ICD-10-CM 2027 diagnosis code
I44.1Atrioventricular block, second degree
I44.1 is a valid, billable ICD-10-CM code for atrioventricular block, second degree. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Mobitz heart block, ICD-10 code for Wenckebach's block or phenomenon.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About I44.1
I44.1 is the ICD-10-CM diagnosis code for atrioventricular block, second degree. It belongs to category I44 (atrioventricular and left bundle-branch block), block I30-I5A (other forms of heart disease) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within I44 (atrioventricular and left bundle-branch block), I44.1 is specifically for atrioventricular block, second degree. Related codes cover atrioventricular block, first degree (I44.0), atrioventricular block, complete (I44.2), other and unspecified atrioventricular block (I44.3), left anterior fascicular block (I44.4), left posterior fascicular block (I44.5), other and unspecified fascicular block (I44.6) and left bundle-branch block, unspecified (I44.7).
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.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 426.12 (Mobitz (type) II atrioventricular block) and 426.13 (other second degree atrioventricular block).
Coding notes
- Atrioventricular block, type I and II
- Möbitz block, type I and II
- Second degree block, type I and II
- Wenckebach's block
Notes that apply from higher levels
Instructions written at a parent level also apply to I44.1.
Broader instructions also apply from Chapter 9: Diseases of the circulatory system.
Alphabetic index entries
9 entriesTerms in the official ICD-10-CM index that lead to I44.1.
- Block, blocked › atrioventricular (incomplete) (partial) › second degree (types I and II)
- Block, blocked › atrioventricular (incomplete) (partial) › types I and II
- Block, blocked › heart › second degree (atrioventricular)
- Block, blocked › Mobitz (types I and II)
- Block, blocked › second degree (types I and II)
- Block, blocked › Wenckebach (types I and II)
- Mobitz heart block (atrioventricular)
- Phenomenon › Wenckebach's
- Wenckebach's block or phenomenon
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 05 · Diseases and Disorders of the Circulatory System
ICD-9-CM equivalent
Converter →- 426.12Mobitz (type) II atrioventricular blockapproximate
- 426.13Other second degree atrioventricular blockapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about I44.1
Is I44.1 billable?
- Yes. I44.1 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I44.1 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I44.1 as a principal diagnosis.
Is I44.1 a CC or MCC?
- No. I44.1 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does I44.1 group to?
- I44.1 is used in the MS-DRG v44.0 logic for MS-DRG 308 (Cardiac Arrhythmia and Conduction Disorders with MCC), MS-DRG 309 (Cardiac Arrhythmia and Conduction Disorders with CC) and MS-DRG 310 (Cardiac Arrhythmia and Conduction Disorders without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for I44.1?
- The CMS General Equivalence Mappings map I44.1 to ICD-9-CM 426.12 and 426.13.