Although concomitant coronary artery disease (CAD) is frequent in patients with severe aortic stenosis (AS), hemodynamic assessment of CAD severity in patients undergoing valve replacement for severe AS is challenging. Myocardial hypertrophic remodeling interferes with coronary blood flow and may influence the values of fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs). The aim of the current study is to investigate the effect of the AS and its treatment on current indices used for evaluation of CAD. The investigators will compare intracoronary hemodynamics before, immediately after, and 6 mo after aortic valve replacement (AVR) when it is expected that microvascular function has improved. Furthermore, the investigators will compare FFR and resting full-cycle ratio (RFR) with myocardial perfusion single-photon emission-computed tomography (SPECT) as indicators of myocardial ischemia in patients with AS and CAD. One-hundred consecutive patients with AS and intermediate CAD will be prospectively included. Patients will undergo pre-AVR SPECT and intracoronary hemodynamic assessment at baseline, immediately after valve replacement [if transcatheter AVR (TAVR) is chosen], and 6 mo after AVR. The primary end point is the change in FFR 6 mo after AVR. Secondary end points include the acute change of FFR after TAVR, the diagnostic accuracy of FFR versus RFR compared with SPECT for the assessment of ischemia, changes in microvascular function as assessed by the index of microcirculatory resistance (IMR), and the effect of these changes on FFR. The present study will evaluate intracoronary hemodynamic parameters before, immediately after, and 6 mo after AVR in patients with AS and intermediate coronary stenosis. The understanding of the impact of AVR on the assessment of FFR, NHPR, and microvascular function may help guide the need for revascularization in patients with AS and CAD planned for AVR.

https://journals.physiology.org/doi/full/10.1152/ajpheart.00541.2021?rfr\_dat=cr\_pub++0pubmed\&url\_ver=Z39.88-2003\&rfr\_id=ori%3Arid%3Acrossref.org

Inclusion Criteria:

• 1. Patient undergoing the procedure is older than 18 years, has severe aortic valve stenosis (according to ESC guidelines) and is planned for cardiac catheterization as part of the pre-operative (SAVR) or pre-percutaneous (TAVI) work up.

  2. The patient has an intermediate (50-90%) coronary lesion that requires further evaluation.

  3. The patient undergoing the procedure is male, or if female, has no childbearing potential or is not pregnant.

Exclusion Criteria:

1. The procedure is an emergency and/or the patient is unstable.
2. Pregnancy or lactation
3. Haemodynamically unstable patients
4. Killip class III-IV heart failure
5. Previous coronary artery by-pass in the artery being assessed
6. Contra-indications for adenosine administration: severe asthma or pre-existing type 2 AV-block
7. No significant coronary artery disease (<50% stenosis on angiography).
8. Critical coronary artery disease deemed by the Heart Team to require immediate revascularization
9. Patients will be excluded from the SPECT study (secondary objective) if they have a left main coronary stenosis >50%, triple vessel disease, previous myocardial infarction in the same coronary artery & tandem lesions (separated by >10mm) requiring independent evaluation in the same coronary artery since these factors interfere with the SPECT analysis.

Patients undergoing routine cardiac catheterization during preparation for TAVI or SAVR, who are found to have coronary artery disease, will be approached to take part.

Entire study population

From inclusion to 6 months

First, microvascular function analysis was based on bolus-thermodilution,recent studies have shown that continuous coronary thermodilution may have better reproducibility. Second, myocardial perfusion SPECT is not the gold standard for non-invasive detection of ischemia.