Evaluation of the Opsens Fractional Flow Reserve (FFR) Wire as a "Work Horse" Wire

EVALUATION OF THE OPSENS FRACTIONAL FLOW RESERVE (FFR) WIRE AS A "WORK HORSE" WIRE

INVESTIGATORS:

PRINCIPAL INVESTIGATOR: BARRY F URETSKY, MD CO-INVESTIGATOR: ABDUL HAKEEM, MD
CO-INVESTIGATOR: MALEK AL-HAWWAS, MD

Introduction The use of fractional flow reserve (FFR) has improved outcomes in percutaneous
coronary interventions (PCI) in patients with symptomatic stable coronary artery disease
(CAD) with intermediate angiographic stenoses. It is a clinical tool used routinely in
cardiac catheterization laboratories throughout the world including the Little Rock VA
hospital. The technique utilizes a pressure transducer constructed as part of an 0.014"
guidewire. The wire is passed distal to the stenosis. Under the condition of maximal
hyperemia induced by a drug, typically adenosine, the pressure proximal to the stenosis, i.e.
aortic pressure or Pa and the pressure distal to the stenosis, Pd, are measured. The ratio,
Pd/Pa, under maximal flow or hyperemia is known as the fractional flow reserve (FFR). An FFR
of <0.80 has been correlated with observed myocardial ischemia using other diagnostic
methods, particularly nuclear stress and dobutamine echo stress testing. The FAME trial
clearly demonstrated its value in improving long-term outcomes as compared to use of
angiography alone (1). As such, the use of FFR is incorporated into both AHA ACC and European
PCI guideline recommendations as part of routine care for intermediate lesions (2,3).

One of the limitations of the use of the FFR pressure wire itself is that its handling
characteristics are somewhat inferior to a standard "work horse" guide wire used for PCI. A
"work horse" guide wire is so defined because it can be used in most PCI cases. It combines a
low tip load (to avoid intimal dissection) with excellent (ideally, one-to-one) torque
transmission and trackability through tortuous lesions. There are several different work
horse wires available. Although the wires may be different for different Cath Labs and
operators, the wires are universally used to maximize safety, efficacy, and efficiency of
PCI.

In patients specifically requiring FFR to determine the value of PCI, it would be ideal if an
FFR wire was as effective as a work horse wire so it could be used in difficult-to-traverse
lesions. However, due to the complex electronics within current FFR wires, handling
characteristics of previously used wires are inferior to current work horse wires. Recently
the FDA has approved an FFR guide wire, OptoWire, (Opsens, Quebec City, Quebec, CAN) using
light transmission to measure pressure rather than electrical transduction (4). It is
commercially available in the United States. Its handling characteristics appear to approach
that of a work horse guide wire and may represent an improvement over electrical transduction
wires. The primary purpose of the present study is to determine how effective this wire is as
a work horse wire in patients in whom FFR is required.

The OptoWire may also have the advantage of less "drift" occuring during the procedure. Drift
refers to the change in pressure due to issues related to the wire and measuring system,
rather than a true change in pressure. All current FFR wire systems demonstrate some degree
of drift requiring measuring pressure of the wire in the aorta after the procedure is
completed to determine if, and to what extent, drift has occurred. Thus, a secondary aim of
this study will determine the degree of drift.

In clinical practice, FFR is performed before, and often after, PCI. In a study of 574
patients treated at the Little Rock VA (IRB Study, #779601), teh investigators found that
approximately 20% of angiographically optimized PCI still had an ischemic FFR. The
investigators further found that this ischemic value could be improved by further treatments
including balloon angioplasty and stenting. Thus, the secondary purpose is to measure FFR
after successful PCI to ascertain the incidence of persistently ischemic FFR after optimized
angiographic stenting to confirm the result from out previous study.

Statistical analysis

This study is descriptive. It will use means and standard deviation for continuous variables
and prevalence or incidence in percentages as appropriate to show results. As there is no
comparator group, comparative statistics will not be employed.

Research aspect of study

The research aspect of the study is limited to the systematic collection and analysis of data
using the Opsens FFR wire with plan for publication. The other aspects of the study are
considered part of routine clinical care. They include passage of FFR wire, measurement of
FFR pre- and post-PCI, and performance of PCI itself.

Significance of study

A wire that can be used as a workhorse as well as be able to measure FFR would be of great
value. The more effective and efficient is the FFR wire in not only measuring pre-PCI FFR but
being able to be used for PCI and be stable and durable enough to be used for post-PCI
optimization, the greater is the probability that this approach will be more generally
adopted into clinical practice. Demonstration that the Opsens FFR wire is effective in this
regard should further this goal.

The investigators previously demonstrated that 21% or about 1 in 5 patients had an ischemic
FFR after satisfactory angiographic result. This study will confirm previous results or
suggest either an over- or under-estimation of that incidence.

Inclusion Criteria:

Patients (age 18-89 years old) eligible and in whom the operator has performed FFR will be
included to systematically evaluate the performance of the OptoWire FFR wire. A total of
1000 consecutive patients deemed to require FFR as part of clinical care will be included.
It is felt that 1000 patients represent a reasonable sample size to study the OptoWire FFR
wire handling characteristics, the primary endpoint of the study

Exclusion Criteria:

1. Not a candidate for FFR

2. Chronic total occlusion lesion

3. Hemodynamically unstable

4. Saphenous vein graft lesions -