The aim of the study is to compare post-interventional fractional flow reserve (FFR) value between optical coherence tomography(OCT)-guided and angiography-guided strategy for treatment of complex coronary lesion.

There has been ample evidence of the role of intracoronary imaging for optimizing the stent, especially among the patients with complex coronary lesions. Intracoronary imaging can be used during the entire process of percutaneous coronary intervention (PCI), from pre-PCI to post-PCI stages. Notably, approximately 15-20% of patients who underwent angiographically successful PCI showed significant stent underexpansion, malapposition, intra-stent thrombus formation, and edge dissection on intracoronary imaging studies, including optical coherence tomography (OCT).

Meanwhile, the role of pre-interventional fractional flow reserve (FFR) measurement has been well established and recommended by recent guideline. However, although previous studies evaluated the efficacy and safety of FFR-guided decision-making followed by angiographic stent implantation, they did not evaluate functionally optimized revascularization. Actually, the vessels with low post-PCI FFR had substantial proportions of suboptimized stented (underexpansion and acute malapposition) and residual disease in non-stented segments. Furthermore, several large observational studies have suggested that suboptimal physiologic results after PCI is associated with an increased risk of clinical events. Previously, the DOCTORS trial found out that OCT-guided PCI was associated with higher post-PCI FFR than angiography-guided PCI (0.94±0.04 vs. 0.92±0.05, P=0.005).

Therefore, OCT can be a useful tool for acquiring functional optimal results after stent implantation. This synergic effect between OCT and post-PCI FFR can be maximized when the investigators perform PCI for complex lesions. This study sought to evaluate compare post-interventional FFR value between OCT-guided and angiography-guided strategy for treatment of complex coronary lesion.

Inclusion Criteria:

1. Patients >18 years old

2. Patients with stable or unstable angina and complex coronary lesions*

3. Patients who were indicated revascularization

   • Diameter stenosis >90% by angiography
   • Diameter stenosis with 50~90% with pre-interventional FFR ≤0.80

4. Patients who underwent implantation of 2nd generation drug-eluting stent

   • Definitions of complex coronary lesions

     1. True bifurcation lesion (Medina 1,1,1/1,0,1/0,1,1) with side branch ≥2.5mm size
     2. Chronic total occlusion (≥3 months) as target lesion
     3. PCI for unprotected left main (LM) disease (LM os, body, distal LM bifurcation including non-true bifurcation)
     4. Long coronary lesions (implanted stent ≥38 mm in length)
     5. Multi-vessel PCI (≥2 major epicardial coronary arteries treated at one PCI session)
     6. Multiple stents needed (≥3 more stent per patient)
     7. In-stent restenosis lesion as target lesion
     8. Severely calcified lesion (encircling calcium in angiography)
     9. Left anterior descending (LAD), left circumflex artery (LCX), and right coronary artery (RCA) ostial lesion

Exclusion Criteria:

1. Target lesions not amenable for PCI by operators' decision
2. Cardiogenic shock (Killip class IV) at presentation
3. Less than TIMI 3 flow of target vessel after index procedure
4. Intolerance to Aspirin, Clopidogrel, Prasugrel, Ticagrelor, Heparin, Everolimus, Zotarolimus, Biolimus, or Sirolimus
5. Known true anaphylaxis to contrast medium (not allergic reaction but anaphylactic shock)
6. Renal insufficiency such that an additional contrast medium would be harmful for patient
7. Recent ST-segment elevation myocardial infarction (STEMI)
8. Inability to receive adenosine or nicorandil injection
9. Pregnancy or breast feeding
10. Non-cardiac co-morbid conditions are present with life expectancy <2 year or that may result in protocol non-compliance (per site investigator's medical judgment)
11. Unwillingness or inability to comply with the procedures described in this protocol

After publication of first manuscript and trial results, the de-identified data will be shared by permission of principle investigator, when asked

1 year after study completion

After publication of first manuscript and trial results, the de-identified data will be shared by permission of principle investigator, when asked