WASHINGTON (Reuters) – US death rates from heart disease and stroke have fallen by about 30 percent this decade but there are ominous signs the worrisome obesity epidemic could snuff out the progress, experts said this week.

Better control of cholesterol and blood pressure, declining smoking rates and better medical treatments all contributed to the dropping death rates from heart disease.

Heart disease is the number one cause of death in the United States, followed by cancer and stroke.

Preliminary government figures from 2006 indicate the rate of heart disease deaths – including heart attack, heart failure and other conditions – fell about 31 percent from levels recorded in 1999, according to the report.

Death rates from stroke fell by 29 percent.

"We are continuing to see really nice and dramatic reductions in cardiovascular and stroke death rates," said Dr. Donald Lloyd-Jones of Northwestern University in Illinois, who led the report published in the journal Circulation.

If the death rates in 2006 had been at their 1999 levels, there would have been 190,000 more heart disease and stroke deaths that year, Lloyd-Jones added.

But there are signs of trouble for the future.

Among women aged 35 to 54, evidence is emerging indicating an uptick in heart disease and stroke death rates for the first time in four decades, Lloyd-Jones said. Among men in the same age group, there is evidence the death rate declines are flattening out but a reversal has not yet been detected.

That could be the harbinger of a "coming tidal wave of problems from the obesity epidemic," Lloyd-Jones said.

Widespread use of cholesterol-lowering drugs called statins get some of the credit for progress on the cholesterol front.

High cholesterol can cause a dangerous accumulation of fatty deposits inside the arteries that can reduce blood flow or break off and cause heart attacks and strokes.

Similarly, more people are getting treatment for high blood pressure with a variety of drugs. High blood pressure raises the risks of heart attack and stroke.

Figures for 2006 show all forms of cardiovascular disease accounted for 34 percent of deaths in the United States – a total of about 829,000 people, according to the report. The cascade of health effects from worrisome rates of obesity could reverse the progress, according to the report. Government figures show 26 percent of Americans are obese, and state rates reach as high as 33 percent.