A 54-year-old male with history of hyperlipidemia, DM, and AMI with cardiogenic shock s/p ECMO and PCI with stents deployed at P/3 LAD and P/3 LCX. Heart failure symptoms persisted after the procedure. Follow up CAG showed total occlusion of LAD in-stent area. DEB to the CTO lesion and a DES to M/3 LAD de novo lesion were done, as well as POBA to DB ostial lesion. Months later, CAG showed a borderline lesion of DB ostium. FFR=0.7, and improved to 0.72 after POBA. CAG follow up for the DB lesion.

LAB: Hb: 15.1, BUN/Cr: 20/0.9ECG: Sinus rhythm, heart rate 73bpm, RBBB and LPFB pattern, Q waves over lead II/III/aVF.Echocardiography: Generalized hypokinesia of LV with EF 20-25%. AFib during the exam with E/E’med 15.

MCA: Luminal irregularity and patent;LAD: Luminal irregularity, calcification, and slight intimal hyperplasia in the proximal stent (BMS) and middle stent (DES); discrete 70% stenosis at the ostium of main DB; TIMI 3 flow;LCX: Luminal irregularity and ectasia; intimal hyperplasia in the proximal stent; TIMI 2-3 flow; segmental 70-80% stenosisat ostium and proximal part of RI and discrete 80-90% stenosis at OM; RCA: Luminal irregularity and non-dominant vessel; good distal runoff

Left heart catheterization was carried out using the right distal radial artery approach. We utilized an EBU3.5 6Fr guiding catheter to access the LMCA, and a SION wire was threaded to the distal LAD. Optical Coherence Tomography (OCT) was conducted through manipulated contrast injection, unveiling the patency of the previously totally occluded stent at the proximal LAD with complete endothelialization. The minimum in-stent area was measured at 3.99 mm². Subsequently, OCT was performed at the DB ostium, revealing a minimum in-stent area of 2.25 mm² at the proximal DB and 3.57 mm² at the DB ostium.Fractional Flow Reserve (FFR) was recorded at the distal LAD post 200mcg adenosine injection, demonstrating a value of 0.80. Simultaneously, the Resting Full-cycle Ratio (RFR) showed a value of 0.86. The catheter was then pulled back, and FFR was recorded at the distal stent edge, LAD-DB bifurcation, proximal stent edge, and LM ostium, yielding results of 0.91, 0.91, 0.93, and 1.0, respectively.Following this, the pressure wire was advanced to the distal DB. After injecting 200mcg of adenosine, FFR revealed a value of 0.79, and RFR showed 0.87. Considering the previous FFR result of 0.72, an improvement in the condition was noted, leading to the decision to conclude the procedure.

Firstly, the follow-up OCT suggested that blood flow in CTO vessels and microvascular function does not normalize immediately after treatment but improves over time. Possible reasons include microvascular resistance, positive remodeling, and vascular wall hibernation. Secondly, based on OCT evidence, we assert that despite discrepancies between FFR and NHPR, FFR remains the standard and is more reliable. Previous studies reported that insulin-treated diabetes mellitus was a predictor of negative FFR and positive iFR/RFR discrepancy, and there is no association between an increased risk of vessel-oriented composite outcomes and discordance of FFR/RFR after two years.