Gastric bypass associated with greatest improvement in cardiac risk factors



WASHINGTON – One year out from surgery, gastric bypass, gastric sleeve, and gastric banding all showed considerable reductions in cardiac risk factors, but gastric bypass showed the greatest risk reduction of all three, as well as greater improvement in body mass index, according to a study presented at this year’s annual clinical congress of the American College of Surgeons.

Baseline and 1-year postoperative data were collected on 1,398 consecutive bariatric surgery patients by Christopher S. Crowe and his colleagues at Stanford (Calif.) University. The investigators sought to evaluate each type of surgery’s effect on biochemical cardiovascular risk factors. The follow-up rate at 12 months was 77%.

The values measured were hemoglobin A1c, fasting insulin, high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol, triglycerides, high-sensitivity C-reactive protein (CRP), homocysteine, and lipoprotein (a).

Across the three groups, bypass patients tended to be younger by 1-2 years (mean age of this group was 44.3 years), and they had a higher baseline body mass index on average.

Excess weight loss after 1 year averaged 75% in the bypass patients, 55% in the patients with a sleeve, and 40% in those with a band.

When analyzing laboratory values for each group, the investigators found that fasting insulin levels were notably improved in all three groups; but at an improvement rate of 67.0%, the bypass patients had more than double the improvement of the gastric-band patients, while the gastric-sleeve patients showed a 63.7% improvement rate.

The CRP levels also improved dramatically in the bypass patients (67.1%), especially when compared with the band (21.2%) and sleeve (26.3%) groups. In addition, the ratio between triglycerides and HDL, a strong predictor of cardiovascular events, was differentially most improved in the bypass patients (38.5%), although improvement was also seen in both band (20.6%) and sleeve (35.2%) groups.

The investigators also sought to correlate each bariatric procedure’s resultant weight loss to improvement in specific cardiac risk factors. Only bypass was found to have a correlate between weight loss and total cholesterol and LDL reduction.

The triglyceride/HDL ratio improved with weight loss in both the bypass and band surgical groups. However, patients over age 50 and with a BMI greater than 50 kg/m2 had the least improvement in this ratio.

Reduction in CRP level was not found to be related to weight loss for any of the procedures, although CRP did improve substantially after all three operations, primarily in bypass patients. In response to a question from an audience member, Mr. Crowe, a medical student, said this was probably because of changes in patient lifestyle, diet, and medications, as well as smoking cessation, postoperatively.

"When someone comes in for a bariatric procedure, they’re not just receiving the surgery, they are changing a lot about their life," said Mr. Crowe. "Those changes could, in effect, decrease the CRP levels after surgery, without it being weight loss–dependent."

Mr. Crowe reported no relevant disclosures. His coinvestigators reported serving as consultants to Ethicon and Covidien.

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