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ICD-10/I49.9

I49.9 ICD-10-CM Code: Cardiac arrhythmia, unspecified

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.

  • MS-DRG 308 — CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITH MCC (MDC 05)
  • MS-DRG 309 — CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITH CC (MDC 05)
  • MS-DRG 310 — CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITHOUT CC/MCC (MDC 05)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.

Official Registry Overview & Definition

Cardiac arrhythmia, unspecified is a billable ICD-10-CM diagnosis code (I49.9).

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for I49.9 in the official ICD-10-CM tabular list.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Arrhythmia (cardiac) NOS

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

  • bradycardia NOS (R00.1)
  • neonatal dysrhythmia (P29.1-)
  • sinoatrial bradycardia (R00.1)
  • sinus bradycardia (R00.1)
  • vagal bradycardia (R00.1)

Code First

Underlying conditions that must be sequenced before this code.

  • cardiac arrhythmia complicating:
  • abortion or ectopic or molar pregnancy (O00-O07, O08.8)
  • obstetric surgery and procedures (O75.4)

Nearest Codes in This Family

Official ICD-10-CM classifications closest to I49.9 in its code family, with their registry titles.

  • I49.2 — Junctional premature depolarization
  • I49.3 — Ventricular premature depolarization
  • I49.4 — Other and unspecified premature depolarization
  • I49.40 — Unspecified premature depolarization
  • I49.49 — Other premature depolarization
  • I49.5 — Sick sinus syndrome
  • I49.8 — Other specified cardiac arrhythmias
  • I49.81 — Brugada syndrome
  • I49.82 — Ventricular bigeminy
  • I49.89 — Other specified cardiac arrhythmias not elsewhere classified

View all codes in the I49 family

Indexed Clinical Terms (10)

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code.

  • Action, heart, disorder
  • Action, heart, irregular
  • Arrhythmia (auricle)(cardiac)(juvenile)(nodal)(reflex)(supraventricular)(transitory)(ventricle)
  • Disorder (of), heart action
  • Disturbance (s), rhythm, heart
  • Dysrhythmia, cardiac
  • Irregular, irregularity, action, heart
  • Rhythm, disorder
  • Rhythm, escape
  • Rhythm, heart, abnormal