Subannular perforation of left ventricular outflow tract associated with transcatheter valve implantation: pathophysiological background and clinical implications.

OBJECTIVES: Perforation of the subannular left ventricular outflow tract (LVOT) represents an uncommon but almost invariably fatal transcatheter aortic valve implantation (TAVI)-associated complication. The risk factors to predict the occurrence of this devastating complication, particularly in relation to specific LVOT anatomy, have not yet been systematically analysed. We aimed to evaluate the pathophysiological background and possible risk factors for the occurrence of subannular LVOT perforation.
METHODS: A total of 6 (0.7%) consecutive patients (78.8 ± 3.3 years, 83% women) with subannular LVOT perforation complicating TAVI procedure were identified from our institutional TAVI registry, including 900 consecutive patients who underwent TAVI procedure at a single institution between January 2009 and July 2015. Only patients with an intraoperatively confirmed LVOT perforation were included.
RESULTS: The computed tomography (CT)-guided analysis of aortic root/LVOT morphology revealed subannular calcification in close proximity of the anatomically weakest region of muscular LVOT (i.e. in the region of the muscular LVOT between the left fibrous trigone and the left/right commissure) in 5/6 (83%) patients. Moreover, significant annular asymmetry >20% was present in 4/6 (67%) patients and was combined with a severe asymmetric hypertrophy of muscular LVOT.
CONCLUSIONS: Subannular calcification in close proximity of the anatomically unprotected muscular LVOT might represent an important risk factor for the occurrence of subannular LVOT injury. Precise CT-based analysis of patient-specific aortic root anatomy/subannular calcification patterns may be helpful to predict this TAVI-associated complication preoperatively and hence to avoid it in future patients.