Current classifications of Cor Triatriatum Sinister (CTS) do not address the associated heart defects or single ventricle pathology. Therefore, these classifications are not prognostic classifications and only describe the anatomy and the pulmonary venous drainage. The proposed classification considered the associated congenital cardiac lesions and the single ventricle pathology, therefore, it could have prognostic value. Future multicenter studies are required to measure the performance of this classification and its prognostic value in patients with CTS.