ICD-10 Code I48.20 – Chronic atrial fibrillation, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I48.20 – Chronic atrial fibrillation, unspecified
What it is
This code identifies atrial fibrillation that is chronic or longstanding, with no further detail documented about type or cause. Use it when the record confirms ongoing atrial fibrillation but does not specify more.
Clinical signs
Clinical features vary; refer to documentation. Atrial fibrillation is typically an irregularly irregular rhythm, and the diagnosis is usually confirmed by ECG or rhythm monitoring.
When to use this code
Use I48.20 when the provider documents chronic atrial fibrillation and does not name it as paroxysmal, persistent, or permanent. It also fits when the chart states atrial fibrillation is longstanding or chronic without another qualifying detail. If the record gives a more specific subtype, code that instead.
Do not use for
Do not use this code for atrial fibrillation that is clearly documented as paroxysmal, persistent, or permanent. Do not assume chronicity if the note only mentions a single episode; check documentation.
Coding tip
Code the most specific atrial fibrillation type documented, and query the provider if chronicity or subtype is unclear.