I wonder about this. The most common post-COVID cardiac concern is post-COVID myocarditis. From what I've read, it seems like the majority of myocarditis cases have symptoms shortly after infection. I haven't been able to find data on the incidence of myocarditis starting after recovery of symptoms or if initially asymptomatic. Because of that, I don't know how likely it is that he would be suffering from an extreme symptom of myocarditis this far out from his COVID diagnosis if he wasn't previously having symptoms.
Anyway, with all of that being said, I would imagine that any post-COVID screenings for myocarditis would include an echocardiogram and/or a cardiac MRI (which would be easy to do at a major academic hospital). Either one of these two studies should pick up findings that are common in Hypertrophic Cardiomyopathy, which I believe is what Hank Gathers had.
Actually, now that I think about it, a combination of EKG, Echo, and Cardiac MRI should pick up the majority of things that would cause something like this. So I'm curious if we'll ever hear the diagnosis or what their screenings include/were they done.