Unmasking a naked left atrial appendage closure device: A case of a silent embolic threat Simon Schiettekatte, MD, Jens Czapla, MD, Jan Nijs, MD, Mark La Meir, MD, PhD From the Department of Cardiac Surgery of UZ Brussel, Brussels, Belgium. Patients with atrial fibrillation (AF) have a higher risk for thromboembolic events, for which oral anticoagulation is the first choice of therapy. For patients in whom anticoagulation is contraindicated, new therapeutic approaches are needed. Recent studies have shown the noninferiority of percutaneous closure of the left atrial appendage (LAA) compared to oral anticoagulation. Therefore, these devices can be a potential alternative therapy for preventing thromboembolic complications in patients with AF.1–3 However, with intracardiac devices the amount of foreign material can cause thrombus formation. Here we describe a case of intraoperative discovery of a thrombus on an Amplatzer cardiac plug. The thrombus was not visible during peroperative transesophageal echocardiography.
Case report A 65-year-old man was referred to our facility in November 2012. The patient had a left ventricular ejection fraction of 35% due to significant 3-vessel disease indicating the need for coronary artery bypass grafting (CABG). He had a history of AF since 1998 and longstanding persistent AF since 2010. He had undergone 4 electrical cardioversions without success. Because of a cerebrovascular malformation he received only aspirin, although he had a CHADS-VASC score of 3. In April 2011, percutaneous closure of the LAA with an 18-mm Amplatzer plug was performed, after which he received a combination of clopidogrel and aspirin for 1 month and only aspirin thereafter. Before the cardiac procedure (CABG and Cox maze), embolization of cerebrovascular malformations combined with radiotherapy was performed. After the pericardium was opened, we observed that the LAA was involuted and the percutaneous closing device was clearly palpable from the epicardial side. After electrical KEYWORDS Atrial fibrillation; Left atrial appendage; Percutaneous closing device ABBREVIATIONS AF ¼ atrial fibrillation; CABG ¼ coronary artery bypass grafting; LAA ¼ left atrial appendage (Heart Rhythm 2014;11:2314–2315) Dr. La Meir is a consultant for AtriCure. Address reprint requests and correspondence: Dr. Mark La Meir, Department of Cardiac Surgery of UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium. E-mail address: mark. [email protected].
1547-5271/$-see front matter B 2014 Heart Rhythm Society. All rights reserved.
cardioversion, entrance and exit block of the LAA was checked with a Max3 Pen (AtriCure, West Chester, OH) using the ORLab system (AtriCure) to determine whether the LAA still could play a role as a trigger or substrate for AF. No entrance and exit block was measured. Extracorporeal circulation was started and the aorta clamped. The right and left pulmonary veins were isolated with a bipolar clamp (AtriCure). The left atrium was opened via the Waterstone groove. While inspecting the closing device, we observed a small thrombus measuring 6 2.4 mm adherent to the lower border of the Amplatzer, an area of incomplete endothelialization (Figure 1) even after 1.5 years. Preoperative transthoracic echocardiography and peroperative transesophageal echocardiography had shown correct device positioning, no peri-device flow, and no device-related thrombus. The thrombus was removed and the Cox maze procedure continued, followed by CABG. Removal of the device was not attempted because of strong adherence of the device to the orifice of the LAA. Follow-up at 1 month showed sinus rhythm. At 7 months, 24-hour Holter monitoring confirmed sinus rhythm without any episodes of arrhythmia.
Discussion AF is the most common cardiac arrhythmia, causing 15% to 20% of all ischemic strokes.4 The use of oral anticoagulation therapy to reduce systemic embolization is well established. However, maintaining the optimal therapeutic level is difficult in approximately 44% of patients, especially in older patients because of multiple drug and food interactions.5 More invasive solutions to prevent stroke in individuals with AF would be preferable in this patient population. It is assumed that 90% of clinically apparent embolisms in patients with nonrheumatic AF originate from the LAA.6 Previous studies have indicated that LAA obliteration could play an important role in preventing stroke in patients with nonrheumatic AF.6 Several therapeutic options for LAA closure are available. The least invasive consists of percutaneous transcatheter delivery of an LAA occlusion device. Currently 2 devices are widely used: the WATCHMAN LAA system and the Amplatzer cardiac plug. Both devices have proven to reduce hemorrhagic stroke risk. All-cause stroke and all-cause mortality outcomes were not inferior to those of warfarin http://dx.doi.org/10.1016/j.hrthm.2014.10.015
Schiettekatte et al
LAA Closure Device as Source of Thrombus
2315 in preventing ischemic strokes.14 However, long-term safety and efficacy results are still lacking. Endocardial or epicardial closure of the LAA might be an alternative therapy for stroke prevention in patients with AF who are at high risk for systemic embolization and have contraindications for warfarin therapy. A potential risk with percutaneous closure devices is the possibility of incomplete endothelialization. This could partially explain the remaining stroke rate in these patients.
