Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services for:
New or severe chest pressure, tightness, or pain
Severe difficulty breathing, especially at rest
Fainting with chest discomfort or palpitations
Sudden weakness on one side, facial drooping, or trouble speaking
Collapse, unresponsiveness, or absent normal breathing
Acute coronary artery blockage and other emergencies need rapid assessment.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek urgent medical advice for a noticeable decline in breathing, repeated episodes of a fast or irregular heartbeat, or new dizziness.
Palpitations accompanied by weakness or near-fainting should be assessed promptly.
3
Does any of this apply?
Book an appointment
Arrange a routine medical review if you have a new report mentioning subendocardial sclerosis and it has not been explained.
Routine review is also appropriate for gradually increasing tiredness, mild breathlessness, ankle swelling, or recurring palpitations without severe symptoms.
The article also says
Do not assume that sudden chest symptoms are caused by old scar tissue.
Every sign above is quoted from the sofidex article on Subendocardial sclerosis. If you are not sure, err upward — it is always reasonable to be checked.