Intraventricular Stent Loss After Interventional Treatment of a Coronary Dissection — A Case Report

ABSTRACT: The introduction of stents for treatment of coronary lesions markedly improved the outcome of coronary interventions. We report on a female patient who was admitted to our hospital with acute coronary syndrome and stent loss into the left ventricle during coronary intervention performed in another hospital. Stent loss is a very rare but potentially lethal complication of a stent implantation.

J INVASIVE CARDIOL 2011;23:E211–E213

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Case Report. A 75-year-old woman presented with a history of unstable angina and palpitations for 2 months. The patient reported progressive exertional dyspnea (NYHA II). Blood samples were taken and revealed normal myocardial marker levels. The ECG showed atrial fibrillation. The transthoracic echocardiography revealed normal left ventricular function (EF 64%) without wall motion abnormalities, but concentric hypertrophy, mitral valve insufficiency II° with a jet towards the septum, aortic valve sclerosis with central aortic insufficiency I°, and tricuspid valve insufficiency II–III° in combination with a pulmonary arterial pressure (PAP) of 43 mmHg plus central vein pressure. During the hospitalization, the patient developed recurrent non-sustained ventricular tachycardia. A diagnostic coronary angiography was performed, revealing coronary 1-vessel disease with a filiform proximal stenosis of the first diagonal branch of the LAD. After dilatation with a 2 x 9 mm balloon (Maverick Medical), a local dissection occurred. The guiding catheter and the stent, which by then had not been released from the balloon, dislocated by an unintended maneuver to the left ventricle.

The fluoroscopy revealed the location of the stent in projection of the left ventricular outflow tract (LVOT) near the aortic valve. The patient was free of symptoms and transferred to our hospital. At that time, angiography revealed a TIMI 3 flow of the left anterior descending (LAD) and a stable dissection of the ramus diagonalis 1 (RD1) without flow impairment (Figure 1). A coronary intervention was not performed.

On the same day, a nonenhanced computed tomography (CT) of the heart was performed; the lost stent was located in the left ventricle close to the basal anterior wall and presumably attached to the trabecular meshwork. Furthermore, a significant calcification of the mitral valve ring was found (Figure 2).

No surgical or interventional stent removal was performed because of the location and small size of the stent. Based on the clinical course, it was probable that the stent was affixed substantially into the trabecular meshwork and would be endothelialized. The patient was transferred back to the referring hospital and dismissed there without further complications. Three month later, a clinical and fluoroscopy follow-up was performed. The patient was free of symptoms and the stent was localized unchanged in the left ventricular trabecular meshwork.

Discussion. Intraventricular stent losses are a rare entity of interventional cardiology. The reported rate of embolization after attempted stent placement is between 0.32% and 8.4%.^1–3 Previously, stents without strong attachment to the underlying balloon were lost in 0.27–1.04% of cases.^1,2 Currently, the risk for a stent loss seems to be higher using drug-eluting stents than bare-metal stents.^4,5

Stent loss mostly occurs during the retraction of the stent/balloon complex into the catheter. This happens especially when the target lesion was not reached or passed. Risk factors for a stent loss are: 1) vessel tortuosity, 2) calcifications, and 3) passage through a previously implanted stent.¹ If the stent remains intravascular after loss, a stent-thrombosis with acute myocardial infarction may occur. Furthermore, cerebrovascular or peripheral embolization may occur with a potentially lethal course.^1,2 There are different techniques for extraction of unexpanded stents available: balloon-catheters, loop snares, two-twisted guide wires, or retrieval devices, such as myocardial biopsy forceps or multipurpose baskets.² Sometimes the usage of intravascular ultrasound (IVUS) is helpful when fluoroscopy does not reveal the location of the stent (20% of cases).⁶ In most cases, the stents can be extracted without surgical treatment. Alternatively, stents are being implanted or crushed into the wall of the coronary proximally to the attempted lesion.

In this case, the stent could be definitely localized using fluoroscopy and CT-imaging. Since the stent was affixed in the left ventricular trabecular meshwork and stable during the course of time, the risk of extraction of this stent would have been higher than the benefit of extraction. The treatment of intracoronary embolization of coronary stents has been described in many publications, whereas few data are available regarding the treatment of systemic embolization of coronary stents. Overall, the incidence of stent loss decreased over the years due to the increasing experience and improved devices used during PCI. The intracoronary stent loss is associated with increased in-hospital morbidity and mortality due to a pronounced incidence of acute or subacute stent-thrombosis and the need for urgent stent recovery by different interventional devices or, in some cases, by cardiac surgery. Peripheral stent embolization is associated with a relatively benign prognosis^7–9 and associated with a mostly asymptomatic long-term follow-up.^10,11 Moreover, some authors suggest that the removals of catheter remnants or stents are often unnecessary unless these remnants protrude into the ascending aorta, thus creating a pronounced risk of cerebral or peripheral embolization.⁷

There are no guidelines available today regarding the adequate antithrombotic and antiplatelet therapy for the prevention of ischemic events due to cerebral or peripheral embolization of a coronary stent in asymptomatic patients. However, the antithrombotic therapy in the context of intracoronary, cerebrovascular, or peripheral stent implantation has been investigated extensively in recent years. A case report regarding conservative treatment of an undeployed embolized intracoronary stent with antithrombotic and warfarin treatment demonstrated the feasibility of this triple-therapy in cases where an intracoronary stent recovery was not successful or not feasible. Because of the high mortality of an intracoronary stent-thrombosis, a triple therapy may outweigh the increased risk of bleeding in this setting. Regarding the optimal treatment of an asymptomatic non-intracoronary, but intracardial stable stent dislodgment, a conservative strategy using an antiplatelet therapy may be justified, since reliable data concerning the optimal antithrombotic therapy for the prophylaxis of ischemic events after peripheral coronary stent embolization are not available. Furthermore, since the peripheral embolization is associated with a benign prognosis and in most cases with an asymptomatic long-term follow-up, a pronounced antithrombotic therapy for this reason may lead to an increased bleeding risk without leading to a significant reduction of ischemic events and mortality. However, the intraventricular stent has a potentially thrombogenic surface and may facilitate the formation of an intraventricular thrombus. Hence, regular cardiac ultrasound controls may be useful for detecting intraventricular thrombi and to begin anticoagulation therapy or to adjust the concomitant antithrombotic medication.

References

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From the ¹Medizinische Klinik 2, Universität zu Lübeck and ²Klinik für Radiologie und Nuklearmedizin, Universität zu Lübeck, Germany.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. No authors reported conflicts regarding the content herein.
Manuscript submitted December 3, 2010, provisional acceptance given January 3, 2011, final version accepted January 19, 2011.
Address for correspondence: Dr. med. Alexander Joost, Medizinische Klinik 2, Universität zu Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany. Email: alexander.joost@uksh.de