Figure 1 Incomplete endothelialization of an 18-mm Amplatzer plug in the left atrial appendage and thrombus.
therapy.2,3 However, blood clots still may develop on these devices, as noted on echocardiography, necessitating warfarin therapy.7,8 The ASAP trial (ASA Plavix Feasibility Study with Watchman Left Atrial Appendage Closure Technology) suggests 6 months of a thienopyridine antiplatelet agent (clopidogrel or ticlopidine) and lifelong aspirin after implantation of a WATCHMAN device in patients with contraindications for warfarin therapy as an alternative.9 This case demonstrates that incomplete endothelialization of the device could be responsible for thromboembolic events. Another potential complication of percutaneous closing devices is incomplete occlusion of the LAA or migration. The relationship of incomplete occlusion with a higher risk of thromboembolic events in these cases has not been proven.10 Epicardial LAA occlusion, a more invasive procedure, can be performed through a subxyphoid approach by thoracoscopy or thoracotomy. Because of the absence of endocardial material, the potential emboligenic risk of intracardiac foreign material can be avoided. This procedure can be achieved with a suture, a stapler, a clip, or the Lariat device. A second difference of epicardial LAA occlusion is electrical isolation of the LAA due to mechanical clamping or resection.11 Di Biase et al12 suggested that the LAA was the site of origin in 27% of redo AF cases. Excision, ligation, or clipping of the LAA could eliminate this mechanism of AF. A potential risk of epicardial occlusion is recanalization and a remaining appendage stump with possible remaining AF trigger sites. The rate of complete LAA occlusion is 87% by experienced surgeons.13 However, the absence of large randomized controlled trials comparing oral anticoagulant therapy with surgical LAA occlusion is a limitation. New oral anticoagulants such as dabigatran, rivaroxaban, and apixaban have proved to be safer alternatives to warfarin
References 1. Whitlock RP, Hanif H, Danter M. Nonpharmacologic approaches to stroke prevention in atrial fibrillation. Can J Cardiol 2013;29(Suppl):S79–S86. 2. Holmes DR, Reddy VY, Turi ZG, Doshi SK, Sievert H, Buchbinder M, Mullin CM, Sick P. PROTECT AF Investigators. Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial. Lancet 2009;374:534–542. 3. Cruz-Gonzalez I, Yan BP, Lam YY. Left atrial appendage exclusion: state-of-theart. Catheter Cardiovasc Interv 2010;75:806–813. 4. Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH, Hindricks G, Kirchhof P. ESC Committee for Practice Guidelines-CPG; Document Reviewers. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation—developed with the special contribution of the European Heart Rhythm Association. Europace 2012;14:1385–1413. 5. Bungard TJ, Ackman ML, Ho G, Tsuyuki RT. Adequacy of anticoagulation in patient with atrial fibrillation coming to a hospital. Pharmacotherapy 2000;20: 1060–1065. 6. Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996;61:755–759. 7. Cardona L, Ana G, Luísa B, Leal A, António F, Lídia S, Rui Cruz F. Thrombus formation on a left atrial appendage closure device. Circulation 2011;124: 1595–1596. 8. Cruz-Gonzalez I, Martín Moreiras J, García E. Thrombus formation after left atrial appendage exclusion using an Amplatzer cardiac plug device. Catheter Cardiovasc Interv 2011;78:970–973. 9. Reddy VY, Möbius-Winkler S, Miller MA, Neuzil P, Schuler G, Wiebe J, Sick P, Sievert H. Left atrial appendage closure with the Watchman device in patients with a contraindication for oral anticoagulation: the ASAP study (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology). J Am Coll Cardiol 2013;61:2551–2556. 10. Bai R, Horton RP, Di Biase L, et al. Intraprocedural and long-term incomplete occlusion of the left atrial appendage following placement of the WATCHMAN device: a single center experience. J Cardiovasc Electrophysiol 2012;23:455–461. 11. Starck CT, Steffel J, Emmert MY, Plass A, Mahapatra S, Falk V, Salzberg SP. Epicardial left atrial appendage clip occlusion also provides the electrical isolation of the left atrial appendage. Interact Cardiovasc Thorac Surg 2012;15: 416–418. 12. Di Biase L, Burkhardt JD, Mohanty P, et al. Left atrial appendage: an underrecognized trigger site of atrial fibrillation. Circulation 2010;122:109–118. 13. Healey JS, Crystal E, Lamy A, et al. Left Atrial Appendage Occlusion Study (LAAOS): results of a randomized controlled pilot study of left atrial appendage occlusion during coronary bypass surgery in patients at risk for stroke. Am Heart J 2005;150:288–293. 14. Miller CS, Grandi SM, Shimony A, Filion KB, Eisenberg MG. Meta-analysis of efficacy and safety of new oral anticoagulants (dabigatran, rivaroxaban, apixaban) versus warfarin in patients with atrial fibrillation. Am J Cardiol 2012;110:453–460.
