Strategies for Retrieving Embolized Coronary Stents During Percutaneous Coronary Intervention: A Methodological Exploration By Sydney Millis Pavankumar Venkatesan A thesis submitted to the School of Radiologic Sciences in collaboration with a research agenda team In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN RADIOLOGIC SCIENCES (MSRS) WEBER STATE UNIVERSITY Ogden, Utah December 15, 2023 2 THE WEBER STATE UNIVERSITY GRADUATE SCHOOL SUPERVISORY COMMITTEE APPROVAL of a thesis submitted by Sydney Millis Pavankumar Venkatesan This thesis has been read by each member of the following supervisory committee and by majority vote found to be satisfactory. ______________________________ Dr. Tanya Nolan, EdD Chair, School of Radiologic Sciences ______________________________ Chris Steelman, MS Director of MSRS Cardiac Specialist ______________________________ Dr. Laurie Coburn, EdD Director of MSRS RA ______________________________ Dr. Robert Walker, PhD Director of MSRS 3 THE WEBER STATE UNIVERSITY GRADUATE SCHOOL RESEARCH AGENDA STUDENT APPROVAL of a thesis submitted by Sydney Millis Pavankumar Venkatesan This thesis has been read by each member of the student research agenda committee and by majority vote found to be satisfactory. Date ______________________ ____________________________________ Sydney Millis Jan 5, 2024 ____________________________________ Pavankumar Venkatesan ______________________ Table of Contents Chapter 1: Introduction……………………………………………………………………… 1 Background………………………………………………………………………………….1 Statement of the Problem……………………………………………………………………3 Purpose of the Study ………………………………………………………………………...3 Research Questions…………………………………………………………………………. 4 Nature of the Study…………………………………………………………………………. 4 Significance of the Study…………………………………………………………………….4 Definition of Key Terms……………………………………………………………………..5 Summary………………………… ………………………………………………………….5 Chapter 2: Clinical Background………………………………………………………………6 Introduction…………………………………………………………………………………..6 Etiology……………………………………………………………………………………….6 Epidemiology…………………………………………………………………………………7 Pathophysiology………………………………………………………………………………7 History and Physical………………………………………………………………………….8 Evaluation…………………………………………………………………………………….8 Treatment / Management Options……………………………………………… ……………9 Complications………………………………………………………………………………..10 Summary…………………………………………………………………………………….10 Chapter 3: Literature Reviews………………………………………………………………..11 Documentation………………………………………………………………………………11 General Literature Review…………………………………………………………………..11 Causes and Mechanisms of Embolization……………………………………………………12 Methods for Retrieving Coronary Stents……………………………………………………13 Summary ……………………………………………………………………………………13 Case Study Literature Review…………………………………………………… …………14 Use of Gooseneck Snare for retrieval of coronary stent…………………………………….14 Retrieval of coronary stents using an EN snare……………………………………………15 Low-profile balloon catheters for retrieval of coronary stents……………………………….15 Twisted wire technique……………………………………………………………………….16 Use of myocardial biopsy forceps or Alligator forceps……………………………………….16 Crushing Technique……………………………………………………………………………17 Summary………………………………………………………………………………………18 Chapter 4: Research Method…………………………………………………………………... 19 Research Methods and Design(s)…………………………………………………………….19 Population…………………………………………………………………………………… 20 Data Collection, Processing, and Analysis………………………………………………….. 21 Assumptions…………………………………………………………………………………. 21 Limitations…………………………………………………………………………………… 22 Delimitations………………………………………………………………………………… 22 Summary…………………………………………………………………………………….. 22 Chapter 5: Findings………………………………………………………………………….. 23 Results……………………………………………………………………………………….. 23 Evaluation of Findings………………………………………………………………………. 25 Summary………………………………………………………………………………………26 Chapter 6: Implications, Recommendations, and Conclusions………………………………. 27 Implications………………………………………………………………………………….. 27 Recommendations…………………………………………………………………………… 28 Conclusions………………………………………………………………………………….. 29 Abstract Over the years, the occurrence of coronary stent embolization has significantly decreased making it a rarity. However, it still occurs and research must be conducted to determine the optimal retrieval and treatment techniques. This qualitative study includes a systematic review of 12 case studies exploring the various methods of retrieving embolized or lost stents. Out of the 12 case studies, 10 were male and 2 were female. The majority of participants were over the age of 50 with most of them undergoing elective PCI. The most common and successful retrieval technique used was the snare technique, followed by the crushing technique, which has been emerging. Stent loss was most common in the right coronary artery, followed by the circumflex artery. Additional investigation should be conducted to examine the relative efficacy of different methods, which could result in the creation of standardized processes or standards for particular situations. Quality assurance methods should also be considered to evaluate stent retrieval processes and help achieve optimal patient outcomes. This can involve regular assessments of cases, results, and adherence to set procedures to guarantee that best practices are always followed. Because stent embolization is a rare occurrence with new stent technology, stent retrieval techniques are not often well studied or discussed. Physicians may lack awareness of the wide range of techniques available. Further education and awareness on the various options for embolized stent retrieval and treatment are imperative for positive patient outcomes. 