There are so many factors that can be linked to heart issues that I would be careful to just assume these must be due to the vaccine:
1) myocarditis and pericarditis cases in young males were linked to COVID infections and while studies have shown that the MRNA vaccines also led to higher incidences, youths were 6 times more likely to get it from COVID as they were from the vaccine, and the effects lasted longer.
2) the lockdowns in most cases didn't do any good for many peoples cardiovascular health, with many people drinking more and putting on weight, which may also explain why we are seeing more deaths due to diabetes.
Any associated deaths should still be treated as resulting from our response to COVID and will need to be included when somebody gets round to trying to figure out the overall human cost of COVID and governments responses to it.
Using excess deaths is a valid way of measuring the true effects of the disease as its quite easy to establish good baselines and relate any blips to wars, famine, natural disasters etc. However they measure both deaths resulting from COVID infections as wells as deaths caused by our response to trying to combat the infections (vaccines, lockdowns, deaths due to inability to get hospital treatment due to hospital priorities, deaths due to cancers detected too late for the same reason). These latter effects will be continuing for years to come.