good cholesterol) should be at least 35 mg/dL, and your triglyceride (type of fat in blood) level should be less than 200 mg/dL. Regular exercise and a low-fat diet are suggested.
For those with high blood pressure, keeping it under control is important. The target blood pressure should be below 140/90 mm Hg. Lowering salt and alcohol intake could be beneficial.
If you have diabetes, managing your blood sugar levels is a key part of your heart health journey. This can be achieved through a careful diet, consistent exercise, or medication if needed.
Weight management and proper nutrition is another preventive strategy. It’s encouraged to aim for a healthy weight and a body mass index (a measure of body fat based on height and weight) of 25 kg/m.
In terms of physical activity, those at risk for unstable angina (a type of chest pain caused by reduced blood flow to the heart) should avoid heavy physical activity, especially in cold weather.
