Impact Of Incomplete Stent Expansion Distal To The Drug-eluting Stent On Mid-or Long-term Clinical Outcome

Objects: Suboptimal or incomplete stent expansion is associated with increasedrestenosis and stent thrombosis. Inadequate deployment distal to the stent, which maybe attributed to vessel geometry (big vessels in proximal segment and small vessels indistal segment), affect the incidence of in-stent restenosis and stent thrombosis inclinical practice. We retrospectively compared the incidence of in-stent restenosis andstent thrombosis after drug-eluting stent (DES) implantation between incomplete andcomplete stent expansion groups, and investigated whether stent underexpansion hasimpact on the mid-term outcome.Methods: A total of117consecutive patients, implanted with DES, were enrolled inthis retrospective study from January2012to December2012. Patients (with150lesions in total) were followed up for9to12months, and divided into two groups: theincomplete expansion distal to the stent group (n=82) and the complete expansiongroup (n=68). The baseline characteristics, angiographic coronary lesions,device-related variables,(in)complete stent apposition and follow-up data werecollected and analyzed to compare the incidence of in-stent restenosis and stentthrombosis between the two groups.Results: There was no significant difference in the baseline characteristics,anatomical characteristics of coronary lesions and procedure-related parametersbetween patients with incomplete expansion and adequate expansion (P>0.05). Inaddition, no significant difference of QCA values (including preprocedual vesselstenosis, residual stenosis immediately after stent implantation and in-stent restenosisin9th-12th-month follow-up visits) was observed between the two groups (P>0.05).Angiography at follow-up showed that11patients had in-stent restenosis,6(7.3%) inthe incomplete stent expansion group and5(7.4%) in the complete expansion group. The incidence of restenosis and the extent of restenosis in the stent, segment,proximal or distal to the stent between the two groups showed no significantdifference (P>0.05). During the follow-up period, all patients received regular dualanti-platelet therapy (aspirin100mg and clopidogrel75mg per day) without immaturewithdrawl. There was no significance difference in the incidence of MACEs betweenthe two groups (1.2%vs0%, P=0.32).Acute myocardial infarction was observed inone patient in the incomplete stent expansion group50days after procedure. Andthere was no angiographic findings of in-stent restenosis, and the patient wassuspected to develop myocardial infarction due to stent thrombosis. There were nosignificance difference in occurrence of angina graded≥CCS2and that of cTnIperiprocedue between the two groups (14.6%vs11.8%, P=0.28and20.7%vs20.6%，P=0.92).Conclusion: Incomplete stent expansion distal to the stent edge does not increase therisk of in-stent restenosis and thrombosis.