LAS VEGAS (AP) — Democratic presidential candidate Bernie Sanders had a heart attack, his campaign confirmed Friday as the Vermont senator was released from a Nevada hospital.

The 78-year-old was at a campaign event Tuesday when he experienced chest discomfort and was taken to a hospital where he was diagnosed with a heart attack. The senator was transferred to Desert Springs Hospital Medical Center, where doctors inserted two stents to open up a blocked artery in his heart, according to a statement from the Las Vegas doctors.

The doctors, Arturo Marchand, Jr. and Arjun Gururaj, said the rest of his arteries were normal.

A blocked artery can cause a heart attack, which means that an area of the heart is suffering and in danger of damage because it’s not getting enough blood or oxygen. An artery-opening procedure like the one Sanders had, and placing stents, which are tiny scaffolds to keep the artery open, restores blood flow and helps prevent future problems.

The statements from Sanders and his doctors do not indicate whether his heart suffered any permanent damage, or the extent of any. The sooner blood flow is restored, the better the chance of survival without damage, which is why heart experts urge anyone thinking they might be having a heart attack to call 911.

The doctors said the rest of his stay before being discharged Friday was “uneventful with good expected progress.”

The campaign also released a statement from Sanders where he thanked the doctors, nurses and hospital staff.

“After two and a half days in the hospital, I feel great, and after taking a short time off, I look forward to getting back to work,” he said.

Soon after, he posted a video on Twitter showing him standing at a Las Vegas park with his wife.

“I just got out of the hospital a few hours ago and I’m feeling so much better,” Sanders said. “See you soon on the campaign trail.”

He and his wife both thanked people for their warm wishes.

He was expected to return to Vermont.

“There should not be an overreaction to this,” said Dr. Steve Nissen, a heart expert at Cleveland Clinic who has not treated Sanders himself. “If he were my patient, I might ask him to avoid 16-hour days for at least a little bit of time. But there’s absolutely no reason he can’t get back to full activity soon.”

Heart attack patients may be statistically more prone to future heart attacks, Nissen said, but that doesn’t mean Sanders will have another episode or has to slow down for more than a few days or weeks.

“What’s more important than his age is his condition before the event. He strikes me as an incredibly vigorous and energetic guy. People like that tend to do well,” Nissen said, adding that he doesn’t buy the idea that stress causes heart attacks. “The culprit is a blockage in the coronary artery.”

This marks the second time in two months that health problems forced Sanders to cancel campaign events. In September, he backed out of some appearances in South Carolina because he lost his voice. His campaign said at the time that Sanders felt fine.

As the oldest candidate in the Democratic 2020 field, Sanders has sometimes jokingly referenced his age on the campaign trail. He is one of three septuagenarians who are leading the crowded race and have sparked questions within the party about whether Democrats need to coalesce around a younger leader.

Younger candidates, such as 37-year-old South Bend, Indiana Mayor Pete Buttigieg, have said it’s time for a new generation to lead the Democratic Party and the country. Former Obama Housing Secretary Julian Castro appeared to make a jab at 76-year-old former Vice President Biden’s age during the September debate. “Are you forgetting what you said two minutes ago?” the 45-year-old asked.

Former President Jimmy Carter, who turned 95 this week, recently said he hoped there would be an “age limit” for the presidency and said he didn’t believe he could undertake the duties of the job if he were just 80.

Democrats know that if they nominate one of the candidates who is 70 or older, it will be hard for them to use 73-year-old President Donald Trump’s age against him.

Sanders, Biden and 70-year-old Massachusetts Sen. Elizabeth Warren have all pledged to release updated medical records.

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AP Chief Medical Writer Marilynn Marchione in Milwaukee and AP Medical Writer Carla K. Johnson in Seattle contributed to this report.