2026 ICD-10-CM Diagnosis Code I44.1Atrioventricular block, second degree

ICD-10-CM Codes›I00–I99›I30-I5A›I44

ICD-10-CM I44.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I44.1 is a billable ICD-10-CM diagnosis code for atrioventricular block, second degree. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 308 through 310. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Conduction disorders.

Code Identity

ICD-10-CM Code
I44.1
Billable Status
Yes — Valid for Submission
Code Describes
Atrioventricular block, second degree
Short Description
Atrioventricular block, second degree
Same as the full description in the CMS dataset.
Parent Code
I44
Atrioventricular and left bundle-branch block

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI44Atrioventricular and left bundle-branch block
This CodeI44.1Atrioventricular block, second degree

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • EKG: Mobitz type II atrioventricular block
  • High degree second degree atrioventricular block
  • Intermittent second degree atrioventricular block
  • Mobitz type I incomplete atrioventricular block
  • Mobitz type I second degree atrioventricular block on electrocardiogram
  • Mobitz type II atrioventricular block
  • Partial atrioventricular block
  • Second degree atrioventricular block

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Atrioventricular block, type I and II
  • Möbitz block, type I and II
  • Second degree block, type I and II
  • Wenckebach's block

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Block, blocked
      • atrioventricular (incomplete) (partial)
        • second degree (types I and II)
    • Block, blocked
      • atrioventricular (incomplete) (partial)
        • types I and II
    • Block, blocked
      • heart
        • second degree (atrioventricular)
    • Block, blocked
      • Mobitz (types I and II)
    • Block, blocked
      • second degree (types I and II)
    • Block, blocked
      • Wenckebach (types I and II)
    • Mobitz heart block(atrioventricular)
    • Phenomenon
      • Wenckebach's
    • Wenckebach's block or phenomenon

Clinical ClassificationClinical

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

CCSR CIR016
Conduction disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Arrhythmia

An arrhythmia is a problem with the rate or rhythm of your heartbeat. Your heart beats too quickly, too slowly, or with an irregular pattern. Changes in the electrical signals that control your heartbeat cause arrhythmias.

The full article covers:

  • What is an arrhythmia?
  • What causes an arrhythmia?
  • What are the symptoms of an arrhythmia?
  • How is an arrhythmia diagnosed?
  • What are the treatments for an arrhythmia?
  • Can arrhythmias be prevented?

Read the full article at MedlinePlus

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

Convert I44.1 to ICD-9-CMHistory

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

ICD-9-CM
426.12 Atrioven block-mobitz ii
Approximate The match is approximate rather than exact.
ICD-9-CM
426.13 Av block-2nd degree NEC
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I44.1Overview

Is I44.1 (Atrioventricular and left bundle-branch block) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report atrioventricular block, second degree on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I44.1 group to?

When atrioventricular block, second degree is the principal diagnosis on an inpatient stay, it groups to MS-DRG 308, 309, 310, with relative weights from 0.5661 to 1.2040 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I44.1?

Under the General Equivalence Mappings, atrioventricular block, second degree converts to ICD-9-CM 426.12 (atrioven block-mobitz ii) and 426.13 (av block-2nd degree NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.