One Stent Lost in Two Arteries

The use of stents during percutaneous coronary intervention is now increasingly common. Stent embolization into the systemic or coronary circulation before deployment is a rare but recognized complication of coronary stenting, with hazardous risk for the patient.^1–4 Potentially fatal consequences of intracoronary embolization of balloon-mounted stents include coronary thrombosis and subsequent myocardial infarction.^5,6 In the past, manual crimping of stents was associated with a significantly increased risk of stent disengagement and embolization. Although manually crimped stents are seldom used, the problem of stent embolization has not completely been eliminated.³ Furthermore, many of the currently available stents are poorly visible on fluoroscopy before and after deployment. We report the case of a balloon-mounted stent that peeled from the balloon prior to deployment. Intravascular ultrasound (IVUS) performed during the procedure revealed that the stent never arrived at the intended deployment site, and had never expanded. It subsequently embolized to another coronary artery. Case Report. A 49-year-old male with no previous cardiac history was admitted to the Intensive Coronary Care Unit with an acute coronary syndrome. He was a heavy smoker, but had no other risk factors for coronary artery disease. Physical exam and electrocardiogram on admission were normal. Total creatine kinase was within normal limits, but troponin I level was 5.4 ng/ml (normal, 90% stenosis in the mid-left circumflex (LCX) artery (Figure 1A). The left anterior descending (LAD) and right coronary arteries had minor irregularities. A 6 French (Fr) XB 3 guiding catheter (Cordis Corporation, Miami Lakes, Florida) was used to engage the left main coronary artery. A 0.014´´ Galeo® FX2 guidewire (Biotronic GmbH & Co., Berlin, Germany) was advanced across the lesion without difficulty into the distal LCX. Initial IVUS with a 2.9 Fr IVUS JOVUS Avanar F/X imaging catheter (JOMED, Inc., Rancho Cordova, Calif.) revealed a calcified, eccentric plaque with a luminal cross-sectional area of 2.3 mm2 in the mid-portion of the LCX (Figure 2A). The LCX underwent direct stenting with a 2.5 x 9 mm Jostent-FlexMaster® stent (JOMED GmbH, Rangendingen, Germany). The balloon-mounted stent was delivered to the site and inflated at 16 atmospheres with good angiographic result (Figure 1B). The stent was not balloon-mounted at the time of the inflation and had peeled off the balloon inside the guiding catheter before it exited the guiding catheter. It never reached the intended site of deployment, which escaped our attention due to the low radio-opacity of the stent and the calcification of the artery. When the final result was evaluated by IVUS, the stent could not be seen at the lesion site. The treated artery segment was patent, with a cross-sectional area of 5.3 mm² (Figure 2B). The unexpanded stent was seen in the left main coronary artery (Figure 2C). At this stage, we realized that the stent had peeled off of the balloon inside the guiding catheter and had been advanced into the left main by the IVUS catheter, where it was visualized moving freely during IVUS pullback. Unfortunately, during the pullback operation, the guidewire was pulled into the guiding catheter, losing its position in the LCX. A coronary angiogram showed that the unexpanded stent had embolized to the mid-portion of the LAD without interference to coronary blood flow (Figure 1C). The patient was stable during the procedure, without chest pain. The same guidewire was used to cross the unexpanded stent, which was easily retrieved from the LAD with a 4.0 mm gooseneck snare (Microsnare®, Microvena Corporation, White Bear Lake, Minnesota) (Figure 3). A new, 2.5 x 13 mm Multi-Link Pixel® stent (Guidant Corporation, Temecula, California) was successfully deployed at the lesion site in the LCX without any further complications and with good angiographic result. During the procedure, the patient was treated with 5,000 U unfractionated heparin in addition to aspirin and intracoronary nitroglycerine 200 µg prior to each IVUS run. The post-procedural course was uneventful and the patient was discharged the following day on dual antiplatelet therapy with clopidogrel and aspirin. Discussion. Although the majority of currently used stents are factory-mounted systems, the risk of stent embolization has not been completely eliminated. Stent dislodgement from the delivery system most often occurs when the stent-balloon assembly is pulled back into the guiding catheter, or when the target lesion cannot be reached or cannot be passed due to unfavorable anatomy.^7,8 Stent dislodgement from the balloon was more frequent when stents were manually crimped onto the balloon, and although the incidence has significantly declined with the advent of new and improved factory balloon-mounted stents, it has not been completely eliminated. While the importance of radio-opacity for fluoroscopic visibility of the stents cannot be overemphasized, it still remains a fact that many of the modern available balloon-mounted stents have poor radio-opacity. In our patient, the stent had probably detached inside the guiding catheter and had failed to reach the intended site of deployment. It was only after we performed IVUS analysis that we realized that the stent had never reached the designated site, had not been deployed and had never been expanded. The IVUS catheter carried the stent from the guiding catheter into the coronary tree, where it became visible, moving freely during IVUS pullback. Different percutaneous retrieval techniques have been described to retrieve embolized stents from the coronary system and the peripheral circulation, including low-profile angioplasty balloon catheters, gooseneck snares, myocardial biopsy forceps, multipurpose baskets and the use of two twisted guidewires.^3,9,10 Other less optimal options include compressing the stent against the vessel wall with another stent and emergency coronary bypass surgery. In a recent review by Eggebrecht et al.,³ manual crimping of the stent was associated with a significantly higher rate of dislodgement compared to factory-mounted stents and in all cases during retraction of the balloon-stent assembly into the guiding catheter due to failure to reach the lesion site. A low-profile balloon-catheter was the method of choice for retrieving embolized stents, with a high success rate. In conclusion, this report details a rare case of stent dislodgement from the balloon inside the guiding catheter and embolization to a different artery. Due to the poor radio-opacity of the stent, only IVUS performance revealed that the stent had never reached the lesion site and had never been expanded. Better crimping of these stents and improved radio-opacity for easy visualization may prevent the occurrence of this rare but potentially hazardous complication.