2026 ICD-10-CM Diagnosis Code I46.9Cardiac arrest, cause unspecified

ICD-10-CM Codes›I00–I99›I30-I5A›I46

ICD-10-CM I46.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I46.9 is a billable ICD-10-CM diagnosis code for cardiac arrest, cause unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 296 through 298. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac arrest and ventricular fibrillation.

Code Identity

ICD-10-CM Code
I46.9
Billable Status
Yes — Valid for Submission
Code Describes
Cardiac arrest, cause unspecified
Short Description
Cardiac arrest, cause unspecified
Same as the full description in the CMS dataset.
Parent Code
I46
Cardiac arrest

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI46Cardiac arrest
This CodeI46.9Cardiac arrest, cause unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Anoxic encephalopathy
  • Anoxic encephalopathy due to cardiac arrest
  • Asystole
  • Atrial standstill
  • Cardiac arrest
  • Cardiac arrest AND/OR failure following anesthesia AND/OR sedation in labor AND/OR delivery
  • Cardiac arrest due to procedure
  • Cardiac arrest during procedure
  • Cardiac arrest following obstetric procedure
  • Cardiac arrest with successful resuscitation
  • Cardiac arrhythmia during pregnancy
  • Circulatory arrest
  • Collapse
  • Collapse due to cardiac arrest
  • EKG: asystole
  • Hypoxic ischemic encephalopathy
  • Hypoxic ischemic encephalopathy due to cardiac arrest
  • Hypoxic-ischemic coma
  • Idiopathic cardiac arrest
  • Obstetrical cardiac complication of anesthesia AND/OR sedation
  • Obstetrical complication of anesthesia AND/OR sedation
  • Post-cardiorespiratory arrest coma
  • Pulseless electrical activity
  • Sinus arrest

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.

    • Arrest, arrested
      • cardiac

Clinical ClassificationClinical

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

CCSR CIR018
Cardiac arrest and ventricular fibrillation
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Collapse

    failure of a physiologic function or system.

  • Collapse of Device|Collapse

    problem associated with the buckling or crushing of material from external forces.

  • Collapsed Lumen|COLLAPSED LUMEN

    a finding in which the walls of a tube or tubular organ have contorted or buckled into its cavity or channel.

  • Collapsed Lung

    atelectasis of an entire lung.

  • Device Collapser

    a component designed to fold or collapse something.

  • Difficult to Fold or Unfold|Difficult to Fold, Unfold or Collapse

    problem associated with the use of the device in terms of the user experiencing difficulty to close or to spread out/extend length of the device, even if the operation is being performed according to labeled instructions for use.

  • Inferior Vena Cava Collapse Due to Sniff Test Indicator|IVCCSIND|Inferior Vena Cava Collapse Indicator|Inferior Vena Cava Collapse Sniff Ind|Inferior Vena Cava Collapse Sniff Ind

    an indication as to whether resting inferior vena cava diameter is reduced with sniff, which is defined as a sharp inhalation.

  • Shock|Circulatory Collapse

    a life-threatening condition that requires immediate medical intervention. it is characterized by reduced blood flow that may result in damage of multiple organs. types of shock include cardiogenic, hemorrhagic, septic, anaphylactic, and traumatic shock.

Patient EducationClinical

Sudden Cardiac Arrest

Sudden cardiac arrest (SCA) is a condition in which the heart suddenly stops beating. When that happens, blood stops flowing to the brain and other vital organs. If it is not treated, SCA usually causes death within minutes. But quick treatment with a defibrillator may be lifesaving.

The full article covers:

  • What is sudden cardiac arrest (SCA)?
  • How is sudden cardiac arrest (SCA) different from a heart attack?
  • What causes sudden cardiac arrest (SCA)?
  • Who is at risk for sudden cardiac arrest (SCA)?
  • What are the symptoms of sudden cardiac arrest (SCA)?
  • How is sudden cardiac arrest (SCA) diagnosed?
  • What are the treatments for sudden cardiac arrest (SCA)?
  • What should I do if I think that someone has had an SCA?

Read the full article at MedlinePlus

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

Convert I46.9 to ICD-9-CMHistory

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

ICD-9-CM
427.5 Cardiac arrest
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 I46.9Overview

Is I46.9 (Cardiac arrest) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cardiac arrest, cause unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I46.9 group to?

When cardiac arrest, cause unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 296, 297, 298, with relative weights from 0.4551 to 1.5619 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I46.9?

Under the General Equivalence Mappings, cardiac arrest, cause unspecified converts to ICD-9-CM 427.5 (cardiac arrest). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.