ICD-9-CM Diagnosis Code 427.31
Diagnosis Code: 427.31 (Raw: 42731)
Description: Atrial fibrillation
Classification: International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
Fiscal Year: 2026 Reference
CMS Section 111 Status: Valid for reporting (Excluded from No-Fault liability reporting).
Overview & Historical Usage
ICD-9-CM code 427.31 is designated for Atrial fibrillation. While superseded by ICD-10 for current healthcare encounters, it remains a recognized reference code for CMS Section 111 reporting, legacy claims adjudication, and historical clinical data analysis.