The authors can be contacted via Dr. Annapoorna Kini at annapoorna.kini@mountsinai.org.

Clinical history

• A 60-year-old female with past medical history of controlled hypertension, hyperlipidemia, controlled non-insulin dependent diabetes mellitus, peripheral vascular disease, coronary artery disease and prior coronary intervention presented with Canadian Cardiovascular Society (CCS) class III angina on optimal medical therapy and abnormal SPECT MPI with moderate apical ischemia. 

Procedure

• Coronary angiogram demonstrated 70-80 percent stenosis in the mid left anterior descending coronary artery (LAD) at the origin of first diagonal artery (Medina Classification 1,1,0) (Figure 1, arrow).
• Pre-percutaneous coronary intervention (PCI) optical coherence tomography (OCT) imaging revealed a mixed lesion containing a one quadrant calcification (asterisk), fibro-lipidic plaque with lipid pool (7-10 o’clock), and thin fibrous cap (arrow) at the site of minimal lumen area of 1.6 mm² (Figure 2, frame 1). Moderate calcification was detected at the LAD-first diagonal artery bifurcation site, no significant disease involving the ostium of first diagonal artery was detected (Figure 2, frame 3); moderate calcification was also detected at the LAD-septal branch bifurcation site (Figure 2, frame 2).
• With planned provisional stenting, the mid LAD stenosis was initially treated with 3.0mm x 20.0mm Euphora^™ non-compliant balloon inflated to 14 atmospheres followed by PCI with 2.75mm x 38.0mm Promus Premier^™ drug-eluting stent deployed at 12 atmospheres for 30 seconds. 
• Post stenting, there was plaque shift leading to TIMI-2 flow noted in first diagonal artery (Figure 3, frame 1). OCT revealed coronary plaque shift into the orifice of the diagonal side branch (asterisk in Figure 3, frame 1, 2); the septal branch was not compromised (double asterisk in Figure 3, frame 2). OCT imaging confirmed good stent apposition and showed no evidence of significant plaque prolapse or edge dissection. However, it detected stent underexpansion in the middle of the stent with a minimal stent area (MSA) of 3.8 mm².    
• Based on the findings and ongoing symptoms of chest pain, percutaneous transluminal coronary angioplasty (PTCA) of first diagonal artery was performed with a 2.0mm x 12mm Apex Push^™ compliant balloon, resulting in TIMI-3 flow and <30% residual stenosis (Figure 4A). The post-dilation of the LAD stent was performed with a 3.25mm x 15mm Quantum Apex^™ non-compliant balloon inflated at 18 atmospheres for 30 seconds.
• The final OCT pullback revealed significantly improved stent expansion (MSA=5.5mm²) (Figure 4, frame 1). Frame 2 in Figure 4 shows the OCT image corresponding to Figure 3, frame 1, allowing for evaluation of the effect of the PTCA on the side branch ostium. 
• Finally, an off-line analysis of the fate of the side branch was performed using three-dimensional OCT analysis software (QAngio OCT, Medis). Figure 5 shows 3D OCT reconstruction of side branch ostium before PCI (A), after stenting (B), and after post-dilation and PTCA of first diagonal (C) with corresponding measurements of the side branch area.

Conclusions

Occlusion of the side branch after main branch stent implantation is a potential concern during PCI of coronary bifurcations. In this case, OCT imaging made it possible to characterize the side branch occlusion, select an appropriate treatment strategy, and estimate the effect of side branch treatment. In addition, OCT imaging detected stent underexpansion, which resulted in post-dilation.