ICD-10 Code I49.9 – Cardiac arrhythmia, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I49.9 – Cardiac arrhythmia, unspecified
What it is
I49.9 identifies a cardiac arrhythmia when the rhythm disturbance is documented but not further specified. Use it for an abnormal heart rhythm without enough detail to assign a more exact code.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings include an irregular pulse, palpitations, dizziness, or an ECG showing an abnormal rhythm pattern.
When to use this code
Use I49.9 when the provider documents “arrhythmia” or “cardiac arrhythmia” without naming the type, such as atrial fibrillation, flutter, or tachycardia. It also fits when the record confirms a rhythm disorder but lacks enough detail for a more specific code.
Check documentation if the rhythm abnormality is only suspected, transient, or clearly tied to another coded condition. Code the documented specific arrhythmia whenever it is named.
Do not use for
Do not use this code when the record identifies a specific arrhythmia that has its own ICD-10 code. Do not use it for normal sinus rhythm or nonspecific symptoms alone.
Coding tip
If the note says only “arrhythmia,” query for the exact rhythm type before defaulting to I49.9.