Case report A 65-year-old man was referred to our facility in November 2012. The patient had a left ventricular ejection fraction of 35% due to significant 3-vessel disease indicating the need for coronary artery bypass grafting (CABG). He had a history of AF since 1998 and longstanding persistent AF since 2010. He had undergone 4 electrical cardioversions without success. Because of a cerebrovascular malformation he received only aspirin, although he had a CHADS-VASC score of 3. In April 2011, percutaneous closure of the LAA with an 18-mm Amplatzer plug was performed, after which he received a combination of clopidogrel and aspirin for 1 month and only aspirin thereafter. Before the cardiac procedure (CABG and Cox maze), embolization of cerebrovascular malformations combined with radiotherapy was performed. After the pericardium was opened, we observed that the LAA was involuted and the percutaneous closing device was clearly palpable from the epicardial side. After electrical KEYWORDS Atrial fibrillation; Left atrial appendage; Percutaneous closing device ABBREVIATIONS AF ¼ atrial fibrillation; CABG ¼ coronary artery bypass grafting; LAA ¼ left atrial appendage (Heart Rhythm 2014;11:2314–2315) Dr. La Meir is a consultant for AtriCure. Address reprint requests and correspondence: Dr. Mark La Meir, Department of Cardiac Surgery of UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium. E-mail address: mark. [email protected].
1547-5271/$-see front matter B 2014 Heart Rhythm Society. All rights reserved.
cardioversion, entrance and exit block of the LAA was checked with a Max3 Pen (AtriCure, West Chester, OH) using the ORLab system (AtriCure) to determine whether the LAA still could play a role as a trigger or substrate for AF. No entrance and exit block was measured. Extracorporeal circulation was started and the aorta clamped. The right and left pulmonary veins were isolated with a bipolar clamp (AtriCure). The left atrium was opened via the Waterstone groove. While inspecting the closing device, we observed a small thrombus measuring 6 2.4 mm adherent to the lower border of the Amplatzer, an area of incomplete endothelialization (Figure 1) even after 1.5 years. Preoperative transthoracic echocardiography and peroperative transesophageal echocardiography had shown correct device positioning, no peri-device flow, and no device-related thrombus. The thrombus was removed and the Cox maze procedure continued, followed by CABG. Removal of the device was not attempted because of strong adherence of the device to the orifice of the LAA. Follow-up at 1 month showed sinus rhythm. At 7 months, 24-hour Holter monitoring confirmed sinus rhythm without any episodes of arrhythmia.
Discussion AF is the most common cardiac arrhythmia, causing 15% to 20% of all ischemic strokes.4 The use of oral anticoagulation therapy to reduce systemic embolization is well established. However, maintaining the optimal therapeutic level is difficult in approximately 44% of patients, especially in older patients because of multiple drug and food interactions.5 More invasive solutions to prevent stroke in individuals with AF would be preferable in this patient population. It is assumed that 90% of clinically apparent embolisms in patients with nonrheumatic AF originate from the LAA.6 Previous studies have indicated that LAA obliteration could play an important role in preventing stroke in patients with nonrheumatic AF.6 Several therapeutic options for LAA closure are available. The least invasive consists of percutaneous transcatheter delivery of an LAA occlusion device. Currently 2 devices are widely used: the WATCHMAN LAA system and the Amplatzer cardiac plug. Both devices have proven to reduce hemorrhagic stroke risk. All-cause stroke and all-cause mortality outcomes were not inferior to those of warfarin http://dx.doi.org/10.1016/j.hrthm.2014.10.015
Schiettekatte et al
LAA Closure Device as Source of Thrombus
2315 in preventing ischemic strokes.14 However, long-term safety and efficacy results are still lacking. Endocardial or epicardial closure of the LAA might be an alternative therapy for stroke prevention in patients with AF who are at high risk for systemic embolization and have contraindications for warfarin therapy. A potential risk with percutaneous closure devices is the possibility of incomplete endothelialization. This could partially explain the remaining stroke rate in these patients.
