ICD-10-CM Code I48.91

Unspecified atrial fibrillation

Version 2021 Billable Code Family Practice Internal Medicine Cardiology

Valid for Submission

I48.91 is a billable code used to specify a medical diagnosis of unspecified atrial fibrillation. The code is valid for the fiscal year 2021 for the submission of HIPAA-covered transactions. The ICD-10-CM code I48.91 might also be used to specify conditions or terms like accelerated atrioventricular conduction, atrial fibrillation, atrial fibrillation and flutter, atrial fibrillation with rapid ventricular response, atrial flutter, controlled atrial fibrillation, etc

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

Short Description:Unspecified atrial fibrillation
Long Description:Unspecified atrial fibrillation

Index to Diseases and Injuries

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 the code I48.91 are found in the index:


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

  • Accelerated atrioventricular conduction
  • Atrial fibrillation
  • Atrial fibrillation and flutter
  • Atrial fibrillation with rapid ventricular response
  • Atrial flutter
  • Controlled atrial fibrillation
  • Familial atrial fibrillation
  • Lone atrial fibrillation
  • Preexcited atrial fibrillation
  • Rapid atrial fibrillation
  • Transient cerebral ischemia due to atrial fibrillation
  • Ventricular pre-excitation

Clinical Information

  • 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.

Diagnostic Related Groups

The ICD-10 code I48.91 is grouped in the following groups for version MS-DRG V38.0 What are Diagnostic Related Groups?
The Diagnostic Related Groups (DRGs) are a patient classification scheme which provides a means of relating the type of patients a hospital treats. The DRGs divides all possible principal diagnoses into mutually exclusive principal diagnosis areas referred to as Major Diagnostic Categories (MDC).
applicable from 10/01/2020 through 09/30/2021.


Convert I48.91 to ICD-9

  • 427.31 - Atrial fibrillation (Approximate Flag)

Code Classification

  • Diseases of the circulatory system (I00–I99)
    • Other forms of heart disease (I30-I52)
      • Atrial fibrillation and flutter (I48)

Code History

  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016
    (First year ICD-10-CM implemented into the HIPAA code set)
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021

Information for Patients

Atrial Fibrillation

Also called: AF, AFib

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

  • Palpitations -- an abnormal rapid heartbeat
  • Shortness of breath
  • Weakness or difficulty exercising
  • Chest pain
  • Dizziness or fainting
  • Fatigue
  • Confusion

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

  • Atrial fibrillation - discharge (Medical Encyclopedia)
  • Atrial fibrillation or flutter (Medical Encyclopedia)
  • Cardiac ablation procedures (Medical Encyclopedia)
  • Electrocardiogram (Medical Encyclopedia)
  • Holter monitor (24h) (Medical Encyclopedia)

[Learn More]