Observational, prospective, single-arm and multi-center study to assess the safety and feasibility of IVUS imaging in the setting of TAVI and to describe the angiographic and intravascular ultrasound features in patients with coronary arteries deemed at high-risk for coronary artery obstruction following TAVI.

CHIMNEY stenting is a reasonable strategy to manage catastrophic coronary artery obstruction (CAO). However, this technique is frequently used, not for acute catastrophic CAO (clinically evident), but preventively because the operator believes that CAO may occur on complete transcatheter heart valve (THV) deployment or after the protective coronary guidewire is withdrawn (3/5 of cases). Consequently, in current clinical practice, many patients receive CHIMNEY stents that are not required, and thus incur the associated risks of this procedure. To date, operators do not know how many patients, among those underwent preventive CHIMNEY, really required stenting, or on the contrary, did not. Also, accordingly, a real estimation of CAO incidence is not possible, but is likely higher than that reported in previous studies.

At present, no objective measures have been identified that could help operators decide when to deploy a CHIMNEY stent. If it could be demonstrated in the catheterization laboratory that the displaced native or bioprosthetic leaflets were sufficiently far away from the native coronary ostia and the risk for CAO was low, then unnecessary CHIMNEY stenting could be avoided.

Angiographic images do not provide sufficient information to clarify that. The investigation of a coronary ostium at risk of CAO from an intravascular point of view may reveal the presence of the displaced leaflet in front of them, or on the other hand, its absence, supporting operators in the decision to stent or not to stent.

In addition to the potential for IVUS to determine when CHIMNEY stenting should be used, this technique may also be used to optimize the results of CHIMNEY stenting when it has been deployed.

Moreover, IVUS can also be used to assess the result of the BASILICA technique after leaflet laceration.

The hypothesis is that the use of IVUS imaging for the assessment of patency of the coronary ostium and of the relationship of displaced valve leaflets towards the coronary arteries may reveal novel risk factors to predict which are not detectable by traditional angiography.

Inclusion Criteria:

1. Age > 18 years
2. Written informed consent
3. Diagnosis of symptomatic severe aortic stenosis, or clinically relevant degeneration of previously implanted surgical aortic valve bioprosthesis
4. Patient undergoing TAVI according to local institutional protocol and following Heart Team discussion.
5. High-quality ECG gated computed tomography (CT) scan of the heart and aorta
6. Presence of 2 or more of the following risk factors for CAO (high-risk):

6a. TAVI in native valves: height of the coronary ostium (<9 mm), sinuses of Valsalva width <30 mm, leaflet tips extending above the coronary ostia or the sino-tubular junction.

6b. VIV-TAVI (patients undergoing BASILICA as first prevention strategy are also included): surgical bioprosthesis type: with supra-annular position, high leaflet profile, externally mounted leaflets stented valve, stentless valves, and bulky leaflets, low-lying coronary ostia (< 9 mm from the ostia to the sewing ring), narrow sinuses of Valsalva (<30 mm by width for Valsalva sinuses), virtual THV-coronary (VTC) distance <4 mm, virtual THV-STJ (VT-STJ) distance < 2.5-3.5 mm: to be considered in cases where VTC >4mm but the leaflet extends above or very close (up to 2mm below) to the STJ plane.

Exclusion Criteria:

1. Age < 18 years
2. Pregnancy
3. Absence of informed consent
4. Angiographic or functional critical stenosis of the at-risk coronary artery (%DS > 70 for right coronary artery, > 50 for left main, or positive functional assessment), requiring revascularization regardless the risk of CAO.
5. Signs or symptoms of acute (unstable) myocardial ischemia
6. Reduced survival expectancy due to severe co-morbidities (<1 year)