1 Chapter 1: Introduction The most significant development in the percutaneous treatment of coronary artery disease (CAD) has been the use of coronary stents. Dislodging the stent from the balloon catheter before deployment and subsequent dislocation of the stent into the circulatory system are rare but potentially major complications of using stents. It could cause infarction and embolize in the coronary circulation, necessitating immediate coronary artery bypass grafting (CABG). Alternatively, it could result in mortality, peripheral embolization, or embolic cerebrovascular events.1,2 Understanding efficient methods for stent retrieval is essential for reducing these risks because stent loss and embolization during percutaneous angioplasty can have catastrophic effects on patients. This study could increase understanding and awareness of the problem and help find solutions to enhance present procedures, ultimately resulting in more positive patient outcomes. Background In the field of interventional cardiology, there is a lot of interest in the analysis of various techniques for coronary stent retrieval after stent loss and embolization in percutaneous angioplasty. CAD is generally treated using percutaneous coronary procedures, which have a high success rate but also carry a risk of complications such as stent loss and embolization. These issues may result in coronary blockage, perforation, or dissection, which could be extremely detrimental to patients.3 Even though the occurrence of stent embolization and loss has decreased over the years due to improvements in stent technology, these complications still arise. 2 To improve patient outcomes and lower the hazards connected with percutaneous angioplasty, effective stent retrieval, and management techniques are crucial. Stent retrieval methods have included the use of retrieval devices, balloon catheters, and aspiration methods, among others.4 However, there is disagreement over the best strategy for stent retrieval, thus more research is required to determine the best course of action. The importance of this subject stems from its potential to enhance patient outcomes and lower the risks associated with percutaneous angioplasty. This study seeks to provide a better understanding of the problem and offer solutions that can improve existing procedures by analyzing the various approaches for stent retrieval and management during stent loss and embolization. In the end, this could help improve patient outcomes and develop more efficient methods for stent retrieval. Incidence of Stent Loss and embolization Over the Years 3 Statement of the Problem This study addresses concerns with acute coronary stent loss and embolization after percutaneous coronary intervention (PCI) that could potentially result in acute myocardial infarction, increased mortality, and complications. Although there are currently methods for managing and recovering stents in these circumstances, it is not apparent which methods are most effective in reducing the risks associated with these problems. This uncertainty presents challenges for clinicians and may have negative effects on patient outcomes. In order to find the ideal option and ultimately improve patient outcomes, it is important to study the many strategies used to recover or treat embolized and lost coronary stents.3 According to various studies, around 0.2% of patients who underwent PCI experienced stent loss, which led to significant adverse events like acute myocardial infarction and mortality.1,5 A large clinical practice gap exists because there is no recognized, systematic technique for stent retrieval during loss and embolization. Research is required to find efficient and practical ways to retrieve or treat lost stents during these circumstances. Purpose of the Study The purpose of this study is to compare the efficacy and safety of different stent removal and crushing techniques in various scenarios of stent dislodgement. This study includes peer-reviewed case studies of patients who underwent stent retrieval procedures. The data from these studies will be analyzed to identify the most effective technique for each scenario and to evaluate the associated risks and benefits. The primary objective of this study is to provide evidence-based recommendations for clinicians for the most 4 efficient ways to remove and treat embolized stents on optimal embolized stent removal and treatment. These guidelines aim to improve patient outcomes. Research Questions 1. What are the most common reasons for embolization and stent loss during percutaneous angioplasty? 2. What are the current techniques for retrieving coronary stents? 3. Which coronary artery is commonly involved with stent embolization? 4. Is stent loss more common in elective procedures or more urgent procedures, such as STEMIs? Nature of the Study The proposed study will employ a systematic review of case studies and a thorough analysis of various stent retrieval techniques and recent advancements to reduce stent dislodgement during stent loss and embolization during PCI. The primary dependent factors are in-hospital mortality and major adverse cardiovascular events, such as myocardial infarction, death, and target vessel revascularization, while the primary independent variables are stent loss and embolization during PCI. Significance of the Study This study analyzes the different methods used for stent retrieval and management during stent loss and embolization which can result in complications such as coronary occlusion, perforation, or dissection during PCI.6 Understanding efficient methods for stent retrieval is essential for reducing these risks because stent loss and embolization during percutaneous angioplasty can have catastrophic effects for patients. This study will help 5 health care providers understand the problem and find solutions to enhance present procedures and ultimately result in improved patient outcomes. Definition of Key Terms Coronary artery disease (CAD): The formation of atherosclerotic plaque in the vessel lumen characterizes the common heart condition known as coronary artery disease. As a result, the myocardium's ability to receive oxygen is compromised by reduced blood flow.7 Percutaneous coronary intervention (PCI): A non-surgical, invasive procedure to relieve coronary artery narrowing or occlusion and enhance blood flow to the ischemic tissue. The most commonly used techniques for accomplishing PCI are ballooning the narrow segment or implanting a stent to keep the artery open.8 Stent embolization: A very rare complication of percutaneous coronary intervention. When