Why does my doctor think I don’t need an angioplasty and stent?

DEAR DOCTOR K:

A test showed a 50 percent blockage in one of my coronary arteries. That sounds pretty bad to me. But the cardiologist said I didn’t need an angioplasty and stent. Why?

DEAR READER:

Coronary arteries send needed blood to the heart muscle. That blood flow can be blocked by cholesterol-rich plaques of atherosclerosis. When the blockage seriously reduces blood flow, it increases your risk of a heart attack. An angioplasty and stents can be helpful for restoring blood flow, but the procedure is not risk-free.

Every time a doctor considers whether to order a test or a treatment, he or she balances the likely benefit against the likely risk. When an artery feeding the heart muscle is blocked “just” 50 percent, there still is good blood flow to the heart. So the benefit of reducing that blockage is small.

But I’m getting ahead of myself. Let me describe how an angioplasty and stent work. First, the doctor pushes a soft tube (a catheter) from an artery in your leg or arm up to your heart. Inside the catheter is a thinner catheter that has an inflatable balloon near its tip. And inside that catheter is an even thinner wire with a soft tip.

Once the catheter reaches the heart, the doctor guides the wire down the artery until the wire tip is beyond the blockage and the balloon is right where the blockage is. Then the doctor inflates the balloon. This squashes the plaque against the wall of the artery, making the inside of the artery wider. As a result, blood flows through the area more easily.

Around the catheter, surrounding the balloon, is a tiny, expandable mesh wire tube: a stent. When the balloon is inflated at the blockage, the stent also expands. The balloon is then deflated and removed from the body. However, the expanded stent is left in place, keeping the plaque squashed against the wall of the artery and allowing good blood flow through the artery. Most stents are coated with a drug that helps to prevent re-narrowing of the artery.

Minor risks of angioplasty include discomfort and bleeding at the insertion site. Rare but more serious risks (such as a heart attack) occur in about 3 percent of people undergoing the procedure. And to prevent blood clots at the stent site, people need to take anti-clotting medications for up to a year afterward.

As a result, cardiologists typically don’t do angioplasties with stents unless an artery is at least 70 percent blocked. That’s the point at which the benefit of stenting outweighs the risks.

There are many ways to slow the growth of plaques — in your case, to keep the plaque from increasing from 50 percent to 70 percent blockage. If you are not already doing so, ask your doctor if you should be taking medications, such as aspirin, and cholesterol- or blood-pressure-lowering drugs. You should also exercise regularly and eat a heart-healthy diet. Finally, if you smoke, quit.