Bariatric Surgery Gets High Marks for CVD Risk Reduction
By Charles Bankhead, Staff Writer, MedPage Today
Published: September 08, 2011
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
Action Points
Explain that a systematic review found that bariatric surgery significantly reduced risk factors for cardiovascular disease as early as three months after the surgery.
Note that lack of standardization of outcome measures in the different studies included in the review were among a variety of limitations to the analysis.
Obese patients had a 40% reduction in 10-year cardiovascular risk following bariatric surgery, a systematic review of published studies showed.
Average weight loss exceeded 50%, which was associated with significant improvement in cardiovascular risk factors, including hypertension, diabetes, dyslipidemia, C-reactive protein (CRP), and endothelial function.
A majority of the 52 studies included in the analysis demonstrated significant improvement in cardiovascular risk, resulting in a 40% relative risk reduction by the Framingham risk score, as reported online in the American Journal of Cardiology.
"This review highlights the benefits of bariatric surgery in reducing or eliminating risk factors for cardiovascular disease (CVD)," Helen M. Heneghan, MD, of the Cleveland Clinic, and co-authors wrote in conclusion.
"It provides further evidence to support surgical treatment of obesity to achieve CVD risk reduction."
First performed in the 1950s, bariatric surgery has consistently demonstrated the ability to achieve dramatic weight loss in severely obese patients. However, early surgical techniques induced weight loss by means of malabsorption, which was associated with significant nutritional complications.
Modification of the original technique and development of new bariatric procedures have helped reduce the severity of malabsorption problems without minimizing weight-loss efficacy and associated effects on cardiovascular risk factors, the authors wrote in their discussion.
"Indeed, as the field of bariatric surgery has evolved over the past 50 years, weight loss has almost been overshadowed by the extraordinary effects on obesity-related comorbidities," they noted.
Numerous studies have examined the impact of bariatric surgery on individual risk factors. More recently, interest has centered on the surgery's effect on "constellations" of CVD risk factors, including novel biomarkers.
Heneghan and co-authors undertook a systematic review of the literature in an effort to determine the impact of bariatric surgery on CVD risk and mortality.
Beginning with 637 studies reported from 1950 to 2010, the authors trimmed the number to 52, involving a total of 16,867 patients.
The population included in the final analysis had a mean age of 42, and 78% of the patients were women. The patients had a mean baseline body mass index of 49 (range 33 to 58), and the prevalence of selected CVD risk factors included hypertension in 49%, diabetes in 28%, and dyslipidemia in 46%.
Malabsorptive and bypass procedures predominated among surgical technique, as Roux-en-Y gastric bypass and biliopancreatic diversion accounted for 62% of cases.
Median follow-up was 34 months, and excess weight loss averaged 52%. Among studies that reported changes in CVD risk factors, the authors found that hypertension resolved or improved significantly in 68%, diabetes in 75%, and dyslipidemia in 71%.
Mean blood pressure declined from 139/87 mmHg at baseline to 124/77 mmHg. Fasting blood glucose declined from a mean of 126 mg/dL to 92 mg/dL and glycosylated hemoglobin from 7.5% to 6.0%, both of which would be considered clinically meaningful, the authors noted.
Total cholesterol declined from 205 mg/dL to 169 mg/dL, LDL from 118 mg/dL to 94 mg/dL, and triglycerides from 169 mg/dL to 103 mg/dL. Mean HDL level increased from 49 mg/dL to 52 mg/dL.
Two novel markers of CVD risk also improved in the studies that reported the data: CRP declined from 4.5 mg/L to 1.7 mg/L and flow-mediated brachial artery diameter (a measure of endothelial function) increased from 6% to 16%.
Improvement or resolution of CVD risk factors occurred as early as three months after surgery, the authors reported.
As determined by the Framingham risk score, the patients' 10-year coronary heart disease risk averaged 6.27% at baseline and 3.77% at the end of follow-up.
As compared with nonsurgical treatment of individual risk factors, bariatric surgery addresses multiple cardiovascular risk factors and has a larger effect than do medical and other nonsurgical strategies, the authors noted. Nonetheless, the surgery is not without risk and complications, which patients should understand before surgery.
"Bariatric surgery has other significant issues such as surgical morbidity and long-term consequences associated with various procedures, such as nutritional deficiencies," they wrote.
"Nonetheless, in appropriately selected obese patients, surgical intervention compares extremely favorably to nonsurgical therapy and should be considered more often as a lifesaving interdiction rather than a cosmetic operation."
Researchers noted that compliance with medications to reduce CV risk is problematic and lifelong, whereas bariatric surgery to reduce CV risk is performed once and has fairly immediate benefits.
Limitations of the systematic review, according to the authors, included different operating procedures for bariatric surgery, lack of standardization among studies for outcome measures and diagnostic criteria for comorbidities, high attrition for follow-up in the studies, and small number of studies that included biomarkers.
Co-author Stacy A. Brethauer disclosed relationships with Ethicon-Endo, Covidien, and Davol. Co-author Phillip R. Schaueer disclosed relationships with Ethicon-Endo, RemedyMD, Stryker Endoscopy, Davol, W.L. Gore & Associates, Baxtr, BaroSense, SurgiQuest, Cardinal/Snowden Pencer, Allergan, and Surgical Excellence.
From the American Heart Association:
Bariatric Surgery and Cardiovascular Risk Factors
Primary source: American Journal of Cardiology
Source reference:
Heneghan HD, et al "Effect of bariatric surgery on cardiovascular risk profile" Am J Cardiol 2011; DOI:10.1016/j.amjcard.2011.06.076.
