736 Hazy spots: through the eye of optical coherence tomography
Authors: Bianchini Emiliano , Vergallo Rocco , Buonpane Angela , Lombardi Marco , Ricchiuto Alfredo , Trani Carlo , Burzotta Francesco , Aurigemma Cristina , Romagnoli Enrico , Crea Filippo 
Published: December 2021

Abstract

Aims
Acute stent thrombosis after coronary artery stent placement is a rare but serious complication in percutaneous coronary intervention (PCI). Stenting culprit lesions in acute coronary syndrome (ACS) has higher risk of acute stent thrombosis than stable coronary artery disease, and many local and systemic factors may contribute to increase this risk. Tissue protrusion (TP), and in particular, plaque prolapse after PCI can play a role in acute stent thrombosis, and intra-vessel imaging is the principal instrument to identify such underlying lumen alteration after stent implantation, and guide intervention.

Methods and results
We report the case of a 54-year-old man with a history of hypertension, dyslipidemia, type 2 diabetes mellitus, obesity and no other relevant comorbidities in remote history, who underwent a coronary angiography for an unstable angina. A long, calcific sub-occlusion of the left anterior descending artery (LAD), which involved LAD-first diagonal branch (D1) bifurcation (Medina 1.1.1) and LAD-D2 bifurcation (Medina 1.1.0) was found. After deployment of two overlapping drug-eluting stents (DES), (ULTIMASTER TANSEI 3.0 × 38 mm and 3.0 × 21 mm) and struts apposition optimization with sequence of proximal optimization technique (POT) on D1 and D2, and a kissing balloon technique (KS) on LAD-D2 bifurcation, a ‘hazy’ in-stent image was detected right after the LAD-D2 bifurcation, suggesting an acute in-stent thrombosis, in absence of flow alteration (TIMI 3), symptoms or ECG modifications. Multiple thrombus-aspiration were made and resulted in abundant thrombus removal and improvement in the angiographic image, with persistent valid flow on every three vessels (TIMI 3). After 5 days of triple anticoagulant therapy with ticagrelor, cardioaspirin and UFH infusion, he underwent a new coronary angiography control. A similar ‘hazy’ image was detected right after LAD-D2 bifurcation within the LAD. An optical coherence tomography (OCT) pullback was made to assess the nature of the angiographic finding. OCT showed good struts apposition in almost every cross-sectional images, but an evident TP was detected right on the angiographic hazy spot. OCT allowed to evaluate the lipid-richness of the stented plaque and the nature of the TP, which was mixed with evident both white and red thrombus apposition (minimum luminal area measured 4.5 mm2). OCT guided a new PCI, with a stent-in-stent implantation on LAD. TP was absent on the post-PCI OCT run.

Conclusions
In this report, we showed the usefulness of OCT in revealing a potential high risk thrombogenic source. OCT not only characterized something that angiography alone couldn’t, but suggested the etiology of the amount of thrombus removed by the vessel during the first PCI. Indeed, despite an optimized cycle of anticoagulant therapy, OCT still revealed several mixed thrombus apposition on the TP, and this suggested its role in the acute stent thrombosis. OCT guided the choice to appose a new stent-in-stent to solve a potential thrombogenic source.