Atrial fibrillation and flutter (I48) ICD-10-CM
The I48 code range covers atrial fibrillation and flutter with 13 ICD-10-CM diagnosis codes. 9 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the I48 Range 13 codes · 9 billable
- I48 Atrial fibrillation and flutterNon-billable
- I48.0 Paroxysmal atrial fibrillation
- I48.1 Persistent atrial fibrillationNon-billable
- I48.11 Longstanding persistent atrial fibrillation
- I48.19 Other persistent atrial fibrillation
- I48.2 Chronic atrial fibrillationNon-billable
- I48.20 Chronic atrial fibrillation, unspecified
- I48.21 Permanent atrial fibrillation
- I48.3 Typical atrial flutter
- I48.4 Atypical atrial flutter
- I48.9 Unspecified atrial fibrillation and atrial flutterNon-billable
- I48.91 Unspecified atrial fibrillation
- I48.92 Unspecified atrial flutter
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the I48 range.
Atrial Fibrillation
Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.
Atrial Flutter
Rapid, irregular atrial contractions caused by a block of electrical impulse conduction in the right atrium and a reentrant wave front traveling up the inter-atrial septum and down the right atrial free wall or vice versa. Unlike ATRIAL FIBRILLATION which is caused by abnormal impulse generation, typical atrial flutter is caused by abnormal impulse conduction. As in atrial fibrillation, patients with atrial flutter cannot effectively pump blood into the lower chambers of the heart (HEART VENTRICLES).
About the I48 Code Range
ICD-10 codes I48 and its subcategories are used to diagnose and document different types of atrial fibrillation and atrial flutter, which are heart rhythm disorders involving rapid and irregular beating of the atria. These codes differentiate specific forms such as paroxysmal, persistent, longstanding persistent, chronic, permanent atrial fibrillation, and typical or atypical atrial flutter.
These codes help medical coders identify conditions like paroxysmal atrial fibrillation (I48.0), also called "atrial fibrillation with rapid ventricular response" or "non-rheumatic atrial fibrillation." Persistent forms include persistent atrial fibrillation (I48.1) and its longstanding variant (I48.11). Chronic and permanent types are coded as I48.20 and I48.21, respectively. The section also covers atrial flutter, with typical (I48.3) and atypical (I48.4) forms, distinguished by their EKG patterns. Unspecified categories (I48.9, I48.91, I48.92) allow documentation when precise subtypes aren't determined. The codes are essential for diagnosing these arrhythmias, tracking their progression, and guiding treatment decisions in cardiac care settings.
Questions About This Page
How many billable codes are in the I48 range?
Of the 13 codes in this range, 9 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the I48 range classify?
The range classifies atrial fibrillation and flutter. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
