I t is a busy day in your ED:

A 60 y/o female refers a retrosternal pain radiates to right arm that lasts more than 20 minutes.

A 50 y/o male refers a pressure in his chest, with tachycardia and sweating.

A 75 y/o female refers a sharp and stabbing pain exacerbates by forceful breathing.

In all cases the ECGs are nondiagnostic.
Do these clinical features help to predict an acute myocardial infarction (AMI)?

Conclusion

The incipit of the third universal definition of myocardial infarction (ESC guidelines 2012) is: “myocardial infarction can be recognised by clinical features, including ECG findings, elevated values of biochemical markers of myocardial necrosis and by imaging”.
About clinical features the definition is vague: possible ischaemic symptoms, or the duration of the pain is usually > 20 min, miocardial infarction may occurr with atypical symptoms.
The previous pictures are merciless, typical and atipical symptoms have the same value.

PS: The sweating (only if observed) is the only clinical feature that increases significantly the likelihood of AMI.

Bibliography

K Thygesen
Third universal definition of myocardial infarction
Eur Heart J 33, 2551-2567, 2012

R Body
The value of symptoms and signs in the emergent diagnosis of acute coronary syndromes
Resuscitation 81, 281-286, 2010