Beyond the Segmental Code: Anatomic Diversity and Surgical Pathways in Left Atrial Appendage Isomerism with the {A,L,I} Combination

Background/Objectives: Left atrial appendage isomerism (LAAI) is associated with substantial variation in venous connections and intracardiac anatomy. A subgroup of LAAI patients has L-loop ventricular topology together with a particular great artery relationship—a combination that corresponds historically to Van Praagh’s {A,L,I} segmental notation—but this subgroup has not been separately characterized. We aimed to describe the anatomical spectrum, rhythm and conduction abnormalities, biventricular repair eligibility, and surgical pathways in this subgroup.