2026 ICD-10-CM Diagnosis Code I49.5Sick sinus syndrome

ICD-10-CM Codes›I00–I99›I30-I5A›I49

ICD-10-CM I49.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I49.5 is a billable ICD-10-CM diagnosis code for sick sinus syndrome. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 308 through 310. Coders also document this condition as autosomal recessive sick sinus syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac dysrhythmias.

This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such cardiac arrhythmias (other).

Code Identity

ICD-10-CM Code
I49.5
Billable Status
Yes — Valid for Submission
Code Describes
Sick sinus syndrome
Short Description
Sick sinus syndrome
Same as the full description in the CMS dataset.
Parent Code
I49
Other cardiac arrhythmias

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI49Other cardiac arrhythmias
This CodeI49.5Sick sinus syndrome

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Autosomal recessive sick sinus syndrome
  • Complete deafness
  • Congenital deafness
  • Familial sick sinus syndrome
  • Postoperative cardiac arrhythmia
  • Postoperative sinus node dysfunction
  • Sick sinus syndrome
  • Sinoatrial node dysfunction and deafness
  • Tachycardia-bradycardia

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Tachycardia-bradycardia syndrome

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Bradycardia(sinoatrial) (sinus) (vagal)
      • tachycardia syndrome
    • Bradytachycardia
    • Dysfunction
      • sinoatrial node
    • Pause, sinoatrial
    • Sick
      • sinus (syndrome)
    • Syndrome
      • bradycardia-tachycardia
    • Syndrome
      • sick
        • sinus
    • Syndrome
      • tachycardia-bradycardia
    • Tachycardia
      • paroxysmal (sustained) (nonsustained)
        • with sinus bradycardia
    • Tachycardia
      • sick sinus

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR017
Cardiac dysrhythmias
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Sick Sinus Syndrome

    a condition caused by dysfunctions related to the sinoatrial node including impulse generation (cardiac sinus arrest) and impulse conduction (sinoatrial exit block). it is characterized by persistent bradycardia, chronic atrial fibrillation, and failure to resume sinus rhythm following cardioversion. this syndrome can be congenital or acquired, particularly after surgical correction for heart defects.

Patient EducationClinical

Arrhythmia

An arrhythmia is a problem with the rate or rhythm of your heartbeat. Your heart beats too quickly, too slowly, or with an irregular pattern. Changes in the electrical signals that control your heartbeat cause arrhythmias.

The full article covers:

  • What is an arrhythmia?
  • What causes an arrhythmia?
  • What are the symptoms of an arrhythmia?
  • How is an arrhythmia diagnosed?
  • What are the treatments for an arrhythmia?
  • Can arrhythmias be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I49.5 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
427.81 Sinoatrial node dysfunct
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I49.5Overview

Is I49.5 (Other cardiac arrhythmias) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report sick sinus syndrome on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I49.5 group to?

When sick sinus syndrome is the principal diagnosis on an inpatient stay, it groups to MS-DRG 308, 309, 310, with relative weights from 0.5661 to 1.2040 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I49.5?

Under the General Equivalence Mappings, sick sinus syndrome converts to ICD-9-CM 427.81 (sinoatrial node dysfunct). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.