In patients undergoing emergency percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI), several thrombectomy and distal protection devices have been evaluated in order to either remove thrombus and plaque components at the occlusion site, or trap embolic materials, respectively. The effect of thrombectomy devices on myocardial perfusion have been conflicting: some studies^1–3 show a benefit, while others suggest a detrimental effect on myocardial salvage resulting in increased infarct size.⁴ Specifically, unrestricted use of distal embolic protection devices did not result in improved microvascular flow or reperfusion success, reduced infarct size or increased eventfree survival,^5,6 suggesting that only selected patients might benefit from this strategy.

We report a case of successful extraction of a massive coronary thrombus by the unusual use of the Spider^™ filter device (ev3 Inc., Plymouth, Minnesota).

Case Report. A 78-year-old male with typical cardiovascular risk factors was admitted to the emergency room for anterior acute STEMI. Transradial emergency coronary angiography showed a proximal, subtotal left anterior descending artery (LAD) stenosis with thrombolysis in myocardial infarction (TIMI) 1 flow (Figure 1A). After crossing the lesion with a floppy wire, a large thrombus, extending from the proximal stenosis up to a few millimeters before the trifurcation of the LAD with the diagonal branch, became evident (Figure 1B). According to our practice, intracoronary abciximab was administered, and multiple manual thrombus aspirations were performed using the Diver^™ catheter (Invatec, Roncadelle, Italy). However, despite macroscopic thrombus removal (Figure 2), partial thrombus dislodgment occurred, with abrupt closure of the LAD at the level of the trifurcation (Figure 1C). Additional thrombus aspirations and balloon dilatations of both the LAD and diagonal branches only resulted in restoration of normal flow in both branches of the diagonal, whereas the LAD remained persistently occluded (Figure 1D). Thus, we decided to capture the thrombus by using a filter device. A 4 mm Spider filter was positioned in the occluded LAD immediately beyond the thrombus (Figure 1E). We gently retrieved the filter in fully-open configuration in the proximal LAD (Figure 1F), and then inserted it, partially closed, into the guiding catheter which was deeply engaged in the proximal LAD. Complete removal of the thrombotic material and TIMI 3 flow were achieved, with no significant residual stenosis at the occlusion site (Figure 1G). Macroscopic evaluation of the filter revealed a large red thrombus both inside the filter and surrounding its external surface (Figure 3). Final stenting of the proximal LAD stenosis with a 5.0 x 16 mm bare-metal stent was performed, producing a good angiographic result (Figure 1F).

Discussion. This is the first case, to our knowledge, of the use of a Spider filter to trap and remove coronary thrombus, refractory to both aspiration and dilatation, in the setting of primary PCI. Indeed, in this case, after failing to remove the thrombus by manual aspiration and fragmenting it by multiple balloon inflations, we intentionally used the Spider filter, in a “Fogarty-like” fashion, to extract the thrombus from the occluded LAD.

There are 3 previous cases that describe a similar approach, 2 of which were outside the setting of emergency PCI,⁷ and 1 in the setting of primary PCI.8 In all of these cases, a FilterWire^™ (Boston Scientific, Natick, Massachusetts) was used, and the culprit artery was the right coronary artery. In the first 2 cases, the filter was placed inside the coronary artery before stent implantation, with the aim of capturing the embolized thrombus, but since the thrombus remained attached to the vessel wall distal to the stent, the filter was used in the open configuration to ensnare the thrombus. In the other case,⁸ the filter was advanced distal to the occlusion, and was then deployed and removed in the open configuration, with entrapment of the clot.

Our case owns some relevant differences compared to the previously reported cases: (1) the Spider filter was chosen due to its low-profile delivery system,⁹ which, unlike the Filter- Wire, allowed us to use a regular wire to pass alongside the thrombus and to position the filter beyond it, minimizing the risk of dislodgment; (2) the conformation of the Spider filter,although potentially more traumatic for the arterial wall than the FilterWire, facilitated the entrapment of the thrombus within the nitinol mesh of the basket; (3) the presence of thrombus in the LAD carried the risk of embolization into the circumflex artery while retrieving the filter. Thus, we removed the filter, only partially closed by the retrieval system, into theguiding catheter that had to be selectively and deeply engaged in the proximal LAD.

We cannot underestimate the potential risks of the procedure described in this case. Indeed, the retrieval maneuver, especially in the case of calcified lesions or tortuosity, might have caused dissection of the left main artery or entrapment of the filter itself inside the coronary artery. Placing a “buddy wire” in the LAD before retrieving the filter would have rendered this a safer procedure.

In conclusion, a “Fogarty-like” use of filter distal protection devices can safely remove large thrombi from occluded coronary arteries, although it must be considered a last-resort rescue technique.