What is trimetazidine, and would it have helped Kamila Valieva of Russia?

When news broke that Kamila Valieva, the 15-year-old figure skater who helped propel Russia to gold in the team competition, had tested positive for a banned substance before the Olympics, the episode raised questions that have come up many times before in doping scandals.

Did the drug make a difference? Could it have helped her?

The heart expert Dr. Benjamin J. Levine, a professor of exercise science at the University of Texas Southwestern Medical School, said no.

“The chance that trimetazidine would improve her performance, in my opinion, is zero,” Dr. Levine said.

“The only chance would be for it to hurt her,” he added.

The drug, also known as TMZ, is prohibited by the World Anti-Doping Agency under the category of hormone and metabolic modulators, a class of drugs that athletes have been known to use for performance enhancement. It was added to the list of prohibited substances in 2014. It is not approved for sale in the United States.

Its intended use is to increase blood flow to the heart in patients who have chest pain because their cardiac arteries are blocked.

A very similar drug, ranolazine, is approved in the United States for the same indication. It is not very effective, Dr. Levine said, and is rarely used.

Trimetazidine has been proposed to alter the heart’s fuel in a way that would improve performance. But blood flow to the heart is not a problem in events like skating, nor is the type of fuel the heart uses.

“The heart has plenty of blood,” Dr. Levine said. “And the heart is so good at using different fuels.”

The reason skaters find the ending of their routines more difficult than the start is not because their hearts need oxygen or fuel, he said. “It is because their legs get tired.”

The real question, he adds, is “Who gave her this drug? And why would they think it is a reasonable thing to do?”

“Every elite athlete knows about the banned substance list and every physician has the list and checks it every time he gives an athlete a drug,” Dr. Levine said, adding, “How could they have given this drug to the best skater in the world?”

This isn’t the first time trimetazidine has been used by Olympians. In 2014, the Chinese swimmer Sun Yang tested positive for it and was suspended for three months. The Russian bobsledder Nadezhda Sergeeva was disqualified and banned for eight months after testing positive for the drug at the 2018 Games.