Characteristics of Earlier Versus Delayed Presentation of Very Late Drug‐Eluting Stent Thrombosis: An Optical Coherence Tomographic Study

Background The pathophysiology underlying very late drug‐eluting stent ( DES ) thrombosis is not sufficiently understood. Using optical coherence tomography, we investigated characteristics of very late stent thrombosis ( VLST ) according to different onset times. Methods and Results A total of 98 patients from 10 South Korean hospitals who underwent optical coherence tomography for evaluation of very late DES thrombosis were retrospectively included in analyses. VLST occurred at a median of 55.1 months after DES implantation. All patients were divided into 2 equal groups of earlier versus delayed presentation of VLST , according to median onset time. In total, 27 patients were treated with next‐generation DES and 71 with first‐generation DES . Based on optical coherence tomography findings at thrombotic sites, main VLST mechanisms were as follows, in descending order: neoatherosclerosis (34.7%), stent malapposition (33.7%), and uncovered struts without stent malapposition or evagination (24.5%). Compared with patients with earlier VLST , patients with delayed VLST had lower frequency of uncovered struts without stent malapposition or evagination (34.7% versus 14.3%, respectively; P =0.019). Conversely, the frequency of neoatherosclerosis was higher in patients with delayed versus earlier VLST (44.9% versus 24.5%, respectively; P =0.034). The frequency of stent malapposition was not different between patients with earlier and delayed VLST (34.7% versus 32.7%, respectively; P =0.831). The frequency of stent malapposition, evagination, and uncovered struts was still half of delayed VLST . Conclusions The pathological mechanisms of very late DES thrombosis changed over time. Delayed neointimal healing remained a substantial substrate for VLST , even long after DES implantation.