Atrial Fibrillation ICD-10 Codes (I48)

Atrial fibrillation is coded in the ICD-10-CM I48 category, subdivided by how the AFib behaves over time. Here is a quick reference — always confirm against the current ICD-10-CM release.

Atrial fibrillation ICD-10 codes

Atrial flutter codes

Learn the difference between the two rhythms in our flutter vs fibrillation guide.

Coding tips

• Code to the highest specificity documented — paroxysmal, persistent, or permanent.
• Use the unspecified code (I48.91) only when the type isn't documented.
• Capture related conditions separately (e.g. long-term anticoagulant use, Z79.01).

Frequently asked questions

What is the ICD-10 code for atrial fibrillation?

Atrial fibrillation is coded in the I48 category — for example, I48.0 for paroxysmal, I48.21 for permanent, and I48.91 for unspecified atrial fibrillation. Always verify against the current ICD-10-CM release.

What is the ICD-10 code for unspecified atrial fibrillation?

I48.91, used when the specific type of atrial fibrillation is not documented.

How is atrial flutter coded in ICD-10?

Typical atrial flutter is I48.3, atypical is I48.4, and unspecified atrial flutter is I48.92.

What is the ICD-10 code for paroxysmal atrial fibrillation?

I48.0.