SAN FRANCISCO (March 11, 2013)--Heart bypass surgery is one of the most common operations in the world and patients often are given a choice of how to have it done.

The usual method involves stopping the heart and putting the patient on a heart-lung machine while doctors create detours around clogged arteries.

The operation also can be performed while the heart is still beating, but some research suggests results are not as good.

Two large studies found the methods equally safe and effective after one year.

One study involved people 75 and older, a group thought to be at high risk for complications from stopping the heart.

The studies were discussed Monday at a cardiology conference in San Francisco.