a stent inadvertently dislodges from the balloon, it is encountered. If untreated, the consequences range from bypass surgery to death.9 Summary The proposed study will examine the various techniques used in PCI for stent retrieval and management during stent loss and embolization. The study's objectives are to identify the most suitable stent removal method for each circumstance and find solutions for embolized stents. The research questions cover typical scenarios in which a stent can dislodge and the success rates of different stent retrieval techniques in each situation. The importance of the study lies in reducing the risks of stent loss and embolization during PCI, identifying how cases of stent loss and embolization have been reduced in the last few years and ultimately improving patient outcomes. The goal of the study is to 6 determine the best procedures for recovering a coronary stent if it is lost or becomes embolized while undergoing percutaneous angioplasty. Chapter 2: Clinical Background Introduction Coronary artery disease (CAD) occurs when a coronary artery becomes obstructed due to the accumulation of plaque. This causes a lack of blood flow and oxygen supply for perfusing the myocardium. CAD is the leading cause of death worldwide, and its prevalence is increasing over time. CAD remains one of the leading causes of death in the United States and worldwide.7 Etiology A variety of factors, including both modifiable and nonmodifiable risk factors, contribute to CAD. Age, gender, family history, and genetics are examples of unmodifiable factors that cannot be changed. Modifiable risk factors such as smoking, obesity, lipid levels, and psychosocial factors can be altered through lifestyle changes. However, smoking remains as the primary contributor of coronary artery disease.10 A significant modifiable risk factor for CAD is hypercholesterolemia. Elevated levels of high-density lipoprotein (HDL) have been shown to reduce the incidence of CAD, whereas elevated levels of low-density lipoprotein (LDL) increase the risk of CAD. Identifying and treating both unmodifiable and modifiable risk factors is crucial to preventing CAD.7 Epidemiology Both developed and developing nations are affected by CAD. In fact, CAD accounts for 32.7% of all cardiovascular diseases and 2.2% of the world's overall disease burden.7 In 7 the United States, CAD is responsible for one-third of all deaths in people over the age of 35, and nearly half of middle-aged men and one-third of middle-aged women are projected to have symptoms of CAD. Every year, more than 600,000 people experience a first myocardial infarction, and approximately 300,000 patients are diagnosed with recurrent CAD. Although the incidence of CAD has decreased over the years, non-ST elevation ACS (NSTE-ACS) has increased, with NSTE-ACS increasing from 19% in 1994 to 59% in 2006.11 Regardless of gender, it has been found that the prevalence of CAD rises with age.7 Pathophysiology The development of atherosclerotic plaque in arteries narrows the vessel lumen and reduces blood flow. When lipid-rich macrophages accumulate in the subendothelial space, they form fatty streaks and form plaques. Plaques may stabilize over time with fibrous caps and calcifications may occur or may enlarge over time. When the lesion becomes hemodynamically significant, symptoms of angina can occur. Acute coronary syndrome (ACS) manifesting as unstable angina, non-ST-segment elevation myocardial infarction (NSTEMI), or ST-segment elevation myocardial infarction (STEMI) can be caused by plaque rupture and can also lead to thrombosis. CAD can be classified as either ACS or stable ischemic heart disease.7 History and Physical When evaluating patients suspected of having coronary artery disease, a detailed physical examination and history-taking are essential. Family history of ischemic heart disease, 8 lifestyle factors like smoking and diet, and symptoms like chest pain with pain radiating to the neck, arm, back or jaw, and lower extremity edema should also be assessed. Additionally, evaluating for acute distress, jugular venous distention, and peripheral edema during the physical examination is also important.7 Evaluation Various diagnostic methods are available to assess CAD. An electrocardiogram is one of the basic diagnostic tests available. Both acute and long-term pathological conditions can be identified. An electrocardiogram is a viable option for diagnosing CAD, as it is easily available. Echocardiography is used as a non-invasive method to assess any regional wall motion abnormalities, valve sizes, and ventricular function. Exercise tests can be performed by physical or pharmacological methods which can evaluate suspected or equivalent angina pectoris. CAD can be detected by abnormal changes in an electrocardiogram during a stress test or by symptoms during testing. Although noninvasive, exercise stress testing may not be the best option for all patients due to physical challenges. A chest x-ray also provides clear information about the heart and lungs in case of pleural effusion, aneurysm, or hypertrophy. Blood tests can provide diagnostic data on heart enzymes such as troponin in cases of myocardial infarction. Cardiac catheterization is the most accurate method for assessing ischemic CAD, but it is invasive and carries some risks. This is associated with the use of contrast agents and can cause allergic reactions and kidney-related disorders in some patients with pre-existing disorders.7 9 Treatment/ Management options CAD can manifest as stable ischemic heart disease or ACS. Stable ischemic heart disease is characterized by stable angina, presenting with chest pain or tightness, aggravated by exercise or extreme emotions, and relieved by rest or nitroglycerin. Management includes both non-pharmacological and pharmacological methods. Non-pharmacological interventions include lifestyle changes such as smoking cessation, regular exercise, weight loss, and healthy eating. Pharmacological methods include medical therapy with low-dose aspirin, beta-blockers, nitroglycerin, and