2027 ICD-10-CM Diagnosis Code Q24.2Cor triatriatum

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q24

ICD-10-CM Q24.2
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q24.2 is a billable ICD-10-CM diagnosis code for cor triatriatum. 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. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 61 closely related codes. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q24.2
Billable Status
Yes — Valid for Submission
Code Describes
Cor triatriatum
Short Description
Cor triatriatum
Same as the full description in the CMS dataset.
Parent Code
Q24
Other congenital malformations of heart

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ24Other congenital malformations of heart
This CodeQ24.2Cor triatriatum

Present on Admission (POA)Billing

Q24.2 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.

  • Cor triatriatum
  • Cor triatriatum with some pulmonary veins to proximal chamber draining to left atrium
  • Cor triatriatum with some pulmonary veins to proximal chamber draining to right atrium and others connecting directly to left atrium
  • Divided left atrium
  • Divided left atrium with all pulmonary veins to proximal chamber and then to left atrium
  • Divided left atrium with all pulmonary veins to proximal chamber and then to left atrium with additional pulmonary venous chamber communication
  • Divided left atrium with all pulmonary veins to proximal chamber and then to left atrium with additional pulmonary venous chamber communication to right atrium
  • Divided left atrium with all pulmonary veins to proximal chamber and then to left atrium with additional pulmonary venous chamber extracardiac communication
  • Divided left atrium with all pulmonary veins to proximal chamber without communication to left atrium
  • Divided left atrium with all pulmonary veins to proximal chamber without communication to left atrium with pulmonary venous chamber communication to right atrium
  • Divided left atrium with nonrestrictive outlet of proximal chamber to left atrium
  • Divided left atrium with some pulmonary veins to proximal chamber
  • Divided left atrium with some pulmonary veins to proximal chamber draining to left atrium and others connecting anomalously
  • Divided left atrium with some pulmonary veins to proximal chamber draining to left atrium and others connecting directly to left atrium
  • Divided left atrium with some pulmonary veins to proximal chamber draining to right atrium
  • Divided left atrium with some pulmonary veins to proximal chamber draining to right atrium and others connecting anomalously
  • Divided right atrium

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q24.2: its own notes plus those printed at Q24 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.

Excludes1

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

From Q24 Other congenital malformations of heart applies to 9 codes
  • endocardial fibroelastosis (I42.4)

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 Q24.2, its category, or a range that includes it.

Use Additional Code 1

These codes say to use an additional code from the note, and Q24.2 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

Clinical InformationClinical

  • Cor Triatriatum

    a malformation of the heart in which the embryonic common pulmonary vein was not incorporated into the left atrium leaving behind a perforated fibromuscular membrane bisecting the left atrium, a three-atrium heart. the opening between the two left atrium sections determines the degree of obstruction to pulmonary venous return, pulmonary venous and pulmonary arterial hypertension.

Patient EducationClinical

Aneurysms

An aneurysm is a bulge or "ballooning" in the wall of an artery. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body. If an aneurysm grows large, it can burst and cause dangerous bleeding or even death.

Read the full article at MedlinePlus

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

Convert Q24.2 to ICD-9-CMHistory

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

ICD-9-CM
746.82 Cor triatriatum
Exact Match The mapping is direct, with no qualifiers.

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 Q24.2Overview

What is the ICD-10 code for cor triatriatum?

The ICD-10-CM code for cor triatriatum is Q24.2 (sometimes written as Q242). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q24.2 (Other congenital malformations of heart) a billable code?

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

What MS-DRG does Q24.2 group to?

When cor triatriatum 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 Q24.2 a CC or MCC?

CMS lists Q24.2 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 61 closely related codes in its exclusion list.

Is Q24.2 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 cor triatriatum on inpatient claims. The code appears in the Congenital malformations of the circulatory system (Q20-Q28) range of the CMS exempt list.