Q26.3
BillablePartial anomalous pulmonary venous connection
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Q26.3 an HCC code?
No. Q26.3 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for Q26.3
For Q26.3to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed Q26.3 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Q26.3 is the ICD-10-CM diagnosis code for partial anomalous pulmonary venous connection. A birth defect where some (but not all) of the pulmonary veins that return blood from the lungs connect to the wrong location instead of the left atrium. Q26.3 sits in the ICD-10-CM chapter for congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (q00-qa0), within the section covering congenital malformations of the circulatory system (q20-q28).
Q26.3 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
This code maps to HCC 191 (Obesity) in the RxHCC model with RAF 0.0, which appears to be an incorrect mapping as this is a congenital heart condition often requiring surgical intervention. The zero RAF weight may not reflect the specialized cardiac care and medications typically needed.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q26.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Specify which pulmonary veins are affected (right upper, right lower, left upper, left lower) in documentation
- •This condition may be asymptomatic or discovered incidentally on imaging
Clinical Significance
Partial anomalous pulmonary venous connection can cause right heart volume overload and may lead to arrhythmias, heart failure, and pulmonary hypertension if left untreated. The condition requires ongoing cardiac monitoring and often surgical repair.
Documentation Requirements
- ✓Echocardiographic identification of anomalously connected pulmonary veins
- ✓Specification of which veins are anomalously connected
- ✓Assessment of right heart volume overload
- ✓Associated atrial septal defect documentation
- ✓Hemodynamic significance evaluation
- ✓Surgical repair recommendations and timing
- ✓Long-term arrhythmia monitoring requirements
- ✓Exercise tolerance and functional assessment
Commonly Confused Codes
- •Q26.2 — Total anomalous pulmonary venous connection (all veins affected)
- •Q26.4 — Anomalous pulmonary venous connection, unspecified (extent not specified)
- •Q21.1 — Atrial septal defect (commonly associated but different primary defect)
- •Q26.8 — Other congenital malformations of great veins (less specific)