May 11, 2010 -- New medical and surgical treatments for heart disease may grab headlines. But it is improvements in risk factors such as lowering cholesterol levels and blood pressure that account for nearly half of the decline in heart disease deaths, according to a new study.
''Behavior changes and modification of risk factors accounted for 48% of the overall decreased mortality rate,'' says study author Harindra C. Wijeysundera, MD, an interventional cardiologist at the Sunnybrook Health Sciences Centre in Toronto, Ontario.
The study is published in the Journal of the American Medical Association.
''What was surprising to us was that although the medical and surgical treatments improve, behavior change and risk factors continue to be important," says Wijeysundera, who is also an investigator at the Toronto Health Economics and Technology Assessment Collaborative.
Coronary artery disease, the buildup of plaque inside heart arteries, is still the leading cause of death, even though mortality rates from coronary artery disease have decreased over the past three decades. Wijeysundera and his colleagues wanted to find out the factors underlying the decrease, as this is critical for planning health policy and creating prevention and treatment strategies.
Improved Heart Disease Risks & Lower Deaths: Study
The researchers compared the death rates from coronary artery disease in Ontario in the years 1994 and 2005. The study, says Wijeysundera, is one of the first to look at a very recent time period. During the time period, the death rate from coronary artery disease dropped by 35%, from 191 to 125 deaths per 100,000 residents. That translated to about 7,585 fewer coronary artery disease deaths in 2005, mostly in those aged 75 to 84.
They used a model that integrates data on population size, coronary artery disease death rates, risk factor changes, and changes in the use of treatments to see which factors made the difference. Risk factors included smoking, diabetes, obesity, blood pressure, blood cholesterol, and exercise.
''We only looked at therapies we knew were efficacious," Wieysundera tells WebMD, in an effort to figure out how much impact each type had on lowering death from heart disease. Many more medications for treating heart disease are available now than in the 1970s and 1980s. Surgical treatment options have been improved, too.
Improved Heart Disease Risks and Lower Deaths: Study Results
The researchers expected medications and surgical treatments would have played a clearly dominant role. Yet, they found just 43% of the lowered death rate could be attributed to medical and surgical treatments. (The model couldn’t account for 9% of the declining death rate.)
When they focused further on the role specific treatments play in reducing the death rate, they found that acute or emergency treatment such as primary angioplasty (a procedure to open blocked or narrowed blood vessels to the heart) accounted for less than 1% of the lower death rate.
"We are not saying that primary angioplasty does not work and that all those acute surgical treatments don't work. They work fabulously well," he says.
But the big picture is that many more people are living with chronic coronary artery disease (and being successfully treated or managed with medication and/or lifestyle changes) than are needing emergency treatment, says Wijeysundera.
''We tend to look at therapies in isolation" when trying to figure out if they are effective. "It was eye opening to me to have all these therapies lined up and take a big-picture view and see how much impact each of those therapies had on the overall reduction in mortality."
But the researchers also found a dark side: The increase in diabetes and obesity found over the time period was linked to an increase in coronary artery disease death rates.
''The absolute increase in diabetes was really small," Wijeysundera says, "1% from 1994 to 2005, but that translates to an increase in mortality [from coronary artery disease] of 6%, just due to the diabetes."
The average BMI rose by 0.4, translating to a 2.3% increased coronary artery disease death rate.
While the numbers may seem small, Wijeysundera calls it ''a worrisome trend."
Study Take-Home Points
The message for people: High-tech surgery isn't the end-all, nor are medications. "Even in this era, when we have many, many good medications available to us, all of which work quite well, the most basic things -- exercise, eating properly, avoiding diabetes, and ensuring an ideal body weight" -- have a tremendous impact on outcome, Wijeysundera says.
The study analysis was funded in part by the Canadian Institute of Health Research and the Ministry of Health and Long-Term Care of Ontario.
Improving Heart Disease Risks: Second Opinion
The results from the new study reaffirm those from other research conducted from 1980 to 2000, says P.K. Shah, MD, director of cardiology for the Cedars Heart Institute, Cedars Sinai Medical Center, Los Angeles, who reviewed the results for WebMD.
''The results are remarkably similar," he says. ''You get the most bang for the buck with prevention."
''Acute, aggressive intervention like angioplasty yield a much smaller gain," he says. "By simply focusing on acute intervention, we are going to miss the boat." Refocusing attention on prevention and risk factor modification and disease management of the coronary artery disease are key, he says.
Shah worries that the gains made in lowered death rates will be ''neutralized" by the effects of increasing obesity and diabetes.