This randomized controlled trial compared OCT-guided PCI to angiography-guided PCI. The OCT group had a larger minimum stent area post-PCI but no difference in target vessel failure at 2 years. While OCT guidance reduced stent thrombosis and complications, it did not decrease major adverse cardiac events due to the low rate of ischemia-driven revascularization in both groups. The results demonstrate the benefits of OCT for optimization but need longer term follow-up to assess clinical outcomes fully.

1. ILUMIEN – IV Trial
By Dr. Aman Kedia
Under the guidance of –
Dr. S S Kothari Sir
Dr. Jayal Shah sir
Dr. Tarun Madan Sir
Dr. Riyaz Charaniya sir
Dr. R. K. Dake sir
Dr. Hemal Thakkar sir

3. About OCT
• Optical Coherence Tomography (OCT) is a light-based imaging
modality that can provide in vivo high-resolution images of the
coronary artery with a level of resolution (axial 10-20 μm) ten times
higher than IVUS but with a penetration depth limited to 1.5-2 mm.
• The technique uses low-coherent near infrared light to create high-
resolution cross sectional images of the vessel. OCT, originally
described in the early 1990s, was first applied in the field of
ophthalmology.
• The vascular application, initiated in the mid 90s demonstrated the
potential of the technique to identify clinically relevant coronary
artery morphology with a level of resolution never reached before in
vivo.

4. Limitations of angiography
• Under /over estimation of lesion extent and severity
• Poor intra /inter observer correlation
• Low resolution
• Less sensitive to assess plaque characteristics
• Images the lumen and not the vessel wall

5.  Advantages of OCT
• Precise quantification of diseases extent and severity
• Good intra / inter observer correlation
• High resolution
• Ability to assess plaque characteristics
• 360 degree measurements
• Images the vessel wall too
• Accurate sizing vessels

6. OCT v/s IVUS

7. Timeline of ILUMIEN Trial

8. ILUMIEN – IV : OPTIMAL PCI
• prospective, large-scale, single-blind, randomized trial that was
conducted to determine whether OCT-guided PCI would improve
procedural and clinical outcomes as compared with angiography-
guided PCI
• two primary efficacy end points were :
1. Primary Imaging Endpoint - the Minimum Stent
Area(MSA) after PCI as assessed with OCT , and
2. Primary Clinical Endpoint – Target Vessel Failure(TVF)
at 2 years .

9. Inclusion Criteria
Either criterion 1 and/or 2 must be present :
1. High-risk patient – i.e. medically treated Diabetes
2. High-risk lesion –
• Lesion causing NSTEMI or STEMI > 24 hours duration
• Long lesion of atleast more than or equal to 28mm length
• Bifurcation lesion needing 2 stents
• Severe calcification
• CTO lesion
• In-Stent Restenosis

10. Exclusion Criteria
• STEMI ≤24 hours
• Creatinine clearance ≤30 ml/min/1.73 m²
• CHF -Killip class ≥2
• LVEF ≤30%

11. • The trial was conducted at 80 sites in 18 countries.
• It was conducted from May 2018 to Dec 2020 and published in
August 2023.
• total of 2487 patients underwent randomization.
• 1233 patients were assigned to undergo OCT-guided PCI, and
1254 to undergo angiography-guided PCI.

14. Intervention -
For patients in the OCT group :
• Before a stent was implanted, OCT was used to determine the best
method of lesion preparation and stent placement .
• Stent size selection was based on the basis of vessel diameter and
length measurements at the proximal and distal segments.
• After stent placement, OCT was used to optimise the result of
implantation on the basis of stent expansion, artery dissection,
stent malopposition, and residual atherosclerotic disease in the
reference segment.
. For patients in the Angiography group :
• OCT was used to take a final set of images after the PCI procedure
for comparison of outcomes.

16. Results
• The Analysis is based upon Imaging and Clinical based –
Primary and Secondary Endpoints.

17. Imaging Endpoint -
Final post-pci Minimum Stent Area assessed by OCT in each arm :
• The minimum stent area after PCI was 5.72±2.04
mm2 in the OCT group and 5.36±1.87 mm2
in the angiography group (mean difference, 0.36 mm²;
95% confidence interval [CI]
• OCT-assessed stent expansion, procedural success, intrastent area,
and total flow area appeared to be greater in the OCT group

18. Primary Clinical Endpoint
• Target Vessel Failure(TVF) - composite of Target Vessel-MI, Target
Vessel Revascularization (TVR) assessed upto 2 years.
At a median follow-up of 729 days (interquartile
range, 709 to 742), target-vessel failure occurred
in 88 patients in the OCT group and in 99 patients in the angiography
group (Kaplan–Meier
estimates, 7.4% and 8.2%, respectively; hazard
ratio, 0.90; 95% CI, 0.67 to 1.19; P=0.45) – Statistically Insignificant.

21. Safety Endpoints
• Stent thrombosis within 2 years occurred in 6 patients (0.5%) in the
OCT group and in 17 patients (1.4%) in the angiography group.
• PCI-related angiographic complications had occurred in 48 of 1320
patients (3.6%) in the OCT group and in 74 of 1387 patients (5.3%) in
the angiography group

23. Discussion
This trial showed that OCT guidance resulted in a larger
Minimum Stent Area after PCI than angiography guidance,
but there was no apparent difference in a composite of
death from cardiac causes, Target Vessel-MI, or Ischemia
Driven – Target Vessel Revascularization (ID-TVR) at the end
of 2 years.

24. • Previous studies have shown that Intravascular Imaging-guided PCI as
compared to Angiography guidance alone resulted in larger luminal
dimension and thus lesser Major Adverse Cardiac Events.
However most studies used IVUS-guided PCI, and RCT to compare OCT-
guided versus Angiography alone PCI were not designed to detect
differences in clinical outcomes.
Moreover, the findings in this trial is also driven by the low incidence of
Ischemia-driven Target Vessel Revascularization in each group (5.6%).

25. Positives from the trial
• OCT-guided group showed a much lower rate of In-stent Thrombosis
compared to Angiography guidance alone arm. This is due to lesser
stent malopposition, tissue protrusion and edge dissection.
This finding is consistent with findings of previous Intravascular
Imaging-guided PCI.

26. Limitations of the trial
• Being a multicenter trial, the effect of operator experience on results
could have varied.
• Limited follow-up of patients during the Covid-19 pandemic could
have resulted in lesser rates of Revascularization.
Longer term follow-up would be necessary to determine whether
the incidence of end points of clinical events remain the same or vary.