Entrapment of a Drug-Eluting Stent in Left Anterior Descending Artery and Left Main Artery (Full Title Below)

Entrapment of a Drug-Eluting Stent in Left Anterior Descending Artery and Left Main Artery Leading to a Life-Threatening Complication

ABSTRACT:Sudden stent loss after stent entrapment in a tight coronary lesion is an unexpected and devastating complication. Proper and timely steps without pressing the panic button are necessary. We describe a case of entrapment of a sirolimus-eluting stent into the left coronary artery system. Although the entrapped drug-eluting stent was successfully removed using a snare device, excessive guide manipulation under this life-threatening condition led to extensive left main and left circumflex artery dissection. This was immediately rescued by direct stenting to the left main and circumflex arteries. The usage of snare device in this bail-out situation was successful, safe and prevented emergency bypass surgery. J INVASIVE CARDIOL 2010;22:E90–E92 Key words: stent loss, stent entrapment, snare, dissection Contemporary percutaneous coronary intervention (PCI) using drug-eluting stents (DES) and the newer equipment continue to revolutionize the revascularization procedure, making it more physician- and patient-friendly. Although the incidence of stent loss (SL) during PCI has decreased due to the remarkable improvement of the stent delivery system with the advent of machine-crimped, premounted DES, unexpected stent entrapment and subsequent SL during the DES positioning into a complex lesion can still occur, albeit rarely. ¹ Once intracoronary embolization of the stent due to SL occurs during the procedure, this devastating complication can lead to coronary thrombosis, myocardial infarction, cardiogenic shock and even patient death on the table. ² Several urgent retrieval methods for this type of bail-out situation have been described. We describe the use of a snare device to successfully retrieve a stent that was entrapped in the proximal left anterior descending (LAD) artery. This technique can be a rapid, effective and elegant solution for this type of urgent situation. Case Report. A 76-year-old female with typical exertional chest pain was admitted electively for coronary angiography (CAG). The proximal-to-mid LAD at the first diagonal branch (D1) bifurcation level showed diffuse severe, irregular concentric stenosis, the D1 proximal segment including the ostium showed mild discrete stenosis and the proximal left circumflex artery (LCX) showed mild diffuse concentric stenosis (Figure 1A). Aspirin 200 mg, clopidogrel 600 mg were preloaded orally, as well as low-molecular-weight heparin (LMWH) enoxaparin 1 mg/kg subcutaneously twice daily before and after percutaneous coronary intervention (PCI). During PCI, a reduced dose of unfractionated heparin (UFH, 50 unit/kg) was given and the target activated clotting time (ACT) was 200–300 seconds. Via left femoral artery access, a 7 Fr, JL4 guiding catheter was engaged in the left coronary artery. A Balanced Middle Weight (BMW, Guidant Corp., Santa Clara, California) 0.014 inch guidewire was inserted into the LAD and a Whisper wire (Abbott Vascular, Abbott Park, Illinois) into the D1. Sequential predilatation was performed using a 2.0 x 20 mm Sprinter balloon (Medtronic, Inc., Minneapolis, Minnesota) at 6 atm and a 2.5 x 20 mm Maestro balloon (Abbott) at 10 atm on the proximal LAD lesion. we attempted to deploy a 2.5 x 33 mm Cypher sirolimus-eluting stent (Cordis Corp., Miami Lakes, Florida) across the lesion, but failed to achieve an ideal implantation position. While attempting to pull the stent out from the mid-LAD culprit lesion for further predilatation and/or debulking, the stent balloon and the 0.014 inch coronary guidewire suddenly came out, and only the unexpanded, entrapped stent itself remained in the proximal left main (LM) artery to the mid-LAD (Figure 1B). Immediate contrast dye injection showed drastically reduced distal LAD flow (thrombolysis in myocardial infarction [TIMI] 1). The patient became hypotensive with chest pain, and urgent surgical a backup call was initiated. Immediate rewiring into the lumen of unexpanded entrapped stent was successfully performed using a 0.014 inch guidewire (BMW) (Figure 1B). An Amplatz Microsnare gooseneck loop snare (Microvena Corp., White Bear Lake, Minnesota) was successfully used to retrieve the entrapped stent (Figure 1C). During this urgent bail-out situation, repetitive forceful guiding catheter manipulation and contrast dye injection produced a very large intimal dissection from the LM os to the proximal LAD and LCX with acute thrombosis (Figure 1D). After starting intravenous unfractionated heparin (24,000 units/24 hours) and intracoronary nitroglycerin, direct stenting with a 2.75 x 23 mm Cypher in the proximal LCX at 10 atm and a 4.0 x 12 mm Driver stent (Medtronic) in the LM artery was successfully performed at 12 atm (Figure 2A). The post-PCI intravascular ultrasound (IVUS) study using the Clearview Ultra IVUS system (Boston Scientific