FFR and IFR Assessment Prior to TAVR in Severe Aortic Stenosis
Both FFR and IFR are safe and feasible for assessing coronary lesions in TAVR candidates, but IFR may be particularly advantageous because it does not require vasodilator administration and is less influenced by the hemodynamic effects of the stenotic aortic valve. 1
Guideline-Directed Approach to Coronary Assessment
Invasive coronary angiography is indicated in all patients being evaluated for TAVR to identify concomitant coronary artery disease, which is present in 40-75% of TAVR candidates. 1 The 2020 ACC/AHA guidelines specifically state that coronary angiography should be performed in patients with symptoms of angina, objective evidence of ischemia, decreased LV systolic function, history of CAD, or coronary risk factors (including men >40 years of age and postmenopausal women). 1
Physiologic Assessment: FFR vs IFR
When anatomic coronary stenosis is identified on angiography, invasive functional assessment using either FFR or IFR is safe and feasible in TAVR candidates. 1 The key distinction between these modalities in the context of severe aortic stenosis:
Advantages of IFR:
- Does not require adenosine or other vasodilator administration, avoiding potential hemodynamic complications in patients with severe AS 1
- Less influenced by the hemodynamic effects of the stenotic aortic valve compared to FFR 1
- Measured during the wave-free period of diastole when microvascular resistance is naturally stable
- Simpler procedural workflow without need for hyperemic agents
FFR Considerations:
- Requires adenosine administration, which can cause hypotension in AS patients who are preload-dependent
- May be affected by the altered hemodynamics of severe AS, potentially reducing accuracy
- Both FFR and IFR are mentioned as options, but randomized clinical trials validating the utility of both are ongoing 1
Clinical Decision Algorithm for Revascularization
The decision to perform PCI should be driven by both clinical factors (presence of angina or ischemia, ability to take dual-antiplatelet therapy) and anatomic factors (lesion location and complexity, technical feasibility). 1 Specifically:
- Patients with left main or proximal CAD: Consider PCI prior to TAVR 1
- Complex bifurcation left main and/or multivessel CAD with SYNTAX score >33: Consider surgical AVR with CABG instead of TAVR 1
- Significant proximal CAD in major coronaries: PCI should be considered even in the absence of symptoms, as this represents a different population than typical asymptomatic stable CAD 2
Timing of Revascularization
Staged PCI before TAVR is the most common strategy in clinical practice and is associated with lower contrast volume and reduced renal failure compared to concomitant TAVR with PCI. 1 The typical approach is to perform PCI at least 1 month before TAVR, as this was the design used in all existing clinical trials. 2
Alternative to Invasive Assessment
In patients with low pretest probability of CAD and normal renal function, coronary CT angiography combined with CT-derived FFR (CT-FFR) can potentially reduce the need for invasive angiography by 65-68% while maintaining 100% sensitivity for detecting significant CAD. 3 However, this approach is limited in patients with severe coronary calcifications (Agatston score ≥400), who represent approximately 70% of TAVR candidates. 4
Common Pitfalls to Avoid
- Do not perform stress testing in patients with severe AS, as it may be contraindicated and will not change management 5
- Do not extrapolate standard appropriate use criteria for PCI in asymptomatic patients to the TAVR population, as these represent fundamentally different clinical scenarios 2
- Avoid vasodilators and maintain careful blood pressure control during catheterization, as AS patients are preload-dependent and cannot compensate for volume depletion 6
- Do not assume all coronary lesions require revascularization—the Heart Valve Team should decide on a case-by-case basis, though there are no RCTs to definitively guide this decision 1