Predictors of stent strut malapposition in calcified vessels using frequency-domain optical coherence tomography.

Background and Aims. Malapposition of stent struts to the arterial wall and suboptimal stent expansion have been linked with poor outcomes following percutaneous coronary intervention (PCI). The purpose of this study was to use optical coherence tomography (OCT) to investigate stent strut malapposition in relation to calcium distribution. Methods and Results. Twenty-three PCI patients underwent OCT before and after scent deployment. Patient and procedural details and lesion characteristics - including the extent and depth of calcification - were measured, and the number of malapposed struts following final postdilatation was quantified. Patient and lesion characteristics associated with malapposition were assessed using univariate and multivariate analyses. The mean lesion length was 25.2 +/- 10.8 mm, with a minimal lumen area (MLA) of 2.2 +/- 1.2 mm(2). Eight percent of all stent struts were malapposed, most commonly in the proximal part of the scent. By univariate analysis, the percentage of malapposed struts was found to correlate with the circumferential extent of calcification (P=.04); however, no correlation was seen with the depth of calcification. Using multivariate analysis, the circumferential extent of vessel wall calcification was the only plaque feature found to correlate with the percentage of malapposed struts (P=.01). Conclusions. Using OCT to assess vessel wall characteristics, the circumferential extent of superficial calcification seen, and not the depth, correlated well with the percentage of malapposed struts following PCI.