John Fetterman, the lieutenant governor of Pennsylvania and Democratic senate nominee, said Friday that he “almost died” after suffering a stroke on 13 May. Fetterman, whose health problems have reportedly prompted concerns about his campaign, also revealed that he had cardiomyopathy, which makes it more difficult for the heart to pump blood throughout the body.

In a statement, Fetterman admitted that he had neglected his health. “As my doctor said, I should have taken my health more seriously. The stroke I suffered … didn’t come out of nowhere,” he said in a note, according to CBS News’s Ed O’Keefe.

Fetterman provided a timeline of his health issues – and lapses in caring for them – in his statement. “Back in 2017, I had swollen feet and went to the hospital to get checked out,” Fetterman said. “That’s when I learned I had a heart condition. Then, I didn’t follow up.”

“I thought losing weight and exercising would be enough,” Fetterman continued. “Of course it wasn’t.”

“I want to emphasize that this was completely preventable. My cardiologist said that if I had continued taking the blood thinners, I never would have had a stroke. I didn’t do what the doctor told me,” Fetterman also said.

Fetterman said he wouldn’t make the same mistake again and is following his physicians’ advice to rest and focus on recovery.

“It will take some more time to get back on the campaign trail like I was in the lead-up to the primary. It’s frustrating – all the more so because this is my own fault – but bear with me, I need a little more time,” he said. “I’m not quite back to 100% yet, but I’m getting closer every day.”

Fetterman also made public a statement from his cardiologist. In 2017, the doctor diagnosed him with atrial fibrillation as well as a “decreased heart pump” – but Fetterman “did not go to any doctor for 5 years”.

The doctor said that Fetterman’s present condition was “stable” and that he had a pacemaker-defibrillator, adding, “The prognosis I can give for John’s heart is this: if he takes his medications, eats healthy, and exercises, he’ll be fine.

“If he does what I’ve told him, and I do believe that he is taking his recovery and his health very seriously this time, he should be able to campaign and serve in the US Senate without a problem.”

Some Democrats previously told NBC News that they worried about Fetterman’s health and felt that his team hadn’t been transparent when he was admitted to hospital several weeks ago. In a report published Thursday on NBC News, an elected Pennsylvania Democrat pointed to the unclear timing of when Fetterman would campaign again, saying “a lot of us Democratic party types are very nervous about it”.

“I think people I’ve talked to – myself included – don’t know what to make of it,” a longtime Democratic strategist in Pennsylvania told NBC News. “It’s not like Fetterman has close institutional allies, so Dems are calling around wanting to ask the question, but no clue where to get a sense of how serious it is.”

Several hours after Fetterman spoke about his health, David McCormick conceded Pennsylvania’s Republican Senate primary to Dr Mehmet Oz, a celebrity heart surgeon backed by Donald Trump. Oz’s win sets the stage for a general election between him and Fetterman, which could easily turn into one of the US’s most important races, as the victor might determine which party controls the Senate.