Recurrent left ventricular outflow tract obstruction after septal myectomy: analysis of causes and secondary correction

Objective. To analyze the causes of primary septal myectomy failures considering own experience of redo surgeries and strategies of interventions. Material and methods. A retrospective analysis included 8 patients (mean age 52±11 years) who underwent surgery between 2018 and 2025. Redo surgery was performed for recurrent left ventricular outflow tract (LVOT) obstruction after previous septal myectomy in other cardiac centers. Upon admission, mean LVOT gradient was 60 mm Hg at rest and 99 mm Hg under load with severe mitral regurgitation. Results. Insufficient baseline interventricular septal (IVS) resection was identified as the primary cause of residual LVOT obstruction in all patients. According to MRI and intraoperative data, insufficient resection area was localized in the middle third of IVS in 4 cases and extended to apical region in other 4 cases. In one case, predominantly apical hypertrophy was present. In all cases, intraoperative testing before resection confirmed high pressure gradient. Conclusion. The dominant cause of obstruction recurrence after septal myectomy is technically inadequate primary resection, most often in distal (midventricular and apical) parts of interventricular septum. This may be due to fear of iatrogenic septal defect after excessively deep resection and poor visualization of these areas through aortic approach.