By Patrick Wingrove

PHILADELPHIA (Reuters) -Novo Nordisk on Saturday said the heart protective benefits of its wildly popular Wegovy obesity treatment are due to more than weight loss alone, according to new data presented at a major medical meeting on Saturday.

Early data from the Danish drugmaker's Select trial released in August demonstrated that Wegovy, which has been shown to help patients lose an average of 15% of their weight, also reduced incidence of heart attack, stroke or death from heart disease by 20%.

Full results from the study, presented at the American Heart Association annual scientific meeting in Philadelphia in front of a standing room only crowd and published in the New England Journal of Medicine, suggest the drug has other beneficial effects beyond the known health benefits from losing weight.

The heart risk difference between patients who received Wegovy, known chemically as semaglutide, and those on placebo began to appear almost immediately after starting treatment, researchers said.

In the study of overweight and obese patients based on body mass index who had preexisting heart disease but not diabetes, Wegovy reduced the risk of non-fatal heart attack by 28%, non-fatal stroke by 7% and heart-related death by 15% compared to a placebo.

Given that patients had not started losing weight when the cardiovascular benefits first appeared suggests the heart protection was not purely the result of weight loss, Novo said.

Dr Chad Weldy, a cardiologist at Stanford University, said on the sidelines of the conference that it was important to note that the trial did not study how semaglutide might stop heart disease from happening and only looked at how to stop it from getting worse.

Despite that, the size of the patient population covered by this trial should make doctors think about the sorts of patients who should be prescribed Wegovy based on the data.

"Anyone who has had a heart attack or obstructive coronary disease and has a body mass index of more than 27 fits in with this study, which is a very large patient population," he said.

Dr Bruno Halpern, head of the obesity center at Hospital 9 de Julho in São Paulo, Brazil, also said at the conference that Wegovy should now be a frontline treatment for heart disease.

The study researchers said that while understanding of the mechanisms of the cardiovascular protection from semaglutide remain speculative, there was a consistent effect on associated risk factors that support the idea that multiple pathways are behind the drug's clinical benefit.

The associated risk factors include inflammation, blood pressure and blood sugar control, all of which can impact heart health.

John Deanfield, one of the study's authors and cardiology professor at University College London, said at the medical meeting that the trial data would spur a debate over where Wegovy fits into doctors' treatments.

"When do we start these drugs in our patients? How do we stop them? How much weight do we want them to lose to get the benefit?" he said.

Patients on Wegovy experienced decreases in C-reactive proteins, an indication of inflammation, similar to those reported with cholesterol lowering statins, which are known to significantly lower heart risks, researchers reported.

"The cardiovascular benefit (of Wegovy) is a combination of many factors, but I would call out glycemic (blood sugar) control, weight loss and inflammation," Martin Lange, Novo Nordisk's head of development, said in an interview.

In the 17,604-patient trial with a mean duration of 33 months, almost 1,500 of those taking Wegovy discontinued treatment due to adverse side effects, mostly gastrointestinal disorders like nausea and vomiting, compared to 718 patients in the placebo group, according to the study.

Though the trial was not conducted to test weight loss, participants lost an average of nearly 10% of their total body weight. Novo said patients in the heart study were not required to track diet and exercise as they are in obesity trials.

The study showed Wegovy to be safe and well-tolerated in line with previous semaglutide trials, Novo said.

It was unclear whether the results could be applied to all GLP1-class drugs or were specific to semaglutide, Barclays analyst Emily Field said in an interview.

Lange said he expected the company's application to have Wegovy's label updated to include the heart benefits to be approved in the U.S. in the first half of next year and in the EU in the second half. Drug regulators can update the information on medicine labels to include new data or reflect new indications for use after initial approval.

U.S. and UK drug regulators approved Eli Lilly's rival weight-loss treatment on Wednesday, which had previously been approved and marketed as Mounjaro for diabetes.

(Reporting by Patrick WingroveEditing by Caroline Humer, Bill Berkrot and Diane Craft)