Wiki CHF Stage B

if you are looking at your ICD book, in the Alphabetic index -

Failure --
-heart - -
- Stage B - see also Failure, heart by type as diastolic or systolic I50.9

if you do not know if the type of heart failure is systolic or diastolic and are able to query the provider, I suggest you do so.

if you do not know the type and are unable to query the provider, then it looks like it would be appropriate to code I50.9.