Heart attack (myocardial infarction) leads to cardiac arrest all the time. That's how people die from heart attacks. If someone has a myocardial infarction and

Heart attack (myocardial infarction) leads to cardiac arrest all the time. That's how people die from heart attacks. If someone has a myocardial infarction and then goes into cardiac arrest with a shockable rhythm, shocking is absolutely the appropriate thing to do. (But it is only a temporizing measure - if the person does not get treatment for the underlying myocardial infarction, they will simply go into cardiac arrest again.)