ICD-10-CM 2027
ICD-10 code for fascicular left block
From the official ICD-10-CM alphabetic index entry “Block, blocked › fascicular (left)”. Page updated September 29, 2026.
About coding fascicular left block
The ICD-10-CM code for fascicular left block is I44.60 (Unspecified fascicular block). The official index lists 4 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on I44.60.
Within I44.6, choose I44.60 (Unspecified fascicular block) only when documentation doesn't support a more specific option: other fascicular block (I44.69).
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.
More specific fascicular left block codes (official index)
Common questions about fascicular left block ICD-10 codes
What is the ICD-10 code for fascicular left block?
- I44.60 — Unspecified fascicular block. More specific codes apply when the documentation supports them: I44.4, I44.5, I45.0, I44.69.
What is the ICD-10 code for anterior fascicular left block?
- I44.4 — Left anterior fascicular block.
What is the ICD-10 code for posterior fascicular left block?
- I44.5 — Left posterior fascicular block.
What is the ICD-10 code for right fascicular left block?
- I45.0 — Right fascicular block.
Is I44.60 billable?
- Yes. I44.60 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I44.60 be used as a principal diagnosis?
- It can, but When it is the principal diagnosis, Medicare considers it a questionable reason for an inpatient admission, so claims may be reviewed.
Is I44.60 a CC or MCC?
- No. I44.60 is neither a CC nor an MCC under MS-DRG v44.0.