ICD-10-CM 2027
ICD-10 code for block arrhythmia
From the official ICD-10-CM alphabetic index entry “Arrhythmia (auricle)(cardiac)(juvenile)(nodal)(reflex)(supraventricular)(transitory)(ventricle) › block”. Page updated September 29, 2026.
About coding block arrhythmia
The ICD-10-CM code for block arrhythmia is I45.9 (Conduction disorder, unspecified).
Within I45, choose I45.9 (Conduction disorder, unspecified) only when documentation doesn't support a more specific option: right fascicular block (I45.0), other and unspecified right bundle-branch block (I45.1), Bifascicular block (I45.2), Trifascicular block (I45.3), nonspecific intraventricular block (I45.4), other specified heart block (I45.5), Pre-excitation syndrome (I45.6) and other specified conduction disorders (I45.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 308 (Cardiac Arrhythmia and Conduction Disorders with MCC, relative weight 1.1806), DRG 309 (Cardiac Arrhythmia and Conduction Disorders with CC, relative weight 0.7316) and DRG 310 (Cardiac Arrhythmia and Conduction Disorders without CC/MCC, relative weight 0.568), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about block arrhythmia ICD-10 codes
What is the ICD-10 code for block arrhythmia?
- I45.9 — Conduction disorder, unspecified.
Is I45.9 billable?
- Yes. I45.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I45.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I45.9 as a principal diagnosis.
Is I45.9 a CC or MCC?
- No. I45.9 is neither a CC nor an MCC under MS-DRG v44.0.