Question: Answer: Reason: ICD-9 official guidelines explain that "when a 'code first' note is present and an underlying condition is present the underlying condition should be sequenced first" (www.cdc.gov/nchs/icd/icd9cm_addenda_guidelines.htm). But don't omit 414.2 just because it comes second. Indicating the patient has chronic total occlusion may help support a physician's choice to perform more difficult treatments.