2027 ICD-10-CM Diagnosis Code I51.1Rupture of chordae tendineae, not elsewhere classified
ICD-10-CM Codes›I00–I99›I30-I5A›I51
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 229
- Chronic Condition
I51.1 is a billable ICD-10-CM diagnosis code for rupture of chordae tendineae, not elsewhere classified. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other and ill-defined heart disease.
For Medicare Advantage risk adjustment, I51.1 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.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I51.1 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.
- Abnormality of mitral chordae tendinae
- Abnormality of right atrioventricular valve chordae tendinae
- Abnormality of tricuspid chordae tendinae
- Acute mitral regurgitation
- Acute mitral regurgitation from chordal rupture
- Mitral chordae rupture
- Postprocedural mitral valve regurgitation
- Postprocedural mitral valve regurgitation due to papillary muscle and chordal rupture
- Rupture of chordae tendineae
- Rupture of left atrioventricular valve chordae tendinae
- Rupture of right atrioventricular valve chordae tendinae
- Ruptured tricuspid chordae
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I51.1: its own notes plus those printed at I51 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 as current complication following acute myocardial infarction (I23.4)
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.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name I51.1, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming I51.1: they are not reported together with it, unless the two conditions are unrelated.
- I23.4 Rupture of chordae tendineae as current complication following acute myocardial infarctionrupture of chordae tendineae not specified as current complication following acute myocardial infarction (I51.1)
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 Diseases
Heart disease is a general term that includes many types of heart problems. It's a type of cardiovascular disease, which means heart and blood vessel disease.
The full article covers:
- What is heart disease?
- What are the types of heart disease?
- What causes heart diseases?
- Who is more likely to develop heart diseases?
- What are the symptoms of heart disease?
- How are heart diseases diagnosed?
- What are the treatments for heart disease?
- Can heart diseases be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I51.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I51.1Overview
What is the ICD-10 code for rupture of chordae tendineae, not elsewhere classified?
The ICD-10-CM code for rupture of chordae tendineae, not elsewhere classified is I51.1 (sometimes written as I511). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I51.1 (Complications and ill-defined descriptions of heart disease) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report rupture of chordae tendineae, not elsewhere classified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I51.1 group to?
When rupture of chordae tendineae, not elsewhere classified 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 I51.1 a CC or MCC?
CMS lists I51.1 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 I51.1 be reported with I23.4?
Not as a rule. The Excludes1 note on I51.1 lists "rupture of chordae tendineae as current complication following acute myocardial infarction (I23.4)". 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 HCC is I51.1?
I51.1 (rupture of chordae tendineae, not elsewhere classified) 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 I51.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I51.1 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.