moderate-to-high-intensity statins. If that does not control symptoms, other drugs such as beta-blocker titrations, calcium channel blockers, and long-acting nitrates may be considered.12 Percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) may be required if medical therapy fails to relieve angina. ACS is a sudden onset of chest pain and tightness that needs immediate evaluation and treatment. Management depends on the type of ACS: ST-segment elevation myocardial infarction (STEMI) or non-ST-segment elevation ACS (NSTE-ACS). STEMI requires rescue PCI and thrombolytic therapy if PCI is not available. Management of NSTE-ACS includes anticoagulant therapy within 24 hours and early invasive therapy. Medications such as sublingual aspirin, nitrates, high-dose statins, beta-blockers, and P2Y12 inhibitors may also be administered.7 Complications Congestive heart failure, arrhythmias, and ACS are all complications of CAD. Congestive heart failure results from inadequate ventricular filling or ejection of blood to the systemic circulation.13 It can cause a wide range of symptoms including pulmonary edema and shortness of breath. Arrhythmias can cause palpitations, rapid heartbeat, 10 fatigue, or dizziness. ACS occurs when a coronary artery that supplies part of the heart muscle is completely blocked. Immediate cardiac catheterization is required.14 Mitral regurgitation, ventricular free wall rupture, and pericarditis are also other major complications of CAD.7 Summary CAD is caused by plaque buildup in the coronary arteries, reducing the supply of blood and oxygen to the heart. Risk factors such as age, smoking, obesity, and high cholesterol make it a leading cause of death worldwide. Diagnostic tests include electrocardiogram, echocardiography, stress tests, and blood tests, with cardiac catheterization being the most accurate but the most invasive. Treatment options include lifestyle changes, medications, and revascularization. Chapter 3: Literature Reviews Documentation Several search engines and databases, including PubMed, Google Scholar, Science Direct and the Weber State University Stewart Library were used to perform a study of literature on coronary stent retrieval during stent loss and embolization. Search words and phrases that were used include “coronary stent retrieval,” “stent loss,” “stent embolization,” “stent migration,” “stent removal,” “device embolization” and “foreign material retrieval.” The goal of this review of the literature is to assess the current research on coronary stent retrieval and treatment during stent embolization. It will include a comprehensive review of the existing literature and provide information on how the incidences of stent loss cases have decreased significantly. 11 General Literature Review Because they lessen artery recoil and the risk of restenosis after PCI, coronary stents have transformed the practice of interventional cardiology.15 The two most frequent side effects following stent implantation are in-stent restenosis and stent thrombosis.1 A less frequent but potentially fatal PCI problem called stent loss during attempted deployment has not received much attention. The procedure for extracting a stent from a coronary artery after it has been implanted or has slipped from the balloon during expansion is known as coronary stent retrieval. When the stent has moved from its original position or has embolized in a distal vessel, producing ischemia or infarction, stent retrieval is necessary. Coronary stent dislodgement occurs from 0.29% to 0.32% of PCI cases.1 Even though stent loss and embolization are uncommon, they can cause serious morbidity and mortality if not treated immediately.16 Severe coronary lesion characteristics such as angulated or tortuous vessels and calcified lesions, insufficient support of the guiding catheter, stent physical characteristics, and inadequate lesion preparation are the most likely factors linked to a higher risk of stent embolization. Different interventional techniques have been described for removing unexpanded stents from the coronary circulation, including the use of balloon catheters, loop snares, two twisted guide wires, or retrieval tools (biliary or myocardial biopsy forceps, multipurpose baskets). There could be instances in cases where each method or combination of these methods is attempted until the stent is retrieved. This analysis will focus on different methods used for the retrieval of coronary stents during stent loss or embolization. 12 Causes and Mechanisms of Embolization Stent design, deployment method, and patient characteristics are only a few of the variables that might lead to stent loss and embolization. If the stent is not sufficiently expanded or does not adhere to the artery wall sufficiently, stent migration/loss may occur. In some instances, anatomical issues like the vessel's tortuosity or calcification may be the cause of stent migration. Although stenting failure and embolization are relatively uncommon problems, they can have severe effects such as myocardial infarction, emergency coronary artery bypass graft surgery, stroke, and even death.17,18 Stent dislodgement is an uncommon but serious complication of PCI, and its incidence ranges from 0.29% to 0.32%.1 Methods for Retrieving Coronary Stents Stent retrieval aims to remove the stent from the coronary artery with the least amount of damage to the artery and its surroundings. The location, type, and clinical state of the patient all influence the method for stent retrieval. Snares, baskets, and forceps are just a few of the retrieving tools that are accessible. The most popular method for retrieving coronary stents are snare devices. They are made of a looped wire that is inserted into the stent and then tightly wound around it to enable controlled removal.18 Snares can occasionally be challenging to position, especially when the stent is located deeply within the vessel. Similar to snares, basket devices are deployed all the way around the stent. They are very helpful for recovering stents from coronary arteries that have moved to the distal location.19 The