I’ll see your “high-level U.S. institution” and raise you a couple more studies supporting benign outcomes for prolonged PR intervals without complicating factors.
Obviously, some debate remains on the subject. What strikes me is the absence of convincing evidence that sudden cardiac death (the purported focus of fearmongers like Steve Kirsch) is a consequence of PR interval prolongation under 300 msec, a lack of data showing that pilots are keeling over from Covid-19 vaccination, and the chief medical officer of the American College of Cardiology finding that the latest FAA guidelines are reasonable.
http://techarp.com/facts/faa-admit-pilot-ekgs-vaccines/
Oh, and that last article contains evidence refuting the idea that the FAA has rushed to put pilots into the air who are allegedly unfit due to Covid-19 vaccination:
"Fact #6 : FAA Considered Long PR Interval Normal Before COVID-19 Vaccines
“The FAA had earlier released a document that said that a first-degree AV block with PR interval between 0.21 and 0.29 seconds is considered normal.”
“That document was published on 3 July 2019 – more than 5 months before the first COVID-19 outbreak in China, and more than 17 months before the first COVID-19 vaccine was approved!”
I’m curious whether Dr.T2 is loath to fly as a result of the new FAA guidelines. Personally, I have no qualms.