Clinical evaluation of the Hydra self-expanding THV: 30 days results from the GENESIS-II study

Published in congress: EuroPCR 2024

Dr. Mahmut Buğrahan Çiçek

Introduction:
The Hydra transcatheter aortic valve (THV) is a device used in the treatment of patients with severe aortic stenosis who are at high surgical risk. The Hydra THV features supra-annular valve placement and an active release mechanism, which are designed to improve hemodynamic performance and procedural safety in the treatment of severe aortic stenosis. The GENESIS-II study aims to evaluate the safety and performance of the Hydra THV. The study's findings suggest that the Hydra THV could be a safe and effective treatment option for high surgical risk patients. Additionally, the clinical outcomes of this study have been compared with the control group from the historical GENESIS study.

Objective:
The primary objective of the study is to evaluate the safety and performance of the improved Hydra THV model in patients with severe aortic stenosis who are at high surgical risk. The Hydra transcatheter aortic valve used in the GENESIS-II study is equipped with an active release mechanism for strut deployment, distinguishing it from the Hydra THV used in previous studies. This study examines the implantation success, hemodynamic performance, and clinical outcomes of the Hydra THV and compares them with the control group from the GENESIS study.

Methods:
This study is a prospective, multicenter, non-randomized investigation conducted at 19 different centers between November 2021 and November 2023. A total of 40 patients with severe aortic stenosis and high surgical risk were included in the study. Inclusion criteria were patients diagnosed with severe aortic stenosis, those at high surgical risk, and those suitable for transfemoral TAVR (Transcatheter Aortic Valve Replacement). Exclusion criteria included cardiogenic shock, severe renal failure, inability to cross the lesion, being under 18 years of age, or pregnancy. The primary performance endpoint was device success at implantation. Hemodynamic parameters included mean aortic gradient and effective orifice area (EOA). Patients were monitored and followed up for 30 days post-procedure.

Results:
The mean aortic gradient decreased from 53.1 mmHg pre-procedure to 8.4 mmHg at 30 days post-procedure. The EOA reached 1.9 cm². In terms of New York Heart Association (NYHA) functional class, 73.7% of patients showed at least one class improvement. Regarding para-valvular leak, no severe para-valvular leaks were observed post-procedure and at 30 days. In the six-minute walk test, the mean walking distance increased from 217.0 meters pre-procedure to 275.9 meters at 30 days.
In terms of clinical outcomes, all-cause mortality at 30 days was reported at 2.5%. The device success rate of Hydra THV at implantation was 95%. Additionally, the rate of new permanent pacemaker implantation at 30 days was 7.5%.

Commentary:
The GENESIS-II study demonstrates that the improved Hydra THV model is an effective and safe treatment option for patients with severe aortic stenosis at high surgical risk. The device's high success rate and low complication rates are notable. Improvements in NYHA functional class and increased six-minute walk test distances reflect significant enhancements in patients' quality of life. The low incidence of paravalvular leak and the maintenance of hemodynamic outcomes compared to the previous GENESIS study support the safety and efficacy of the Hydra THV. These findings suggest that the Hydra THV could see broader acceptance in clinical practice. However, further long-term follow-up studies are needed to determine whether these positive short-term results translate into long-term clinical benefits.