Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services now for new or returning chest pressure, tightness, or pain; discomfort spreading to the arm, jaw, neck, back, or abdomen; severe shortness of breath; collapse; or unresponsiveness.
After discharge, seek emergency help for symptoms your discharge plan identifies as an emergency, especially recurring chest discomfort, fainting, severe breathing difficulty, or signs of stroke such as facial drooping, arm weakness, or trouble speaking.
And for anyone, someone who:
Contact your healthcare team promptly about worsening medicine side effects, increasing swelling, problems at a catheter or surgical wound, or difficulty following your treatment plan.
And for anyone, someone who:
Do not use a routine message service.
Routine follow-up is used to review medicines, recovery, driving, work, physical activity, and cardiac rehabilitation.
Keep these appointments even when you feel well.
Every sign above is quoted from the sofidex article on Heart attack first aid. If you are not sure, err upward — it is always reasonable to be checked.