stent is intended to be physically grasped and removed from the coronary artery using forceps devices. They offer a great level of control over the stent during retrieval, making them especially helpful for stents that have embedded 13 themselves in the vessel wall.2 The small-balloon technique, which can only be employed if the guidewire position is preserved through the lost stent, is another commonly used retrieval method.12 Using this simple method, a small balloon is advanced through the detached stent, inflated distally, and retracted, causing the misplaced stent to be moved into the guiding catheter. Summary Stent dislodgement and embolization are rare occurrences during PCI, however, the methods for retrieving the lost stents must be well studied. There is little recent research that has been done on the most effective way to treat and retrieve embolized and lost stents due to the reduced number of incidences over the years. This study aims to synthesize current literature to find the optimal treatment for embolized stents which will help improve patient outcomes. Case Study Literature Review Use of Gooseneck Snare (Goose Neck Snare; Medtronic, Minneapolis, MN) for retrieval of coronary stent A flexible wire with a loop at the end that is used to catch and extract the stent normally makes up the gooseneck snare (see Appendix A). Compared to more invasive surgical procedures, using a gooseneck snare to retrieve a coronary stent is seen as a less invasive treatment that can lower the risk of problems.17 The Gooseneck snare has a 0.018-inch shaft diameter and is tipped with a closed wire loop 2 mm in diameter that is 90 degrees to the shaft axis. The wire within the 2.3F outer plastic catheter known as "the Wanderer" can be advanced or retracted to open or close the snare. The embolized stent's distal end is covered by the snare, which is then fastened tightly. The snare and the stent can then be 14 removed together.2 When a stent is dislodged, the snare is introduced via the guiding catheter into the site of capture and the snare is retracted, capturing the stent within the loop and removing it from the body. Several case studies20,21,22, have shown to be successful in retrieving the stent after using the Gooseneck snare. In some cases because the Gooseneck snare has only one loop, the use of both EN snare (Merit Medical Systems, South Jordan, UT) and Gooseneck snare together have facilitated retrieval of the stent which dislodged into the femoral artery.23 Retrieval of coronary stents using an EN snare (Merit Medical Systems, South Jordan, UT) Three interlaced loops are used in the EN Snare Endovascular Snare System's construction to help remove and control foreign items from inside the body (see Appendix B). Nitinol, which is extremely elastic, offers flexibility, kink resistance, and torque management. The EN Snare's rotating and expanding design allows for optimum coverage and recovery in a range of vessel sizes. The EN Snare loops have platinum strands inserted for optimum fluorescence viewing. In a case study published by Senior et al 24, the use of an EN snare in the right coronary artery helped operators retrieve the stent after attempting to recover it with a small balloon catheter through it. Since the EN snare comes with three interlaced loops there’s a higher chance of capturing the stent than through a single loop of nitinol (Gooseneck snare).25 Low-profile balloon catheters for retrieval of coronary stents Most low-profile angioplasty balloon catheters with a nominal size of 1.5 mm and a length of 20 mm are used to cross into the stent lumen. The catheters non-inflated balloon tips have an outside diameter of 0.576 mm (0.023 inches), which enables the retrieval 15 balloon to be advanced into the embolized stent on the guide wire. After being inflated to 1-2 atm to link the stent to the retrieval balloon, it is usually retracted into the guiding catheter.2 To use the small balloon catheters for retrieval, the stent lumen has to be partially expanded to be able to pass the catheter through the stent and inflate the balloon. Wire access must be maintained for the stent to be accessed with the balloon catheter. Twisted wire technique In this technique, the operator inserts two guidewires and twists them along the embolized stent to cause the stent to be entangled with the wires (see Appendix C). The operator then pulls the stent through the guide catheter after the wires attach to the stent. It is suggested to examine the distal flow during this process to assess the effectiveness of the twisted wire method since its loss suggests either failure or insufficient resolution. It is recommended that the operator should have prior training in this procedure to prevent coronary artery dissection. The patient in the case study had stenosis in the left anterior descending coronary artery and was being treated with angioplasty.9 The stent then embolized or migrated from the target vessel into the distal left circumflex artery during the procedure. Utilizing a radial approach and a twisting guide wire technique, the retrieval process was carried out.9 The migrated stent was captured and removed from the migration site using the twisting guide wire approach, which makes use of a guidewire with a pre-formed shape.9 Use of myocardial biopsy forceps or Alligator forceps Using retrieval tools such as myocardial biopsy forceps, alligator forceps, or its combination with the guiding catheter has been attempted during stent retrieval (see Appendix D). Some of the case studies even have a combination of the balloon catheter 16 and forceps to remove it from the femoral sheath.13,14 In this case study published by Eeckhout E et al 19, a 55-year-old man with angina underwent an elective proximal right coronary artery stenting procedure. The right coronary artery was catheterized after premedication and heparin administration, and stenosis was accessed with a balloon on a guidewire. The Wiktor 3.5mm stent was implanted, however, due to poor trackability, it extubated and became stuck in the ascending aorta. The stent was eventually