We have ICD-10 codes mapped by IMO vendor and found that I99.8 is mapped to indicate Ischemic Vascular Disease. Their response to our question about this code was:
_The IMO term “ischemic vascular disease” is correctly mapped to ICD-10-CM preferred primary code I99.8. This follows ICD-10 index guidance for: Ischemia, ischemic I99.8. This mapping has been validated by AHIMA. ICD-10 code I99.8 is a valid, complete code.

IMO terms are mapped context free using only the term description meaning itself and mapped to ICD-10-CM following the ICD-10-CM Official guidelines for Coding and Reporting index and tabular instructions. ICD-10Data.com is a General Equivalence Mapping (GEM) cross mapping (cross walk) between ICD-9-CM and ICD-10-CM. It is not a substitute for the official ICD-10-CM index and tabular. IMO terms are mapped independently to each classification system following the index and tabular guidelines. We do not cross-map between code sets._

Requesting addition of I99.8 to be added to value set
2.16.840.1.113883.3.464.1003.104.12.1003 - Diagnosis: Ischemic Vascular Disease