Heart attack rates fell 24 percent in California between 2000 and 2008, probably because of better care, U.S. researchers reported on Wednesday.
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.
Dr. Robert Yeh of Massachusetts General Hospital and Harvard Medical School in Boston and colleagues said the 24 percent 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."
His team used data from the 3 million people in the Kaiser Permanente Northern California health system.
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 percent between 1999 and 2008.
The most dramatic decrease — 62 percent 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.
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.
The declines accompany bans on smoking in public places. Also, doctors have become better at treating high blood pressure and cholesterol.
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 percent in men and 23 percent 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.
They also contended that the "rate of improvement has slowed down or stopped," and that the risk of heart attack might rebound unless greater emphasis is placed on prevention.
Yeh said the California data showed no evidence that the trend was slowing down.
"My guess overall is that either these trends are occurring elsewhere, or that they will occur as more guideline-based preventions extend throughout the United States and other health systems," he said.