ATLANTA — Jill DeMaster had a hole in her heart and a recurring pain in her head.

But after doctors closed the hole, a normally benign heart defect found in about 20 percent of people, DeMaster, 33, was confident the migraines that have plagued her for the last 13 years would subside.

On Monday, researchers here presented the results of the first rigorous clinical trial of closing the hole as a treatment specifically for migraine, a condition that affects about 30 million Americans.

The researchers found that the treatment led to a significant reduction in the frequency and duration of migraines but did not eliminate them in most of the patients. The findings, which involved a group of severe migraine sufferers, were presented at the American College of Cardiology's annual scientific sessions.

"It's very encouraging," said Matthew Wolff, a cardiologist and associate professor of medicine at the University of Wisconsin Medical School, who was not involved in the study.

In the study, 74 patients had the hole between the upper chambers of the heart — known as a patent foramen ovale — closed by a physician using a catheter threaded up through a vein from the groin. A matched group of 73 patients also were put under general anesthesia but underwent a sham procedure, designed to prevent the placebo effect that is common in migraine treatment trials.

Three people in both groups had a complete cessation of migraines after six months.

More promising was the finding that 42 percent of those in the treatment group had at least a 50 percent reduction in the number of days they had migraines, compared with 23 percent in the sham group.

In addition, over the last two months, there has been a trend toward a greater improvement in the treatment group, said co-author Andrew Dowson, a headache specialist at King's College Hospital in London.

The study suggests that a patent foramen ovale is only one cause of migraines, said David Williams, a cardiologist with the Rhode Island Cardiology Center who was not a part of the study.

Researchers say it will take some time to prove that the procedure is a viable treatment for migraines. But DeMaster said she's convinced.

"My expectation is I'll be able to function like a 33-year-old again," she said.