Unless the toxicology somehow comes back with "yeah he ate some poisonous seeds" which would thereby imply that this could be the cause of the heart attack, I really doubt we'll ever know the true cause. Could it just have been cardiomyopathy caused by shit diet, drinking, and duster? Absolutely. Could it have been congenital? Possibly. Could it have been a heart attack caused by what people were speculating earlier, like pancreatitis? Also yes (e.g. pancreas implodes, releases enzymes which can directly damage heart tissue or even just cause a blood pressure imbalance that throws someone into an infarction...). Could it have been his teeth? Very likely (bacteria in the teeth/gums can travel directly to your heart which is why some people with heart issues have to eat antibiotics 12 hours before they go to the dentist, every time).
In the end who knows. God speed, little Boglim