Stent fracture and restenosis in the drug-eluting stent era

Delayed strut fracture of sirolimus-eluting stent: A significant problem or an occasional observation?

In-stent restenosis after implantation of sirolimus-eluting stents (SES) still occur in some cases and stent fracture was recently suggested as a new potential mechanism of restenosis. We report a case of delayed stent strut fracture after percutaneous coronary intervention with SES. Until now, three cases regarding Cypher stent fracture have been reported in the literature. Further investigation should be performed to elucidate the clinical significance of stent fractures of SES.

Renal Artery Thrombosis Caused by Stent Fracture in a Single Kidney Patient

PURPOSE

To report a case of incomplete expansion, fracture, and thrombosis of a stent in the renal artery.

CASE REPORT

A 47-year-old man with right renal artery occlusion underwent direct stenting of the left renal artery using a balloon-expandable stent. Completion angiography showed satisfactory patency of the vessel although the stent was not fully expanded in its central segment. The patient received 5000 units of heparin during the procedure, but no additional anticoagulant or antiplatelet therapy in the peri/postinterventional period. Twenty-five days later, he presented with acute renal insufficiency and uncontrolled hypertension. Angiography revealed in-stent thrombosis and collateral flow in the distal segment of the left renal artery. He underwent an aortorenal bypass, which salvaged the kidney. The stent, after removal from the vessel, was fractured and not completely expanded.

CONCLUSIONS

Incomplete expansion and fracture of the stent associated with insufficient antiplatelet therapy produced in-stent thrombosis. Collateral flow prevented kidney necrosis.

Nonuniform Strut Distribution Correlates With More Neointimal Hyperplasia After Sirolimus-Eluting Stent Implantation

Background— Little is known about causes of intimal hyperplasia (IH) after sirolimus-eluting stent (SES) implantation.

Methods and Results— Intravascular ultrasound was performed in 24 lesions with intra-SES restenosis and a comparison group of 25 nonrestenotic SESs. To assess stent strut distribution, the maximum interstrut angle was measured with a protractor centered on the stent, and the visible struts were counted and normalized for the number of stent cells. In SES restenosis patients, minimum lumen site was compared with image slices 2.5, 5.0, 7.5, and 10.0 mm proximal and distal to this site. The minimum lumen site had a smaller IVUS lumen area at follow-up (2.7±0.9 versus 6.2±1.9 mm 2 ; P <0.01), larger maximum interstrut angle (135±39° versus 72±23°; P <0.01), larger IH area (3.4±1.5 versus 0.6±1.1 mm 2 ; P <0.01) and thickness (0.7±0.3 versus 0.1±0.2 mm; P <0.01) at maximum interstrut angle, and fewer stent struts (4.9±1.0 versus 6.0±0.5; P <0.01) even when normalized for the number of stent cells (0.78±0.15 versus 0.97±0.07; P <0.01). Compared with nonrestenotic SES, the restenosis lesions also had a smaller minimal lumen area, larger IH area, thicker IH at maximum interstrut angle, fewer stent struts, and larger maximum interstrut angle. Multivariate analysis identified the number of visualized stent struts normalized for the number of stent cells and maximum interstrut angle as the only independent IVUS predictor of IH cross-sectional area ( P <0.01 and P <0.01), minimum lumen area ( P <0.01 and P <0.01), and IH thickness ( P <0.01 and P <0.01).

Conclusions— The number and distribution of stent struts affect the amount of neointima after SES implantation.

Routine sirolimus eluting stent implantation for unselected in-stent restenosis: insights from the rapamycin eluting stent evaluated at Rotterdam Cardiology Hospital (RESEARCH) registry

OBJECTIVE

To assess the effectiveness of routine sirolimus eluting stent (SES) implantation for unselected patients with in-stent restenosis and to provide preliminary information about the angiographic outcome for lesion subgroups and for different in-stent restenosis patterns.

DESIGN

Prospective, single centre registry.

SETTING

Tertiary referral centre.

PATIENTS

44 consecutive patients (53 lesions) without previous brachytherapy who were treated with SES for in-stent restenosis were evaluated. Routine angiographic follow up was obtained at six months and the incidence of major adverse cardiovascular events was evaluated.

RESULTS

At baseline, 42% of the lesions were focal, 21% diffuse, 26% proliferative, and 11% total occlusions. Small vessel size (reference diameter < or = 2.5 mm) was present in 49%, long lesions (> 20 mm) in 30%, treatment of bypass grafts in 13%, and bifurcation stenting in 18%. At follow up, post-SES restenosis was observed in 14.6%. No restenosis was observed in focal lesions. For more complex lesions, restenosis rates ranged from 20-25%. At the one year follow up, the incidence of death was 0, myocardial infarction 4.7% (n = 2), and target lesion revascularisation 16.3% (n = 7). The target lesion was revascularised because of restenosis in 11.6% (n = 5).

CONCLUSIONS

Routine SES implantation is highly effective for focal in-stent restenosis and appears to be a promising strategy for more complex patterns of restenosis.

Late incomplete lesion coverage following Cypher stent deployment for diffuse right coronary artery stenosis

The availability of the only drug eluting stent currently approved in the USA has been limited, so that operators often resort to the deployment of multiple undersized stents and post-stenting high pressure inflations with larger balloons to achieve optimal lesion coverage and stent expansion. A case of stent fracture following percutaneous coronary intervention in which this strategy was used is reported.