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Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome
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Heart, Lung and Circulation (2016) xx, 1–3 1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2016.09.008
BRIEF COMMUNICATION
Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome Muhammad [1_TD$IF]Asrar[3_TD$IF] ul Haq, [4_TD$IF]FRACP a,b*, Matthew Erickson, [6_TD$IF]789FRACP[5_TD$IF] a, James Rankin, [10_TD$IF]FRACP a, Alan Whelan, FRACP[1_TD$IF] a a
Department of Cardiology, Fiona Stanley Hospital, Perth, WA, Australia Department of Medicine, University of Melbourne, Melbourne, Vic, Australia
b
Received 3 April 2016; accepted 9 September 2016; online published-ahead-of-print xxx
The Bioresorbable Vascular Scaffold ([12_TD$IF]BVS, Abbott Vascular[13_TD$IF], [14_TD$IF]Santa Clara, Cal, USA) is an exciting advance in percutaneous coronary intervention providing a temporary drug eluting scaffold resorbed in two to five years. We present two cases of late scaffold thrombosis associated with strut fracture during the period of resorption, at 20 and 24 months following BVS implantation. We propose luminal migration of malapposed struts following strut fracture during resorption as a potential mechanism for late scaffold thrombosis and acute coronary syndrome. Keywords
Bioresorbable vascular scaffold Stent thrombosis Acute coronary syndrome
The Bioresorbable Vascular Scaffold (BVS, Abbott Vascular) is[2_TD$IF] an exciting advance in percutaneous coronary intervention providing a temporary drug eluting scaffold resorbed in two to five years [1]. Improved clinical outcomes including late lumen gain, preserved pulsatile characteristics of the vessel and a physiological vascular response to various stimuli, proposed once the BVS resorption is complete, in contrast to metal stents that provide a permanent rigid structure to mechanically restrain the vessel wall [2,3]. Comparisons with metallic stents suggest encouraging outcomes in selected patients and lesions sets [4] while we await further randomised data from broader patient populations. We present two cases of late scaffold thrombosis associated with strut fracture during the period of resorption, at 20 and 24 months following BVS implantation. We propose luminal
migration of malapposed struts following strut fracture during resorption as a potential mechanism for late scaffold thrombosis and acute coronary syndrome. Case 1: A 72-year-old man presented with an inferior ST-segment elevation myocardial infarction (STEMI). Coronary angiography showed a focal thrombotic mid right coronary artery lesion, within two overlapping BVS implanted 20 months prior for an inferior STEMI (3.5 x 28 minimally overlapped proximally with 3.5 x 18 mm, post-dilated with 3.75 non-compliant balloon at 20 atm). The thrombotic lesion was within the distal scaffold and beyond the site of overlap. The patient was on single antiplatelet therapy at presentation. Thrombus aspiration of the lesion was performed followed by optical coherence tomography (OCT; Video 1). There were uncovered and malapposed struts identified in the central lumen of the distal scaffold intimately associated
*Corresponding author at: Department of Cardiology, Fiona Stanley Hospital, 102-118 Murdoch Dr, Murdoch WA 6150, Australia. Tel.: +61 8 6152 2222, Email: [email protected] © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Asrar ul Haq M, et al. Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.09.008
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with in-scaffold red thrombus (Figure 1, panels A-C). No plaque rupture was identified. This is suggestive of thrombus formation associated with luminal migration of partially resorbed scaffold struts at a site of malapposition and incomplete endothelialisation. Acute mechanical disruption of the scaffold by the thrombus aspiration catheter cannot be excluded but seems unlikely. The entire scaffolded segment was treated with metallic drug-eluting stents (4.0 x 32 and 4.0 x 28 mm Promus Premier, Boston Scientific[15_TD$IF], Mascot, NSW,[16_TD$IF] Australia post dilated with 4.5 non-compliant balloon at 18 atm). Excellent apposition was confirmed with OCT. Case 2: A 36-year-old man presented with an acute coronary syndrome associated with transient ST-segment elevation in the anterior ECG leads. Coronary angiography showed a hazy, mid left anterior descending artery lesion, at the site of a single BVS implanted two years prior (3.0 x 18 mm, post dilated with 3.25 non-compliant balloon at 18 atm). Optical coherence tomography of the lesion (Video 2) revealed partially resorbed scaffold struts appropriate for the ‘‘resorption phase’’, neointimal hyperplasia in the distal scaffold segment, and areas of neoatherosclerosis (Figure 1, panel E). Uncovered and malapposed struts were identified in the proximal segment with overlapping struts associated with in-scaffold red thrombus (Figure 1, panel F). No plaque
rupture was identified. The scaffold was successfully embedded in the arterial wall with a metallic drug-eluting stent (3.0 x 24 mm Promus Premier, post dilated with 3.5 noncompliant balloon at 16 atm).
