Anatomic features within the heart could help predict increased stroke risk among patients with patent foramen ovale, a condition in which a hole present in the heart during fetal development does not close properly at birth, according to a new study by Allegheny General Hospital researchers.

The findings were presented yesterday at scientific sessions of the American Heart Association in Orlando, Fla.

Though the results are preliminary, they may eventually lead to better identification of patients who could benefit from surgery to close the hole, said Dr. Robert Biederman, the study's principal investigator and a cardiologist at Allegheny General.

The hole, known as a foramen ovale, is located in the atrial septum, the wall separating the heart's two upper chambers. When it fails to close properly -- a problem that occurs in about 25 percent of the population -- it is known as a patent foramen ovale.

Most patients have no symptoms, but the condition is associated with increased risk for stroke.

Normally, patients with patent foramen ovale who have had strokes or transient ischemic attacks, known as mini-strokes, are placed on blood-thinning medication to prevent clots. While those medications are not always effective or without risks, Dr. Biederman said, government guidelines generally call for surgical intervention to close the hole only after patients have had another medical problem like a second stroke or heart attack.

A number of studies have tried to better determine who might benefit most from surgical closure, but the answer has been elusive, he said.

The latest findings, if confirmed by other studies, could lead to an "easily identifiable marker for stroke risk that would allow us to more effectively care for these patients," he said.

Dr. Biederman and his colleague, Dr. Mark Doyle, also of Allegheny General's Gerald McGinnis Cardiovascular Institute, performed a blinded retrospective analysis of 100 patients who had transesophageal echocardiography, a test that shows the anatomy of the heart and nearby structures. The study grouped patients based on whether a passageway was present between two wall layers of the atrial septum and, if so, assessed its size.

Nineteen of the study patients had strokes and 81 did not. Among the stroke patients, nine had a patent foramen ovale, and eight of those patients had a larger separation -- at least one centimeter long and one-quarter of a centimeter wide -- between the two wall layers. Of the 81 patients who did not have strokes, only four had the larger separation.

If the results hold true, patients at greatest risk might be evaluated just by assessing this specific feature of their atrial septum, Dr. Biederman said. Those patients could potentially have a minimally invasive procedure to repair the foramen ovale and "forgo a lifelong dependency on blood thinning medication," he said.

Dr. Biederman said researchers have since reviewed 250 cases with similar results.