Correlation between 3D Quantitative Angiography Based FFR and luminal obstruction as detected by Optical Coherence Tomography (OCT): the FAST OCT study

Angiography-based fractional flow reserve (3D-angio-based FFR) is an emerging
technology with a high diagnostic performance as compared to invasively
measured FFR and could provide an easy, safe, and cost-effective solution for
functional evaluation of coronary artery stenosis without the need for a costly
pressure wire and hyperemic agent. However, 3D-angio-based FFR is still
hampered by a significant *grey zone* that might warrant the use of additional
diagnostic tools and has not been tested in patients presenting with acute
coronary syndromes (ACS). An important limitation since up to 31% of those
cases present with a plaque rupture/erosion or calcified nodules located in
*angiographically non-significant* coronary lesions. Optical coherence
tomography (OCT) conversely offers high-resolution intracoronary imaging
allowing accurate pre- percutaneous coronary intervention (PCI) assessment of
lesion and plaque characteristics, and post-PCI results.
Although post stenting low 3D-angio-based FFR values have been associated with
a significantly increased risk for future major adverse events, they typically
preclude any statements on the exact aetiology of the pressure drop over the
intracoronary segment assessment. In this scenario, OCT has the ability to
accurately identify specific post-PCI patterns related with significant changes
in FFR values in order to improve future outcomes.

The aim of the FAST OCT study is to define the correlation between
3D-angio-based FFR values and OCT findings in a pre- and post-PCI setting in
patients with non-ST segment elevation acute coronary syndromes (NST-ACS). The
results will be used to power future studies on OCT-based lesion stratification
in angiographically proven intermediate lesions to determine indication for PCI
and optimize post-PCI long-term outcomes.

Prospective, multicentre, single arm, investigator-initiated study.

Coronary angiography and OCT assessment of all epicardial vessels (>=2,5 mm)
with intermediate to severe stenosis before and after PCI (if performed). The
use of intracoronary physiology (either FFR or pressure wire-derived
non-hyperemic pressure ratio indexes(NHPR)) is strongly recommended per
clinical practice guidelines. 3D-angio-based FFR analyses before and after PCI
(if performed) will be performed offline in all vessels with intermediate to
severe stenosis. Patients will be followed up until discharge. No clinical
follow-up will be performed after discharge.

Pressure wire-based FFR or NHPR will be used at the discretion of the operator
following current clinical practice guidelines.
Previous studies have demonstrated that both FFR- and OCT-guided PCI is safe
and improves future clinical outcomes as compared to angiography-guided PCI
alone. The potential risks of this study include the known risks of any
currently used standard procedure to assess and to treat obstructive coronary
artery disease. All patients will receive standard care which includes double
antiplatelet therapy, statins and lifestyle changes recommendations according
to current European guidelines. Patients participating in this study will
potentially benefit from receiving a more accurate assessment of the severity
of the lesions and appropriate guidance of the PCI.