extracted using a shortened guiding catheter with integrated retrieval forceps after unsuccessful attempts to retrieve it with the catheter. The right coronary artery was discovered to be blocked during the procedure and a second Wiktor stent was implanted. Crushing Technique An alternative strategy known as "stent crushing" is taken into consideration when conventional stent retrieval methods are unsuccessful or pose a significant risk to the patient. With this method, the stent is purposefully compressed against the vessel wall with another stent mounted onto a balloon. This method effectively embeds the stent within the vessel framework. The risk of the stent or embolic material dislodging and causing downstream blockages is significantly decreased by firmly anchoring the stent within the vessel wall. When traditional retrieval methods fail or present unacceptably high risks, this technique offers a workable solution. It is important to stress that stent crushing should only be used when other retrieval techniques are impractical or involve too many risks.26,27 In the case study presented by Abdelaziz A et al 28, a stent dislodges during coronary intervention in the left main (LM) coronary artery. Despite initial attempts using a snare, the crushing technique was employed to address the dislodged stent effectively. Two 17 stents were deployed in the LM-LAD and LCX arteries, with rewiring of the LAD using two wires to prevent further slippage. Proximal optimization was performed, resulting in the restoration of normal Thrombolysis in Myocardial Infarction (TIMI) III flow in the left coronary system. It was found that the stent crushing technique was the preferred approach for managing stent dislodgment during percutaneous coronary intervention involving the right coronary artery.23 However, multiple research studies have reported comparable outcomes between the stent crushing and culotte techniques when addressing dislodged stents in coronary artery bifurcation lesions.29 Summary The use of a gooseneck snare, an EN snare, low-profile balloon catheters, the twisted wire approach, myocardial biopsy, or alligator forceps are a few of the techniques that can be used to recover dislodged coronary stents. If other methods have failed, the stent can also be crushed against the vessel wall. The selection of a method is based on several variables, including the size and location of the dislodged stent, the operator's expertise and skill, and the availability of the necessary tools. Each method has advantages and disadvantages. The success rates of each technique have been documented in several case studies4, however, which technique is most appropriate in a given circumstance depends on the history and situation of the patient. Chapter 4: Research Method The study aims to address concerns with coronary stent loss and embolization after percutaneous coronary intervention (PCI). Using data from peer-reviewed case studies, the analysis compares the effectiveness and safety of several stent removal strategies in a wide range of stent dislodgement circumstances. The study aims to determine the most 18 efficient technique for each situation and analyze the associated risks and benefits to provide clinicians with evidence-based advice on the best stent removal approach which will have the potential to minimize complications and enhance patient outcomes. The study is critical for bridging a clinical practice gap and identifying workable strategies for recovering stents during embolization. The research questions focus on understanding the causes of embolization during percutaneous angioplasty, the techniques for retrieving coronary stents, their success rates, along the potential risks and complications associated with coronary stent retrieval. Specifically, the goal of this study is to determine the most common reasons for stent embolization and loss, the current methods for stent retrieval, and their efficacy in clinical practice. Additionally, the study aims to explore ways to avoid stent loss. Research Methods and Design(s) A search for peer-reviewed and published case studies on coronary stent embolization and stent retrieval was conducted in Google Scholar, PubMed, Science Direct, and Weber State University Stewart Library databases. The selected case studies bibliographies were manually searched for more pertinent research. Studies that documented the incidence of stent loss, associated retrieval methods, and clinical outcomes were included. A systematic review of case studies on coronary stent embolization and stent retrieval is the research design for this study using PRISMA guidelines. The process of discovering and examining case studies that provide information on the frequency of stent loss, associated retrieval techniques, and clinical outcomes was completed. The choice of this research design enables a thorough review of the information on stent loss, retrieval techniques, and clinical outcomes and aligns with the study's objectives. Case studies are helpful in 19 giving precise, in-depth information on particular cases that include clinical presentations, therapeutic modalities, and results. A thorough evaluation of several case studies can shed light on the prevalence of stent loss, the efficacy of retrieval techniques, and the overall clinical consequences related to stent loss. The frequency of stent retrieval techniques, age, sex, history of CAD, past history of myocardial infarction, target vessel, mechanisms of loss, clinical presentation, and treatment, including the use of retrieval devices/techniques, were among the data that were extracted. A systematic review offers a thorough and organized way to combine the evidence from case studies to evaluate stent loss prevalence, retrieval techniques, and clinical outcomes. A methodical approach helps to reduce bias and guarantee that all pertinent data is included, resulting in a more comprehensive grasp of the subject and highlighting potential topics for further research. Population The population in this study includes both males and females over the age of 30 who have