Increased obesity hindering success at reducing heart disease risk

The dramatic increase in overweight and obesity in adult Americans over the past 20 years has undermined public health success at reducing risk for heart disease, according to research presented at the American Heart Association's Scientific Sessions 2009. In a new study, researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1988-94, representing 8,264 adult men and women, 20 to 85 years old. All had complete risk factor profiles of their blood pressure, fasting glucose, low density lipoprotein (LDL or "bad" cholesterol) and smoking status.

Researchers found that during this time period, the average body mass index (BMI) increased from 26.5 to 28.8 kg/m2, a significant change. BMI – a measure of body fatness – is calculated by dividing a person's weight in kilograms by height in meters squared. In the same period, the number of people with optimal blood pressure decreased from 48 percent in NHANES III, 1988-94, to 43 percent in NHANES in 2005-06, and the number of people with optimal fasting glucose decreased from 67 percent to 58 percent. Both blood pressure and blood glucose are closely linked to obesity and these adverse trends track with the change in body weight.

The study also found the decreasing prevalence of optimal blood pressure and fasting glucose appeared to undermine improved LDL cholesterol and smoking status. The number of people with optimal LDL increased from 22 percent to 28 percent over time, while the number of lifetime nonsmokers improved from 45 percent to 50 percent, according to the study findings. There was no net change in the proportion of people with all optimal risk factors.

"Despite focused public health efforts, there is no net improvement in the overall cardiovascular risk factor profile over the past two decades in the U.S. population," said Kami Banks, M.D., M.P.H., lead investigator of the study and a cardiology research fellow in the Division of Cardiology at the University of Texas Southwestern Medical Center in Dallas.

Banks is calling on the medical community to put more emphasis on prevention to reverse the obesity trend.

"Lifestyle changes and physical activity are key," she said. "As physicians we need to prescribe prevention — writing exercise prescriptions and healthy dietary prescriptions just like we prescribe medication."

Researchers are expanding the study to analyze the data by gender and race, Banks said.

Co-authors are James A. deLemos, M.D.; Jarett D. Berry, M.D.; Colby Ayers, M.S.; Andrew Owens, M.D.; Anand Rohatgi, M.D.; Sandeep R. Das, M.D., Daren K. McGuire, M.D.; Amit Khera, M.D.

Author disclosures are on the abstract. The National Institutes of Health partially funded the study.

Contact information: Dr. Banks can be reached at (214) 648-3111 and kamakki.banks@utsouthwestern.edu. (Please do not publish contact information.)

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For Release 2:15 p.m. ET, Tuesday, Nov. 17, 2009

Abstract 1563 — Weight loss in obese patients may correct abnormalities of right-sided heart chambers

Weight loss has a significant beneficial effect on the metabolism, structure and function of the right side of the heart, according to researchers at Washington University in St. Louis, Mo.

Obesity is a major risk factor for right-sided heart failure and atrial fibrillation.

The researchers studied the effect of weight loss in 30 obese patients. Ten women underwent gastric bypass surgery, while 20 men and women received a supervised diet. Researchers measured the structure and function of the heart with echocardiography and metabolism with PET scans.

All patients lost about 17 percent of their body weight during an average 11 months. Overall weight loss showed:

• A 15 percent improvement in the diastolic function of the right ventricle;
• About a 15 percent improvement in oxygen consumption requirement; and
• About a 16 percent reduction in the size of the right atrium.

Clinical trials are needed to determine "if these beneficial changes in the heart result in decreased risk of right-sided heart failure and atrial fibrillation," researchers said.

Note: Actual presentation time is 10:45 a.m., Wed., Nov. 18, 2009.

Abstract 4034 — Weight-loss surgery in morbidly obese patients may shrink enlarged heart

Weight loss surgery could help shrink hearts enlarged because of the extra demand caused by obesity, researchers said. An enlarged heart can lead to heart failure.

Researchers assessed the left ventricular geometric pattern in 47 morbidly obese patients before and after weight-loss surgery. The findings showed that body mass index dropped from 46.8 kg/m2 before surgery to 33.9 six months after surgery and 30.7 after one year. Researchers also found:

• Average left ventricular mass decreased by 18.4 percent.
• The left ventricular geometric pattern returned to normal in 31.5 percent of patients.
• The relative parietal thickness returned to normal in 95.8 percent of patients.

The American Heart Association recommends that healthcare providers properly evaluate risk going into surgery for severely obese patients. All severely obese patients referred for surgery should undergo a comprehensive medical history, physical examination and additional blood chemistry testing as clinically indicated.

Note: Actual presentation time is 2:15 p.m.., Wed., Nov. 18, 2009.

Source: American Heart Association