ICD-10 Code I49.5 – Sick sinus syndrome (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I49.5 – Sick sinus syndrome
What it is
I49.5 identifies sick sinus syndrome, a disorder of the heart’s natural pacemaker. It means the sinus node does not generate or conduct impulses normally, causing inappropriate slow or irregular heart rhythms.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include sinus bradycardia, sinus pauses, alternating slow and fast rhythms, dizziness, syncope, or fatigue when the sinus node is dysfunctional.
When to use this code
Use I49.5 when the provider documents sick sinus syndrome, sinus node dysfunction, or related sick sinus disease. Apply it when the diagnosis is established on the record, not merely suspected. If the chart only describes bradycardia without sinus node dysfunction, check documentation before coding.
Do not use for
Do not use this code for isolated bradycardia, atrial fibrillation, or other arrhythmias unless sick sinus syndrome is specifically documented. Do not assign it when the record lacks a confirmed diagnosis.
Coding tip
Code the documented sinus node disorder exactly as stated and verify whether the provider also records associated arrhythmias or pacemaker status.