Angina – Diagnosis, Symptoms, and Treatment

What is Angina?

Stable angina is another term for chest pain that occurs with activity and improves with rest or a medication called nitroglycerine.  Angina typically affects older individuals with high blood pressure, diabetes, and elevated cholesterol.  People with angina are at increased risk for cardiovascular conditions such as heart attack, peripheral vascular disease, and stroke. There are multiple types of angina, the majority of them can lead to severe heart disease and even a heart attack within months to years if not treated.  

Due to the increased risk of serious medical conditions in people that are suffering from angina. Understanding its symptoms, causes, and basic treatments is critical.

What Causes Angina?

Angina is caused by reduced blood flow to the heart during physical activity. This leads to a reduction in the amount of oxygen reaching the heart muscle and results in pain. Conditions such as advanced age, smoking, elevated cholesterol, high blood pressure, and diabetes promote the formation of fatty plaques in the arteries of the heart.  Plaque buildup in the arteries of the heart leads to blockages and reduced blood flow to the heart tissue.

When you exercise, your heart is squeezing faster and harder, this causes it to use more energy and oxygen. Normally the blood vessels leading to the heart increase in size and direct more blood to the stressed heart. Plaques in the arteries of the heart restrict blood flow and prevent this natural increase in blood flow to the heart muscle. This is why the chest pain, difficulty breathing, and exercise intolerance seen in angina resolve with rest as the heart’s energy requirements quickly decrease when you are no longer exercising. 

How Common is Angina?

Angina is extremely common - In fact, approximately 9.8 million Americans currently suffer from angina and about 500,000 new cases of angina occur each year.

As mentioned, people with angina are generally older adults with other risk factors such as smoking history, elevated blood pressure, high cholesterol, and diabetes.  This collection of risk factors is exceedingly common in Western society due to our diet and lack of physical activity.

Signs and Symptoms

By definition, angina is chest pain that occurs with activity and improves with rest or nitroglycerine.  Other symptoms that may occur during angina attacks include:

• Difficulty breathing
• Low energy
• Exercise intolerance
• Profuse sweating
• Nausea or vomiting

These symptoms are very similar to those of a heart attack. If you are experiencing these symptoms for the first time seeking emergency medical care is critical. If you or a loved one has been diagnosed with angina but has symptoms that do not resolve with 5 minutes of rest or a dose of nitroglycerine you should contact 911, as this may be a sign of a heart attack. 

There is another type of angina known as “unstable angina.” Patients with unstable angina are those that have a proven diagnosis of angina that used to resolve with rest or nitroglycerin. But now have pain that continues even with rest or nitroglycerin. Unstable angina is a sign that the blockages in the heart have become more severe and now require treatment to prevent injury to the heart muscle. 

Diagnosis

Angina is suspected based on the symptoms listed above and the diagnosis is typically confirmed with a stress test.  There are various types of stress tests.  Your doctor may have you exercise on a treadmill while monitoring your symptoms, blood pressure, heart rate, and electrocardiogram (stress ECG).. If you have an abnormal ECG at baseline, they might not be able to interpret the ECG during exercise, so they may perform other tests that provide similar information - a stress echocardiogram or nuclear stress test.

During a stress echocardiogram, your doctor will look at an ultrasound of your heart before and immediately after exercise. By looking at how the walls of the heart move they can determine if areas of the heart are not getting enough blood flow.  Similarly, during a nuclear stress test, your doctor will evaluate your heart before and after exercise using nuclear imaging, a test that uses a non-dangerous injection of a radioactive fluid to track the amount of blood entering each area of the heart.  If your heart pumps abnormally after exercise or does not absorb the radiation from the injection, this can suggest that it is not receiving enough blood during physical activity.

Sometimes, individuals might not be able to use a treadmill due to severe arthritis in the hips or knees, or because they are paraplegic or unable to walk.  During these circumstances, your doctor can administer an intravenous medication (e.g., adenosine, dobutamine) to mimic physical activity.  In other words, your doctor will administer medications that activate your heart as if you were exercising.  They can then perform any one of the imaging studies mentioned above (eg, echocardiogram, nuclear study) to evaluate your heart function before and after the intravenous medication is given.

If your stress test results come back positive - meaning you most likely have a significant blockage in the arteries of the heart - your cardiologist will likely recommend angiography.

Angiography is a procedure by which your cardiologist accesses the arteries of your heart by advancing a thin flexible tube known as a catheter through an artery in your groin or arm.  They then inject a dye into the heart blood vessels to evaluate for any blockages.  If they see blockages in the heart arteries, they can deploy a stent to open up these blockages.

Angina Medication and Treatment

The first step in reducing angina and cardiovascular risk involves lifestyle modification such as diet and exercise.  Patients are usually encouraged to have a diet low in sodium and saturated fat, and high in fruits and vegetables.  Always consult your cardiologist for their recommendations in regards to exercise as your activity level may need to be modified depending on various factors – too much physical exertion may actually be dangerous depending upon the size and locations of the blockages that are leading to your angina.

Angina can be treated with several classes of medications including:

• Nitrates
  • nitroglycerine
  • isosorbide mononitrate,
  • isosorbide dinitrate
• Beta-blockers 
  • Coreg (carvedilol)
  •  Lopressor (metoprolol)
• Calcium channel blockers
  • Norvasc (amlodipine)
  • Cardizem CD (diltiazem)
  • Adalat (nifedipine)

The nitrate medications work by increasing the blood flow around the plaques that are leading to angina and decreasing the amount of work your heart needs to do when pumping blood. This decreases the oxygen usage of the heart and can reduce or eliminate angina symptoms. Some nitrates such as nitroglycerin are taken only when you experience symptoms. Others like isosorbide mononitrate and dinitrate are taken on a daily basis. 

Beta-blockers and calcium channel blockers work by reducing both the heart rate and blood pressure. Reducing the heart rate decreases the oxygen usage of the heart and can help to prevent angina symptoms from occurring. Reducing blood pressure also decreases the stress on the heart and decreases the risk of angina symptoms returning.

Your doctor may also prescribe low-dose aspirin, cholesterol-lowering medication (eg, Lipitor (atorvastatin), Pravachol (pravastatin)), and other blood pressure reducing medications (e.g. diuretics).  If you have diabetes, they may also recommend oral antidiabetic agents (e.g. metformin, glipizide) and sometimes insulin.  Smoking is the number one cause of preventable death and is a major risk factor for heart disease, so if you smoke, tobacco cessation is always encouraged.

Besides medications, your cardiologist may recommend interventional procedures such as stent placement in the narrowed arteries of the heart.  These can be drug-eluting stents or non-drug-eluting stents.  Depending on the type of stent you receive, you may have to take a medication called Plavix (clopidogrel), which acts similarly to aspirin, stopping new blockages from forming around the newly placed stents.

References:

1. Gibbons RJ, Chatterjee K, Daley J, et al. ACC/AHA/ACP-ASIM guidelines for the management of patients with chronic stable angina: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Chronic Stable Angina). J Am Coll Cardiol. 1999 Jun;33(7):2092-197. - https://www.ahajournals.org/doi/full/10.1161/01.cir.99.21.2829
2. Wee Y, Burns K, Bett N. Medical management of chronic stable angina. Aust Prescr. 2015 Aug;38(4):131-6 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4653970/