Cardiac ischemia occurs when there’s a temporary reduction in blood flow to the heart, which deprives it of oxygen. This usually happens when an artery leading to the heart becomes temporarily blocked so it can’t properly supply the heart with the oxygen it needs. Typically, a person with cardiac ischemia has chest pain and shortness of breath. But not everyone has this “classic" presentation. Some people, instead, may experience a silent cardiac ischemic event or silent ischemia.
What is Silent Ischemia?
Silent ischemia is when the heart doesn’t receive adequate blood flow or oxygen, but the person doesn’t have the classic symptoms of chest pain and shortness of breath. In fact, many people have no symptoms at all.
Other people have vague symptoms such as indigestion, fatigue, and anxiety as the only indication that things aren't right with their heart. These people have underlying coronary artery disease, but it’s not readily apparent. If cardiac ischemia occurs and blood flow to the heart isn’t restored promptly, it can lead to a “silent" heart attack. Needless to say, this makes it important to diagnose silent cardiac ischemia quickly.
Certain Groups of People Are at Higher Risk for Silent Ischemia
Older people, those with diabetes, and people who have had a heart attack or have undergone surgical treatment for coronary artery disease are more likely to experience a silent cardiac ischemic event. Women are also more likely not to have the classic symptoms of chest pain and shortness of breath when their hearts aren’t receiving adequate blood and oxygen. This increases the risk that coronary artery disease or a heart attack will not be diagnosed as quickly in a woman.
How is Silent Ischemia Diagnosed?
One of the most common tests doctors order when they suspect silent heart problems is an exercise stress test. When the heart is stressed through exercise, changes can often be picked up on an EKG tracing.
In other cases, a doctor may order a nuclear imaging study – a more sensitive test that detects areas of the heart that aren’t being oxygenated properly. Another test that’s helpful is a stress echocardiogram. This study uses sound waves to look at the way the walls of the heart moves when it’s stressed. This will often be abnormal in people who have had a silent cardiac ischemic event.
If any of these tests are positive, a doctor may recommend cardiac catheterization to better evaluate the extent of the heart disease – to see what type of treatment is needed.
Treatment of Silent Cardiac Ischemic Events
Silent cardiac ischemia can sometimes be treated with medications that relax the blood vessels leading to the heart and reduce the workload on the heart. If the underlying heart disease is extensive, an angioplasty with stent placement or heart bypass may be needed to reduce the risk of further heart damage. It's important to consider all of the treatment options, and discuss them at length with your doctor.
Archives of Internal Medicine. 1991; 151: 2373.
American Journal of Cardiology. 1984; 54: 1195.
Merck Manual. Eighteenth edition. 2006.