PALM BEACH, FLA. — Gastric bypass surgery does more than just cause weight loss. It produces rapid improvements in glucose tolerance, blood pressure, lipid levels, diabetes, and the risk of coronary heart disease as measured by the Framingham risk score, Dr. Alfonso Torquati said at the annual meeting of the Southern Surgical Association.
“We know that weight loss does not lead to the change in coronary heart disease risk. We think that bariatric surgery is metabolic. It bypasses the duodenum and changes the way that glucose and lipid metabolism work,” said Dr. Torquati, a surgeon at Vanderbilt University, Nashville, Tenn.
He and his associates assessed the effect of gastric bypass surgery on coronary heart disease (CHD) risk by calculating the Framingham risk score for 500 consecutive patients just prior to surgery and again 1 year later. All of the patients were treated at Vanderbilt.
The analysis showed that the average 10-year risk of CHD, based on the 1998 formula (Circulation 1998;97:1837–47), was 5.4% when calculated at baseline for the 500 patients who had bariatric surgery. One year after surgery, with complete follow-up of all 500 patients, the average 10-year risk of CHD was 2.7%, a statistically significant drop, reported Dr. William O. Richards, a coauthor and medical director of the Center for Surgical Weight Loss at Vanderbilt.
The cut in CHD risk was due to substantial improvements in systolic blood pressure and serum levels of low-density and high-density lipoprotein, as well as significant drops in the prevalence of type 2 diabetes and metabolic syndrome. (See box.) The average weight loss in these patients during the first year after surgery was 69%.
Significant reductions in risk were seen in all patients, regardless of whether they had diabetes, regardless of their age or gender, and regardless of whether their baseline Framingham risk was low, intermediate, or high. Five-year follow-up data were available for 360 (72%) patients, and their actual rate of CHD was similar to their predicted rate calculated 1 year after surgery, Dr. Richards said.
“As the evidence grows, it becomes harder to ignore that bariatric surgery is a lifesaving intervention,” commented Dr. Eric DeMaria, vice chair of general surgery at Duke University, Durham, N.C.
“If weight loss alone does not drive the benefits of bariatric surgery, then what does?” he asked.
“We find that insulin resistance goes way down in the first weeks after surgery, especially at the level of the liver, before there is significant weight loss,” Dr. Torquati said. “You don't see the same changes with gastric binding, only with bypass,” suggesting that the metabolic changes are somehow linked to duodenal bypass, he said.
ELSEVIER GLOBAL MEDICAL NEWS