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ICD-10-CM 2027 diagnosis code

Q24.6Congenital heart block

✓ Billable / specificPOA exemptMCC — major complication/comorbidity

Q24.6 is a valid, billable ICD-10-CM code for congenital heart block. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

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 Q24.6

Q24.6 is the ICD-10-CM diagnosis code for congenital heart block. It belongs to category Q24 (other congenital malformations of heart), block Q20-Q28 (congenital malformations of the circulatory system) and chapter 17 (congenital malformations, deformations, chromosomal abnormalities, and genetic disorders). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within Q24 (other congenital malformations of heart), Q24.6 is specifically for congenital heart block. Related codes cover Dextrocardia (Q24.0), Levocardia (Q24.1), cor triatriatum (Q24.2), pulmonary infundibular stenosis (Q24.3), congenital subaortic stenosis (Q24.4), malformation of coronary vessels (Q24.5), other specified congenital malformations of heart (Q24.8) and congenital malformation of heart, unspecified (Q24.9).

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.

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 is exempt from present-on-admission (POA) reporting, so no POA indicator is required.

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 746.86 (congenital heart block).

Notes that apply from higher levels

Instructions written at a parent level also apply to Q24.6.

› From Q24 Other congenital malformations of heart
Excludes1
  • endocardial fibroelastosis (I42.4)

Broader instructions also apply from Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders.

Alphabetic index entries

3 entries

Terms in the official ICD-10-CM index that lead to Q24.6.

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.

ICD-9-CM equivalent

Converter →
  • 746.86Congenital heart blockexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about Q24.6

Is Q24.6 billable?

Yes. Q24.6 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can Q24.6 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict Q24.6 as a principal diagnosis.

Is Q24.6 a CC or MCC?

Q24.6 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does Q24.6 group to?

Q24.6 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 Q24.6?

The CMS General Equivalence Mappings map Q24.6 to ICD-9-CM 746.86.