Coronary Lesion Assessment: Are FFR and iFR It?

12th Biennial Meeting of the International Andreas Gruentzig Society:  Rio de Janeiro - February 2-6, 2014

From Session 1: Coronary

Coronary Lesion Assessment:  Are FFR and iFR It?

Moderator:      Steve Bailey
Panelists:      Larry Dean, George Hanzel, Tarek Helmy, Bonnie Weiner, Peter Wijngaard

Framing the question at hand, what is the state of the current knowledge?

Lesion assessment using angiography alone has significant limitations when evaluating intermediate stenosis. When evaluated by intravascular imaging or physiologic tools, more than 40% of stenoses in the 40%-70% range are not flow-limiting. Treating non-flow limiting lesions may place patients at increased risk compared to medial therapy alone from studies such as DEFER and FAME 1.

What are the gaps in the current knowledge?

The data currently available are based upon limited patient populations and extrapolations from studies. The current pharmacologic protocols vary in the assessment of lesion severity. There is concern that we have moved too far in accepting FFR alone as an arbiter for significance of the stenosis. FFR is still used in a minority of cases (approx. 10%) and there is uncertainty about whether it might be optimal to use other methods along with FFR. In addition, there is still uncertainty about specific patient subsets, such as those with chronic total occlusions and those with venous and arterial bypass grafts. The adoption of newer techniques such as instantaneous wave-free ratio (iFR) may alter our approach to lesion assessment.

Newer technology such as CT assessment of lesion stenosis and computer assessed FFR are being investigated. What role these techniques will play in screening patients with stable ischemic heart disease is uncertain.

Our Summary and Recommendations:
Despite the current guideline recommendations, we still need more research to evaluate these techniques in decision making and comparing clinical outcomes. If lesion assessment using these tools is clinically important, they should be used in a greater percentage of eligible patients.

The specific technique warrants additional study.  Optimizing our procedural protocol (agent, route and dose) for the assessment by FFR of borderline cases has to be better characterized or whether we should use iFR in these cases should be investigated.

Prospective evaluation of non-invasive assessment of lesion severity before the catheterization procedure may be an important component of evaluating stable patients with ischemic heart disease and needs more research and outcomes data.