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Featured Interview: John Morton, MD, MPH Is Bariatric Surgery the Best Therapy for Morbid Obesity?
The June issue of CardioSource WorldNews (CSWN) serves up a cover story on Bypassing Obesity: Is the Way to a Healthy Heart Through the Stomach? In this extended interview, John Morton, MD, MPH, chief of bariatric and minimally invasive surgery at Stanford School of Medicine, carves up the topic with CSWN Executive Editor Rick McGuire.
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McGuire: In talking with cardiologists, they are reluctant to consider a surgical procedure for treating morbid obesity. Yet, as JACC Editor-in-Chief Anthony DeMaria, MD, MACC, said recently in a commentary, "it is stunning that few medical interventions (for obesity) are available" and he called surgery "...the best therapy for morbid obesity."1 As a bariatric surgeon, what is your message to cardiologists?
Dr. Morton: What we do in bariatric surgery is essentially preventative — I call it tertiary prevention — because we stop further progression of disease. In a lot of patients, (weight loss surgery) has a great deal of utility because we all know the impact weight has on cardiac function. It's been an interest of mine for a while. I guess I'm a "closet cardiologist" at heart — no pun intended — but I've always enjoyed the field and started looking at the impact of weight loss surgery on cardiac risk factors. We looked at everything from total cholesterol to high sensitivity C-reactive protein and pretty much across the board we saw big improvements. We recently presented 5-year follow-up data (at ACC.13) and these results are not ephemeral; there is a long-term effect.
We have another paper coming out looking at the impact of weight loss on these cardiac risk factors between the different types of surgery: Roux-en-Y gastric bypass (RNYGB), gastric banding, and sleeve gastrectomy. It's an attempt at comparative effectiveness and what we show is all three approaches improve the cardiac risk factors but they all do it in different ways and to different degrees.
One thing I found to be interesting was that some of the improvements were not directly correlated to weight loss. It seems like there may be something else going on independent of weight loss, like hormonal effects. People have looked at this for a while, since at least the late 1980s, and was looked at in the POSCH trial2, a randomized trial comparing traditional medical management versus surgical weight loss.
It's a fascinating field, and for patients who are difficult to manage when it comes to their weight, lipids, or even diabetes — all of which are the big risk factors for heart disease — bariatric surgery is an excellent option and certainly we are doing our part in making sure the surgery is safe. National 30-day mortality rates are about 0.1 percent, which is equivalent to hip replacement surgery or removal of the gall bladder. So we are seeing some long-term effectiveness and safety.
McGuire: In the CSWN cover story, I included two recently published papers: one showing key hormones and amino acids are favorably altered during digestion after bypass surgery3 and another demonstrating that weight-loss surgery normalizes genes involved in burning and storing fat.4 These papers might explain how weight-loss surgery is eliminating some of the symptoms of type 2 diabetes, for example.
Dr. Morton: Yes, the effect (of bariatric surgery) on diabetes has been profound. There's an 82 percent remission rate for diabetes and it is long term. There are actually data that is 15 years out from Sweden, that's pretty long term. How it works exactly, we're all speculating. But again, the unique thing about the bypass is that these results are independent of weight loss and can occur very quickly, maybe even a week after surgery. The speculation is that it's probably hormonal; it does appear there is an increase in GLP-1 (glucagon-like peptide-1), a fantastic regulator of insulin metabolism.5 (Exenatide) is a GLP-1 agonist and it works very well for controlling blood sugar. It also has an important side effect, which is weight loss.
The other thing to consider here in looking at bariatric surgery is how it can be a platform for investigation. We are really seeing a lot of things change very quickly for the better post-surgery. It's a very pronounced, consistent treatment effect and you can look at a lot of different things. There have been a few studies looking at architectural remodeling. I'm at Stanford where we have a lot of cardiology experience, and I've operated on quite a few patients who have pretty low ejection fractions and were slated to potentially haves transplants, but with the weight off, they were no longer on the (transplant) list. Their ejection fractions improved and they no longer required the transplant.