Figure 1 Incomplete endothelialization of an 18-mm Amplatzer plug in the left atrial appendage and thrombus.
therapy.2,3 However, blood clots still may develop on these devices, as noted on echocardiography, necessitating warfarin therapy.7,8 The ASAP trial (ASA Plavix Feasibility Study with Watchman Left Atrial Appendage Closure Technology) suggests 6 months of a thienopyridine antiplatelet agent (clopidogrel or ticlopidine) and lifelong aspirin after implantation of a WATCHMAN device in patients with contraindications for warfarin therapy as an alternative.9 This case demonstrates that incomplete endothelialization of the device could be responsible for thromboembolic events. Another potential complication of percutaneous closing devices is incomplete occlusion of the LAA or migration. The relationship of incomplete occlusion with a higher risk of thromboembolic events in these cases has not been proven.10 Epicardial LAA occlusion, a more invasive procedure, can be performed through a subxyphoid approach by thoracoscopy or thoracotomy. Because of the absence of endocardial material, the potential emboligenic risk of intracardiac foreign material can be avoided. This procedure can be achieved with a suture, a stapler, a clip, or the Lariat device. A second difference of epicardial LAA occlusion is electrical isolation of the LAA due to mechanical clamping or resection.11 Di Biase et al12 suggested that the LAA was the site of origin in 27% of redo AF cases. Excision, ligation, or clipping of the LAA could eliminate this mechanism of AF. A potential risk of epicardial occlusion is recanalization and a remaining appendage stump with possible remaining AF trigger sites. The rate of complete LAA occlusion is 87% by experienced surgeons.13 However, the absence of large randomized controlled trials comparing oral anticoagulant therapy with surgical LAA occlusion is a limitation. New oral anticoagulants such as dabigatran, rivaroxaban, and apixaban have proved to be safer alternatives to warfarin
References 1. Whitlock RP, Hanif H, Danter M. Nonpharmacologic approaches to stroke prevention in atrial fibrillation. Can J Cardiol 2013;29(Suppl):S79–S86. 2. Holmes DR, Reddy VY, Turi ZG, Doshi SK, Sievert H, Buchbinder M, Mullin CM, Sick P. PROTECT AF Investigators. Percutaneous closure of the left atrial appendage versus warfarin therapy for prevention of stroke in patients with atrial fibrillation: a randomised non-inferiority trial. Lancet 2009;374:534–542. 3. Cruz-Gonzalez I, Yan BP, Lam YY. Left atrial appendage exclusion: state-of-theart. Catheter Cardiovasc Interv 2010;75:806–813. 4. Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH, Hindricks G, Kirchhof P. ESC Committee for Practice Guidelines-CPG; Document Reviewers. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation—developed with the special contribution of the European Heart Rhythm Association. Europace 2012;14:1385–1413. 5. Bungard TJ, Ackman ML, Ho G, Tsuyuki RT. Adequacy of anticoagulation in patient with atrial fibrillation coming to a hospital. Pharmacotherapy 2000;20: 1060–1065. 6. Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996;61:755–759. 7. Cardona L, Ana G, Luísa B, Leal A, António F, Lídia S, Rui Cruz F. Thrombus formation on a left atrial appendage closure device. Circulation 2011;124: 1595–1596. 8. Cruz-Gonzalez I, Martín Moreiras J, García E. Thrombus formation after left atrial appendage exclusion using an Amplatzer cardiac plug device. Catheter Cardiovasc Interv 2011;78:970–973. 9. Reddy VY, Möbius-Winkler S, Miller MA, Neuzil P, Schuler G, Wiebe J, Sick P, Sievert H. Left atrial appendage closure with the Watchman device in patients with a contraindication for oral anticoagulation: the ASAP study (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology). J Am Coll Cardiol 2013;61:2551–2556. 10. Bai R, Horton RP, Di Biase L, et al. Intraprocedural and long-term incomplete occlusion of the left atrial appendage following placement of the WATCHMAN device: a single center experience. J Cardiovasc Electrophysiol 2012;23:455–461. 11. Starck CT, Steffel J, Emmert MY, Plass A, Mahapatra S, Falk V, Salzberg SP. Epicardial left atrial appendage clip occlusion also provides the electrical isolation of the left atrial appendage. Interact Cardiovasc Thorac Surg 2012;15: 416–418. 12. Di Biase L, Burkhardt JD, Mohanty P, et al. Left atrial appendage: an underrecognized trigger site of atrial fibrillation. Circulation 2010;122:109–118. 13. Healey JS, Crystal E, Lamy A, et al. Left Atrial Appendage Occlusion Study (LAAOS): results of a randomized controlled pilot study of left atrial appendage occlusion during coronary bypass surgery in patients at risk for stroke. Am Heart J 2005;150:288–293. 14. Miller CS, Grandi SM, Shimony A, Filion KB, Eisenberg MG. Meta-analysis of efficacy and safety of new oral anticoagulants (dabigatran, rivaroxaban, apixaban) versus warfarin in patients with atrial fibrillation. Am J Cardiol 2012;110:453–460.