Corp., Natick, Massachusets) showed that the stent struts were accurately positioned between the distal LM at the LM bifurcation site and the LM os. Although the LM os was accurately covered by the stent, there was still focal significant intimal dissection extending to the aortic wall and to the proximal LAD and LCX beyond the implanted stent strut (Figure 2B). Furthermore, the mid-LAD culprit lesion was predilated with 2.0 x 20 mm Sprinter balloon at 8 atm, and then a 2.75 x 24 mm Taxus paclitaxel-eluting stent (Boston Scientific) stent was successfully deployed at 10 atm with an adequate final angiographic result (Figure 2C). Discussion. In this era of DES technology, the incidence of stent loss following stent entrapment has definitely decreased from 3.4% to 0.32%.1 This could be possibly due to machine-crimping as opposed to manual crimping of the stents. The improved stent retention force, that is the force required to pull the balloon from an undeployed stent, may explain the reduction in the incidence of SL. ³ With manual crimping, there is no circumferential uniformity compared to machine-crimping, thus the chances of SL are higher. In our case, the patient’s proximal vessel tortuosity and calcification may have caused the SL, especially considering that this was a long lesion. Other possible factors include the use of a JL4 guiding catheter, which has relatively limited guiding back-up support, use of a relatively weaker 0.014 inch wire, incomplete predilatation, use of a Cypher stent, which is relatively stiffer than other DES, and the use of a long stent. Successful stenting may have been possible with the use of stiffer wires such as the Pilot series (Abbott Vascular) or the Grandslam (Asahi Intecc, Tokyo, Japan), more aggressive predilatation, noncompliant larger balloons, and more flexible DES such as the Taxus stent and newer-generation DES (Endeavor zotarolimus-eluting stent, Medtronic; Xience everolimus-eluting stent, Abbott Vascular). In our case, post-retrieval dilatation was performed using only a 2.0 mm balloon and a long stent was used. However, it must be noted that in tight, tortuous, calcified and long lesions, more aggressive dilatation with a 2.5 mm noncompliant balloon, use of a stiffer guidewire with a buddy-wire technique and a shorter stent are possible options. SL most often occurs during pullback of the stent balloon assembly, especially when it cannot cross the lesion and is tightly entrapped. There are several methods described for retrieval such as snares, twisted guidewires, a multipurpose basket, a variety of forceps, crushing of the stent to the vessel wall, and even a distal protection device. ^4–6 We decided to use the loop snare and were able to successfully retrieve it. If the stent is not retrieved from the coronary artery, it can lead to serious coronary events such as coronary thrombosis and subsequent myocardial infarctionl or will require urgent open-heart surgery for removal. In our case, there was transient acute thrombosis distal to the entrapped stent and significant reversible diffuse spasm in the proximal diagonal branch. After successful retrieval of the entrapped stent with intravenous unfractionated heparin (UFH) and intracoronary nitroglycerin infusion, the intracoronary thrombosis and spasm disappeared, suggesting the importance of concomitant medical therapy. In this situation, glycoprotein IIb/IIIa receptor blocker administration could be a good option . Catheter-induced iatrogenic coronary artery dissection is a rare event, but can be a life-threatening complication. ⁷ Specifically, most of the reported catheter-induced coronary artery dissection cases involve the RCA. ⁸ Catheter-induced LM dissection with aortic root extension is even RARER. In our case, while attempting mid-LAD revascularization, the guiding catheter was forcefully and excessively manipulated, and the contrast dye was forcefully injected repeatedly. This could be a possible cause for the extensive intimal dissection. We conclude that the successful retrieval of the stent using the loop snare and rescue direct stenting to cover the huge intimal dissection appears to be safe, feasible and effective in this urgent bail-out situation. Great caution should be exercised to avoid SL following entrapment during stent positioning in a complex coronary anatomy. Excessive catheter manipulation and careless contrast dye injection should be avoided in order to limit this kind of iatrogenic disaster.

References

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_________________________________________________________________ From the From the Cardiovascular Center, Korea University Guro Hospital, Seoul, Korea. The authors report no conflicts of interest regarding the content herein. Manuscript submitted September 10, 2009, provisional acceptance given October 15, 2009, final version accepted October 22, 2009. Address for correspondence: Seung-Woon Rha, MD, PhD, Cardiovascular Center, Korea University Guro Hospital, 80, Guro-dong, Guro-gu, Seoul, 152-703, Korea. E-mail: swrha617@yahoo.co.kr