undergone PCI with stent embolization or dislodgement as a complication. This particular population of study consists of individuals who have CAD. Twelve case studies from the years 2005 to 2023 are included within this study. The target vessel, the type of stents employed (bare metal vs. drug-eluting), the application of different retrieval methods, clinical results, and complications associated are all relevant aspects of the population. Data Collection, Processing, and Analysis The data collection process involves following PRISMA guidelines and extracting relevant variables, such as the stent retrieval techniques, age, sex, history of CAD, past history of myocardial infarction, target vessel, mechanisms of loss, clinical presentation, 20 and treatment, including the use of retrieval devices/techniques. The obtained information was entered into an Excel spreadsheet, reviewed for completeness and accuracy, and then processed for analysis. Assumptions Assumptions are made that the case studies chosen are typical of all patients who experience stent embolization and that the data obtained from these studies are reliable and comprehensive. These case studies were published in peer-reviewed journals after a stringent review procedure that was carried out by skilled medical professionals utilizing dependable diagnostic and therapeutic techniques. Because these case studies were published in such publications lend credibility to this study. The study's underlying premise is that a systematic review of case studies is the most effective approach to gaining insights into stent embolization, the effectiveness of retrieval methods, and the overall clinical implications of stent embolization. Primary qualitative research sources such as PRISMA have proven the use of case studies and systematic reviews as suitable research methodologies for assessing medical diseases and therapies and also offer support to this study.30 Limitations • The inclusion of older case studies in the research might have overlooked more recent advancements in stent retrieval techniques. • The study is limited to utilizing case studies that were published only in English. • The sample size of 12 case studies could not be representative of all stent embolization occurrences. 21 • The study's scope is confined to only utilizing data contained within peer-reviewed and published case studies, which might be missing some crucial factors that could have an impact on the efficiency and safety of stent removal methods. Delimitations • Only published case studies that have undergone a stringent peer review procedure are included in the study, guaranteeing the accuracy and authenticity of the information. • The study uses a systematic review method, which enables a comprehensive and wellorganized analysis of the available data. Summary The research methodologies and design utilized to examine the efficacy and safety of various stent retrieval techniques in situations of coronary stent embolization following PCI are described in this study. A systematic evaluation of case reports that detail the frequency of stent embolization, related retrieval techniques, and clinical outcomes was used as the research design. The study's fundamental assumptions are that case studies are representative and reliable and that a systematic review approach is the most effective way to evaluate the efficiency of retrieval techniques and the clinical outcomes of stent embolization. 22 Chapter 5: Findings The purpose of this study is to find the optimal retrieval and treatment techniques for embolized stents by reviewing 12 case studies. The retrieval devices include snares, baskets, forceps, and small balloons. Retrieval techniques include the twisted wire and stent crushing techniques. Results Participants: Out of the 12 case studies, 10 were male, and 2 were female. Age distribution among participants: 1 case was in the 30-40 age group. 1 case was in the 40-50 age group. 5 cases were in the 50-60 age group. 4 cases were in the 60-70 age group. 1 case was over 70 years old. Procedures: Out of the 12 cases, 3 were diagnosed with ST-elevation myocardial infarction (STEMI), and 9 underwent elective procedures. Despite STEMI being an urgent procedure, there were fewer reports of stent embolization compared to elective procedures, which we did not anticipate. Affected Vessels: Right coronary artery: 6 out of 12 cases. Left circumflex artery: 4 out of 12 cases, with 2 cases involving the left anterior descending artery. 23 1 case study involved a saphenous vein graft. 1 case study included the left main coronary artery. We found higher rates of stent embolization in the right coronary artery despite it being the less tortuous and complicated vessel to stent, which we did not anticipate. Retrieval Techniques: Various techniques were used for stent retrieval: Snare technique: 5 cases Crushing technique: 3 cases when the stent couldn't be retrieved Small balloon technique: 1 case Twisted wire technique: 1 case Indigenous snare technique: 1 case Multiple techniques were used in 1 case. Participants: Out of the 12 case studies, 10 were male, and 2 were female. Age distribution among participants: 1 case was in the 30-40 age group. 1 case was in the 40-50 age group. 5 cases were in the 50-60 age group. 4 cases were in the 60-70 age group. 1 case was over 70 years old. 24 Reasons for Stent Embolization: The most common reasons for stent embolization and loss include poor lesion preparation before stenting, deploying the proximal stent before the distal stent, and tortuous patient anatomy. Evaluation of Findings • Affected vessels: The right coronary artery is the most common site for stent dislodgement. The prevalence of embolization occurring in an artery that is typically easier to stent raises questions about if the right coronary artery receives the same amount of attention as other lesions in other arteries. • Gender Imbalance: The study demonstrates a gender imbalance, with a majority of participants being male. • Age Distribution: The age distribution highlights a concentration in the 50-70 age group. This demonstrates the need for special attention for patients in the 50-70year-old age group. • Procedures type: The prevalence of elective procedures over STEMI cases suggests a focus on elective interventions, influencing treatment approaches and patient outcomes. Speed, urgency, or pathology did not have any correlation to stent embolization, which we did not anticipate. • Retrieval Techniques: Diverse retrieval techniques are used, with the snare technique being the most common. 