ICD-10 Code I52: Other heart disorders in diseases classified elsewhere

Key Takeaways

ICD-10 Code I52 (other heart disorders in diseases classified elsewhere) is itself a billable ICD-10-CM code for the 2026 edition – it has no I52.0, I52.1, or I52.8 child codes in the US clinical modification, unlike the WHO international ICD-10.

I52 is a manifestation code, so it can never be submitted as the first-listed or principal diagnosis – the underlying disease must always be coded first, with I52 sequenced immediately after.

Code First applies to congenital syphilis (A50.5), mucopolysaccharidosis (E76.3), and schistosomiasis (B65.0-B65.9). Excludes1 blocks I52 from ever being coded with heart disease in gonococcal infection (A54.83), meningococcal infection (A39.50), rheumatoid arthritis (M05.31), or syphilis (A52.06).

Pabau’s claims management software and AI-powered clinical documentation tools help practices sequence etiology and manifestation codes correctly at the point of care, reducing denials from missing or misordered underlying-disease codes.

ICD-10 Code I52 is the billable ICD-10-CM diagnosis code for other heart disorders occurring as a manifestation of a disease classified elsewhere in the tabular list.

Unlike many three-character categories, I52 does not split into child codes – it is complete and billable at the three-character level. Sequencing trips up coders more often than a missing digit does.

I52 is a manifestation code, so it can never stand alone as the first-listed or principal diagnosis. It also carries its own Code First and Excludes1 notes in the FY2026 ICD-10-CM edition, effective October 1, 2025.

This reference covers the code’s billable status, the Code First and Excludes1 notes that govern it, the etiology/manifestation sequencing rules, how I52 compares with its sibling manifestation codes, and documentation tips to get reimbursement right the first time.

ICD-10 Code I52: Definition, billable status, and 2026 edition details

ICD-10 Code I52 sits within Chapter IX of ICD-10-CM (Diseases of the Circulatory System, I00-I99), the same chapter as I51.5. It belongs specifically to the I30-I5A block, “Other forms of heart disease.” The official description is: Other heart disorders in diseases classified elsewhere.

The code captures heart disorders that arise as a manifestation of an underlying systemic or infectious disease. The primary pathology is coded in a different chapter of ICD-10-CM. The heart involvement is a secondary consequence coded here, immediately after the etiology code.

I52 has no subdivisions in the US clinical modification – the bacterial/protozoal/other split seen in the WHO international ICD-10 (I52.0, I52.1, I52.8) was never carried into ICD-10-CM.

The code is maintained under the CMS ICD-10-CM update process, jointly administered by the National Center for Health Statistics (NCHS) and CMS. I52 has carried this description, unchanged, since ICD-10-CM was first implemented for HIPAA-covered transactions on October 1, 2015.

Is ICD-10 Code I52 billable?

Yes. ICD-10 Code I52 is a billable, specific ICD-10-CM code and is valid for submission on HIPAA-covered transactions in the 2026 edition. It is not a non-billable header code, and it has no I52.0, I52.1, or I52.8 subcodes to choose between – I52 is the complete, submittable code at the three-character level.

Being billable is not the same as being usable on its own. I52 is a manifestation code under the ICD-10-CM etiology/manifestation convention, which means it can never be the first-listed or principal diagnosis on a claim. It must always be sequenced immediately after the code for the underlying disease that caused the heart disorder.

Submitting I52 without a preceding etiology code, or submitting it as the primary reason for the encounter, is a sequencing error, not a specificity error.

• Do use I52 directly on claims. There is no more specific child code to select – I52 is billable as written.
• Do not sequence I52 first. The underlying disease code must always precede it.
• Do not code I52 without an underlying disease code present. A manifestation code reported alone, with no etiology code on the claim, does not meet the convention’s requirements.

Code First and Excludes1 notes for I52

The official ICD-10-CM tabular entry for I52 carries two instructional notes that define exactly how the code may be used: a Code First note, listing the underlying diseases it manifests from, and an Excludes1 note, listing conditions that must never be coded with I52.

Per the CDC/NCHS ICD-10-CM tabular list, these are the complete notes for I52 – there is no separate “Includes” note.

