President Yeltsin's second hospitalization for ischemia just three months after his first attack is not necessarily cause for alarm, a U.S. cardiologist said Thursday.


"Ischemia is often a precursor to heart attack," Dr. George Bren, a Washington-based cardiologist, said in a telephone interview. "How serious his condition is depends on how much of the heart muscle is affected."


The condition itself -- which results when arteries blocked by cholesterol cannot circulate enough blood to the heart muscle -- is very common, said Bren. It is not necessarily life-threatening, but in extreme cases can cause heart attack or death.


If multiple blood vessels are affected Yeltsin may require angioplasty -- a medical procedure in which a thin tube is inserted into the artery to clear out the blockage. A more severe case would call for heart bypass surgery.


Most people who suffer from ischemia do not require surgery. The fact that Yeltsin is back in the hospital so soon after his first ischemia attack in July may be more indicative of difficulties doctors are having in regulating his treatment with drugs, Bren said.


"I assume the treatment strategy will be altered," Bren said, indicating Kremlin doctors may change the president's medication.