Dear
Welcome to HCM
We understand your concerns
I went through your details. Such a health related 
anxiety can definitely trigger anxiety, when you have two experiences of massive heart attacks in your family. But, can you provide a solution? Every doctor will test you according to their knowledge and wisdom. Your doctors did all the tests and they said you are OK. Fine. You should believe them and believe you are perfect.
Everyone are hopeful. Exercise, nutritious food, good life habits, laughing etc are told to be supplements to augment disease free life. But who can be so sure? One more thing you can do is to find a good cardiologist. You should use every available option to find the cardiologist of your choice. then, let him check you. Once he also says you are alright, you should leave the anxiety about your health.
To do that, you may 
consult a psychologist. Psychologist will educate you about anxiety and teach you 
psychotherapy techniques to overcome anxiety.
If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR. Make sure that you include every minute details possible. 
Hope this answers your query. Available for further clarifications.
Good luck.