Code First the underlying disease

A Code First note means the underlying etiology must be sequenced ahead of I52 on the claim. For I52, the tabular list names three underlying diseases:

• Congenital syphilis (A50.5) – other late congenital syphilis, symptomatic
• Mucopolysaccharidosis (E76.3) – the metabolic storage disorder, unspecified type
• Schistosomiasis (B65.0-B65.9) – any code in the schistosomiasis range, depending on the documented species and organ involvement

These are not the only diseases that can produce a secondary heart disorder – they are the specific conditions the ICD-10-CM tabular list names for I52. Whenever one of these three diagnoses is documented alongside a cardiac manifestation that fits I52’s description, the etiology code goes first and I52 follows.

Excludes1 conditions for I52

Excludes1 is a pure exclusion – it means the excluded condition can never be coded at the same time as I52, because the two codes describe mutually exclusive scenarios (a different, dedicated combination code already exists for that etiology). Per the CDC/NCHS tabular list, I52’s Excludes1 note covers heart disease in:

• Gonococcal infection (A54.83) – gonococcal heart infection has its own dedicated code
• Meningococcal infection (A39.50) – meningococcal carditis, unspecified, is coded separately
• Rheumatoid arthritis (M05.31) – rheumatoid heart disease with rheumatoid arthritis has its own combination code
• Syphilis (A52.06) – other syphilitic heart involvement (acquired, not congenital) is coded separately from I52

Note the distinction with the Code First list: congenital syphilis (A50.5) is a Code First etiology for I52, while acquired syphilitic heart involvement (A52.06) is an Excludes1 exclusion. The two syphilis-related codes point in opposite directions for I52, so confirming whether the documentation describes congenital or acquired disease is essential before assigning either code.

For supporting your documentation process, structured medical forms help ensure clinicians capture the underlying disease and its congenital-versus-acquired status at the point of care, rather than leaving that distinction for retrospective coding.

The etiology/manifestation convention and how it applies to I52

The etiology/manifestation convention is the single most important coding rule for ICD-10 Code I52. The convention governs how to code conditions with two components: an underlying disease (the etiology) and a secondary condition that results from it (the manifestation).

Per the CMS ICD-10-CM Official Guidelines for Coding and Reporting, Section I.A.6, the etiology code is always sequenced first. The manifestation code – I52 – follows.

Codes that carry “in diseases classified elsewhere” in their title, like I52, are a hallmark of this convention and are never permitted as a first-listed or principal diagnosis. EHR documentation workflows should enforce this sequencing automatically to prevent submission errors.

The WHO international ICD-10 expresses this same logic through its dagger-asterisk system, with the dagger code (the underlying disease) preceding the asterisk code (the manifestation) – and it is also where I52’s own bacterial/protozoal/other split lives, as I52.0, I52.1, and I52.8.

ICD-10-CM does not use those subcodes or the typographic symbols. It relies instead on the tabular “Code First” and “Use Additional Code” notes to achieve the same sequencing.

I52 vs related heart-disorder manifestation codes

I52 is one of several ICD-10-CM codes in the I30-I5A block that follow the same “in diseases classified elsewhere” pattern: billable at the three-character level, no child codes, and governed by their own Code First and Excludes1 notes. Confusing which one applies is a common source of denials when a systemic disease affects more than one cardiac structure.

Each of these codes carries its own distinct Code First and Excludes1 list – they are not interchangeable, and a code’s Excludes1 note for one etiology does not mean that etiology is unrelated to a different code in this family.

Syphilis and rheumatoid arthritis, for example, appear on the Excludes1 notes for several of these codes, but each points to a different dedicated combination code depending on which cardiac structure is affected. Always check the specific cardiac structure documented before selecting between I32, I39, I41, I43, and I52.

Other Chapter IX codes follow different rules entirely – I00 and I15.1 are both billable on their own, without I52’s manifestation-only restriction.

Documentation requirements to support I52

I52 is defensible only when the chart establishes two things: the specific underlying disease (and, where relevant, whether it is congenital or acquired), and an explicit causal link between that disease and the cardiac manifestation. Without both, coders cannot confirm the sequencing the etiology/manifestation convention requires.

• Name the underlying disease explicitly. The note should state the systemic condition (for example, schistosomiasis, mucopolysaccharidosis, or congenital syphilis) rather than leaving it implied.
• Establish causation, not coincidence. A phrase like “heart disorder due to schistosomiasis” is sufficient. “Heart disorder and schistosomiasis” is not – the conjunction does not establish that one caused the other.
• Distinguish congenital from acquired disease where it changes the code. Congenital syphilis (A50.5) is a Code First etiology for I52. Acquired syphilitic heart involvement (A52.06) is excluded from I52 entirely.
• Sequence etiology first, always. The underlying disease code leads on the claim, with I52 immediately following.
• Check the Excludes1 list before finalizing. Confirm the underlying condition is not gonococcal infection, meningococcal infection, rheumatoid arthritis, or syphilis – each of those has its own dedicated combination code and must never be paired with I52.

