Mechanisms of Very Late Drug-Eluting Stent Thrombosis Assessed by Optical Coherence Tomography
Background—The pathomechanisms underlying very late stent thrombosis (VLST) after implantation of drug-eluting stents (DES) are incompletely understood. Using optical coherence tomography (OCT), we investigated potential causes of this adverse event.
Methods and Results—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 0.4mm. A total of 38 early- and 20 newer-generation DES were suitable for analysis. VLST occurred at a median time of 4.7 years (IQR 3.1 to 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 non-thrombosed regions (ratio of percentages 9.27, 95% CI 4.71 to 17.85, p<0.001 and 7.55, 95% CI 3.34 to 15.09, p<0.001, respectively). The maximal length of malapposed or uncovered struts (3.40mm, 95% CI 2.55 to 4.25 versus 1.29mm, 95% CI 0.81 to 1.77, p<0.001) but not the maximal or average axial malapposition distance was greater in thrombosed compared with non-thrombosed segments. The association of both uncovered and malapposed struts with thrombus were consistent among early- and newer-generation DES.
Conclusions—The leading associated findings in VLST patients in descending order were malapposition, neoatherosclerosis, uncovered struts and stent underexpansion without difference between early- and new- generation DES treated patients. The longitudinal extension of malapposed and uncovered stent was the most important correlate of thrombus formation in VLST.
- Received August 17, 2015.
- Revision received December 28, 2015.
- Accepted January 5, 2016.