ICD-10 Q23.4
Billable / Specific MCCHypoplastic left heart syndrome
About ICD-10-CM Q23.4
ICD-10-CM code Q23.4 represents Hypoplastic left heart syndrome. This is a billable/specific code in the Congenital Malformations chapter (block Q23). The 2026 edition of ICD-10-CM Q23.4 became effective on October 1, 2025.
Coding Tips for Q23.4
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
Q23.4 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inpatient DRG Impact, MCC
codes Hypoplastic left heart syndrome. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for Q23.4
Local Coverage Determinations (LCDs) from CMS MACs that list Q23.4 as a covered diagnosis.
Showing top 10 of 335 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing Q23.4.
2 Aetna
1 Cigna
5 Medicare
CPT Codes Commonly Billed with Q23.4
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert Q23.4 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| Q23.4 | 7467 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To Q23.4
Other codes in section Q20-Q28 (Congenital malformations of the circulatory system).
ICD-10 Q23.4, Billing FAQ
Is ICD-10 code Q23.4 billable? +
Yes, Q23.4 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Is Q23.4 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What ICD-9 codes does Q23.4 map to? +
Per CMS GEMs, Q23.4 maps to ICD-9 codes: 7467. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on July 16, 2026.
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