Weight loss resulting from gastric bypass surgery could improve heart function in people with severe obesity, according to two-year findings from the Utah Obesity Study, published this week.
You can read about the study, by Dr Dr Theophilus Owan of the University of Utah School of Medicine in Salt Lake City, and colleagues, online in the 8 February issue of the Journal of the American College of Cardiology.
Owan and colleagues wrote in their background information that while gastric bypass surgery, a type of procedure that leaves the functional part of the stomach much smaller, is increasingly being used to help severely obese people lose weight, there has been little research on other effects, such as risk factors for heart disease.
Also, while studies have shown there is a link between obesity and cardiovascular disease, it is poorly understood, except to say that obese people often show signs of changes to the structure of the heart.
So for this study, using data available from the two-year results of the Utah Obesity Study, Owan and colleagues set out to test the suggestion, as has been hinted at by other studies, that gastric bypass surgery changes the structure and function of the heart to the benefit of the patient.
They used data from 423 severely obese patients who underwent gastric bypass surgery and from a control group of 733 severely obese counterparts who did not have the surgery.
The results showed that: At the two-year follow up, gastric bypass patients had a significantly large reduction in BMI (Body Mass Index, a measure of obesity that compares a person's weight in kilos to their height in metres squared) compared to the controls (average of -15.4, plus or minus 7.2 kg/m2, versus -0.03 plus or minus 4.0, p<0.0001).
They also experienced significant reductions in waist size, systolic blood pressure, heart rate, triglycerides, LDL ("bad") cholesterol, and insulin resistance, and increase in HDL ("good") cholesterol.
The gastric bypass group showed reductions in "left ventricular (LV) mass index and right ventricular (RV) cavity area" (increases in these two areas have been linked to cardiovascular disease in obese people).
Also, while left atrial volume did not change in the surgery group it increased in the controls.
The surgery group also experienced structural changes in addition to reductions in chamber sizes: there was an "increased LV midwall fractional shortening and RV fractional area change".
Further analysis showed that age, change in BMI, severity of nocturnal hypoxemia, E/E' (a measure of LV filling pressure), and gender were independently associated with LV mass index.
However, whether a patient had surgery or not, change in waist circumference and change in insulin resistance were not linked with LV mass index.The researchers concluded that: "Marked weight loss in patients undergoing GBS [gastric bypass surgery] was associated with reverse cardiac remodeling and improved LV and RV function."
They suggested these findings "support the use of bariatric surgery to prevent cardiovascular complications in severe obesity".
Speculating on the underlying links between gastric bypass surgery and changes to heart function, such as the change in left-ventricular mass, they pointed out that losing a lot of weight after bariatric surgery could set off a number of changes that lead to this kind of outcome.
Some studies have suggested there is a link between "central obesity" and change in left-ventricular structure, but this study did not confirm that, leading Owan and colleagues to suggest it is perhaps obesity in general as opposed to being obese around the middle, that drives the links with cardiovascular risks.
Although this was not a randomized study, the authors also strongly suggest it was the weight loss and not some other effect such as changes in hormones caused by the surgery, that is responsible for the differences they found between the two groups.
"Favorable Changes in Cardiac Geometry and Function Following Gastric Bypass Surgery: 2-Year Follow-Up in the Utah Obesity Study."
Owan, Theophilus, Avelar, Erick, Morley, Kimberly, Jiji, Ronny, Hall, Nathaniel, Krezowski, Joseph, Gallagher, James, Williams, Zachary, Preece, Kevin, Gundersen, Nancy, Strong, Michael B., Pendleton, Robert C., Segerson, Nathan, Cloward, Tom V., Walker, James M., Farney, Robert J., Gress, Richard E., Adams, Ted D., Hunt, Steven C., Litwin, Sheldon E.
J Am Coll Cardiol, 8 February 2011, 57: 732-739.
DOI:10.1016/j.jacc.2010.10.017
Additional source: theheart.org.
Written by: Catharine Paddock, PhD
Copyright: Medical News Today
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