SuspendedNCT05804903EMPIRE-IIUpdated Mar 9, 2026

Investigation of the NVT ALLEGRA Plus THV System in Patients With Severe Aortic Stenosis or Failed Surgical Aortic Bioprosthesis

An interventional study of (ALLEGRA Plus Transcatheter Heart Valve) TAVI in severe calcified aortic stenosis or in failed surgical aortic bioprosthesis in Transcatheter Aortic Valve Implantation, sponsored by NVT GmbH. Suspended at 7 sites in 5 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-09.

Sponsored by NVT GmbH · Not applicable, Interventional, and Treatment

Why this study was suspended

Interim analysis showed ALLEGRA Plus did not provide clinically meaningful benefit over the CE-marked ALLEGRA THV System. Sponsor discontinued ALLEGRA Plus as a standalone product. Not terminated for safety reasons.

Phase: Not applicable
Study type: Interventional
Enrollment: 177
Allocation: Not applicable
Ages: 18 Years and older
Sex: All

Study summary

The EMPIRE II study evaluates the safety and performance of the entire ALLEGRA THV System.

The primary safety endpoint is composite of all-cause mortality or stroke rates at 12 months. And the primary performance endpoint is device success at 7 days.

Based on the outcomes of a study with a similar device and considering a drop-out rate of 5%, 177 patients need to be enrolled in the study.

Conditions studied

Transcatheter Aortic Valve Implantation

Browse trials for

Aortic Valve Stenosis 985

Keywords

TAVI
Aortic valve stenosis
ALLEGRA Plus
IMPERIA
NVT

Who can participate

Ages eligible: 18 Years and older
Sexes eligible: All
Accepts healthy volunteers: No

Inclusion criteria

Symptomatic severe calcific stenosis of a native aortic valve with an AVA ≤1.0 cm2 (or AVA index ≤0.6 cm2/m2), AND mean aortic pressure gradient ≥ 40mmHg OR maximal transaortic velocity ≥4.0m/s OR Doppler velocity index ≤0.25 on site-reported echocardiography OR symptomatic patients with degeneration of a surgical bioprosthetic valve (stenosis +/- insufficiency) on site-reported echocardiography
Local multi-disciplinary Heart Team and Central Screening Committee (CSC) agree on indication and eligibility for TAVI
Age ≥18 years
Patient has signed the Patient Informed Consent Form
Patient is willing and able to comply with requirements of the study, including all follow-up visits

Exclusion criteria

Exclusion Criteria:

Patient will not be included if ANY one of the following conditions exists:

General:

Mean aortic annulus diameter as measured by pre-procedural CT or internal diameter of the bioprosthesis is \<16.5 mm or >27 mm
Echocardiographic evidence of intracardiac thrombus or vegetation (site-reported)
Significant disease of the aorta that would preclude safe advancement of the ALLEGRA Plus THV System
Severe ilio-femoral vessel disease that would preclude safe placement of an 18 Fr introducer sheath or make endovascular access impossible
Porcelain aorta
Severe left ventricular dysfunction with ejection fraction (EF) \<20% (site-reported)
Evidence of active endocarditis or other acute infections
Renal failure requiring continuous renal replacement therapy
Untreated clinically significant coronary artery disease requiring revascularization
Any percutaneous interventional procedure (e.g. PCI with stenting) within 14 days prior of the index procedure
Acute MI ≤30 days prior to the index procedure
Symptomatic carotid or vertebral artery disease requiring intervention or carotid/vertebral intervention within the preceding 45 days
Cerebrovascular accident (CVA) or transient ischemic attack (TIA) ≤6 months or prior CVA with moderate or severe disability (e.g. modified Rankin scale score >2)
History of bleeding diathesis or coagulopathy; acute blood dyscrasias as defined: thrombocytopenia (platelets \<80,000/µl), acute anemia (hemoglobin \<10 g/dl), leukopenia (WBC \<3000/ µl)
Active peptic ulcer or gastrointestinal (GI) bleeding ≤3 months
Severe (greater than 3+) mitral insufficiency (site-reported)
Uncontrolled atrial fibrillation
Required emergency surgery for any reason
Known hypersensitivity to contrast media, which cannot be adequately pre-medicated or contraindication to anticoagulant or anti-platelet medication or to nitinol alloy or to bovine tissue
Life expectancy ≤12 months due to other medical illness
Currently participating in another investigational drug or device study
Hypertrophic obstructive cardiomyopathy
Pregnancy or intend to become pregnant during study participation
Specific exclusions in patients with native aortic valve disease (site-reported):
Unicuspid or bicuspid aortic valve
Non-calcified aortic stenosis
Identified risk of coronary occlusion due to Sinus of Valsalva anatomy and/or bulky calcified aortic valve leaflets in close proximity to coronary ostia
Specific exclusions in patients with degenerated surgical bioprosthetic aortic valves (valve-in-valve) (site-reported):
High risk of coronary occlusion
Partially detached leaflets that may obstruct a coronary ostium