(Editor's note: A recent systematic review of 73 studies involving 19,543 subjects undergoing bariatric surgery for weight loss summarizes remodeling post-bariatric bypass surgery.6)
McGuire: In putting together this story, I found there is not much clinical guidance. There was an American Heart Association Science Advisory released a couple years back, but it contained very little recommendations in terms of who should be considered for this procedure and, if they have coronary heart disease, what does that mean?7 How do you answer those key questions?
Dr. Morton: I think the ideal candidate is someone who has metabolic syndrome because they fulfill the criteria of increased abdominal girth, insulin resistance, and hyperlipidemia. The criteria for us are a BMI of 35 with a serious medical problem or a BMI over 40. You've got to make sure the patient is motivated and understands what they are getting into. And I think if patients go to accredited centers, they are going to get the education, the safety profile, and as a result, they are going to get better and more consistent results. Gerald Reaven, MD, the physician who coined the term syndrome X (before it became known as metabolic syndrome) is a good friend of mine here at Stanford. We've talked about what an incredible change (weight loss) surgery can bring. And I think if we only operated on metabolic syndrome patients or diabetic patients, it would do them a world of good.
McGuire: What about the effects of bariatric surgery on lipids?
Dr. Morton: We all know that some obese patients are really recalcitrant to medication and bariatric surgery can be another tool in our tool kit to help us address these really hard-to-treat patients. There are some side effects with statins that are particularly pronounced in the obese. Two things in particular: one is muscle weakness, which can occur with the use of the statins and certainly obese patients are particularly prone to that; the other big thing is the increase in transaminases with statin therapy. Those problems are both exacerbated with statin use and bariatric surgery can be a nice adjunct to their care if you can avoid those problems.
McGuire: What about a patient with established cardiovascular disease; maybe a history of an myocardial infarction somewhere in their past, they are stable now but have a high Framingham risk score. What would you recommend?
Dr. Morton: I think those patients would benefit from surgery as well. A lot of those risk factors in the Framingham risk score are going to be amenable to change with bariatric surgery and there are data that help support the assumption that bariatric surgery can decrease cardiac risk. There was a study by Ted Adams, PhD, MPH, and colleagues a few years ago comparing those who had surgery versus those who didn't. They saw a pretty profound (40 percent) reduction in cardiac death at seven years.8 If we believe that cardiac risk factors predict future events, then we can extrapolate and feel fairly certain that a decrease in cardiac risk factors ought to decrease cardiac events.
BMI is probably the best thing you can do to help risk stratify patients for referral. I would start out first with BMIs over 35. I would certainly talk to the patient about the different options for weight loss. I'd find out if there is an established accredited (bariatric) center nearby and have a relationship with them. It's a mutual relationship because as bariatric surgeons, we are always mindful that there can be some perioperative risk and having cardiologists assess that risk is very important because cardiac risk assessment in the obese patients is not easy to do. The usual methods, namely echo, are going to be technically difficult. If you try and do a stress test, they generally have exercise intolerance and joint issues that preclude them from being able to complete the stress test. If you do pharmacologic stress tests, again we are going to have difficulty with the imaging. We did a study that we are presenting next week at Digestive Disease Week — it received a poster of distinction award — and it showed that you can risk stratify and predict who will have a cardiac event after surgery. And it's stuff that you might imagine: a low HDL and a higher CRP. We all realize the beneficial aspects of HDL but there are very few things that will truly elevate it, but bariatric surgery is one of them. In a population we've studied, surgery elevates HDL by about 20 percent.
McGuire: You had an interesting paper on the effects of weight loss surgery on brain natriuretic peptide (BNP).9 What did you find?
Dr. Morton: We've seen such good improvement in all the other cardiac risk factors and there was an assumption that the BNP would improve as well after RNYGB surgery. Instead, BNP actually got a little worse; BNP increased to intermediate levels between 100 and 400 pg/ml. We realized that BNP can actually be a marker for weight loss. If you looked at BNP more closely, it looked a lot like growth hormone, which is very much related to some of the changes in metabolism after surgery.
McGuire: At ACC.13 you presented a study of almost 1,400 consecutive surgeries at Stanford. You included sleeve gastrectomy and gastric banding patients and both procedures produced good results, but the Roux-en-Y gastric bypass seemed to be better in terms of beneficial effects on cardiac risk factors, correct?
