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

AIMS: 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. METHODS AND RESULTS: 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). CONCLUSION: FD-OCT assessment of thrombus volume in selected ACS patients is feasible, safe, and could allow clot regression monitoring in vivo.