I48.9 Unspecified atrial fibrillation and atrial flutter
The ICD-10-CM code for Unspecified atrial fibrillation and atrial flutter is I48.9 (FY2026). It is a non-billable category code — select a more specific code below for claims.
Classification
- Section
- I30-I5A: Other forms of heart disease (I30-I5A)
- Category I48
- 13 codes (9 billable)
- FY2026 Status
- Stable since FY2024
Official Coding Guidelines
Presumed relationship due to Index term “with”The classification presumes a causal relationship between hypertension and heart involvement and between hypertension and kidney involvement, as the two conditions are linked by the term “with” in the Alphabetic Index. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated.
Provider must link conditions not specifically indexed as relatedFor hypertension and conditions not specifically linked by relational terms such as “with,” “associated with” or “due to” in the classification, provider documentation must link the conditions in order to code them as related.
Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026