Heart attack rates fell 24 per cent in California between 2000 and 2008, probably because of better care, US researchers said.

The study, in the New England Journal of Medicine, is the first large survey since the adoption of new treatments and medicines for preventing heart attacks. It examined more than 46,000 heart attack hospitalizations.

The decline, which reflects similar trends across the United States, follows bans on smoking in public places. Also, doctors have become better at treating high blood pressure and cholesterol.

Dr Robert Yeh of Massachusetts General Hospital and Harvard Medical School in Boston and colleagues said the 24 per cent drop was seen even though doctors can better detect heart attacks and despite the growing rates of diabetes and obesity, both of which raise the risk of heart attack.

"We would expect an increase in heart attacks because we're picking up more heart attacks than we used to," Yeh said in a telephone interview. "We found that, despite that, they are still going down."

The team used data from the 3 million people in the Kaiser Permanente Northern California health system, the largest medical group in the United States, which paid for part of the study.

The heart attack rate peaked in 1999, dropping by nearly one-quarter through 2008. The rate of deaths in the month after a heart attack also declined by 24 per cent between 1999 and 2008.

The most dramatic decrease -- 62 per cent since 2000 -- came among people suffering from the most damaging type of heart attack, measured as an elevation in the ST segment of the wave that appears on a heart monitor. Such attacks should be rapidly treated with clot-busting drugs or tube-like stents that keep arteries open.

'Consistent trend'

Non-ST segment heart attacks, which are not considered to be as dangerous because they involve a smaller portion of the heart wall, peaked in 2004 and have been declining since. They are often treated with drugs.

"Despite our ability to more easily diagnose heart attacks using sensitive biomarkers, we found a consistent trend of fewer severe ST-elevation myocardial infarctions over the past decade, the type of heart attack we particularly want to prevent," Dr. Alan Go, of Kaiser, who led the study, said in a statement.

Yeh and his colleagues said other population studies, such as those done in Minnesota and Massachusetts, have also suggested that heart attacks are declining.

"But published literature from these studies is limited to data collected before 2002 -- before many current strategies for the prevention and management of cardiovascular disease were implemented more widely in the community," the researchers wrote.

Other research has shown that overall deaths from heart disease have declined by 22 per cent in men and 23 per cent in women since 2000, according to a commentary in the journal by Jeremiah Brown and Gerald O'Connor of the Dartmouth Institute for Health Policy and Clinical Practice in New Hampshire.

But the risk is twice as high for Americans in Oklahoma, the lower Mississippi corridor and Appalachia, possibly because of socioeconomic factors, they said.

"The rate of improvement has slowed down or stopped," they added. – Reuters