Free Coronary Perforation after X-Sizer® Thrombectomy: Experience of Two Cases and Review of the Literature

The X-Sizer® (ev3, Inc., Plymouth, Minnesota) is a novel thrombectomy device that effectively removes intracoronary thrombus. Recent studies suggest that pre-treatment with the X-Sizer before percutaneous coronary intervention (PCI) in a thrombus-laden artery, such as in acute coronary syndrome, can prevent distal embolization, improve final epicardial flow and accelerate ST-segment recovery.^1,2 Coronary perforation is an uncommon, but potentially serious complication of PCI. There are two broad types of coronary perforation, contained and free perforations. Contained perforation can usually be treated by prolonged balloon inflation, reversal of anticoagulation and/or placement of a covered stent without significant sequelae. In contrast, free perforation can lead to cardiac tamponade and is associated with mortality and morbidity in a significant proportion of patients. Little data exist regarding the predictors, treatments and outcomes of coronary perforation due to the X-Sizer device. We present 2 such cases and a review of the literature of 2 other similar free coronary perforations due to the X-Sizer thrombectomy device. Case 1. A 68-year-old woman was admitted because of recent inferior myocardial infarction (MI) with right ventricular involvement. The patient was hemodynamically stable on admission and was submitted for PCI the next morning. Coronary angiography showed a normal left coronary artery system, but a complete occlusion of the ostial right coronary artery (RCA) (Figure 1A). Unfractionated heparin at 5,000 Units, together with bolus and intravenous infusion of abciximab were administered. After cannulation using an 8 French (Fr) Judkins Right 4 guiding catheter, the ostial RCA occlusion was crossed by a 0.014 inch PT ChoICE® hydrophilic floppy guidewire (Boston Scientific Corporation, Maple Grove, Minnesota) and pre-dilated with a 2.0 x 15 mm balloon. Antegrade TIMI 2 flow was established and there was evidence of a large thrombus burden at the angulated proximal RCA. A 2.0 mm X-Sizer was used for thrombectomy, but it failed to cross the angulation at the proximal RCA despite deep-seating the guiding catheter (Figure 1B). Nevertheless, post-thrombectomy contrast injection showed antegrade TIMI 3 flow, reduced thrombus burden, with no evidence of contrast extravasation. A 3.5 x 38 mm stent was deployed over the lesion at 12 atmospheres (atm). Post-stenting angiography showed a free coronary perforation at the proximal RCA angulation (Figure 1C) where the X-Sizer encountered resistance. The patient deteriorated rapidly and became hypotensive. Bedside echocardiography showed a small amount (~ 0.8 cm) of pericardial effusion. A 3.5 mm x 19 mm polytetrafluoroethylene-covered stent was deployed over the perforation site, and this successfully sealed the perforation (Figure 1D). However, the patient remained unstable and died of cardiogenic shock the day after the procedure. Case 2. A 45-year-old male patient was admitted due to acute anterior MI. The patient was submitted for primary PCI. Coronary angiography showed a total occlusion of the proximal left anterior descending artery (LAD) (Figure 2A), while the RCA was normal. Unfractionated heparin, at 3,000 Units, together with bolus and intravenous infusion of eptifibatide, were administered. After cannulation using an 8 XB LAD 3.5 mm guiding catheter, the proximal LAD occlusion was crossed by a 0.01 inch PT ChoICE hydrophilic floppy guidewire. Antegrade flow remained TIMI 0 after the guidewire advancement and a 2.0 mm X-Sizer was used for thrombectomy. Antegrade flow was TIMI 1 after one pass of the thrombectomy device, and there was a remaining thrombus at the proximal LAD after the angulation (Figure 2B). An attempt to cross the LAD angulation using the X-Sizer for further thrombectomy was unsuccessful (Figure 2C). During the process of exchanging the X-Sizer, the systolic blood pressure suddenly dropped to around 50 mmHg, and the patient developed convulsions. The guiding catheter was disengaged during the convulsion, and immediate re-evaluation of the coronary arteries was not possible. The patient deteriorated further and developed electromechanical dissociation. Bedside echocardiography confirmed cardiac tamponade. Pericardiocentesis was performed and 300 ml of blood was drained. A 7 Fr Judkins left 4 guiding catheter was engaged in the left coronary artery and contrast injection confirmed free perforation of the proximal LAD (Figure 2D) at the site of angulation where the X-Sizer encountered resistance. A 3.5 mm x 15 mm balloon was immediately positioned and inflated at the proximal LAD to seal the perforation. External cardiac massage was commenced and the patient was immediately sent for emergency coronary artery bypass graft surgery (CABG). A perforation of 2 mm size at the proximal LAD was detected intraoperatively and was repaired. Saphenous vein grafting to the mid-LAD, ramus intermediate and obtuse marginal arteries was performed. The operation was successful and the patient was discharged from the hospital 17 days after surgery. Discussion The X-Sizer is designed to remove thrombus from coronary and saphenous venous graft lesions. It has atherectomy and thrombectomy capabilities through the action of a helix cutter rotating at 2,100 rotations per minute (rpm), and a vacuum collection chamber for aspiration of excised atheroma, thrombus and debris. It proved effective in improving coronary flow and in reducing the incidence of distal embolization and no-reflow.