Incomplete Stent Apposition after Coronary Stent Implantation: Myth or Reality?

Incomplete stent apposition of low-profile visualized intraluminal support stents in the treatment of cerebral aneurysms

OBJECTIVE

This study retrospectively analyzed the risk factors, management strategies, and complications of incomplete stent apposition (ISA) of low-profile visualized intraluminal support (LVIS) stents after initial deployment in the treatment of cerebral aneurysms.

METHODS

The clinical characteristics of ISA or wall apposition (WA) of LVIS stent after initial deployment were analyzed. The risk factors of ISA were identified using univariate logistic regression analysis and multivariate logistic regression analysis. The clinical characteristics of ISA following different management strategies were also shown.

RESULTS

The retrospective study enrolled 303 patients with 315 LVIS stent-assisted aneurysms. Fifty-nine patients with 59 stents showed ISA after initial deployment. At the end of the study, the presence of ISA was only observed in eight patients (2.5%). The stent-subtended arc angle (>90) and the aneurysm of the internal carotid artery (ICA) were associated with ISA. The stent-subtended arc angle (>90) and stent size (4.5*20 mm) were independent risk factors of ISA. The incidence of thromboembolic events in the ISA group was significantly higher than that in the WA group. After the treatment of ISA, there was no significant difference in good outcomes between patients with ISA and those with WA after initial deployment.

CONCLUSIONS

ISA is more likely to occur at tortuous vessels. The stent-subtended arc angle (>90) and LVIS size (4.5*20 mm) were independent risk factors of ISA. ISA led to significantly increased incidence of thromboembolic events. However, ISA after initial deployment did not affect the patient's prognosis.

Parent vessel size and curvature strongly influence risk of incomplete stent apposition in enterprise intracranial aneurysm stent coiling

BACKGROUND AND PURPOSE

Flexible microstents, such as the closed-cell EN, have facilitated adjunctive coiling of intracranial aneurysms. Little data are available on the ability of the stent struts to maintain vessel-wall apposition once deployed in the tortuous cerebral vasculature and the prevalence of ISA. The purpose of this study was to evaluate the relationship between geometric features of the parent vessel at the stent deployment site and prevalence of ISA.

MATERIALS AND METHODS

Postprocedural 3T-MRA was performed in a cohort of 39 patients undergoing EN stent-assisted intracranial aneurysm coiling. 3T-MRA was analyzed for the presence of ISA and supplemented by angiographic C-arm FPCT (DynaCT). Parent vessel diameter, curvature radius, and stent-subtended arc angle were measured at the site of deployment and analyzed for prediction of ISA in the ICA.

RESULTS

3T-MRA uncovered a unique crescent flow pattern (CS) outside the EN struts, which was confirmed by FPCT to indicate ISA resulting from EN crimping. ISA was detected on 3T-MRA in 19/39 patients (49%). Univariate analysis revealed ISA in the ICA to correlate with a large stent-subtended angle, a small curvature radius, and a large diameter but not stent length or jailing versus a sequential technique. Multivariate analysis identified ISA to correlate with vessel-curvature radius (OR, 253; P = .009), stent-subtended angle (OR, 225; P = .005), and parent vessel diameter (OR, 8.49; P = .044).

CONCLUSIONS

In this study, ISA was detectable by 3T-MRA in a significant proportion of patients undergoing EN stent-assisted coiling of ICA aneurysms in a vessel geometry- and stent-deployment location-dependent manner. This characteristic of EN coiling at this potentially tortuous location should be taken into account when selecting an endovascular strategy.

Delivery technique plays an important role in determining vessel wall apposition of the Enterprise self-expanding intracranial stent

BACKGROUND

The Enterprise (EN) vascular reconstruction device is a self-expanding nitinol stent used as adjunctive support in wide-necked aneurysm coiling. We sought to evaluate the effect of deployment technique on how well the EN stent conforms to the vessel wall around a curve.

METHODS

A flow model consisting of a 3.5 mm diameter silicone tube forming a 7 mm radius curve was visualized using high-resolution flat-panel CT (FPCT; DynaCT). EN stents (4.5 mm × 22 mm) were deployed using three methods: (1) microcatheter pull-back, (2) delivery microwire push and (3) a combination of both methods so as to keep the microcatheter tip centered within the lumen during deployment. FPCT images were visualized using multiplanar reconstruction for evidence of incomplete stent apposition (ISA).

RESULTS

FPCT revealed a critical role for deployment method in stent-wall apposition as noted by the development of a crescent-shaped gap between the stent and the wall. Specifically, the manufacturer-recommended microcatheter pull-back unsheathing technique (method 1) resulted in outer curve ISA, while the microwire push technique (method 2) led to inner curve ISA. Using method 3 in a dynamic push-pull manner minimized both inner and outer curve ISA.

CONCLUSION

The deployment method used to deliver the EN vascular reconstruction device plays a critical role in determining how well its struts appose the vessel wall in vitro. This characteristic must be taken into account when deploying this flexible low-profile stent to avoid ISA in even mildly tortuous anatomy given the possible link between stent malapposition and thromboembolic complications.