ICD-10 Code I51.3 – Intracardiac thrombosis, not elsewhere classified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I51.3 – Intracardiac thrombosis, not elsewhere classified
What it is
I51.3 identifies a blood clot located inside the heart chambers or attached to an intracardiac structure, when it is not classified elsewhere. Use it for documented intracardiac thrombus, not for embolism or superficial clotting.
Clinical signs
Clinical features vary; refer to documentation. Findings may include an imaging-confirmed thrombus on echocardiography or other cardiac study, sometimes in the setting of atrial fibrillation, cardiomyopathy, or prior myocardial injury.
When to use this code
Use I51.3 when the record clearly documents an intracardiac thrombus or clot and no more specific code applies. It may be used when the clot is found incidentally on imaging or evaluated as a known cardiac finding. Check documentation for location and clinical context.
Do not use for
Do not use this code for intracardiac embolism, mural thrombus coded elsewhere, or venous thromboembolism outside the heart. If the documentation names another more specific diagnosis, code that instead.
Coding tip
Confirm that the provider documents the clot as intracardiac and not merely suspected, resolved, or located in another vascular site.