Discussion The mechanism of stent thrombosis is often complex and multifactorial. The most striking feature of the two cases of late scaffold thrombosis presented here is the finding of malapposed and poorly endothelialised struts within the lumen associated with thrombus at 20 months and 2 years respectively. No OCT or IVUS imaging had been performed at the initial implantation leaving us to speculate whether the late malappostion was due to undersizing of scaffolds at implantation or early / late malapposition (positive remodelling) in the period following implatation. The association with a side branch in the first case may be another mechanism for strut malapposition. We propose that as resorption of BVS progresses, struts which are unrestrained by re-endothelialisation or neointima formation, may lose their structural integrity and collapse into the lumen, disrupting laminar flow and increasing the risk of in-situ thrombus formation.
Figure 1 Bioresorbable vascular scaffold associated acute coronary syndrome (A) Angiography in case 1, showing a mid right coronary artery thrombotic lesion at the site of previous overlapping bioresorbable vascular scaffolds (o=overlap). B-C represent their respective panels showing serial OCT frames suggestive of scaffold struts in the lumen not attached to the vessel wall (arrows) covered with extensive red thrombus (T), and a malapposed strut (M). (D) Angiography in case 2 showing mid LAD hazy lesion at the site of previous bioabsorbable vascular scaffold, letters E-F represent their respective panels. (E) OCT showing partially resorbed scaffold struts covered by neointimal layer with areas of neoatherosclerosis (N). (F) OCT showing overlapping strut (arrow) and red thrombus (T). Please cite this article in press as: Asrar ul Haq M, et al. Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.09.008
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Late strut fracture within a partially resorbed BVS
This raises an important question of whether this device may be more susceptible to intermediate-late failure in the context of the scaffold’s architectural degradation. This may increase the risk of late stent thrombosis in a malapposed scaffold as compared to a metallic stent that retains its mechanical strength. A ‘‘resorption fracture’’ of BVS therefore, when not fully endothelialised and incorporated into the vessel wall by a covering tissue layer, may result in dislodgment of the scaffold fragments in the lumen and cause ACS. Excellent scaffold-to-vessel wall apposition of the entire scaffold to promote endothelialisation and embedding the scaffold into the vessel wall may avoid this complication. Longer term dual antiplatelet therapy may be of benefit however cannot be recommended routinely with the current level of evidence. We would encourage the strategy of post dilating the scaffold meticulously and a low threshold for intracoronary imaging. These cases further highlight the importance of minimising early and late malapposition by correct sizing, optimal postdilatation, and possibly avoiding large side-branches. These strategies will likely help achieve the improved late clinical outcomes proposed with this technology.
Funding Sources Nil
Disclosures None
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.hlc. 2016.09.008.
References [1] Onuma Y, Serruys PW, Perkins LE, Okamura T, Gonzalo N, Garcia-Garcia HM, et al. Intracoronary optical coherence tomography and histology at 1 month and 2, 3, and 4 years after implantation of everolimus-eluting bioresorbable vascular scaffolds in a porcine coronary artery model: an attempt to decipher the human optical coherence tomography images in the ABSORB trial. Circulation 2010;122(22):2288–300. [2] Serruys PW, Ormiston JA, Onuma Y, Regar E, Gonzalo N, Garcia-Garcia HM, et al. A bioabsorbable everolimus-eluting coronary stent system (ABSORB): 2-year outcomes and results from multiple imaging methods. Lancet 2009;373(9667):897–910. [3] Serruys PW, Onuma Y, Dudek D, Smits PC, Koolen J, Chevalier B, et al. Evaluation of the second generation of a bioresorbable everolimus-eluting vascular scaffold for the treatment of de novo coronary artery stenosis: 12-month clinical and imaging outcomes. J Am Coll Cardiol 2011;58 (15):1578–88. [4] Ellis SG, Kereiakes DJ, Metzger DC, Caputo RP, Rizik DG, Teirstein PS, et al. Investigators AI. Everolimus-Eluting Bioresorbable Scaffolds for Coronary Artery Disease. N Engl J Med 2015;373(20):1905–15.
