2026 ICD-10-CM Diagnosis Code I46.9Cardiac arrest, cause unspecified
ICD-10-CM Codes›I00–I99›I30-I5A›I46
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 213
- Not Chronic
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, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. This status applies only when the patient is discharged alive, and not when the principal diagnosis is one of 24 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac arrest and ventricular fibrillation.
For Medicare Advantage risk adjustment, I46.9 maps to CMS-HCC Category 213 (Cardio-Respiratory Failure and Shock) under the V28 model, adding a risk factor of about 0.370 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I46.9 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 2026.
Source: CMS Payment Year 2026 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.
- 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.
cardiac I46.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Code HistoryHistory
Questions About I46.9Overview
What is the ICD-10 code for cardiac arrest, cause unspecified?
The ICD-10-CM code for cardiac arrest, cause unspecified is I46.9 (sometimes written as I469). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
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, 791, 793, with relative weights from 0.4551 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.
Is I46.9 a CC or MCC?
CMS lists I46.9 as an MCC (major complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It carries this status only when the patient is discharged alive. It does not count when the principal diagnosis is one of the 24 closely related codes in its exclusion list.
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.
What HCC is I46.9?
I46.9 (cardiac arrest, cause unspecified) maps to CMS-HCC Category 213 (Cardio-Respiratory Failure and Shock), commonly written as HCC 213, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 84 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does I46.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I46.9 adds a risk adjustment factor of about 0.370 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.258 to 0.662 depending on the payment segment). A more severe related category (HCC 211 and HCC 212) supersedes it when both are reported. See the full factor table on the HCC 213 category page.
