Heart tissues originates from cervical part of embryo and then moves to thoracic area. Upper limbs also buds out from cervical segments. So cardiac pain can be anywhere from neck, jaws, arms (left or right), chest and abdomen up to umbilicus. It’s not necessary to have pain in chest, but commonly it starts from chest.
As myocardial pain is mediated by autonomic nerves, unlike other D/D’s pains which is mediated by somatic nerves, so myocardial pain is poorly localised as compared to non myocardial pains which can clearly be pointed. So if pain can be localised with one finger or can be sharply defined it’s likely not myocardial pain which often is diffusely localised.
Also non myocardial pains don’t go to neck or upper limbs and are limited to chest and/or abdomen.
Aortic dissection pain can radiate out of chest along the course of arteries involved. Dissection can also cause AMI or stroke etc due to compromising the arterial lumen. Patients may have history of HTN and pain will be sudden onset central chest or interscapular to start. Also pulses & BP in all 4 limbs may be unequal. If dissection starts from Arch (type 1) then pain will radiate from front to back and it may have acute AR as well, but if dissection involves thoracic aorta (type 2) then pain will just be interscapular to start.
Myocardial pain, due to stimulation of autonomic nerves, is often associated with autonomic symptoms and severity of these symptoms depends on extent of myocardial damage. Hence pain associated with autonomic symptoms such as vomiting, sweating, palpitations etc is more likely myocardial especially infarction.
Unlike pericardial or pleural or chest wall causes of pain, myocardial pain is non pleuritic. Chest wall tenderness with reproducible pain may mean it’s chest wall pain but remember this sign may coexist with underlying additional cause of pain.
Pleuritic pain due to PE or PTX will be sudden onset, but clear lungs with equal breath sounds and usually a clear Chest X-ray mean PE, whereas PTX will have hyper resonant percussion, reduced air entry and abnormal chest X-ray.
PE may also cause central heavy pain similar to myocardial ischemia pain due to RV Ischemia. PE can also central chest pain stretching of Pulmonary arteries due to elevated Pulmonary pressure and P2 may be loud. Risk factors for PE or DVT may be there as well.
Associated cardiac symptoms such as dyspnea, heart failure, palpitations, syncope etc make it more cardiac rather than other causes.
Myocardial pain is classically central in chest, poorly localised, heaviness type pain.
Exertional chest pain which relieves with rest or GTN, indicates stable angina but other varieties of angina usually occur at rest (unstable, and vasospastic) or during sleep (nocturnal/decubitus) etc & unstable angina doesn’t respond to nitrates. So absence of exertional characteristic or no response to GTN doesn’t exclude myocardial pain (rather may mean worse type of myocardial pains).
ECG changes, elevated cardiac enzymes surely make it cardiac but normal ECG doesn’t exclude myocardial causes as ECG doesn’t cover all areas of myocardium and normal enzymes only exclude infarction but not angina.
Myocardial pain can also be a diagnosis of exclusion if no other cause is found. Even if all the above patterns are not there, and one isn’t confident to exclude myocardial causes, treat as myocardial pain unless effectively excluded. Underlying risk factors such as DM, HTN, hyper lipidemia, strong family history of premature CAD, atherosclerotic disease elsewhere such as CVA or PVD etc help to think in favour of CAD related myocardial pain.