CHICAGO (AP) - White-coat hypertension - blood pressure that's high only in the doctor's office - is not just a harmless case of the nerves but may signal early heart damage that should not be ignored, new research suggests.

The condition may require treatment either with diet and exercise or medication, Italian researchers say, entering a sharply divided field of medical opinion on just what white-coat hypertension signifies.

Several studies have addressed the issue over the past decade, with some researchers arguing that patients whose blood pressure is normal except during doctor visits probably are just anxious about seeing a physician.

The new study used heart imaging tests to compare white-coat patients with patients with true hypertension and those with normal blood pressure.

The tests focused on the heart's left ventricle, one of the lower blood-pumping chambers, which in white-coat patients showed early signs of cardiovascular disease, including enlargement and thicker walls. No enlargement was found in patients with normal blood pressure.

The study by Dr. Anna Grandi and colleagues at the University of Insubria in Varese, Italy, appears in Monday's edition of Archives of Internal Medicine.

Though the changes found in white-coat patients weren't as significant as those in patients with true hypertension, they suggest some strain is being put on the heart and indicate an increased risk of developing cardiovascular disease, including heart attacks, down the road, said Dr. Daniel W. Jones, hypertension director at the University of Mississippi Medical Center and an American Heart Association spokesman.

While the study is not the first to link the condition with heart abnormalities, it is perhaps the most convincing, Jones said.

"It's the strongest evidence that we have to date regarding office hypertension" and its risks, Jones said. "The evidence looks persuasive."

National Institutes of Health hypertension guidelines have no definitive recommendations for treating white-coat hypertension, leaving it up to doctors to decide whether to prescribe treatment, including medication, Jones said.

Jones said he generally recommends high blood pressure drugs for his patients with white-coat hypertension, and said he suspects the study will lead other doctors to do the same.

An Archives editorial said the study "doesn't settle the argument" but presents compelling evidence that the condition should be treated, not ignored.

Since treatment "usually does not involve complicated or dangerous regimens, it is good policy to treat white-coat hypertensives," Dr. Marvin Moser of Scarsdale, N.Y., said in the editorial.

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