036: In vivo monitoring of intra-coronary thrombus regression by serial optical coherence tomography analysis: feasibility and first-in-man results

Abstract

Time-domain optical coherence tomography (TD-OCT) allows assessment of the anatomy and features of unstable coronary artery lesions, including discrimination between the thrombotic and atherosclerotic plaque components. We sought to investigate the feasibility of thrombus quantification and its monitoring in patients with high thrombotic burden acute coronary syndromes. Patients with successfully revascularized acute coronary syndromes and a large thrombus burden on initial coronary angiography who beneficiated from repeated TD-OCT examinations in our institution were suitable for inclusion. Coronary lesion stenosis degree was determined by quantitative coronary angiography (QCA) methods. Thrombus volume, maximal surface and minimal luminal area (MLA) were quantified by serial area measurement within the athero-thrombotic culprit lesion in 1 mm intervals before any stenting. Eleven patients underwent 2 consecutive TD-OCT examinations. The OCT image quality was suitable for thrombus quantification in n=9 subjects (89% men/ age=62.4±5.7y/ 89% STEMI). All patients were under anticoagulant and dual antiplatelet therapy between the two procedures (mean delay: 4.1±0.4 days). No adverse events were observed following OCT analysis. We measured a progressive reduction of thrombus burden between the two analysis, as assessed by the decrease of thrombus volume (5.3±1.7 vs.11.0±3.4 mm3, p=0.004), length (7.4±1.0 vs. 10.9±1.8 mm, p=0.02) and increase of MLA (2.5±0.6 mm2 vs. 1.8±0.3 mm2, p=0.02). However, the degree of stenosis analyzed by QCA didn’t significantly decrease over time (49.7±4.6% vs. 55.7±6.6%, p= 0.15). The thrombus volume reduction was time dependent, as witnessed by the high correlation between the percentage of thrombus volume decrease and the delay between analysis (R=0.87, p=0.002). The observed thrombus volume reduction rate was evaluated to 12% of the initial volume per day under medical therapy. TD-OCT assessment of thrombus volume in patients with ACS is feasible, safe and could allow in vivo clot regression monitoring.