BACKGROUND: Optical coherence tomography (OCT) can detect detailed plaque features in native coronary arteries. Stent struts cause shadows that partially obscure the vessel wall, but plaque features can still be seen. We investigated the impact of stent artefact on plaque quantification and whether the plaque behind struts is associated with microvascular dysfunction.
METHODS: Patients retrospectively recruited from two centres, underwent OCT pre- and post-stenting on the same vessel segment. Lipid (LA) and calcium (CA) were measured as arcs. Macrophages, microchannels and cholesterol crystals were counted. Subsequently, we determined whether stented plaque features were associated with reduced TIMI flow grade in consecutive patients who underwent OCT post-stenting.
RESULTS: In 52 patients the lipid arc was similar pre- vs post-stent: median (55º [13º-93º] vs. 40º [18º-87°]; difference 1º [-7º to 16º], p = NS). Pre- and post-stent lipid were strongly correlated (r = 0.92, p < 0.001). In a further 128 patients those with reduced (TIMI ≤ II) vs normal flow post percutaneous coronary intervention (PCI) showed more plaque behind struts: lipid (89º [50º-139º] vs 62º [29º-88°]; p < 0.001); and calcium (24º [6º-45º] vs 7° [0º-34º]; p = 0.031). Multivariate logistic regression analysis showed that abnormal TIMI flow post-stenting was associated with diabetes (Odds ratio [OR] 2.87, CI 1.01-8.19, p = 0.048), LA (OR 1.29, 95% CI 1.14-1.38, p < 0.001) and CA (OR 1.26, CI 1,07-1.40, p = 0.005).
CONCLUSIONS: Plaque behind the struts can be accurately quantified using OCT. Furthermore, OCT plaque features in stented segments are associated with microvascular dysfunction post PCI.