2027 ICD-10-CM Diagnosis Code I48.0Paroxysmal atrial fibrillation

ICD-10-CM Codes›I00–I99›I30-I5A›I48

ICD-10-CM I48.0
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I48.0 is a billable ICD-10-CM diagnosis code for paroxysmal atrial fibrillation. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 308 through 310, 791, 793. Coders also document this condition as atrial fibrillation due to heart valve disorder. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac dysrhythmias.

For Medicare Advantage risk adjustment, I48.0 maps to CMS-HCC Category 238 (Specified Heart Arrhythmias) under the V28 model, adding a risk factor of about 0.299 for a community, non-dual, aged beneficiary in payment year 2027.

This medical diagnosis code is frequently used in Family Practice, Internal Medicine, and Cardiology medical specialties to designate conditions such other forms of heart disease.

Code Identity

ICD-10-CM Code
I48.0
Billable Status
Yes — Valid for Submission
Code Describes
Paroxysmal atrial fibrillation
Short Description
Paroxysmal atrial fibrillation
Same as the full description in the CMS dataset.
Parent Code
I48
Atrial fibrillation and flutter

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI48Atrial fibrillation and flutter
This CodeI48.0Paroxysmal atrial fibrillation

Medicare Risk Adjustment (HCC)Billing

I48.0 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.

CMS-HCC V28 Category (Payment Model)
HCC 238— Specified Heart Arrhythmias
Payment HCC · PY 2027 one of 17 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.299
community, non-dual, aged · ranges 0.245–0.407 across segments
Hierarchy
Top of its hierarchy
HCC 238 is not superseded by any other condition category
Prior Model (CMS-HCC V24)
HCC 96
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 96 · ESRD (V21): HCC 96 · ESRD (V24): HCC 96
ESRD V21 weights: 0.093 dialysis, 0.247–0.303 functioning graft · ESRD V24 weights: 0.049 dialysis, 0.227–0.346 functioning graft
Part D (RxHCC)
RxHCC 193 — Atrial Arrhythmias
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Atrial fibrillation due to heart valve disorder
  • Atrial fibrillation with rapid ventricular response
  • Non-rheumatic atrial fibrillation
  • Paroxysmal atrial fibrillation
  • Paroxysmal atrial fibrillation due to heart valve disorder
  • Paroxysmal atrial fibrillation with rapid ventricular response

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I48.0: its own notes plus those printed at Chapter 9. A note printed at a category, block or chapter applies to every code under it.

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 9 (I00-I99) Diseases of the circulatory system applies to 1,433 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • transient cerebral ischemic attacks and related syndromes (G45.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name I48.0, its category, or a range that includes it.

Excludes2 1

These codes carry an Excludes2 note naming I48.0: its condition is not part of those codes, and both may be reported when the patient has both.

  • R00 Abnormalities of heart beat
    specified arrhythmias (I47-I49) names I47-I49, which includes this code

Code Also 1

These codes say I48.0 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • M35.81 Multisystem inflammatory syndrome
    cardiac arrhythmia (I47-I49.-) names I47-I49, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR017
Cardiac dysrhythmias
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Paroxysmal Atrial Fibrillation

    a disorder characterized by an electrocardiographic finding of episodic atrial fibrillation with abrupt onset and termination.

Patient EducationClinical

Atrial Fibrillation

Atrial fibrillation, also known as AFib or AF, is one of the most common types of arrhythmias. Arrhythmias are problems with the rate or rhythm of your heartbeat. They can cause your heart to beat too slowly, too fast, or in an irregular way.

The full article covers:

  • What is atrial fibrillation (AFib)?
  • What causes atrial fibrillation (AFib)?
  • Who is more likely to develop atrial fibrillation (AFib)?
  • What are the symptoms of atrial fibrillation (AFib)?
  • What other problems can AFib cause?
  • How is atrial fibrillation (AFib) diagnosed?
  • What are the treatments for atrial fibrillation (AFib)?
  • Can atrial fibrillation (AFib) be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I48.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
427.31 Atrial fibrillation
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I48.0Overview

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

The ICD-10-CM code for paroxysmal atrial fibrillation is I48.0 (sometimes written as I480). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I48.0 (Atrial fibrillation and flutter) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report paroxysmal atrial fibrillation on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does I48.0 group to?

When paroxysmal atrial fibrillation is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 309, 310, 308, with relative weights from 0.5686 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I48.0?

Under the General Equivalence Mappings, paroxysmal atrial fibrillation converts to ICD-9-CM 427.31 (atrial fibrillation). The mapping is approximate, so confirm the match fits the documentation.

What HCC is I48.0?

I48.0 (paroxysmal atrial fibrillation) maps to CMS-HCC Category 238 (Specified Heart Arrhythmias), commonly written as HCC 238, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 96 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 193.

Does I48.0 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, I48.0 adds a risk adjustment factor of about 0.299 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.245 to 0.407 depending on the payment segment). HCC 238 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 238 category page.