Standard lifestyle changes help treat silent ischemia

ASK DOCTOR K By Anthony L. Komaroff, M.D.

DEAR DOCTOR K:

The results of a recent stress test showed that I have “silent ischemia.” I haven’t felt any pain or discomfort. I wouldn’t even have known about it if not for the stress test. Does it need to be treated if it’s not causing any symptoms?

DEAR READER:

The word “ischemia” comes from a Latin term that means “stopping blood.” If a stress test shows you have cardiac ischemia, blood flow to a part of your heart muscle is less than the heart muscle needs when you exercise. The most likely culprit is a coronary artery narrowed by cholesterol-laden plaque.

A bout of ischemia can happen when your heart is made to work harder, such as during exercise, anger or emotional stress. The resulting shortfall in oxygen-rich blood to your heart muscle can cause the chest discomfort known as angina. This pain may spread to your shoulders, arms, neck or jaw.

But here’s a little-known fact: Sometimes ischemia causes no symptoms. You might not feel anything at all. This so-called silent ischemia is surprisingly common. Approximately 2 to 4 percent of middle-aged U.S. men are estimated to have it. And about 10 percent of middle-aged U.S. men who have cardiac risk factors — such as obesity, smoking, high cholesterol and uncontrolled high blood pressure — may have silent ischemia.

In people with diabetes, the risk may be higher. That’s because diabetes increases the risk of having heart disease, and because diabetes injures the nerves that feel heart pain, making it silent.

I spoke to my colleague Dr. Peter Stone, director of the vascular profiling research group at Brigham and Women’s Hospital. He said that people with heart disease may have five to 10 times as many episodes of silent ischemia as angina. Silent ischemia is exactly like angina, except that you don’t feel it.

Some people have only angina and others have only silent episodes. But most people with narrowed arteries have both types.

Having ischemia — whether it’s painful or not — makes you more prone to having a heart attack or to develop a dangerous heart rhythm that can cause sudden death. (Sudden death can occur without a heart attack, and many heart attacks do not lead to sudden death).

That’s why it’s important to treat ischemia, even if you’re not experiencing any symptoms. Your risk of heart attack or sudden death is particularly high if you have other factors that raise your risk of heart disease.

Treatment begins with lifestyle changes. Follow the standard heart-protecting habits: eat right, get regular exercise and maintain a healthy weight. Also, keep blood pressure and cholesterol down — with medications if necessary. Ischemia may also be treated with drugs, including: — beta blockers, which lower the heart’s workload; — calcium-channel blockers and nitrates, which widen blood vessels;

— ranolazine (Ranexa), a drug that appears to increase blood flow to areas of the heart affected by ischemia.

If your ischemia is severe, you may need an artery-opening procedure called angioplasty.

Dr. Komaroff is a physician and professor at Harvard Medical School.