Patients with obesity who had bariatric surgery had a lower risk of having a major adverse cardiovascular event (MACE) or dying from all causes during a median 7-year follow-up, compared with similar patients who did not undergo surgery.
Dr. Philippe Bouchard
These findings, from a province-wide retrospective cohort study from Quebec, follow two recent, slightly shorter similar trials.
Now we need a large randomized clinical trial (RCT), experts say, to definitively establish cardiovascular and mortality benefits in people with obesity who have metabolic/bariatric surgery. And such a trial is just beginning.
Philippe Bouchard, MD, a general surgery resident from McGill University in Montreal presented the Quebec study in a top papers session at the annual meeting of the American Society for Metabolic & Bariatric Surgery.
The findings showed that, among obese patients with metabolic syndrome, bariatric/metabolic surgery is associated with a sustained decrease in the incidence of MACE and all-cause mortality of at least 5 years, Dr. Bouchard said.
“The results of this population-based observational study should be validated in randomized controlled trials,” he concluded.
In the meantime, “we believe our study adds to the body of evidence in mainly two ways,” Dr. Bouchard told this news organization in an email.
It has a longer follow-up than recent observational studies, “a median of 7 years, compared to 3.9 years in a study from the Cleveland Clinic, and 4.6 years in one from Ontario, he said.
“This allows us to [estimate] an absolute risk reduction of MACE of 5.11% at 10 years,” he added. This is a smaller risk reduction than the roughly 40% risk reduction seen in the other two studies, possibly because of selection bias, Dr. Bouchard speculated.
“Second, most of the larger cohorts are heavily weighted on Roux-en-Y gastric bypass,” he continued. In contrast, their study included diverse procedures, including sleeve gastrectomy, duodenal switch, and adjustable gastric banding.
“Given the rise in popularity of a derivative of the duodenal switch – the single-anastomosis duodenal-ileal bypass with sleeve gastrectomy (SADi-S) – we believe this information is timely and relevant to clinicians,” Dr. Bouchard said.
RCT on the subject is coming
“I totally agree that we need a large randomized controlled trial of bariatric surgery versus optimal medical therapy to conclusively establish” the impact of bariatric surgery on cardiovascular outcomes, said the assigned discussant, Mehran Anvari, MD. And their research group is just about to begin one.
Dr. Mehran Anvari
In the absence of RCT data, clinicians “may currently not refer [eligible] patients for bariatric surgery because of the high risk they pose,” said Dr. Anvari, professor and director of the Centre for Minimal Access Surgery of McMaster University, Hamilton, Ont., and senior author in the Ontario study.
Furthermore, an important point is that the current trial extended the follow-up to 7 years, he told this news organization in an email.
That study included patients with diabetes and hypertension, he added, whereas his group included patients with a history of cardiovascular disease and/or heart failure.
“We hope these studies encourage general practitioners and cardiologists to consider bariatric surgery as a viable treatment option to prevent and reduce the risk of MACE in the obese patients [body mass index >35 kg/m2] with significant cardiovascular disease,” he said.
“We have embarked on a pilot RCT among bariatric centers of excellence in Ontario,” Dr. Anvari added, which showed the feasibility and safety of such a study.
He estimates that the RCT will need to recruit 2,000 patients to demonstrate the safety and effectiveness of bariatric surgery in reducing MACE and cardiac and all-cause mortality among patients with existing cardiovascular disease.
This “will require international collaboration,” he added, “and our group is currently establishing collaboration with sites in North America, Europe, and Australia to conduct such a study.”