But the stenosis typical improves or resolves without sequelae for patients who stick with dual antiplatelet therapy.
In-stent stenosis is a common mid-term angiographic finding among patients whose aneurysms are treated with flow diverters, according to a study published online September 7, 2018, ahead of print in the Journal of NeuroInterventional Surgery. Among those maintained on dual antiplatelet therapy, though, the stenosis typically improves or resolves without sequelae.
Lead author Fahad Essbaiheen, MD (The Ottawa Hospital, Canada), and colleagues conducted a retrospective review of all 36 patients treated with the SILK flow diverter (Balt) between July 2012 and June 2016 at their center for whom short-term (4 ± 2 months) and long-term (> 1 year) follow-up with digital subtraction angiograms were available. For each patient, in-stent restenosis was graded as mild (< 25%), moderate (25-50%), or severe (> 50%).
All patients were given dual antiplatelet therapy according to the institution protocol, which consists of daily 81 mg aspirin and 75 mg clopidogrel, initiated 5 days prior to flow diverter deployment. If urgent management was required, loading doses of 325 mg aspirin and 300 mg clopidogrel were administered the day before the procedure. If resistance to clopidogrel was suspected, 90 mg ticagrelor was administered twice daily instead, with an initial loading dose of 180 mg for urgent cases.
After the procedure, patients were maintained on aspirin indefinitely. Clopidogrel or ticagrelor were continued until the first (short-term) angiographic follow-up. They were discontinued only if there was no evidence of in-stent stenosis. If in-stent stenosis was still present at 1-year (long-term) angiographic follow-up, dual antiplatelet therapy was maintained and stent patency was assessed annually via cerebral angiography.
At mid-term follow-up, in-stent restenosis was identified in 16 of 36 patients (44%). Of these patients, 11 had mild (69%), three had moderate (19%), and two had severe (12%) in-stent restenosis. The stenosis was diffuse in 11 patients (69%) and focal in five (31%). All patients were asymptomatic, but 13 were maintained on dual antiplatelet therapy, and three on aspirin alone.
No Sequelae When Antiplatelet Therapy Maintained
At long-term follow-up, in-stent restenosis was found to be completely resolved in 11 patients and improved in three. In the final two patients, the stenosis had worsened. No cases of de novo in-stent restenosis were observed.
Univariate analysis revealed no significant predictors of in-stent restenosis. Factors evaluated were gender, age, the presence of subarachnoid hemorrhage, aneurysm size, location, occlusion status, and poststenting angioplasty.
To date, senior author Daniela Iancu, MD (The Ottawa Hospital) told Neurovascular Exchange, none of the patients in their series with in-stent stenosis have experienced any clinical symptoms. The presence of in-stent stenosis may increase the risk of subsequent stroke, however.
The clinical implications of the findings, she explained, depend on previous practice. Clinicians who are considering stopping dual antiplatelet therapy less than 12 months after stent implantation should first look for the presence of in-stent stenosis, she recommended. If it is present, antiplatelet therapy should not be discontinued.
Essbaiheen F, AlQahtani H, Almansoori TM, et al, et al. . J NeuroIntervent Surg. 2018;Epub ahead of print.
Essbaiheen and Iancu report no relevant conflicts of interest.