Harvard Heart Letter

When to treat a narrowed heart artery

Ask the doctor

Q. A test showed a 50% blockage in one of my major heart arteries. That sounds pretty bad to me, but the cardiologist said I didn't need a stent. Why?

A . Your reaction is not unusual. Many people find it hard to understand why that degree of blockage wouldn't be treated with a stent—a tiny, flexible mesh tube that props open a newly cleared artery. But while stents can be helpful, they're not risk-free. The procedure to open the artery (angioplasty) involves threading a balloon-tipped tube from the wrist or the top of the thigh up to the heart. Minor risks include discomfort and bleeding at the insertion site. Rare but more serious risks (such as a heart attack) occur in about 3% 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% blocked. That's the point at which the benefit of stenting seems to outweigh the risks.

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