Specific code 2014 ICD-9-CM Diagnosis Code 426.3
Other left bundle branch block
  • Billable Code
  • Questionable As Admission Dx
  • Short description: Left bb block NEC.
  • ICD-9-CM 426.3 will be replaced by an equivalent ICD-10-CM code (or codes) when the United States transitions from ICD-9-CM to ICD-10-CM on October 1, 2015.
  • ICD-9-CM 426.3 is a billable medical code that can be used to specify a diagnosis on a reimbursement claim.
Disease Synonyms
  • Complete left bundle branch block
  • Electrocardiogram: left bundle branch block
  • Left bundle branch block
  • Left main stem bundle branch block
Clinical Information
  • An impairment of transmission of the cardiac electrical impulse along the fibers of the left main bundle branch, or both the left anterior fascicle and left posterior fascicle. This conduction disturbance is characterized by wide (greater than 0.11s) qrs complexes. The diagnostic criteria consist of prolongation of the qrs complexes (over 0.11s) with neither a q wave nor an s wave in lead v1 and in the "properly placed" v6. A wide r wave with a notch on its top ("plateau") is seen in these leads. In hearts with an electrical (and anatomic) vertical position a small q wave may be seen in avl in the absence of mi. Right chest lead v1 may or may not show an initial r wave, but the latter should be present in lead v2.
  • An impairment of transmission of the cardiac electrical impulse along the fibers of the left main bundle branch, or both the left anterior fascicle and left posterior fascicle. This conduction disturbance is characterized by wide (greater than 0.11s) qrs complexes. The diagnostic criteria consist of prolongation of the qrs complexes (over 0.11s) with neither a q wave nor an s wave in lead v1 and in the properly placed v6. A wide r wave with a notch on its top (plateau) is seen in these leads. In hearts with an electrical (and anatomic) vertical position a small q wave may be seen in avl in the absence of mi. Right chest lead v1 may or may not show an initial r wave, but the latter should be present in lead v2. (nci)
Applies To
  • Left bundle branch block:
    • NOS
    • anterior fascicular with posterior fascicular
    • complete
    • main stem
ICD-9-CM Coding Information
  • 426.3 is not usually sufficient justification for admission to an acute care hospital when used a principal diagnosis.
Convert to ICD-10-CM: 426.3 converts approximately to:
  • 2014 ICD-10-CM I44.7 Left bundle-branch block, unspecified
ICD-9-CM Volume 2 Index entries containing back-references to 426.3:
  • Block
    • bundle branch (complete) (false) (incomplete) 426.50
      • bilateral 426.53
      • left (complete) (main stem) 426.3
        • with right bundle branch block 426.53
        • anterior fascicular 426.2
          • with
            • posterior fascicular block 426.3
            • right bundle branch block 426.52
        • hemiblock 426.2
        • incomplete 426.2
          • with right bundle branch block 426.53
        • posterior fascicular 426.2
          • with
            • anterior fascicular block 426.3
            • right bundle branch block 426.51
      • right 426.4
      • Wilson's type 426.4
    • heart 426.9
      • first degree (atrioventricular) 426.11
      • second degree (atrioventricular) 426.13
      • third degree (atrioventricular) 426.0
      • bundle branch (complete) (false) (incomplete) 426.50
        • bilateral 426.53
        • left (see also Block, bundle branch, left) 426.3
        • right (see also Block, bundle branch, right) 426.4
      • complete (atrioventricular) 426.0
      • congenital 746.86
      • incomplete 426.13
      • intra-atrial 426.6
      • intraventricular NEC 426.6
      • sinoatrial 426.6
      • specified type NEC 426.6
    • intraventricular (diffuse) (myofibrillar) 426.6
      • bundle branch (complete) (false) (incomplete) 426.50
        • bilateral 426.53
        • left (see also Block, bundle branch, left) 426.3
        • right (see also Block, bundle branch, right) 426.4
  • Bundle
    • branch block (complete) (false) (incomplete) 426.50
      • bilateral 426.53
      • left (see also Block, bundle branch, left) 426.3
      • right (see also Block, bundle branch, right) 426.4
  • Degeneration, degenerative
  • Sclerosis, sclerotic
ICD-9-CM codes are used in medical billing and coding to describe diseases, injuries, symptoms and conditions. ICD-9-CM 426.3 is one of thousands of ICD-9-CM codes used in healthcare. Although ICD-9-CM and CPT codes are largely numeric, they differ in that CPT codes describe medical procedures and services. Can't find a code? Start at the root of ICD-9-CM, check the 2014 ICD-9-CM Index or use the search engine at the top of this page to lookup any code.