Dr. Morton: Yes, that is exactly right; gastric bypass is better for cardiac risk factors.10 It's just like any other aspect of medicine, when you have different therapies, you can get potentially different results. Our procedure of choice at Stanford is still the gastric bypass. If we are trying to decide which procedure works best for a patient we take into account individual characteristics. The other two procedures, the band and the sleeve, are probably not going to be offered to patients who have bad acid reflux disease because these procedures could actually make them worse. In a population with a BMI of over 50, the gastric bypass is more effective as well. For a variety of reasons, we see bigger improvements with the bypass.
McGuire: What is your take-home message for cardiologists?
Dr. Morton: We are all in this together, in the sense that we are working towards the same goals to improve the health of patients at cardiac risk. Virtually all of our patients have cardiac risk factors and we can see improvements with bariatric surgery. We partner with cardiologists for cardiac risk assessment. Bariatric surgery is a wonderful platform to investigate what happens to lipid metabolism or cardiac metabolism afterwards. We want to partner with cardiologists to deal with two of the biggest cardiac risk factors there are, which are obesity and diabetes.
I am secretary-treasurer of The American Society of Metabolic and Bariatric Surgery and, on behalf of our nearly 4,000 members, we're looking to partner with others in the medical community around a common objective, which is to increase the health of the obese patient. We've started a brand new meeting, it's called Obesity Week and its inaugural meeting will be in November in Atlanta. One of our partners is The Obesity Society, a group of obesity researchers and internists, but we are eventually looking to expand this to other partners. Next year we'll be partnering with clinical endocrinology and we would love to have ACC be a part of this because there is a lot of overlap and we could dedicate a portion of Obesity Week to obesity in cardiac disease. We'd love to partner with the ACC on other educational and training initiatives as well, because I believe we should be working very closely together. My presentation at Digestive Disease Week says that "the way to the heart is through the stomach," because I really do think a lot of our risk is engendered by what eat.
References:
1. DeMaria AN. The Multiple Challenges of Obesity. J Am Coll Cardiol 2013;61:784-6. http://content.onlinejacc.org/article.aspx?articleid=1569998
2. Buchwald H, Varco RL, Matts IP, et al. Effect of partial ileal bypass surgery on mortality and morbidity from coronary heart disease in patients with hypercholesterolemia. N Engl J Med l990;323:946-55.
3. Lindqvist A, Spégel P, Ekelund M, et al. Effects of ingestion routes on hormonal and metabolic profiles in gastric-bypassed humans. J Clin Endocrinol Metab 2013;98:E856-61.
4. Barres R, Kirchner H, Rasmussen M, et al. Weight loss after gastric bypass surgery in human obesity remodels promoter methylation. Cell Rep 2013;3:1020-7.
5. Schernthaner G, Morton JM. Bariatric surgery in patients with morbid obesity and type 2 diabetes. Diabetes Care 2008;31 Suppl 2:S297-302.
6. Vest AR, Heneghan HM, Agarwal S, Schauer PR, Young JB. Bariatric surgery and cardiovascular outcomes: a systematic review. Heart 2012;98:1763-77.
7. Poirier P, Cornier MA, Mazzone T, et al. Bariatric Surgery and Cardiovascular Risk Factors: A Scientific Statement From the American Heart Association. Circulation 2011;123:1683-701.
8. Adams TD, Gress RE, Smith SC, et al. Long-term mortality after gastric bypass surgery. N Engl J Med 2007;357:753-61.
9. Changchien EM, Ahmed S, Betti F, et al. B-type natriuretic peptide increases after gastric bypass surgery and correlates with weight loss. Surg Endosc 2011;25:2338-43.
10. Woodard GA, Peraza J, Bravo S, et al. One year improvements in cardiovascular risk factors: a comparative trial of laparoscopic Roux-en-Y gastric bypass vs. adjustable gastric banding. Obes Surg 2010;20:578-82.
Keywords: Bariatric Surgery, Gastrectomy, Gastric Bypass, Tertiary Prevention, Weight Loss, Obesity, Morbid, Lipids, Cardiovascular Diseases, Risk Factors, Diabetes Mellitus, Natriuretic Peptide, Brain
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