ObjectivesHypertrophic obstructive cardiomyopathy (HOCM) may be treated by septal myectomy. Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common complication, but little is known about its incidence after septal myectomy. The objectives were to (i) evaluate the prevalence of CSA-AKI after septal myectomy and (ii) identify potential perioperative and phenotype-related factors contributing to CSA-AKI. DesignRetrospective database analysis with new data analysis. SettingSingle expertise university academic centre for septal myectomy HOCM patients. ParticipantData from 238 HOCM patients operated with septal myectomy between 2005-2022. InterventionsCSA-AKI was stratified by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines by measurement of creatinine and urine production. Important HOCM phenotype-related and perioperative factors were analysed for their possible association with CSA-AKI. Measurements and Main ResultsCSA-AKI occurred in 45% of patients, of these, 55% were classified as KDIGO stage I, and the remaining 45% as stage II, with no chronic kidney damage being observed. Moreover, there were no phenotypical or perioperative characteristics that were more prevalent in the CSA-AKI cohort. However, the use of beta-blockers and coronary artery disease were more prevalent in the CSA-AKI cohort. ConclusionsCSA-AKI is a common complication after septal myectomy, but was transient and kidney function recovered in all patients.