One of yes. However there are two other issues that may have caused this as well. Some are saying this could be similar to what happened to Hank Gathers. Pistol Pete as well.
It could be something like hypertrophic cardiomyopathy, which is inherited and causes the heart to thicken without cause. Or it could've been a pulmonary embolism, which could be traced back to COVID since one of the side effects, is the blood is left in a thickened state, which makes it more likely to clot. Facts are though we don't know and we may never know.