2027 ICD-10-CM Diagnosis Code I23.4Rupture of chordae tendineae as current complication following acute myocardial infarction
ICD-10-CM Codes›I00–I99›I20-I25›STEMI
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 229
- Chronic Condition
I23.4 is a billable ICD-10-CM diagnosis code for rupture of chordae tendineae as current complication following acute myocardial infarction. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 306 through 307. 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. It does not count, however, when the principal diagnosis is one of 17 closely related codes. Coders also document this condition as cardiac rupture due to and following acute myocardial infarction. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complications of acute myocardial infarction.
For Medicare Advantage risk adjustment, I23.4 maps to CMS-HCC Category 229 (Unstable Angina and Other Acute Ischemic Heart Disease) under the V28 model, adding a risk factor of about 0.240 for a community, non-dual, aged beneficiary in payment year 2027.
This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such selected atherosclerosis, ischemia, and infarction.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I23.4 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 2027.
Source: CMS Payment Year 2027 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.
- Cardiac rupture due to and following acute myocardial infarction
- Mitral valve regurgitation due to acute myocardial infarction
- Mitral valve regurgitation due to acute myocardial infarction with papillary muscle and chordal rupture
- Rupture of chordae tendinae due to and following acute myocardial infarction
- Rupture of chordae tendineae
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I23.4: its own notes plus those printed at block I20-I25 and Chapter 9. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- rupture of chordae tendineae not specified as current complication following acute myocardial infarction (I51.1)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- systemic connective tissue disorders (M30-M36)
- transient cerebral ischemic attacks and related syndromes (G45.-)
Code Also
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name I23.4, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming I23.4: they are not reported together with it, unless the two conditions are unrelated.
- I51.1 Rupture of chordae tendineae, not elsewhere classifiedrupture of chordae tendineae as current complication following acute myocardial infarction (I23.4)
Excludes2 2
These codes carry an Excludes2 note naming I23.4: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Heart Attack
A heart attack, also called a myocardial infarction, is a type of heart disease. It happens when blood flow to the heart suddenly becomes blocked. Without the blood coming in, the heart can't get oxygen. If not treated quickly, the heart muscle begins to die.
The full article covers:
- What is a heart attack?
- What heart attack risk factors can be changed?
- What heart attack risk factors can't be changed?
- What causes a heart attack?
- What are the symptoms of a heart attack?
- How is a heart attack diagnosed?
- What is the treatment for a heart attack?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I23.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I23.4Overview
Is I23.4 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report rupture of chordae tendineae as current complication following acute myocardial infarction on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I23.4 group to?
When rupture of chordae tendineae as current complication following acute myocardial infarction is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 307, with relative weights from 0.9146 to 1.5457 depending on complications. Higher weights mean higher Medicare reimbursement.
Is I23.4 a CC or MCC?
CMS lists I23.4 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 17 closely related codes in its exclusion list.
Can I23.4 be reported with I51.1?
Not as a rule. The Excludes1 note on I23.4 lists "rupture of chordae tendineae not specified as current complication following acute myocardial infarction (I51.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of I23.4?
Under the General Equivalence Mappings, rupture of chordae tendineae as current complication following acute myocardial infarction converts to ICD-9-CM 429.5 (chordae tendinae rupture). The mapping is approximate, so confirm the match fits the documentation.
What HCC is I23.4?
I23.4 (rupture of chordae tendineae as current complication following acute myocardial infarction) maps to CMS-HCC Category 229 (Unstable Angina and Other Acute Ischemic Heart Disease), commonly written as HCC 229, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 86 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 188.
Does I23.4 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I23.4 adds a risk adjustment factor of about 0.240 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.240 to 0.458 depending on the payment segment). A more severe related category (HCC 228) supersedes it when both are reported. See the full factor table on the HCC 229 category page.
