ICD-10 Code I50.21 – Acute systolic (congestive) heart failure (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I50.21 – Acute systolic (congestive) heart failure
What it is
This code identifies a sudden episode of heart failure caused by impaired left ventricular systolic function. It means the heart is not pumping effectively, leading to fluid backing up in the circulation.
Clinical signs
Common findings include shortness of breath, fatigue, and signs of fluid overload such as edema or pulmonary congestion. Clinical features vary; refer to documentation.
When to use this code
Use I50.21 when the provider documents acute systolic heart failure, acute on chronic systolic heart failure, or acute decompensation with reduced pumping function. Apply it only when the record clearly supports systolic dysfunction rather than another heart failure type. Check documentation if the type is not specified.
Do not use for
Do not use this code for diastolic heart failure, unspecified heart failure, or chronic systolic heart failure without an acute component. If the record only says congestive heart failure, check documentation.
Coding tip
Look for the exact heart failure type and acuity in the provider note before assigning I50.21.