''The cardiac size and function were restored toward normal in the people who got the gastric bypass surgery," says researcher Sheldon Litwin, MD, chief of cardiology at the Medical College of Georgia.
''We hypothesized that it would have this effect, but it is nice to prove it," says researcher Sheldon Litwin, MD, chief of cardiology at the Medical College of Georgia.
The study results support the use of bariatric surgery to prevent cardiovascular complications, according to Litwin.
The findings are similar to previous studies, he says, but his study included more people and a longer follow-up than other studies. The new study also compares those who had the surgery with those who did not, finding the surgery patients fared better in terms of not only weight loss but heart functioning.
The study is published in the Journal of the American College of Cardiology.
Obesity and Changes in the Heart
Severely obese people experience what is called adverse ''cardiac remodeling," Litwin says. The left atrium and the left ventricle commonly get bigger. The left atrium receives oxygen-rich blood from the lungs and pumps it down into the left ventricle, which pumps it out to the body.
When the left ventricle gets too thick and too big, it can affect people's ability to exercise, Litwin tells WebMD. The enlargement of the left atrium boosts the risk of an abnormal heart rhythm, atrial fibrillation, in turn increasing the risk of stroke, he says.
These cardiac changes also increase the risk of heart failure and death.
In the study, the 423 patients who had the surgery were on average age 42; the 733 who didn't have surgery were on average age 46.
All patients in the surgery group had the Roux-en-Y procedure. In this surgery, the stomach is made smaller by creating a small pouch at the top of the stomach using surgical staples or a plastic band, and then the stomach is connected to the middle part of the small intestine, bypassing some of the small intestine.
As a result, the patient eats less and absorbs less food.
At the study's start and end, the researchers measured height, weight, heart rate, blood pressure, blood glucose, cholesterol, and other factors. The researchers performed echocardiography, the use of ultrasound to study the heart's motions and structure, on most of the patients at the study's start and two years later.
Effect of Gastric Bypass on the Heart
At the study's start, the average body mass index (BMI) of those who had surgery was 47.9 (30 and higher is termed obese; 40 and up severely obese). The BMI of those who didn't have surgery averaged about 45.
After two years, those who had surgery reduced their BMI by 15.4, while those in the non-surgery group reduced it only slightly, by 0.03.
At the study's start, the average weight of those who had surgery was 299 pounds; at the end of two years, their weight averaged 200 pounds.
The patients who didn't have surgery weighed, on average, 279 pounds at the start and 273 at the end of the study.
The weight loss was associated with either stabilization or partial reversal of the cardiac changes, Litwin found, while continued obesity tended to be linked with a modest progression of the cardiac changes.
In the surgery patients, the left ventricular mass was reduced, Litwin found. The left atrial volume didn't change in the surgery patients, but it increased in those who didn't have surgery. He found improvements in the working of the left and right ventricles in surgery patients.
The new research is ''more detailed and bigger than previous studies," says Bruce M. Wolfe, MD, president of the American Society for Metabolic and Bariatric Surgery, who reviewed the new findings for WebMD.
"This [new study] is more up to date, with detailed parameters from the echo [echocardiogram], and has the comparative group to validate the assumption that you need to lose weight to have the improvements," says Wolfe, a professor of surgery at Oregon Health & Science University in Portland.
Would the findings apply to other weight reduction surgeries, such as the popular Lap-Band, in which a band is applied to the upper part of the stomach to reduce the amount of food the stomach can hold?
Wolfe suspects so, but cannot say for sure. ''In bariatric surgery there is a variable weight loss response," he says, whatever the procedure used. If those who had Lap-Band had weight losses comparable to what the researchers found in the recent study, he says the same effect on the heart could be possible.