Optical coherence tomography assessment of the impact of colchicine on non-culprit coronary plaque composition after myocardial infarction

Aims Low-dose colchicine reduces the risk of cardiovascular events after myocardial infarction (MI). The purpose of this study was to assess the effect of colchicine post-MI on coronary plaque morphology in non-culprit segments by optical coherence tomography (OCT).Methods and results COCOMO-ACS was a double-blind, placebo-controlled trial that randomized 64 patients (median age 61.5 years; 9.4% female) with acute non-ST-segment elevation MI to colchicine 0.5 mg daily or placebo for a median of 17.8 months in addition to guideline-recommended therapy. Participants underwent serial OCT imaging within a matched segment of non-culprit coronary artery that contained at least one lipid-rich plaque causing >= 20% stenosis. The primary outcome was the change in minimum fibrous cap thickness (FCT) in non-culprit segments from baseline to final visit. Of those randomized, 57 (29 placebo, 28 colchicine) had evaluable imaging at baseline and follow-up. Overall, colchicine had no effect on relative (placebo +48.0 +/- 35.1% vs. colchicine +62.4 +/- 38.1%, P = 0.18) or absolute changes in minimum FCT (+29.2 +/- 20.9 mu m vs. + 37.2 +/- 21.3 mu m, P = 0.18), or change in maximum lipid arc (-38.8 +/- 32.2 degrees vs. -54.8 +/- 46.9 degrees, P = 0.18) throughout the imaged non-culprit segment. However, in patients assigned colchicine, cap rupture was less frequent (placebo 27.6% vs. colchicine 3.6%, P = 0.03). In post hoc analysis of 43 participants who had been followed for at least 16 months, minimum FCT increased to a greater extent in the colchicine group (placebo +38.7 +/- 25.4% vs. colchicine +64.7 +/- 34.1%, P = 0.005).Conclusion In this study, OCT failed to detect an effect of colchicine on the minimum FCT or maximum lipid arc of plaques in non-culprit segments post-MI. The post hoc observation that minimum FCT increased to a greater extent with colchicine after more prolonged treatment suggests that longer-term studies may be required to detect the effect of anti-inflammatory therapies on plaque morphology by OCT.Clinical trial number Australian New Zealand Clinical Trials Registry Identifier, ACTRN12618000809235, registered on the 11 May 2018. Graphical Abstract (Top left) Schematic of study design. (Top right) Example from colchicine group of matched optical coherence tomography (OCT) images at baseline and follow-up showing change in minimum fibrous cap thickness (FCT). (Bottom) Graphs summarize results from both groups for % change in minimum FCT in the overall cohort and in the post hoc analysis of 43 participants followed for at least 16 months, and for absolute change in maximum lipid arc in the overall cohort. DAPT, dual antiplatelet therapy; m, months; NSTEMI, non-ST-segment elevation myocardial infarction.