2026 ICD-10-CM Diagnosis Code I50.33Acute on chronic diastolic (congestive) heart failure

ICD-10-CM Codes›I00–I99›I30-I5A›I50

ICD-10-CM I50.33
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I50.33 is a billable ICD-10-CM diagnosis code for acute on chronic diastolic (congestive) heart failure. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 291 through 293. Coders also document this condition as acute diastolic heart failure. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Heart failure.

This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such heart failure.

Code Identity

ICD-10-CM Code
I50.33
Billable Status
Yes — Valid for Submission
Code Describes
Acute on chronic diastolic (congestive) heart failure
Short Description
Acute on chronic diastolic (congestive) heart failure
Same as the full description in the CMS dataset.
Parent Code
I50.3
Diastolic (congestive) heart failure

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI50Heart failure
This CodeI50.33Acute on chronic diastolic (congestive) heart failure

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute diastolic heart failure
  • Acute exacerbation of chronic heart failure
  • Acute on chronic diastolic heart failure
  • Chronic diastolic heart failure
  • Diastolic heart failure

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.

    • Failure, failed
      • heart (acute) (senile) (sudden)
        • with
          • decompensation
            • with
              • normal ejection fraction
    • Failure, failed
      • heart (acute) (senile) (sudden)
        • with
          • decompensation
            • with
              • preserved ejection fraction
    • Failure, failed
      • heart (acute) (senile) (sudden)
        • with
          • decompensation
            • diastolic
    • Failure, failed
      • heart (acute) (senile) (sudden)
        • diastolic (congestive) (left ventricular)
          • acute (congestive)
            • and (on) chronic (congestive)
    • Failure, failed
      • heart (acute) (senile) (sudden)
        • diastolic (congestive) (left ventricular)
          • chronic (congestive)
            • and (on) acute (congestive)

Clinical ClassificationClinical

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

CCSR CIR019
Heart failure
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Heart Failure

Heart failure means that your heart can't pump enough oxygen-rich blood to meet your body's needs. Heart failure doesn't mean that your heart has stopped or is about to stop beating. But without enough blood flow, your organs may not work well, which can cause serious problems.

The full article covers:

  • What is heart failure?
  • What causes heart failure?
  • Who is more likely to develop heart failure?
  • What are the symptoms of heart failure?
  • What other problems does heart failure cause?
  • How is heart failure diagnosed?
  • What are the treatments for heart failure?
  • Can heart failure be prevented?

Read the full article at MedlinePlus

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

Convert I50.33 to ICD-9-CMHistory

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

ICD-9-CM
428.33 Ac on chr diast hrt fail
Approximate The match is approximate rather than exact.
ICD-9-CM
428.33 Ac on chr diast hrt fail
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
428.0 CHF NOS
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 I50.33Overview

Is I50.33 (Diastolic (congestive) heart failure) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report acute on chronic diastolic (congestive) heart failure on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I50.33 group to?

When acute on chronic diastolic (congestive) heart failure is the principal diagnosis on an inpatient stay, it groups to MS-DRG 291, 292, 293, with relative weights from 0.5660 to 1.2838 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I50.33?

Under the General Equivalence Mappings, acute on chronic diastolic (congestive) heart failure converts to ICD-9-CM 428.33 (ac on chr diast hrt fail), 428.33 (ac on chr diast hrt fail), and 428.0 (CHF NOS). 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.