Posts suggest without evidence that vaccine caused J.J. Watt’s AFib

On Sept. 28, Arizona Cardinals defensive end J.J. Watt revealed on Twitter that he had experienced atrial fibrillation, an irregular and rapid heart rhythm that can cause blood clots in the heart and increase the risk of stroke and heart failure. 

An image shared on Instagram suggests it happened because Watt received the COVID-19 vaccination. 

"‘Fully vaccinated’ NFL megastar JJ Watt says his heart went into ‘A-fib’ this week, had to be shocked into rhythm," reads a screenshot of a blog post headline. 

"Since when do football players in the best shape of their lives go into A-fib?" an Instagram post sharing this screenshot said. "Pretty sure I got a hint… #Whaccine #TheThing."

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We reached out to Watt’s representative and the Arizona Cardinals but didn’t hear back. The blog itself provides no evidence to corroborate its claim. Forbes reported in December 2021 that although Watt hasn’t explicitly said he’s vaccinated against COVID-19, he’s among several players "on 100% vaccinated teams according to their head coaches or teammates." 

Kliff Kingsbury, the Cardinals’ head coach, said in September 2021 that the team was 100% vaccinated. Watt had signed a two-year contract with the Cardinals about six months earlier. 

The Associated Press reported Oct. 2 that Watt "doesn’t know what caused the irregular heartbeat." On Twitter, he said he "went into A-fib" on Sept. 28 and had his heart "shocked back into rhythm" Sept. 29, and he played in a game Oct. 2 against the Carolina Panthers. 

"I talked to cardiologists and electrophysiologists from all over the country," Watt said during a postgame press conference. "I was assured multiple times from multiple people that there was nothing else you could do. I could play like normal and something could happen the next day or never again in 20 years. So I was assured, and I went back to practice on Friday and here we are."

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Many athletes are prone to AFib, a CBS News affiliate in Milwaukee reported after Watt’s health scare. Dr. Atul Bhatia, an electrophysiologist at a medical center there, told the outlet that athletes typically have good heart health, but because they train so intensively, they are at higher risk for AFib. 

"They are more prone to develop atrial fibrillation, just because of the super trained heart," Bhatia said. "There are many, many individuals, in athletics, in the field of sports, who have this condition undiagnosed."   

The virus that causes COVID-19, meanwhile, has been connected to new-onset AFib cases, said Dr. Eduardo Sanchez, chief medical officer for prevention at the American Heart Association, in a Sept. 14 statement. According to a published study, new-onset AFib cases were identified in 1 in 20 patients hospitalized with COVID-19. (Watt tested positive for COVID-19 in August.) 

Sanchez said "we can’t stress enough the connections between COVID-19 and cardiovascular disease. … We urge everyone who is eligible to get the vaccine and all recommended boosters. The side effects of the vaccine have proven to be minimal and far outweigh the risk of getting COVID." 

We found no evidence to support the claim that COVID-19 vaccines caused Watt’s atrial fibrillation. We rate that False.