Metabolic Surgery Post-MI Trims CV Events Long Term

Patrice Wendling

November 05, 2020

Beyond the well-established benefits of sustained weight loss and improved type 2 diabetes, metabolic surgery performed after myocardial infarction (MI) lowered the long-term risk of cardiovascular events, according to a new registry study.

The risk of major adverse cardiovascular events (MACE), second MI, and death was more than halved in metabolic-surgery patients than in matched nonsurgical peers.

"This clearly indicates the surgery has an outcome and you should perhaps consider the surgery to be a cardiometabolic surgery, not just metabolic surgery," Erik Näslund, MD, PhD, Karolinska Institutet, Stockholm, Sweden, told | Medscape Cardiology. "This is an area that needs to be explored more."

Although plentiful in the setting of diabetes, research into the effects of bariatric surgery on severely obese patients with coronary artery disease (CAD) has been limited and results mixed.

Canadian researchers recently reported significantly higher rates of early and late MACE after bariatric surgery in patients who had CAD. A second study from the same group, however, found similar rates of late mortality, MI, and repeat revascularization in patients with prior myocardial revascularization who underwent bariatric surgery vs matched CAD controls who did not.

For the present study, published October 28 in Circulation, Näslund and his colleagues used the SWEDEHEART registry of heart-disease patients and Scandinavian Obesity Surgery Registry to identify 566 patients who had undergone metabolic surgery after an MI and evenly matched 509 patients by sex, age, year of MI, and body mass index to controls who had an MI but no metabolic surgery.

Their mean age was 53 years, 57% were men, and the time from MI to surgery or start of follow-up averaged 4.8 years among cases and 4.6 years among controls. In the surgery group, Roux-en-Y gastric bypass with a small (< 25 mL) gastric pouch was used in 91% of patients and sleeve gastrectomy in 9%.

Postoperative complications were reported in 42 of 502 patients, including 20 patients requiring significant surgical intervention, two needing ICU care, and one death secondary to massive postoperative bleeding.

The study wasn't designed to look at the safety of the surgery, but "what we can say is that there doesn't look as if there is a very high increased risk of having a complication if you had an MI and undergo bariatric surgery," Näslund said. "Again, these people need to be worked up as you would any patient who's had an MI that undergoes surgery. As cardiologists, we wait 6 months after an MI, and so on and so forth."

At 8 years, 18.7% of the metabolic surgery group had experienced a MACE, compared with 36.2% of the nonsurgical group. The results remained unchanged after multivariable adjustment (adjusted hazard ratio [aHR], 0.44; 95% CI, 0.32 - 0.61).

The cumulative incidence of mortality was 11.7% with metabolic surgery and 21.4% without surgery (aHR, 0.45; 95% CI, 0.29 - 0.70) and was 5.4% vs 17.9% for MI (aHR, 0.24; 95% CI, 0.14 - 0.41).

Metabolic surgery patients also had a lower risk of new-onset heart failure (2.0% vs 4.9%) but similar rates of stroke (3.5% vs 5.4%) and new-onset atrial fibrillation (8.7% vs 9.9%).

Asked how to reconcile the results with studies suggesting an obesity paradox, or better outcomes with higher BMI, Näslund said it's too simplistic to say it's all weight loss. "The obesity paradox is not necessarily applicable to this because there are a lot of things that are ongoing that might affect the outcome that are not related to obesity or the change in obesity."

For example, diabetes was in clinical remission in more than half of patients 1 year after surgery (52.3%) and remission was observed for hypertension in 24.7%, dyslipidemia in 35.6%, and sleep apnea in 66.1%. These numbers held steady at 2 years, at 51%, 21.6%, 29%, and 67.1%, respectively.

In addition, postprandial plasma concentrations of the gut hormone, glucagon-like peptide-1, are significantly increased after contemporary metabolic surgery, he noted.

"Overall, our data indicate that metabolic surgery may be an important secondary prevention strategy in the growing population of severely obese individuals with established coronary artery disease," Näslund and colleagues write.

To test this, the team is planning a randomized controlled trial of bariatric surgery in about 300 patients with CAD followed for about 5 years, he said.

Although Swedish patients are generally healthier than the US general population, the present results are generalizable — but post-MI patients must be committed, Näslund said. "For all bariatric surgery, it's important that the patient wants to undergo the surgery because it has a big impact on that patient's daily life. That's one of the most important things — you need clearly to want to do it."

The study was supported by grants from Region Örebro County and Stockholm City Council. Co-author Johan Ottosson, MD, PhD, reported serving on advisory boards for Johnson & Johnson and Vifor Pharma; the other authors have disclosed no relevant financial relationships.

Circulation. Published online October 26, 2020. Abstract

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