Optical Coherence Tomography in Very Late DES Thrombosis
What are the mechanisms underlying very late stent thrombosis (VLST), as assessed by optical coherence tomography (OCT) in patients treated with early- and newer-generation drug-eluting stents (DES)?
Between August 2010 and December 2014, 64 patients were investigated at the time-point of VLST as part of an international OCT registry. OCT pullbacks were performed after restoration of flow and analyzed at 0.4 mm. A total of 38 early- and 20 newer-generation DES were suitable for analysis. The investigators reported frame-level, segment-level, and stent-level analyses.
VLST occurred at a median time of 4.7 years (interquartile range, 3.1-7.5). An underlying putative cause by OCT was identified in 98% of cases. The most frequent finding was strut malapposition (34.5%), neoatherosclerosis (27.6%), uncovered struts (12.1%), and stent underexpansion (6.9%). Uncovered and malapposed struts were more frequent in thrombosed compared with nonthrombosed regions (ratio of percentages, 9.27; 95% confidence interval [CI], 4.71-17.85; p < 0.001 and 7.55, 95% CI, 3.34-15.09; p < 0.001, respectively). The maximal length of malapposed or uncovered struts (3.40 mm, 95% CI, 2.55-4.25 vs. 1.29 mm, 95% CI, 0.81-1.77; p < 0.001), but not the maximal or average axial malapposition distance was greater in thrombosed compared with nonthrombosed segments. The association of both uncovered and malapposed struts with thrombus was consistent among early- and newer-generation DES.
The authors concluded that the leading associated findings in VLST patients in descending order were malapposition, neoatherosclerosis, uncovered struts, and stent underexpansion.
This study suggests that OCT is able to identify the underlying putative cause of VLST in the majority of cases. A combination of multiple mechanisms of VLST within the same lesion was more frequently observed than the presence of a single cause and included malapposition, neoatherosclerosis, uncovered struts, and stent underexpansion in order of frequency. Furthermore, the most frequent mechanisms for VLST were comparable between different generations of DES devices. Additional research is indicated to assess whether use of OCT in patients with VLST will improve clinical outcomes.
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