A selection of resources
There seems to be a dearth of guidelines on the diagnosis of cardiomyopathy for generalists. NICE suggests considering the diagnosis if low probability of the cardiomyopahty if angina-like pain but low probability of coronary vessel disease
European society of Cardiology have a guidelines but mainly seems to be after a diagnosis has been suggested and therefore less helpful for an emergency practitioner.
Some of the finest free to access resources out there
Dense but necessary
Comprehensive guide to paediatric cardiomyopathy.
A readable and open-access guide to the types of cardiomyopathy