Q24.4 Congenital subaortic stenosis

Billable ICD-10-CM code, FY2026. Acts as a Major Complication or Comorbidity (MCC) as a secondary diagnosis. Exempt from present-on-admission (POA) reporting.

Applies from Q24 Other congenital malformations of heart

Excludes1 (never code together)

• endocardial fibroelastosis (I42.4)

MS-DRG index

Defines the logic of DRG(s) 306-307 in MDC 05.

Approximate ICD-9-CM (GEMs)

• 746.81 Subaortic stenosis

Code annotations containing back-references to Q24.4

Back-references to Q24.4

• Type 1 Excludes: Q23.0 Congenital stenosis of aortic valve ("congenital subaortic stenosis (Q24.4)")

Back-references to Q24

• Code Also: I27.21 Secondary pulmonary arterial hypertension ("congenital heart disease (Q20-Q28)")
• Type 2 Excludes: P29 Cardiovascular disorders originating in the perinatal period ("congenital malformations of the circulatory system (Q20-Q28)")
• Code Also: Z71.87 Encounter for pediatric-to-adult transition counseling ("congenital malformations of the circulatory system (Q20-Q28)")

Diagnosis Index entries for Q24.4

• Anomaly, anomalous (congenital) (unspecified type) › heart › valve NEC › aortic › stenosis › subaortic
• Stenosis, stenotic (cicatricial) › subaortic (congenital)
• Stricture › subaortic

Nearby codes

• Q24 Other congenital malformations of heart
• Q24.0 Dextrocardia
• Q24.1 Levocardia
• Q24.2 Cor triatriatum
• Q24.3 Pulmonary infundibular stenosis
• Q24.4 Congenital subaortic stenosis (this code)
• Q24.5 Malformation of coronary vessels
• Q24.6 Congenital heart block
• Q24.8 Other specified congenital malformations of heart
• Q24.9 Congenital malformation of heart, unspecified