If you live in New York, your chances of dying from a heart attack may be twice as great as in New Mexico, according to a study that finds "significant" geographic differences in heart-disease death rates.

The national Centers for Disease Control reported Thursday that heart-disease rates were generally highest in concentrated, urbanized areas of the Northeast or Midwest, while the West had the lowest rates."We're talking about thousands of deaths difference between the low states and the high states," said Dr. Patrick L. Remington, a CDC researcher.

Heart disease is the leading killer in the United States, taking more lives each year than all other causes combined, according to the American Heart Association. In 1985, 540,800 Americans died of ischemic, or blocked-artery, heart disease - most commonly heart attacks, according to CDC statistics.

Remington said the stress of urbanization itself is probably not to blame for the high rates in the densely populated Northeast and Midwest, but many people in those regions probably have lifestyles that could lead to more heart attacks.

"Just living in a big city doesn't appear to be a risk factor," he said. "But more desk jobs, and greater reliance on automobiles, all are part of a sedentary lifestyle that contributes to greater risk of a heart attack."

He said lack of exercise contributes to weight gain, higher cholesterol levels, stress and high blood pressure - all factors in heart disease.

"Lack of exercise can be directly connected to all these factors," Remington said.

Another likely cause of significant state-to-state discrepancies, Remington said, is the prevalence of cigarette smoking.