CPT code 33257 denotes an add-on cardiac surgical procedure performed at the same time as another cardiac operation to ablate abnormal atrial tissue and reconstruct the left and right atria for treatment of atrial fibrillation. As an adjunct to primary cardiac surgeries, this code captures the incremental work of atrial tissue destruction and chamber reconstruction and is relevant for surgical billing, quality reporting, and perioperative resource planning nationwide. Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find clinical context on the procedure’s purpose and typical setting, payer coverage considerations, commonly associated modifiers, and related coding topics to support accurate claim submission and auditing. The publication also outlines common billing scenarios where this add-on code applies during concomitant procedures and highlights documentation elements that typically accompany surgical atrial ablation and reconstruction claims. Data not available in the input for specific payer rates, associated taxonomies, and ICD-10 diagnosis pairings are noted where applicable.