A Novel Use for a Distal Embolic Protection Device: Stent Retrieval

Stent embolization is an uncommon but potentially serious complication of percutaneous coronary intervention (PCI). The incidence of coronary stent embolization is 0.3–8.3% and varies with stent type, need for manual crimping, and clinical situation.^1–4 There are numerous case reports describing methods for retrieving embolized coronary stents. These methods include the use of angioplasty balloons and snares.^5–9 In some of these situations, the goal has been complete removal of the stent. In others, the goal has been simply to retrieve the stent from the coronary circulation in favor of release of the stent into the peripheral circulation. Despite these methods, the stent retrieval is unsuccessful in at least 30% of these cases and serious consequences may result.^3,4 Given the difficulty in utilizing snares and balloons for stent retrieval, we describe a new method of stent retrieval utilizing a distal embolic protection device. Case Report. A 61-year-old male with a history of coronary bypass grafting ten years prior to admission was referred for cardiac catheterization. The indication for cardiac catheterization was unstable angina. Angiography revealed a 90% stenosis in the ostium of the SVG to the obtuse marginal branch, as well as an 80% lesion in the distal portion of the graft (Figure 1A). Stenting with distal embolic protection was planned, utilizing a 7 Fr Amplatz guide and a Filterwire (Boston Scientific, Natick, Massachusetts). After positioning the Filterwire in the most distal portion of the vein graft (Figure 1B), an Express2 4.5 x 12 mm stent (Boston Scientific) was delivered to the distal graft, but the lesion could not be covered due to the Filterwire location. Thus, an attempt was made to withdraw the stent into the guide and we considered other options for distal SVG stenting. As the stent entered the Amplatz guide, it was stripped off the delivery balloon, leaving it free on the proximal portion of the Filterwire (Figure 1C). The stent could not be retrieved with an Amplatz Goose Neck^® Snare (ev3, Plymouth, Minnesota). A buddy wire was placed in order to attempt passage of the snare over the buddy wire or passage of a second balloon distal to the stent (with the hope that low pressure inflation of the distal balloon would allow the stent to be trapped proximal to the balloon and pulled back into the guide). Neither of these techniques were successful. The stent was retrieved using a novel technique (Figure 1D): The fully deployed filterwire was pulled into the guide with the stent trapped and crushed into the tip of the guide. While maintaining traction on the wire-guide combination, the entire guidewire-stent assemblywas removed intact via the femoral artery sheath. Subsequently, the graft lesions were wired without distal embolic protection and stents were placed proximally and distally without complications. Discussion. The largest stent embolization registry reported to date included 387 patients with 411 stent embolizations.⁴ The technical challenge afforded by stent embolization is emphasized in this study; successful stent retrieval was achieved in only 30% of the cohort, and mortality among patients with unsuccessfully retrieved stents was 17% versus 0.9% for those with successful stent retrieval. While other studies have had a higher success rate for retrieval of embolized stents,³ there is at least a minority of patients in whom embolized stents will truly be “lost” in the distal vasculature due to the inability of snare and balloon-based techniques to capture the embolized stent. Given the technical challenges and serious consequences associated with coronary stent embolization, new techniques to improve stent retrieval are of interest. We present here a novel method for retrieving a coronary stent utilizing a distal embolic protection device. The Filterwire distal embolic protection device is one of two FDA-approved techniques for improving saphenous vein graft stenting.¹⁰ The construction of this particular distal embolic protection device (basket retrieval) makes it theoretically not only a capture device for emboli, but for larger objects as well. In this particular case, it was utilized to capture a stent lost on the proximal wire. Note was made that this technique was only utilized after standard techniques failed (second wire with attempted distal balloon inflation, and attempted retrieval with a snare). Also, notably, retrieval of the fully expanded Filterwire basket through two severe vein graft lesions did not lead to acute disruption of the vein graft. Our case study is consistent with a prior report describing the similar utilization of distal balloon occlusion device for stent retrieval.¹¹ The current case study extends these observations to the utilization of a basket retrieval-type distal protection device. The incidence of stent embolization has clearly decreased since the era of manual crimping of coronary stents.^1,4 Nevertheless, the rare occurrence of this PCI-related complication can present a challenging technical situation for interventional cardiologists. Given the infrequency of embolization, interventional cardiologists may be expected to be less well trained in the use of snare techniques, making retrieval rates even lower than the 30–70% rates seen in prior studies.^3,4 The use of basket retrieval devices for stent embolization is an attractive option. The use of this option in other situations (i.e., when the stent is not free on the already deployed Filterwire) may be feasible; as lower-profile basket retrieval devices are developed, the ability to pass the embolized stent without pushing the free stent forward will determine the applicability of such an approach.

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