What is ICD-10 code I23.8?

I23.8 is the ICD-10-CM diagnosis code for Other current complications following acute myocardial infarction. Other heart-related complications that occur immediately following a heart attack, not specified elsewhere. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I23.8 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I23.8 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. I23.8 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. I23.8 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for I23.8?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For I23.8, V28 maps to Unstable Angina and Other Acute Ischemic Heart Disease at RAF 0.000 while V24 mapped to Unstable Angina and Other Acute Ischemic Heart Disease at RAF 0.274. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting I23.8?

Use this code only for complications occurring within the acute post-MI period Document the specific complication in the medical record for clarity and potential use of more specific codes Because I23.8 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

I23.8 ICD-10 Code: Other current complications

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupI23.8Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Ischemic heart diseases (I20-I25)

I23.8

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Other current complications following acute myocardial infarction

Other heart-related complications that occur immediately following a heart attack, not specified elsewhere.

Buddy Insight

Other current complications following acute myocardial infarction serves as a catch-all for post-myocardial infarction complications not specifically classified elsewhere, such as Dressler-like inflammatory reactions, pericardial effusion without hemopericardium, or ventricular aneurysm formation during the acute phase.

CMS-HCC V28

Mapped

HCC 229

Unstable Angina and Other Acu...

RAF 0.0

CMS-HCC V24

Mapped

HCC 87

Unstable Angina and Other Acu...

RAF 0.274

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 87

Unstable Angina and Other Acu...

RAF 0.0

RXHCC

Mapped

HCC 188

Coronary Artery Disease and A...

RAF 0.0

Code Trumping

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Code Book Path

Official

I23Certain current complications following ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction (within the 28 day period)

I23.8Other current complications following acute myocardial infarction

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I23.8 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I23.8 in this effective period.

Related Child Codes

Official

I23.0Hemopericardium as current complication following acute myocardial infarction

I23.1Atrial septal defect as current complication following acute myocardial infarction

I23.2Ventricular septal defect as current complication following acute myocardial infarction

I23.3Rupture of cardiac wall without hemopericardium as current complication following acute myocardial infarction

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

Includes

Official

ICD-10-CM does not list Includes notes for I23.8 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for I23.8 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for I23.8 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for I23.8 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I23.8 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of a specific complication occurring during the acute post-myocardial infarction period

Temporal relationship to the acute myocardial infarction

Description of the specific complication (even though the code is 'other')

The underlying acute myocardial infarction coded separately (I21.x)

MEAT Support

HCC Buddy guidance

Documentation of a specific complication occurring during the acute post-myocardial infarction period

Temporal relationship to the acute myocardial infarction

Description of the specific complication (even though the code is 'other')

The underlying acute myocardial infarction coded separately (I21.x)

Audit Caution

HCC Buddy guidance

Using this code when a more specific I23 code exists for the documented complication

Not reviewing all I23 subcategories before defaulting to I23.8

Failing to code the underlying acute myocardial infarction separately

Using this code for late effects or sequelae that occur beyond the acute phase

Common Mistakes

HCC Buddy guidance

I23.0-I23.7 — Specific post-myocardial infarction complication codes: use these when a specific complication is documented

I24.1 — Dressler's syndrome: a specific post-myocardial infarction complication with its own code

I25.3 — Aneurysm of heart: may be more appropriate for ventricular aneurysm depending on timing

I23.7 — Postinfarction angina: specific code for angina during recovery

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is I23.8 an HCC code?

Yes. I23.8 maps to Unstable Angina and Other Acute Ischemic Heart Disease under the CMS-HCC V28 risk adjustment model (and Unstable Angina and Other Acute Ischemic Heart Disease under V24).

HCC Category Mapping

V28HCC 229, Unstable Angina and Other Acute Ischemic Heart Disease

0.000

V24HCC 87, Unstable Angina and Other Acute Ischemic Heart Disease

0.274

ESRDHCC 87, Unstable Angina and Other Acute Ischemic Heart Disease

0.000

RxHCCHCC 188, Coronary Artery Disease and Angina

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for I23.8

For I23.8to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed I23.8 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

I23.8 is the ICD-10-CM diagnosis code for other current complications following acute myocardial infarction. Other heart-related complications that occur immediately following a heart attack, not specified elsewhere. I23.8 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering ischemic heart diseases (i20-i25).

Under the CMS-HCC V28 risk adjustment model, I23.8 maps to Unstable Angina and Other Acute Ischemic Heart Disease (HCC 229) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, I23.8 mapped to the same category but with a base RAF weight of 0.274, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Use this code only for complications occurring within the acute post-MI period. Because I23.8 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for I23.8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only for complications occurring within the acute post-MI period
•Document the specific complication in the medical record for clarity and potential use of more specific codes

Clinical Significance

Documentation Requirements

✓Documentation of a specific complication occurring during the acute post-myocardial infarction period
✓Temporal relationship to the acute myocardial infarction
✓Description of the specific complication (even though the code is 'other')
✓The underlying acute myocardial infarction coded separately (I21.x)
✓Evidence that no more specific I23 code applies

Commonly Confused Codes

•I23.0-I23.7: Specific post-myocardial infarction complication codes: use these when a specific complication is documented
•I24.1: Dressler's syndrome: a specific post-myocardial infarction complication with its own code
•I25.3: Aneurysm of heart: may be more appropriate for ventricular aneurysm depending on timing
•I23.7: Postinfarction angina: specific code for angina during recovery