CPT code 33420 represents a mitral valve commissurotomy performed on the beating heart to dilate the mitral valve leaflets without cardiopulmonary bypass. Nationally, this code captures a surgical approach for treating mitral valve stenosis that avoids arresting the heart and bypass support, which can affect resource use, operative planning, and inpatient care pathways. Key payers relevant to coverage and payment analyses include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.

Readers will find a concise overview of the clinical intent of the service, how it is typically delivered (operating room or catheterization laboratory in hospital settings), and why it matters for surgical and cardiology service lines. The publication provides benchmarks for utilization and payment where available, highlights policy and coding considerations relevant to surgical cardiac services, and situates the procedure in clinical context for mitral stenosis management. Data not available in the input will be identified as such; the content focuses on national-level interpretation rather than state-specific rules.