Answer: No it should not be reported because it is unrelated to the participation in the study.
Explanation:
The study was based on health and hygiene and disease prevention. Based on this study the diseases that can be taken into consideration which is related to health and hygiene.
The heart attack is not a disease which is caused by being into an unhygienic environment.
So, heart attack cannot be reported to IRB because the study was not based on this topic.