ICD-10 Code B33.20 – Viral carditis, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B33.20 – Viral carditis, unspecified
What it is
B33.20 identifies viral inflammation of the heart muscle or surrounding cardiac tissue when the specific viral cause is not documented. Use it when the record states viral carditis but does not name a more specific form.
Clinical signs
Clinical features vary; refer to documentation. Standard references describe chest pain, palpitations, shortness of breath, fatigue, or arrhythmias in viral cardiac inflammation, but the chart should support the diagnosis.
When to use this code
Use B33.20 when the provider documents viral carditis and no organism or more specific cardiac diagnosis is available. It also fits unspecified viral cardiac inflammation noted after evaluation, testing, or discharge summary documentation. If the record only suggests a viral illness with cardiac symptoms, check documentation before coding.
Do not use for
Do not use this code for bacterial, rheumatic, or noninfectious myocarditis/carditis. If the documentation identifies a more specific viral condition or another cardiac diagnosis, code that instead.
Coding tip
Code from the provider’s exact wording and look for the specific cardiac structure involved before defaulting to B33.20.