Bush Given Anticoagulant Drug to Cut Risk of Stroke : Presidency: Brief relapse of irregular heartbeat is quickly corrected. He is due to get a thyroid scan today.

President Bush suffered another brief episode of irregular heartbeat overnight, the White House said Wednesday, and an anticoagulant has been added to his drug regimen in an apparent effort to lessen the risk of a stroke.

But the White House emphasized that the President’s relapse of atrial fibrillation, which occurred Tuesday night, was corrected in a matter of minutes and that he was free of any further symptoms.

“There is no change in his clinical condition,” White House Press Secretary Marlin Fitzwater said at a briefing. “He continues without any symptoms.”

Fitzwater said that the President had begun taking coumadin, an anticoagulant, in addition to the drug therapy started over the weekend to correct his irregular heartbeat. Patients with atrial fibrillation are at slight risk of developing blood clots in the atria of the heart that can break free and travel to the brain, causing a stoke.

Bush spent Saturday and Sunday nights at Bethesda Naval Medical Center after complaining of shortness of breath while jogging at Camp David Saturday afternoon. He returned to work Monday after his heartbeat had stabilized, presumably in response to medication. Besides coumadin, Bush is taking the drugs digoxin and procainamide to treat the fibrillation.

Bush returned to the naval medical center Wednesday morning and was given a drink of radioactive iodine in preparation for a thyroid scan scheduled at the facility this morning. The President’s physicians have said that tests indicate the atrial fibrillation was caused by an overactive thyroid gland.

At a press conference, Bush said that his doctors have advised him to temporarily ease up on his athletic activities but not to curtail his official schedule. He said that he is happy the underlying problem that caused his atrial fibrillation has been found.

“The good news is that once the thyroid is corrected, that means there’s no problem on the heart--thyroid connected to the heart bone, you know,” he said. “And I think it’s going to be all right. And they’ve assured me that it can be OK.”

The thyroid, a small organ in the neck, secretes a hormone called thyroxine. Excessive production of thyroxine, or hyperthyroidism, “is one of the most common endocrine disorders in medicine,” said USC’s Dr. Richard Horton, an endocrinologist. “Several studies have shown that 0.5% to 1% of all patients admitted to hospitals have thyroid disease. . . . The good news is that it explains the President’s problem, is easily treatable and essentially curable.”

Dr. James R. Hurley, a thyroid specialist at Cornell University Medical College, said that the scan Bush is scheduled to undergo this morning will indicate which type of hyperthyroidism he is experiencing. Once this is determined, a course of treatment will be prescribed.

Horton said that a patient typically is given one of two drugs, propylthiouracil or methimazole, for a week to 10 days to block production of thyroxine and bring body functions back to normal.

Hurley said that the most likely course of longer-term therapy is to take radioactive iodine for several months. This reduces the amount of hormone produced by the thyroid and sometimes destroys the gland itself, a result that poses little danger, experts said. In such cases, patients typically take thyroxine pills to replace the missing hormone.

“You try to give exactly the right amount (of radioactive iodine) to the point where the gland is making the right amount of hormone but that’s hard to do,” Hurley said. “A lot of doctors deliberately destroy the gland. If you don’t do that, then you take a chance that the patient will stay with hyperthyroidism--and that drags the whole thing out.”

Meanwhile, the White House said that the President, who already has switched to decaffeinated coffee as a result of his irregular heartbeat, also has been advised by his physicians to temporarily forgo alcohol while his thyroid condition is being treated. Stimulants such as caffeine and alcohol have been associated with the onset of atrial fibrillation.

Times science writer Thomas H. Maugh II in Los Angeles contributed to this story.

THE THYROID

* The thyroid gland is a small organ in the neck that secretes the hormone thyroxine, which regulates how fast tissues throughout the body burn sugar and produce energy.

* Excessive production of thyroxine results in a condition called hyperthyroidism, which generally is associated with the presence of goiter, a gross swelling of the thyroid gland.

* Other symptoms, particularly in older patients, include the rapid heartbeat experienced by President Bush. Increased appetite, weight loss, irritability, insomnia and more frequent bowel movements may also occur. The President’s wife, Barbara, suffers from a disorder that causes the eyes to bulge.

* Treatment usually includes medication to to block production of thyroxine and bring body functions back to normal. Once the condition is stabilized, in about a week, the patient is then given a small dose of radioactive iodine, which is absorbed by the gland. The iodine destroys some cells, which brings thyroxine production back to normal.