hiii dear anxiety can result of unconcerned fear,, conflict that occur in past is producing anxiety unconsciously you can to predict it may have several reasons mostly chemical neurotransmitter changes in brain psychological stress and event reactivating conflict that occur in past feeling of heart attack is like panic attack which is type of anxiety disorder u have to take treatment plz consult psychiatrist for it paroxetine and clonazepam like remedy can help you dose is depends upon severity and episodes doctor will guide you further apart from that meditation and exercise will help proper sleep and diet avoid smoking take regular medicines for hypertension do pleasurable activities give time for hobbies and music all of this will help you to control daily stress and anxiety get well soon take care thank you