Bernie Sanders, one of the front-runners in the race to become the Democratic Party presidential flag-bearer, suffered a heart attack, a statement from his campaign team has confirmed.
Mr Sanders had complained of pain in his chest and had to be rushed to the hospital in Nevada where he underwent surgery.
The surgery was conducted with the aim of removing a blockage in the 78-year-old's artery.
Arturo Marchand and Arjun Gurura, who operated on the Vermont senator, said that the rest of his arteries were normal and advised him to keep checking up with his personal physician.
They said that the diagnosis found that he has myocardial infarction.
"The Senator was stable upon arrival and taken immediately to the cardiac catheterization laboratory, at which time two stents were placed in a blocked coronary artery in a timely fashion, " a statement from the doctors seen by newsrooms read.
Mr Sanders will remain in Las Vegas before heading off to his residence in Burlington, Vermont.
He waved to reporters with a smile as he left the hospital where he had been undergoing treatment.
It was not immediately clear what impact, if any, the diagnosis would have on the legislator's second presidential run.