Intra-coronary thrombus evolution during acute coronary syndrome: regression assessment by serial optical coherence tomography analyses

We investigated the feasibility of thrombus quantification by frequency-domain optical coherence tomography (FD-OCT) methods in patients with highly thrombotic acute coronary syndrome (ACS) treated by deferred stenting strategy.Patients were suitable for inclusion if they presented (i) an ACS that was successfully revascularized by manual thrombo-aspiration and (ii) a large residual thrombus on coronary angiography and initial FD-OCT analysis. These patients underwent a second procedure including FD-OCT analysis after several days of optimal antithrombotic therapy. Serial area measurements within the athero-thrombotic culprit lesion were performed to evaluate the OCT-thrombus score, volume, and length. Sixteen patients (88% men/age = 59.3 ± 4.1 years/94% STEMI) were included in the study. The mean delay between OCT analyses was 3.9 ± 0.3 day. No adverse event was observed during this interval. We observed a reduction of thrombus burden between the two analyses, as assessed by the significant reductions in OCT-thrombus score (22.3 ± 2.6 vs. 10.3 ± 1.3, P < 0.001), OCT-thrombus volume (9.6 ± 2.3 vs. 3.6 ± 0.9 mm(3), P = 0.003), and OCT-thrombus length (11.1 ± 1.4 vs. 7.4 ± 0.8 mm, P = 0.01). The percentages of OCT-thrombus score and volume reduction were highly correlated with the inter-OCT analyses delay (respectively ρ = 0.65 and ρ = 0.84, P < 0.01 for both).FD-OCT assessment of thrombus volume in selected ACS patients is feasible, safe, and could allow clot regression monitoring in vivo.