Late expansion of mechanically expanding transcatheter aortic valves

Several studies have demonstrated better hemodynamic stability of mechanically expanding valves following transcatheter aortic valve replacement (TAVR). This study aims to assess the expansion or recoil of transcatheter aortic valves using multidetector computed tomography (MDCT). This was a retrospective study. Among 873 patients who underwent TAVR with balloon-expandable (SAPIEN 3) or mechanically expanding valves (LOTUS) at Keio University Hospital between 2013 and 2020, those who underwent serial MDCT and echocardiographic assessment (pre-procedure, discharge, 6 months, 1 year, and 2 years post-TAVR) as our hospital protocol were included in this analysis (N = 30; LOTUS = 12; SAPIEN 3 = 18). The pre- and post-procedural echocardiographic data and the valve expansion rate evaluated by MDCT were compared between the groups. In LOTUS valves, late-phase expansion was observed on computed tomography (mean expansion rate, 83.8% at discharge and 86.8%, 2 years postoperative, p < 0.001), and a gradual increase in the aortic valve area was observed on echocardiography (aortic valve area: 1.45 cm² at discharge and 1.51 cm², 2 years postoperative, p = 0.01). Conversely, in SAPIEN 3, valve expansion was not seen in the late phase (mean expansion rate, 84.5% at discharge and 83.8%, 2 years postoperative) with a decrease in the aortic valve area (1.41 cm² at discharge and 1.37 cm², 2 years postoperative, p = 0.04). The expansion of the middle portion of the LOTUS valves was attributed to the increase in the aortic valve area. In conclusion, this study demonstrated the greater late-phase expansion and better valve performance of mechanically expanding valves.