2027 ICD-10-CM Diagnosis Code Q20.6Isomerism of atrial appendages

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q20

ICD-10-CM Q20.6
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q20.6 is a billable ICD-10-CM diagnosis code for isomerism of atrial appendages. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 306 through 307. The code is exempt from POA reporting. Coders also document this condition as abnormality of left atrial appendage. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q20.6
Billable Status
Yes — Valid for Submission
Code Describes
Isomerism of atrial appendages
Short Description
Isomerism of atrial appendages
Same as the full description in the CMS dataset.
Parent Code
Q20
Congenital malformations of cardiac chambers and connections

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ20Congenital malformations of cardiac chambers and connections
This CodeQ20.6Isomerism of atrial appendages

Present on Admission (POA)Billing

Q20.6 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the circulatory system (Q20-Q28).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abnormality of left atrial appendage
  • Abnormality of right atrial appendage
  • Isomerism of atrial appendages
  • Isomerism of left atrial appendage
  • Isomerism of right atrial appendage
  • Laterality sequence
  • Mirror imaged atria
  • Right atrial appendage - left - juxtaposition

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q20.6: its own notes plus those printed at Q20 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Isomerism of atrial appendages with asplenia or polysplenia

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Q20 Congenital malformations of cardiac chambers and connections applies to 9 codes
  • dextrocardia with situs inversus (Q89.3)
  • mirror-image atrial arrangement with situs inversus (Q89.3)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • inborn errors of metabolism (E70-E88)

Notes

General instructions on how these codes are used.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • Codes from this chapter are not for use on maternal records

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Q20.6, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming Q20.6: they are not reported together with it, unless the two conditions are unrelated.

  • Q24.0 Dextrocardia
    isomerism of atrial appendages (with asplenia or polysplenia) (Q20.6)
  • Q89.0 Congenital absence and malformations of spleen
    isomerism of atrial appendages (with asplenia or polysplenia) (Q20.6)

Use Additional Code 1

These codes say to use an additional code from the note, and Q20.6 is one of the codes named.

  • Q87.88 CTNNB1 syndrome
    congenital heart malformations (Q20.0-Q24.9) names Q20.0-Q24.9, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL001
Cardiac and circulatory congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Congenital Heart Defects

Congenital heart defects (CHDs) are problems with the structure of the heart. "Congenital" means that that the problems are present at birth. These defects happen when a fetus's heart doesn't develop normally during pregnancy. Congenital heart defects are the most common type of birth defect.

The full article covers:

  • What are congenital heart defects?
  • What causes congenital heart defects?
  • Who is more likely to have a baby with a congenital heart defect?
  • What are the symptoms of congenital heart defects?
  • What other problems do congenital heart defects cause?
  • How are congenital heart defects diagnosed?
  • What are the treatments for congenital heart defects?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Q20.6 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
745.8 Septal closure anom NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Q20.6Overview

What is the ICD-10 code for isomerism of atrial appendages?

The ICD-10-CM code for isomerism of atrial appendages is Q20.6 (sometimes written as Q206). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q20.6 (Congenital malformations of cardiac chambers and connections) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report isomerism of atrial appendages on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Q20.6 group to?

When isomerism of atrial appendages is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 307, with relative weights from 0.9146 to 1.5457 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q20.6 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for isomerism of atrial appendages on inpatient claims. The code appears in the Congenital malformations of the circulatory system (Q20-Q28) range of the CMS exempt list.

Can Q20.6 be reported with Q89.3?

Not as a rule. The Excludes1 note at Q20, which applies to Q20.6, lists "dextrocardia with situs inversus (Q89.3)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).