Leverage clinical documentation tools that let clinicians structure notes so the etiology and manifestation relationship is explicit, not implied. This matters most in primary care, where GP software often carries the systemic-disease diagnosis long before a cardiology referral confirms the manifestation.

A structured health risk assessment questionnaire at intake helps surface these systemic conditions early. Maintaining HIPAA-compliant clinical workflows throughout the documentation process protects both accurate coding and patient data integrity.

Common coding errors with I52 and how to avoid them

Four errors account for most I52 claim problems. Each has a clear corrective action.

Submitting I52 as the first-listed or only diagnosis

Because I52 is billable, it is tempting to treat it like any other standalone diagnosis code. It is not. I52 is a manifestation code and can never be the principal or first-listed diagnosis – the underlying disease code must appear first on the claim.

A claim that carries I52 with no preceding etiology code does not meet the sequencing requirement, regardless of I52’s billable status.

Assuming I52 still has child codes

Coders familiar with the WHO international ICD-10, or with older training materials, sometimes look for I52.0, I52.1, or I52.8 in ICD-10-CM. Those subdivisions exist only in the WHO version – the US clinical modification collapses them into the single, billable I52.

Searching an EHR’s code library for an “I52.x” variant that does not exist wastes time and risks defaulting to an incorrect code from an unrelated chapter.

Coding I52 alongside an Excludes1 condition

Gonococcal infection, meningococcal infection, rheumatoid arthritis, and syphilis each have a dedicated combination code for their cardiac involvement. Reporting I52 alongside any of these on the same claim violates the Excludes1 note and creates an audit vulnerability. When one of these four conditions is the documented etiology, use its dedicated combination code instead of I52.

Confusing congenital and acquired syphilis coding

Syphilis appears on both sides of I52’s instructional notes, which makes it a frequent source of error. Congenital syphilis (A50.5) is a Code First etiology – it is coded before I52 when a heart disorder results.

Acquired syphilitic heart involvement (A52.06) is an Excludes1 exclusion – it is never coded with I52 at all. Confirming whether the documentation describes congenital or acquired disease is essential before assigning either pathway – sexual health clinic software should flag the distinction automatically when congenital status isn’t yet confirmed.

How Pabau supports accurate ICD-10 I52 coding workflows

Most claim errors on secondary cardiac diagnoses trace back to the same problem: the EHR and the billing system are not talking to each other in real time.

Coders work from notes that are incomplete or structured in a way that obscures the etiology/manifestation relationship. By the time the claim reaches the payer, the sequencing is wrong or the etiology code is missing entirely.

Pabau, an all-in-one practice management system, connects the clinical record directly to the billing workflow through its claims management software. Diagnosis codes are assigned at the point of documentation, cutting the delay between physician notes and claim submission. For practices managing patients with systemic diseases that produce secondary cardiac diagnoses, this integration reduces the manual handoffs where sequencing errors typically occur.

Understanding how practice management and EMR platforms differ helps practices choose the right infrastructure for both care delivery and coding accuracy. Pabau combines both functions in a single platform, so the clinical documentation from the encounter flows directly into the billing queue without re-entry.

Practices that handle medical documentation this way, rather than as a bolt-on step, report fewer code-assignment errors on complex, multi-code diagnoses.

Reduce coding errors on complex diagnoses

Pabau connects clinical documentation to billing workflows in one platform, so ICD-10 code sequencing happens at the point of care, not as a manual afterthought. See how practices managing secondary cardiac diagnoses use Pabau to reduce claim denials.

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Conclusion

ICD-10 Code I52 is billable on its own, but sequencing trips up more claims than a missing subcode ever would. I52 can never be the first-listed or principal diagnosis.

The underlying disease – congenital syphilis, mucopolysaccharidosis, or schistosomiasis, per the Code First note – must always be coded first, and gonococcal infection, meningococcal infection, rheumatoid arthritis, and syphilis must never be coded alongside it at all.

Pabau’s integrated approach to clinical documentation and claims processing helps practices catch these sequencing issues before submission. If your team is managing patients with underlying systemic conditions that produce secondary cardiac diagnoses, see how Pabau handles the full documentation-to-billing workflow – explore HIPAA-compliant practice workflows or speak to the team about your specific coding environment.

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