Optical coherence tomography in unprotected left main coronary artery stenting

Aims: Delayed or incomplete stent endothelisation and stent malapposition may predispose to DES thrombosis that can be a catastrophic event in the left main coronary artery (LMCA). OCT can accurately identify stent struts and arterial tissue, but is limited by the need of vessel blood clearance and penetration; also no data exist on its use in LMCA. We sought to verify whether optical coherence tomography (OCT) can accurately assess arterial wall response after drug eluting stent (DES) implantation in the LMCA. Methods and results: OCT images were obtained in 15 patients (mean age 70.7 +/- 8.0 years) six months after LMCA DES implantation. Acquisitions were performed without proximal balloon occlusion during iso-osmolar contrast injection through a 6 Fr guiding catheter without side holes at a speed of 2-3 mL/sec. Offline image analyses were performed to evaluate assessable stent area (all slices), strut coverage, apposition, and abnormal tissue responses for every three slices (=every 0.45 mm). All OCT images were obtained without periprocedural complications. Overall, 69 +/- 20% of the stent inner area was analysable; this corresponded to 2.7 +/- 0.8 analysable quadrants per slice. Out of 1,281 struts, 1,136(88.7%) were well apposed and fully covered, 101 (7.8%) were uncovered; and 45 (3.5%) were malapposed although nine of the malapposed struts (20%) were covered by some tissue. In five patients OCT detected abnormal intraluminal tissue, and in two cases this finding was related to uncovered struts. Conclusions: OCT assessment of vascular response after LMCA DES implantation is safe and feasible. Further development of OCT imaging technology will be necessary for complete evaluation of LMCA stents.