Women have lower risk of developing heart disease after bariatric surgery than men, research shows

American Society for Metabolic and Bariatric Surgery (ASMBS)Nov 7 2016

Women have about a 20 percent less chance of developing heart disease after weight-loss surgery than men, according to new research presented today at ObesityWeek 2016, the largest international event focused on the basic science, clinical application and prevention and treatment of obesity. The annual conference is hosted by the American Society for Metabolic and Bariatric Surgery (ASMBS) and The Obesity Society (TOS).

According to researchers from Stanford University School of Medicine, while both genders significantly reduce their risk of developing cardiovascular disease over a 10-year period, women seem to benefit more. One year after surgery, women reduced their risk by 41 percent, while men reduced their risk of heart disease by 35.6 percent.

"This study shows there is a gender disparity in cardiac outcomes for patients undergoing bariatric surgery," said lead study author John M. Morton, MD, Director of Bariatric Surgery at Stanford Hospital & Clinics and immediate past-president, ASMBS. "The findings suggest that women may have an enhanced mechanism of response to bariatric surgery, which leads to greater normalization of biochemical cardiac risk factors."

The study followed 1,989 patients who underwent laparoscopic Roux-en-Y gastric bypass or laparoscopic sleeve gastrectomy at the Stanford BMI Clinic. Biochemical cardiac risk factors (BCRFs) including hemoglobin A1c, total cholesterol, HDL, LDL, triglycerides, C-reactive protein (CRP), lipoprotein(a), homocysteine, and BNP, were collected preoperatively and 12 months after surgery. The Framingham Coronary Heart Disease Risk Score was used to estimate the risk of a heart attack in 10 years before surgery and at the one-year mark.

At one year, women had greater improvement than men for the Framingham Coronary Heart Disease Risk Score -- 44.7 percent vs. 41.4 percent. In addition, women who had bariatric surgery had an absolute lower relative risk than men at one year with a one-year risk score of 5.11 vs 11.2 respectively. In addition, women had less abnormal HDL or good cholesterol levels than men at one year -- 10.1 vs 21.8, respectively. Finally, excess weight loss was greater for women -- Men: 65.9% ± 21.1%, Women: 73.3% ± 23.8%.

"Obesity is a major and modifiable risk factor for heart disease, the leading cause of death in the United States for both men and women," said Stacy Brethauer, MD, a bariatric surgeon at the Cleveland Clinic and ASMBS President-Elect, who was not involved in the study. "This study suggests, however, that men and women may respond differently to bariatric surgery when it comes to heart health despite comparable weight loss."

The effect of gender on 12-month post-op change in BCRFs through a linear regression analysis when controlling for age, change in BMI, # of pre-op co-morbidities, and change in cardiac risk factors levels demonstrated: HbA1c: Men decrease by 0.44% (p=0.000), Triglycerides: Men decrease by 26.7 mg/dl (p=0.005), CRP: Women decrease by 4.23 mg/L (p=0.000).

Notable reductions in the 10-year risk of developing cardiovascular disease for both genders post-surgery were noted with women demonstrating significantly lower risk compared to men pre- and post-surgery. Men were able to normalize levels of HbA1c and triglycerides and waist circumferences better than women post-surgery. Men may be more metabolically receptive to bariatric surgery. Women were able to normalize levels of CRP better, maintain higher HDL levels, and had a higher percent of excess weight loss following surgery compared to men. Each gender showed significant cardiac risk improvement in response to bariatric surgery, however that may be through gender-distinct mechanisms.

Metabolic/bariatric surgery has been shown to be the most effective and long lasting treatment for morbid obesity and many related conditions and results in significant weight loss. The Agency for Healthcare Research and Quality (AHRQ) reported significant improvements in the safety of metabolic/bariatric surgery due in large part to improved laparoscopic techniques. The risk of death is about 0.1 percent and the overall likelihood of major complications is about 4 percent.

According to the Centers for Disease Control and Prevention (CDC), in 2011-2014, the prevalence of obesity was just over 36 percent in adults, with a higher prevalence among women than men (38.3% vs. 34.3%) and older than younger adults (37% vs. 32.3%). Obese is medically defined as having a body mass index (BMI), a measure of height to weight, that's more than 30. The ASMBS estimates about 24 million Americans have severe obesity, which would mean a BMI of 35 or more with an obesity-related condition like diabetes or a BMI of 40.​