Study design

Phase: Not applicable
Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Enrollment: 177 participants (estimated)

Study arms

Experimental
TAVI in severe calcified aortic stenosis or in failed surgical aortic bioprosthesis
Device: (ALLEGRA Plus Transcatheter Heart Valve) TAVI in severe calcified aortic stenosis or in failed surgical aortic bioprosthesis

Interventions

Device(ALLEGRA Plus Transcatheter Heart Valve) TAVI in severe calcified aortic stenosis or in failed surgical aortic bioprosthesis
Implantation of the ALLEGRA Plus Transcatheter Heart Valve in severe calcified aortic stenosis or in failed surgical aortic bioprosthesis

What researchers measure

Primary outcomes

Composite of all-cause mortality or stroke rates
Time frame: 12 months

Secondary outcomes

All-cause mortality rate
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Cardiovascular mortality rate
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Any stroke rate
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Transient ischemic attack rate
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Device success rate
Device success at 30 days (In-hospital may be used if 30-day data are not available): * Technical success * Freedom from mortality * Freedom from surgery or intervention related to the device (excluding permanent pacemaker) or to a major vascular or access-related or cardiac structural complication * Intended performance of the valve‡(mean gradient\<20 mmHg, peakvelocity\<3 m/s, Doppler velocity index ≥0.25, and less than moderate aortic regurgitation
Time frame: 30 days
Effective orifice area (EOA) as assessed by transthoracic echocardiogram (TTE)
as determined by an independent Echo Core Lab
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Transvalvular mean and peak pressure gradient as assessed by transthoracic echocardiogram (TTE)
as determined by an independent Echo Core Lab
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Transvalvular mean and peak pressure gradient as assessed by transthoracic
as determined by an independent Echo Core Lab
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
NYHA classification
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Life-threatening/major bleeding (BARC 3b or more)
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Major vascular complications according to VARC-3
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
Early safety profile according to VARC-3
Time frame: 30 days
Quality of life as assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ-12)
Assessed with the Kansas City Cardiomyopathy Questionnaire (KCCQ-12). Patients are asked questions about physical limitation, symptom frequency, quality of life, and social limitation. Responses are given on a Likert scale that for each individual item is scored on a scale of 0-100 with higher scores indicating better health.
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years
New pacemaker implantation rate
Time frame: 7 days, 30 days, 6 months, 12 months, 2 years, 3 years , 4 years, 5 years

Study locations

7 sites

Oulu University Hospital
Oulu, 90220, Finland
Deutsches Herzzentrum Berlin
Berlin, 13353, Germany
Klinika Kardiochirurgii
Gdansk, 80-214, Poland
III Katedra Kardiologii
Katowice, 40-635, Poland
Reina Sofia Hospital
Córdoba, 14004, Spain
Hospital La Paz
Madrid, 28046, Spain
Herzzentrum - Luzerner Kantonsspital
Lucerne, 6000, Switzerland

Registry details

Key details

Study ID: NCT05804903
Lead sponsor: NVT GmbH
Responsible party: Sponsor
First posted: Apr 7, 2023
Start date: Nov 24, 2023
Primary completion: Aug 31, 2025
Completion: Aug 1, 2030 (estimated)
Last update: Mar 9, 2026

Oversight

Data monitoring committee: Yes
FDA-regulated drug: No
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

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