Bariatric Surgery and Cardiovascular Risk Factors: A Scientific Statement From the American Heart Association
The following are 10 points to remember about bariatric surgery and cardiovascular risk factors:
1. The National Institutes of Health suggests that bariatric surgery be considered for patients with a body mass index (BMI) over 40 kg/m2 or >35 kg/m2 when comorbidities such as hypertension or diabetes mellitus are present. Studies have noted improved survival for severely obese patients while operative mortality rates are low (between 0.1% and 2.0% depending on type of procedure). Obesity shortens life. Compared to a normal weight adult, a 25-year-old male with severe obesity has a 22% reduction in his expected lifespan. Data from the National Health and Nutrition Examination Survey suggest that a white woman age 20-30 years with a BMI ≥45 kg/m2 will lose 8 years of life, whereas a similar male will lose 13 years of life.
2. The most rapidly growing segment of the obese population is those who are severely obese. Between 1986 and 2000, rates of adults with a BMI >30, 40, and 50 kg/m2 have doubled, quadruped, and quintupled, respectively. An estimated 31 million Americans meet the definition of severely obese and could qualify for bariatric surgery. Severe obesity disproportionately affects blacks, women, young adults, and those with lower socioeconomic status.
3. Bariatric surgery includes restrictive and hybrid procedures. Restrictive procedures induce weight loss by reducing oral intake through reductions in the stomach pouch or the diameter of the opening to the stomach. The hybrid procedures include reduction in the stomach pouch and realignment of the digestive track, which leads to malabsorption. An example of the hybrid procedure is the Roux-en-Y gastric bypass.
4. Mortality rates are generally low and depend on type of procedure in addition to patient-related factors such as body habitus, age, and comorbidities. Early complications include thromboembolism, pulmonary or respiratory insufficiency, hemorrhage, peritonitis, and wound infection. Late complications include gastrointestinal obstruction (gastric and intestinal), marginal ulceration, and complications due to malabsorption.
5. Average weight loss after bariatric surgery ranges from 50% to 70%; restrictive procedures are associated with slower weight loss and greater weight gain long-term.
6. Bariatric procedures have been observed to improve systemic insulin sensitivity, improve metabolic syndrome criteria, and prevent diabetes. For diabetic patients, reversal of diabetes mellitus can be observed in up to 72% of patients post-bariatric surgery.
7. Improvements in lipids may occur after bariatric surgery. In one study, 82% of patients were able to discontinue their lipid-lowering therapy after weight loss surgery. Greater impact has been noted after Roux-en-Y procedures, as compared to gastric procedures. Of note, significant improvements are seen in high-density lipoprotein with weight loss after bariatric surgery; however, some studies have not found the amount of weight loss to be predictive of changes in lipids. Weight loss associated with bariatric surgery has also been shown to improve nonalcoholic fatty liver disease including steatosis, inflammation, and fibrosis.
8. Other improvements in cardiovascular risk factors related to bariatric surgery include improvements in blood pressure and improvements in sleep apnea.
9. Future areas of research include a better understanding of the process of weight loss and satiety. Understanding regulatory factors involved in appetite is a key component to long-term weight loss.
10. Post-surgical care includes careful follow-up for diet. For restrictive procedures, patients are required to limit caloric intake, whereas for malabsorptive procedures, lifelong supplementation of vitamins and minerals is often required. Patients may experience dumping syndrome with symptoms of flushing, palpitations, epigastric pain, and vomiting after consumption of sugars. An interdisciplinary team which includes a dietician is useful to assist patients to adapt their eating behaviors in the postoperative period. Patients should be counseled about the possibility of weight regain and the steps to prevent significant weight gain long-term.
Keywords: Inflammation, Bariatric Surgery, Follow-Up Studies, Gastric Bypass, Body Weight, Weight Gain, Feeding Behavior, Obesity, Morbid, Energy Intake, Diet, Nutrition Surveys, Hypertension, United States, Diabetes Mellitus
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