Incomplete stent apposition of the closed cell–design Enterprise stent following stent-mediated coil embolization of intracranial aneurysms has been associated with increased risk of periprocedural thromboembolic events. In this study, the authors seek to determine the natural history of incomplete stent apposition and evaluate the clinical implications of the phenomenon.
Since January 2009, all patients receiving Enterprise stents in the treatment of intracranial aneurysms at the authors' institution have undergone serial 3-T MRI with incomplete stent apposition identified by the crescent sign on multiplanar reconstructions of MR angiograms. Magnetic resonance images and MR angiograms obtained at 3, 9, and 18 months after stent-assisted coil embolization were analyzed along with admission and follow-up clinical medical records. These records were evaluated for any radiographic and clinical, transient or permanent ischemic neurological events.
Fifty patients receiving Enterprise stents were eligible for inclusion and analysis in the study. Incomplete stent apposition was identified in postoperative imaging studies in 22 (44%) of 50 patients, with 19 (86%) of 22 crescent signs persisting and 3 (14%) of 22 crescent signs resolving on subsequent serial imaging. Delayed ischemic events occurred in 8 (16%) of 50 cases, and all cases involved patients with incomplete stent apposition. The events were transient ischemic attacks (TIAs) in 5 cases, asymptomatic radiographic strokes in 2 cases, and symptomatic strokes and TIAs in the final case. There were no delayed ischemic events in patients who did not have incomplete stent apposition. Only 1 of the delayed ischemic events (2%) was permanent and symptomatic. The postoperative presence of a crescent sign and persistence of the crescent sign were both significantly associated with delayed ischemic events (p < 0.001 and p = 0.002, respectively).
Incomplete stent apposition is a temporally persistent phenomenon, which resolves spontaneously in only a small minority of cases and appears to be a risk factor for delayed ischemic events. Although further follow-up is needed, these results suggest that longer duration of antiplatelet therapy and clinical follow-up may be warranted in cases of recognized incomplete stent apposition.
Abbreviations used in this paper:DWI = diffusion-weighted imaging; ICES = Interstate Collaboration of Enterprise Stent/Coiling; ISA = incomplete stent apposition; MRA = MR angiography; mRS = modified Rankin Scale; SAH = subarachnoid hemorrhage; TIA = transient ischemic attack.
Address correspondence to: Adel M. Malek, M.D., Ph.D., Department of Neurosurgery, Tufts Medical Center, 800 Washington Street, Box 187, Proger 7, Boston, Massachusetts 02111. email: firstname.lastname@example.org.
Please include this information when citing this paper: published online March 15, 2013; DOI: 10.3171/2013.2.JNS121427.
DashtiSRFiorellaDToledoMMHuYMcDougallCGAlbuquerqueFC: Proximal migration and compaction of an Enterprise stent into a coiled basilar apex aneurysm: a posterior circulation phenomenon?. J Neurointerv Surg2:356–3582010
FiorellaDAlbuquerqueFCWooHRasmussenPAMasarykTJMcDougallCG: Neuroform stent assisted aneurysm treatment: evolving treatment strategies, complications and results of long term follow-up. J Neurointerv Surg2:16–222010
GaoBMalekAM: Possible mechanisms for delayed migration of the closed cell—designed Enterprise stent when used in the adjunctive treatment of a basilar artery aneurysm. AJNR Am J Neuroradiol31:E852010. (Letter)
Gutiérrez-ChicoJLRegarENüeschEOkamuraTWykrzykowskaJdi MarioC: Delayed coverage in malapposed and side-branch struts with respect to well-apposed struts in drug-eluting stents: in vivo assessment with optical coherence tomography. Circulation124:612–6232011
HellerRSMieleWRDo-DaiDDMalekAM: Crescent sign on magnetic resonance angiography revealing incomplete stent apposition: correlation with diffusion-weighted changes in stent-mediated coil embolization of aneurysms. Clinical article. J Neurosurg115:624–6322011
LubiczBFrançoisOLevivierMBrotchiJBalériauxD: Preliminary experience with the enterprise stent for endovascular treatment of complex intracranial aneurysms: potential advantages and limiting characteristics. Neurosurgery62:1063–10702008
MoccoJFargenKMAlbuquerqueFCBendokBRBoulosASCarpenterJS: Delayed thrombosis or stenosis following enterprise-assisted stent-coiling: is it safe? Midterm results of the interstate collaboration of enterprise stent coiling. Neurosurgery69:908–9142011
Sanchez-RecaldeAMorenoRBarrealesLRiveroFGaleoteGJimenez-ValeroS: Risk of late-acquired incomplete stent apposition after drug-eluting stent versus bare-metal stent. A meta-analysis from 12 randomized trials. J Invasive Cardiol20:417–4222008