25 Summary The analysis of these results inspires more investigation and discussion in the study's later sections. It demands a thorough examination of the possible effects of sex disparity, the role of aging on patient outcomes, the type of procedure (STEMI or elective), and the impact of retrieval techniques on the safety and success of these procedures. Chapter 6: Implications, Recommendations, and Conclusions Even though stent embolization has lessened over the years with improvements in stent technology and design, it still occurs. Optimal stent retrieval techniques must be studied to help improve patient outcomes when stent embolization does occur. This study aims to find and review the most successful stent loss treatment and technique. This study does have limitations as the case studies that are included are only peer-reviewed and in English. The case studies included could not represent all of the stent embolization occurrences throughout the years. However, based on the 12 case studies in this review, we aim to answer the research questions, give recommendations, and form conclusions. Implications Future studies using a large patient population who had undergone stent retrieval after embolization may examine the relative efficacy of various retrieval methods and their influence on clinical outcomes. This might aid in the creation of standard guidelines for stent retrieval techniques. Despite the notable decline in the frequency of stent embolization, it is still essential for interventional cardiologists to be trained in stent retrieval procedures in case of emergencies as even suggested by 2023 ACC/AHA guidelines.31 The difficulty that medical personnel may encounter when these occurrences do occur is highlighted by their 26 rarity. Therefore, it is essential to make sure that physicians are ready for these rare but crucial instances. Even though the incidence is generally minimal, healthcare professionals must continue their education and skill development. This approach ensures that they are proficient and confident in addressing these challenging scenarios, contributing to enhanced patient safety and optimal outcomes when stent retrieval is required. Recommendations With the popularity of using the snare method to retrieve embolized stents, our recommendation would be to utilize this method first before employing another method due to its success rates. However, other unconventional methods such as the crushing technique should be considered in the treatment of lost coronary stents if other methods have failed. There are many factors to consider when choosing a retrieval technique. Each case is different, and each patient has unique anatomy which should be taken into consideration when making a decision on which method to employ. Because stent embolization is a rare occurrence with new stent technology, stent retrieval techniques are not often well studied or discussed. Physicians may lack awareness of the wide range of techniques available. Further education and awareness on the various options for embolized stent retrieval and treatment is imperative for positive patient outcomes. While the snare method is the most common technique, it may not be appropriate for every situation or patient. Cardiac catheterization laboratories should also be properly equipped with various stent retrieval devices besides snares, as other devices are underutilized in laboratories today. 27 Extra caution and care should be taken when working in the right coronary and circumflex arteries. We have found that stent embolization has occurred most frequently in these vessels. Stents should be well opposed to the vessel wall and be sized appropriately to prevent the stent from migrating. Additionally, distal lesions should be stented first before proximal lesions. Conclusions To conclude, there was no proven standard method for the retrieval and treatment of lost coronary stents from our research. Different techniques and devices can be used depending on the severity of the lesion, the experience of the operator and staff, and the patient’s anatomy. Every case is different, and each patient is unique. Interventional cardiologists and cardiac catheterization laboratory staff should receive thorough training and education on stent retrieval to effectively handle such situations when they occur. 28 Appendix A PCR. Snare technique in the event of wire loss: GooseNeck. Accessed November 20, 2023. https://www.pcronline.com/Cases-resources-images/Complications/Implantloss/Coronary-embolised-devices/Guidewire-loss/Additional-Links/Snare-techniqueGooseNeck 29 Appendix B EN Snare® Endovascular Snare System. Merit Medical. Accessed November 20, 2023. https://www.merit.com/peripheral-intervention/intervention/snares-accessories/en-snareendovascular-snare-system/ 30 Appendix C Colón-Arias F, Moronta-Franco M, Gutiérrez-Martínez A. Coronary stent embolization during percutaneous coronary intervention: Successful retrieval using twisting guide wire technique by radial approach. 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Circ Cardiovasc Interv. 2023;16(4). doi:10.1161/hcv.0000000000000088 Sydney and Pavankumar Thesis Interim Agreement Report Created: 2024-01-05 By: Cathy Wells (cathywells@weber.edu) Status: Out for Signature Transaction ID: CBJCHBCAABAAHTxTZOKefzki8t7p4bQWucv9eADU1kj5 2024-08-09 Agreement History Agreement history is the list of the events that have impacted the status of the agreement prior to the final signature. A final audit report will be generated when the agreement is complete. 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