Background
Transaxillary (TAx) transcatheter aortic valve implantation (TAVI) is a preferred alternative access in patients ineligible for transfemoral TAVI.

Aims
This study used the Trans-AXillary Intervention (TAXI) registry to compare procedural success according to different types of transcatheter heart valves (THV).

Methods
For the TAXI registry anonymized data of patients treated with TAx-TAVI were collected from 18 centers. Acute procedural, early and 1-month clinical outcomes were adjudicated in accordance with standardized VARC-3 definitions.

Results
From 432 patients, 368 patients (85.3%, SE group) received self-expanding (SE) THV and 64 patients (14.8%, BE group) received balloon-expandable (BE) THV. Imaging revealed lower axillary artery diameters in the SE group (max/min diameter in mm: 8.4/6.6 vs 9.4/6.8 mm; p < 0.001/p = 0.04) but a higher proportion of axillary tortuosity in BE group (62/368, 23.6% vs 26/64, 42.6%; p = 0.004) with steeper aorta-left ventricle (LV) inflow (55° vs 51°; p = 0.002) and left ventricular outflow tract (LVOT)-LV inflow angles (40.0° vs 24.5°; 0.002). TAx-TAVI was more often conducted by right sided axillary artery in the BE group (33/368, 9.0% vs 17/64, 26.6%; p < 0.001). Device success was higher in the SE group (317/368, 86.1% vs 44/64, 68.8%, p = 0.0015). In logistic regression analysis, BE THV were a risk factor for vascular complications and axillary stent implantation.

Conclusions
Both, SE and BE THV can be safely used in TAx-TAVI. However, SE THV were more often used and were associated with a higher rate of device success. While SE THV were associated with lower rates of vascular complications, BE THV were more often used in cases with challenging anatomical circumstances.