Unstable angina or sometimes referred to as acute coronary syndrome causes unexpected chest pain, and usually occurs while resting. The most common cause is reduced blood flow to the heart muscle because the coronary arteries are narrowed by fatty buildups (atherosclerosis) which can rupture causing injury to the coronary blood vessel resulting in blood clotting which blocks the flow of blood to the heart muscle.
Unstable angina should be treated as an emergency. If you have new, worsening or persistent chest discomfort, you need to go to the ER. You could be having a heart attack which puts you at increased risk for severe cardiac arrhythmias or cardiac arrest, which could lead to sudden death. Learn about an unstable form of angina called Prinzmetal angina.
Causes of Unstable Angina: Blood clots that block an artery partially or totally are what causes unstable angina. Blood clots may form, partially dissolve, and later form again and angina can occur each time a clot blocks blood flow in an artery. Learn more about excessive blood clotting.
Symptoms of Unstable Angina - The pain or discomfort:
- Often occurs while you may be resting, sleeping, or with little physical exertion
- Comes as a surprise
- May last longer than stable angina
- Rest or medicine usually do not help relieve it
- May get worse over time
- Can lead to a heart attack
First, your healthcare provider will need to find the blocked part or parts of the coronary arteries by performing a cardiac catheterization. In this procedure, a catheter is guided through an artery in the arm or leg and into the coronary arteries, then injected with a liquid dye through the catheter. High-speed X-ray movies record the course of the dye as it flows through the arteries, and doctors can identify blockages by tracing the flow. An evaluation of how well your heart is working also can be done during cardiac catheterization. View an illustration of a cardiac catheterization.
Next, based on the extent of the coronary artery blockage(s) your doctor will discuss with you the following treatment options:
- Percutaneous coronary intervention (PCI) may be required to open a blocked coronary artery. Briefly, this procedure involves undergoing cardiac catheterization followed by using a catheter with a small inflatable balloon at the tip (View an illustration of a cardiac catheter). The balloon is inflated, squeezing open the fatty plaque deposit located on the inner lining of the coronary artery. Then the balloon is deflated and the catheter is withdrawn. This procedure is often followed by insertion of a stent to then keep the coronary artery vessel propped open to allow for improved blood flow to the heart muscle.
- Coronary artery bypass graft surgery may be indicated depending on the extent of coronary artery blockages and medical history. In this procedure, a blood vessel is used to route blood around the blocked part of the artery, forming a kind of detour.
For more information, talk to your doctor.
This content was last reviewed July 2015.