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ICD-10-CM 2027 diagnosis code

I23.4Rupture of chordae tendineae as current complication following acute myocardial infarction

✓ Billable / specificMCC — major complication/comorbidity

I23.4 is a valid, billable ICD-10-CM code for rupture of chordae tendineae as current complication following acute myocardial infarction. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Rupture of chord tendne as current comp following AMI

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About I23.4

I23.4 is the ICD-10-CM diagnosis code for rupture of chordae tendineae as current complication following acute myocardial infarction. It belongs to category I23 (certain current complications following ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction (within the 28 day period)), block I20-I25 (ischemic heart diseases) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within I23 (certain current complications following ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction (within the 28 day period)), I23.4 is specifically for rupture of chordae tendineae as current complication following acute myocardial infarction. Related codes cover hemopericardium as current complication following acute myocardial infarction (I23.0), atrial septal defect as current complication following acute myocardial infarction (I23.1), ventricular septal defect as current complication following acute myocardial infarction (I23.2), rupture of cardiac wall without hemopericardium as current complication following acute myocardial infarction (I23.3), rupture of papillary muscle as current complication following acute myocardial infarction (I23.5), thrombosis of atrium, auricular appendage, and ventricle as current complications following acute myocardial infarction (I23.6), Postinfarction angina (I23.7) and other current complications following acute myocardial infarction (I23.8).

Don't report I23.4 together with the conditions in its Excludes1 note: rupture of chordae tendineae not specified as current complication following acute myocardial infarction (I51.1).

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 306 (Cardiac Congenital and Valvular Disorders with MCC, relative weight 1.546) and DRG 307 (Cardiac Congenital and Valvular Disorders without MCC, relative weight 0.9148), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 429.5 (rupture of chordae tendineae).

Coding notes

Excludes1Not coded here — never report together with this code
  • rupture of chordae tendineae not specified as current complication following acute myocardial infarction (I51.1)

Notes that apply from higher levels

Instructions written at a parent level also apply to I23.4.

Broader instructions also apply from I20-I25 Ischemic heart diseases and Chapter 9: Diseases of the circulatory system.

Alphabetic index entries

4 entries

Terms in the official ICD-10-CM index that lead to I23.4.

Codes whose notes reference I23.4

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 429.5Rupture of chordae tendineaeapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about I23.4

Is I23.4 billable?

Yes. I23.4 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can I23.4 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict I23.4 as a principal diagnosis.

Is I23.4 a CC or MCC?

I23.4 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does I23.4 group to?

I23.4 is used in the MS-DRG v44.0 logic for MS-DRG 306 (Cardiac Congenital and Valvular Disorders with MCC) and MS-DRG 307 (Cardiac Congenital and Valvular Disorders without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for I23.4?

The CMS General Equivalence Mappings map I23.4 to ICD-9-CM 429.5.