2021 ICD-10-CM Diagnosis Code I44.5

Left posterior fascicular block

    2016 2017 2018 2019 2020 2021 Billable/Specific Code Questionable As Admission Dx
  • I44.5 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2021 edition of ICD-10-CM I44.5 became effective on October 1, 2020.
  • This is the American ICD-10-CM version of I44.5 - other international versions of ICD-10 I44.5 may differ.
ICD-10-CM Coding Rules
  • I44.5 is not usually sufficient justification for admission to an acute care hospital when used a principal diagnosis.
The following code(s) above I44.5 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to I44.5:
  • I00-I99
    2021 ICD-10-CM Range I00-I99

    Diseases of the circulatory system

    Type 2 Excludes
    • certain conditions originating in the perinatal period (P04-P96)
    • certain infectious and parasitic diseases (A00-B99)
    • complications of pregnancy, childbirth and the puerperium (O00-O9A)
    • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
    • endocrine, nutritional and metabolic diseases (E00-E88)
    • injury, poisoning and certain other consequences of external causes (S00-T88)
    • neoplasms (C00-D49)
    • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
    • systemic connective tissue disorders (M30-M36)
    • transient cerebral ischemic attacks and related syndromes (G45.-)
    Diseases of the circulatory system
Approximate Synonyms
  • Left posterial fascicular hemiblock (heart rhythm)
  • Left posterior hemiblock
Clinical Information
  • An impairment of transmission of the cardiac electrical impulse along the fibers of the left posterior fascicle. In pure left posterior fascicular block (lpfb), the impulse emerges from the unblocked anterosuperior division, thus producing small q waves in leads ii, iii, and avf. Thereafter, the impulse moves through the electrically predominant left ventricle in an inferior and rightward direction, thus explaining the s waves in leads i and avl as well as the r waves in leads ii, iii, and avf.
  • An impairment of transmission of the cardiac electrical impulse along the fibers of the left posterior fascicle. In pure left posterior fascicular block (lpfb), the impulse emerges from the unblocked anterosuperior division, thus producing small q waves in leads ii, iii, and avf. Thereafter, the impulse moves through the electrically predominant left ventricle in an inferior and rightward direction, thus explaining the s waves in leads i and avl as well as the r waves in leads ii, iii, and avf. Left posterior fascicular block is characterized by all of the following: right-axis deviation with frontal qrs axis between +90 degrees and +180 degrees; rs in leads i and avl and qr in inferior leads (q waves 40 ms) qrs duration <120 ms.
ICD-10-CM I44.5 is grouped within Diagnostic Related Group(s) (MS-DRG v38.0):
  • 308 Cardiac arrhythmia and conduction disorders with mcc
  • 309 Cardiac arrhythmia and conduction disorders with cc
  • 310 Cardiac arrhythmia and conduction disorders without cc/mcc

Convert I44.5 to ICD-9-CM

Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
  • 2021 (effective 10/1/2020): No change

Diagnosis Index entries containing back-references to I44.5:
  • Block, blocked
    • bundle-branch (complete) (false) (incomplete) I45.4
      ICD-10-CM Diagnosis Code I45.4

      Nonspecific intraventricular block

        2016 2017 2018 2019 2020 2021 Billable/Specific Code
      Applicable To
      • Bundle-branch block NOS
      • left I44.7
        ICD-10-CM Diagnosis Code I44.7

        Left bundle-branch block, unspecified

          2016 2017 2018 2019 2020 2021 Billable/Specific Code Questionable As Admission Dx
        • hemiblock I44.60
          ICD-10-CM Diagnosis Code I44.60

          Unspecified fascicular block

            2016 2017 2018 2019 2020 2021 Billable/Specific Code Questionable As Admission Dx
          Applicable To
          • Left bundle-branch hemiblock NOS
          • posterior I44.5
    • fascicular (left) I44.60
      ICD-10-CM Diagnosis Code I44.60

      Unspecified fascicular block

        2016 2017 2018 2019 2020 2021 Billable/Specific Code Questionable As Admission Dx
      Applicable To
      • Left bundle-branch hemiblock NOS
      • posterior I44.5

ICD-10-CM Codes Adjacent To I44.5
I42.9 Cardiomyopathy, unspecified
I43 Cardiomyopathy in diseases classified elsewhere
I44 Atrioventricular and left bundle-branch block
I44.0 Atrioventricular block, first degree
I44.1 Atrioventricular block, second degree
I44.2 Atrioventricular block, complete
I44.3 Other and unspecified atrioventricular block
I44.30 Unspecified atrioventricular block
I44.39 Other atrioventricular block
I44.4 Left anterior fascicular block
I44.5 Left posterior fascicular block
I44.6 Other and unspecified fascicular block
I44.60 Unspecified fascicular block
I44.69 Other fascicular block
I44.7 Left bundle-branch block, unspecified
I45 Other conduction disorders
I45.0 Right fascicular block
I45.1 Other and unspecified right bundle-branch block
I45.10 Unspecified right bundle-branch block
I45.19 Other right bundle-branch block
I45.2 Bifascicular block

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.