I have picked up congenital aortic valve issues in people well into their 50s that somehow weren’t picked up before. They are usually asymptomatic and depending on the issue the murmur can come and go. Endocarditis from drug use can cause sudden aortic issues. Usually the cardiomyopathy is a result of the valve issue whatever it was. I don’t know why the coroner called it idiopathic i haven’t seen the report. Like anyone else coroners have varying levels of skill and experience. It may be they were not certain what caused the valve issue or it may have multifactoral with something like endocarditis on a congenitally abnormal valve. unfortunately it is not uncommon to diagnose valve issues at the time of death in young people. But if your world view requires it to be secondary to the covid vaccine you can join the rest of the small but vocal group here who feels the same.
Actually, I was thinking cocaine. Anytime an actor drops dead, my first biased assumption is drugs.