^1,2 Despite the potential benefits of the X-Sizer device, published data on only a small series of patients are available to date, and knowledge about the limitations of the device is minimal. Complications, including distal embolization, dissection, guidewire fracture and coronary perforation have been reported.^3–7 Free coronary perforation is an uncommon but potentially serious complication of X-Sizer thrombectomy. A total of 183 cases of X-Sizer thrombectomy have been performed at our institution, with 3 cases of coronary perforation (free perforation, n = 2; contained perforation, n = 1), and a resulting incidence rate of 1.6%. This is similar to the incidence rates (0–6.3%) reported in other series (Table 1).^1–4,8–10 Apart from our 2 cases, we found 2 additional reported cases of free coronary perforation from X-Sizer use in the literature.^6,7 Together, the 4 cases are summarized in Table 2, which highlights several intriguing findings. The indication for all of the procedures was either acute or recent MI. This is expected, as almost all MIs are due to thrombotic occlusion of the coronary arteries, and the main purpose of the X-Sizer device is to reduce the thrombus burden. A hydrophilic floppy guidewire was used in 3 of the 4 cases (the guidewire used in the remaining case was not specified). Sanmartin et al.,⁶ in their report, suggested that advancement of the flat and rigid X-Sizer catheter over a floppy wire through the coronary artery has the potential to facilitate progression of the cutting surface against the vessel wall, resulting in free perforation of the artery. Our 2 cases are in agreement with this and support this claim. In 3 of the 4 cases, the culprit for the MI was an angulated lesion. A 2 mm device was used in all of the cases. These findings raise the concern that the 2 mm device is more bulky and less flexible, and therefore more likely to cause coronary perforation at an angulation. At least in our 2 cases, resistance was encountered during the advancement of the 2 mm X-Sizer over the angulation, and pushing force was used to try to overcome it. Based on these 4 cases of free coronary perforation, we advocate the use of a more flexible 1.5 mm X-Sizer whenever there is an angulation at the target lesion, especially when a glycoprotein (GP) IIb/IIIa inhibitor has been administered. Use of a stiff guidewire instead of a hydrophilic floppy guidewire should be considered, as it has been suggested that stiff guidewires have a lower risk of fracture during X-Sizer thrombectomy.5 Advancing the X-Sizer forcefully across an angulation whenever resistance is encountered should be discouraged. There was a delay in the occurrence of coronary perforation after thrombectomy with the X-Sizer. The contrast injections immediately following X-Sizer thrombectomy in our 2 cases showed no evidence of instant contrast extravasation. In the first case, free contrast extravasation was demonstrated only after coronary stent implantation. Yet, the stent was appropriately sized and the perforated site was precisely at the angulation where the X-Sizer encountered resistance. In the second case, the patient developed symptoms of cardiac tamponade during the process of exchanging the X-Sizer, and no other device therapies were used in between. Therefore, we believe that the X-Sizer was the device responsible for the perforation in both cases. Placement of a covered stent has been reported to be a safe and feasible therapeutic strategy for the treatment of coronary perforation.¹¹ Three of the 4 patients received a covered stent, which effectively sealed the perforation. In our second case, both the guiding catheter and the guidewire were disengaged during the convulsion and resuscitation of the patient. The patient remained critically ill and the operation theater was ready for emergency CABG by the time we re-cannulated the artery. We therefore decided to occlude the perforation with a balloon, instead of placing a covered stent, which requires more preparation time and accurate placement.¹¹ Our 2 reported cases of free coronary perforation occurred in relatively large vessels (reference vessel diameters of 3.84 mm and 3.42 mm, respectively), as the X-Sizer is indicated in vessels > 3 mm.1 It is conceivable that the risk would be higher in small vessels. Finally, the 2 cases were performed by 2 operators with 10 and 5 years of PCI experience, respectively. This suggests that free coronary perforation due to X-Sizer thrombectomy can occur with relatively experienced operators. Conclusion Free coronary perforation is a rare but potentially serious complication of X-Sizer thrombectomy. Particular attention should be paid in angulated lesions, especially when a GP IIb/IIIa inhibitor is administered. Usage of a 1.5 mm device and a stiff guidewire may be considered in patients who are deemed to be at high risk for coronary perforation. Acknowledgement. The authors wish to thank the Publication Support Unit at the National University Hospital for their assistance in the preparation of this manuscript. Email: leerch@hotmail.com

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