I48.91 - Unspecified atrial fibrillation

Version 2023
ICD-10:I48.91
Short Description:Unspecified atrial fibrillation
Long Description:Unspecified atrial fibrillation
Status: Valid for Submission
Version:ICD-10-CM 2023
Code Classification:
  • Diseases of the circulatory system (I00–I99)
    • Other forms of heart disease (I30-I5A)
      • Atrial fibrillation and flutter (I48)

I48.91 is a billable ICD-10 code used to specify a medical diagnosis of unspecified atrial fibrillation. The code is valid during the fiscal year 2023 from October 01, 2022 through September 30, 2023 for the submission of HIPAA-covered transactions.

The code is commonly used in family practice, internal medicine , cardiology medical specialties to specify clinical concepts such as other forms of heart disease.

Unspecified diagnosis codes like I48.91 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

The code is linked to some Quality Measures as part of Medicare's Quality Payment Program (QPP). When this code is used as part of a patient's medical record the following Quality Measures might apply: Atrial Fibrillation And Atrial Flutter: Chronic Anticoagulation Therapy.

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

Clinical Information

Index to Diseases and Injuries References

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for this diagnosis code are found in the injuries and diseases index:

Convert to ICD-9 Code

Source ICD-10 CodeTarget ICD-9 Code
I48.91427.31 - Atrial fibrillation
Approximate Flag - The approximate mapping means there is not an exact match between the ICD-10 and ICD-9 codes and the mapped code is not a precise representation of the original code.

Quality Payment Program Measures

When code I48.91 is part of the patient's diagnoses the following Quality Measures apply and affect reimbursement. The objective of Medicare's Quality Measures is to improve patient care by making it more: effective, safe, efficient, patient-centered and equitable.

Quality Measure Description Quality Domain Measure Type High Priority Submission Methods
Atrial Fibrillation and Atrial Flutter: Chronic Anticoagulation TherapyPercentage of patients aged 18 years and older with nonvalvular atrial fibrillation (AF) or atrial flutter who were prescribed warfarin OR another FDA-approved oral anticoagulant drug for the prevention of thromboembolism during the measurement period.Effective Clinical CareProcessNOClaims, Registry

Patient Education


Atrial Fibrillation

An arrhythmia is a problem with the speed or rhythm of the heartbeat. Atrial fibrillation (AF) is the most common type of arrhythmia. The cause is a disorder in the heart's electrical system.

Often, people who have AF may not even feel symptoms. But you may feel :

AF can lead to an increased risk of stroke. In many patients, it can also cause chest pain, heart attack, or heart failure.

Doctors diagnose AF using family and medical history, a physical exam, and a test called an electrocardiogram (EKG), which looks at the electrical waves your heart makes. Treatments include medicines and procedures to restore normal rhythm.

NIH: National Heart, Lung, and Blood Institute


[Learn More in MedlinePlus]

Code History