Silent Ischemia

Ischemia is a condition where the flow of oxygen-rich blood to a part of the body is restricted. Cardiac ischemia refers to lack of blood flow and oxygen to the heart muscle. It occurs when an artery becomes narrowed or blocked for a short time, preventing oxygen-rich blood from reaching the heart. If ischemia is severe or lasts too long, it can cause a heart attack (myocardial infarction) and can lead to heart tissue death. In most cases, a temporary blood shortage to the heart causes the tremendous pain of angina pectoris. Patients with silent ischemia have pain-free ischemia. It is dangerous because it may cause a heart attack with no prior warning.

How Common is Silent Ischemia and Who is at Risk?

The American Heart Association estimates that 3 to 4 million Americans have episodes of silent ischemia. People who have had previous heart attacks or those who have diabetes are especially at risk for developing silent ischemia. Heart muscle disease (cardiomyopathy) caused by silent ischemia is among the more common causes of heart failure in the United States.

Major risk factors include:

• Previous heart attack
Coronary artery disease
Diabetes
• High blood pressure (hypertension)
• Cardiomyopathy
• Obesity
• Smoking
• Alcohol and drug abuse

Symptoms

Silent ischemia has no symptoms. Researchers have found that patients who have noticeable chest pain may also have episodes of silent ischemia.

Diagnosis

Along with a complete history and physical examination, an exercise stress test and/or Holter monitoring can be used to confirm a diagnosis of silent ischemia.

Treatment

Treatment for ischemia is similar to that for any form of cardiovascular disease and usually begins with the following lifestyle changes:

• Quitting smoking
• Controlling high blood pressure, cholesterol, and diabetes
• Limiting or avoiding alcohol consumption
• Adopting healthy eating habits
• Maintaining a healthy weight
• Exercising in a doctor-approved program

Other treatment goals include improving blood flow to the heart and reducing the heart’s need for oxygen.

Aspirin, anticoagulants, or other blood-thinning agents may be prescribed to prevent blood clots from forming. Oxygen may be administered to ease breathing, and pain killers may be used for pain. Medicines that slow heart rate, open and relax blood vessels, and otherwise reduce the burden on the heart have also been effective in treating silent ischemia. Patients who do not respond well to medical treatment may need percutaneous coronary intervention or coronary artery bypass (CABG) surgery.


Resources

Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Cond/silent.cfm
American Heart Association www.americanheart.org/presenter.jhtml?identifier=4720