Question 1

What is ICD-10 code I39?

Accepted Answer

I39 is the ICD-10-CM diagnosis code for endocarditis and heart valve disorders in diseases classified elsewhere. Heart valve inflammation and damage that occurs as a complication of another disease classified elsewhere in the ICD-10 system. I39 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering other forms of heart disease (i30-i5a).

I39 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

This code requires a secondary diagnosis code to identify the underlying disease causing the endocarditis.

Question 2

Is I39 an HCC code?

Accepted Answer

No. I39 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is I39 billable?

Accepted Answer

Yes. I39 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. I39 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.

Question 4

What is the V28 vs V24 difference for I39?

Accepted Answer

I39 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards I39 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting I39?

Accepted Answer

This code requires a secondary diagnosis code to identify the underlying disease causing the endocarditis Use this code when endocarditis is a manifestation of conditions like syphilis, tuberculosis, or other systemic diseases

I39

Is I39 an HCC code?

What This Code Means

Coding Tips

Excludes 1 — Do NOT code together

Code First

Code Hierarchy

Open I39 in the Interactive Encoder