Serious heart and stroke events followed 0.12% of bariatric surgeries, concentrated in advanced organ disease

Serious heart and stroke complications around the time of weight-loss surgery are rare, but a new analysis of more than a million US operations gives a clearer picture of who is most likely to have one.

Researchers at the University of Arizona in Phoenix and Mayo Clinic in Phoenix looked at 1,095,255 adults who had a first-time sleeve gastrectomy or Roux-en-Y gastric bypass between 2019 and 2024. Within 30 days of surgery, 1,368 of them had what doctors call a major adverse cardiac or cerebrovascular event. That works out to 0.12 percent, or roughly 1 in every 800 patients.

That phrase describes a grouped measure. It combines several serious outcomes into one count, usually heart attack, stroke and death from a cardiovascular cause. The published summary does not spell out the exact list the researchers used, so it is not possible to tell from it which of those events made up the 1,368.

Events were less common after sleeve gastrectomy than after gastric bypass

The researchers report that these events happened more often after Roux-en-Y gastric bypass than after sleeve gastrectomy.

Gastric bypass is the more involved of the two operations. It makes the stomach smaller and also reroutes part of the small intestine. A sleeve gastrectomy removes a portion of the stomach and leaves the intestine alone.

The published summary does not give a separate event rate for each operation, so how big that gap is cannot be pinned down from what has been released.

Advanced organ damage mattered more than a long list of diagnoses

The team used a multivariable analysis. That is a statistical method that weighs many patient characteristics at the same time, so the contribution of each one can be estimated while the others are held steady. It is a way of asking which factors still matter once the obvious overlaps between them are accounted for.

The factors that stood out on their own were dialysis dependence, a previous heart attack, a previous pulmonary embolism, male sex, diabetes treated with insulin, and taking a larger number of blood pressure medicines. A pulmonary embolism is a blood clot that has travelled to the lungs.

The blood pressure finding is worth unpacking. Each additional blood pressure medicine a patient was taking was linked to higher odds of an event. The researchers read this not as the medicines causing harm, but as a marker of how hard that person's blood pressure has been to control. Needing four drugs to manage blood pressure points to more advanced disease than needing one.

In the smaller group of patients for whom heart failure was recorded, heart failure was also linked to higher risk on its own.

The authors' overall conclusion is that risk tracked less with simply having a common condition and more with signs that a condition had already done damage. Diabetes that has reached the point of needing insulin, kidney disease that has reached the point of needing dialysis, and blood pressure that resists several drugs all point in the same direction. On that basis the authors argue that preoperative assessment should focus on patients with end-organ disease, insulin dependence, hard-to-control high blood pressure and established cardiovascular disease.

The published summary does not say how much each risk factor added

This is registry data, gathered as part of routine accredited practice rather than in a trial. It can show which patients had events. It cannot prove that any one characteristic caused them, and patients with these markers differ from other patients in many ways at once.

The summary released by the journal names the strongest predictors but does not publish the odds ratios, the figures that would show how much each factor raised risk. Without them a reader cannot tell whether dialysis dependence, for example, roughly doubled the risk or raised it far more. The full paper is behind a paywall and was not available for this report.

The analysis also stops at 30 days, so it describes the period around the operation and says nothing about heart risk over the months and years that follow.

The data come from centers accredited through the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program, which is run jointly by the American College of Surgeons and the American Society for Metabolic and Bariatric Surgery. Results from accredited centers will not necessarily match what happens elsewhere.

The authors frame the question against a changing patient population and note that GLP-1 medicines are now widely used before surgery. The study did not test whether those medicines change heart risk around an operation, and nothing in it should be read as an answer to that question.

Anyone weighing weight-loss surgery should go through their own cardiac history with their surgical team rather than applying these overall figures to themselves. This article describes a research finding and is not medical advice.