New studies on Type A behavior indicate that being an impatient workaholic doesn't necessarily hurt your heart, but distrusting others and having a low boiling point does.

The term "Type A" probably has outlived its usefulness, and people should concentrate on understanding anger's poisonous effects on the heart, Dr. Redford B. Williams Jr. of Duke University Medical Center said at a meeting of the American Heart Association."Being a workaholic, being in a hurry, interrupting people are not necessarily bad for your heart," Williams said Monday. "What is bad is if you have high levels of hostility and anger, and you don't bother to hide it when dealing with other people."

Experts for many years had thought classic Type A's - aggressive, rush-rush people - were setting themselves up for heart attacks.

"Many of us had thought that the definition of Type A was too broad," said Dr. Wayne J. Katon of the University of Washington. "Dr. Williams is narrowing it down."

In a study to be published in Psychosomatic Medicine, Williams and colleagues described a follow-up study of 118 students who took a personality test during law school. Twenty-five years later, 20 percent of those who scored in the highest quarter on the hostility scale had died, compared with 5 percent of those who scored lowest.

The research showed that being paranoid or neurotic or avoiding social contact were not associated with heart attacks. Instead, those at high risk tend to harbor a cynical mistrust of other people's motives. They get angry often and openly express their displeasure, rather than holding it in.

Williams said this makeup could be a problem for perhaps 20 percent of the population, and they probably have these tendencies from birth.

Such people tend to get furious, for instance, in slow-moving bank lines. They complain to themselves about why other customers haven't filled out their deposit slips ahead of time and may show unhappiness by making sour faces or even surly comments to those ahead of them.

"I'm not talking about anxiety waiting in line," Williams said. "I'm talking about anger."

There is no evidence to support the common belief that people are better off expressing their anger rather than keeping it to themselves, Williams said.

Whether people can help themselves by trying to control their feelings of rage is still not clear, but Williams said that such attempts at behavior change are harmless and may help.