Please cite this article in press as: Asrar ul Haq M, et al. Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.09.008
Heart, Lung and Circulation (2016) xx, 1–3 1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2016.09.008
BRIEF COMMUNICATION
Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome Muhammad [1_TD$IF]Asrar[3_TD$IF] ul Haq, [4_TD$IF]FRACP a,b*, Matthew Erickson, [6_TD$IF]789FRACP[5_TD$IF] a, James Rankin, [10_TD$IF]FRACP a, Alan Whelan, FRACP[1_TD$IF] a a
Department of Cardiology, Fiona Stanley Hospital, Perth, WA, Australia Department of Medicine, University of Melbourne, Melbourne, Vic, Australia
b
Received 3 April 2016; accepted 9 September 2016; online published-ahead-of-print xxx
The Bioresorbable Vascular Scaffold ([12_TD$IF]BVS, Abbott Vascular[13_TD$IF], [14_TD$IF]Santa Clara, Cal, USA) is an exciting advance in percutaneous coronary intervention providing a temporary drug eluting scaffold resorbed in two to five years. We present two cases of late scaffold thrombosis associated with strut fracture during the period of resorption, at 20 and 24 months following BVS implantation. We propose luminal migration of malapposed struts following strut fracture during resorption as a potential mechanism for late scaffold thrombosis and acute coronary syndrome. Keywords
Bioresorbable vascular scaffold Stent thrombosis Acute coronary syndrome
The Bioresorbable Vascular Scaffold (BVS, Abbott Vascular) is[2_TD$IF] an exciting advance in percutaneous coronary intervention providing a temporary drug eluting scaffold resorbed in two to five years [1]. Improved clinical outcomes including late lumen gain, preserved pulsatile characteristics of the vessel and a physiological vascular response to various stimuli, proposed once the BVS resorption is complete, in contrast to metal stents that provide a permanent rigid structure to mechanically restrain the vessel wall [2,3]. Comparisons with metallic stents suggest encouraging outcomes in selected patients and lesions sets [4] while we await further randomised data from broader patient populations. We present two cases of late scaffold thrombosis associated with strut fracture during the period of resorption, at 20 and 24 months following BVS implantation. We propose luminal
migration of malapposed struts following strut fracture during resorption as a potential mechanism for late scaffold thrombosis and acute coronary syndrome. Case 1: A 72-year-old man presented with an inferior ST-segment elevation myocardial infarction (STEMI). Coronary angiography showed a focal thrombotic mid right coronary artery lesion, within two overlapping BVS implanted 20 months prior for an inferior STEMI (3.5 x 28 minimally overlapped proximally with 3.5 x 18 mm, post-dilated with 3.75 non-compliant balloon at 20 atm). The thrombotic lesion was within the distal scaffold and beyond the site of overlap. The patient was on single antiplatelet therapy at presentation. Thrombus aspiration of the lesion was performed followed by optical coherence tomography (OCT; Video 1). There were uncovered and malapposed struts identified in the central lumen of the distal scaffold intimately associated
*Corresponding author at: Department of Cardiology, Fiona Stanley Hospital, 102-118 Murdoch Dr, Murdoch WA 6150, Australia. Tel.: +61 8 6152 2222, Email: [email protected] © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: Asrar ul Haq M, et al. Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.09.008
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with in-scaffold red thrombus (Figure 1, panels A-C). No plaque rupture was identified. This is suggestive of thrombus formation associated with luminal migration of partially resorbed scaffold struts at a site of malapposition and incomplete endothelialisation. Acute mechanical disruption of the scaffold by the thrombus aspiration catheter cannot be excluded but seems unlikely. The entire scaffolded segment was treated with metallic drug-eluting stents (4.0 x 32 and 4.0 x 28 mm Promus Premier, Boston Scientific[15_TD$IF], Mascot, NSW,[16_TD$IF] Australia post dilated with 4.5 non-compliant balloon at 18 atm). Excellent apposition was confirmed with OCT. Case 2: A 36-year-old man presented with an acute coronary syndrome associated with transient ST-segment elevation in the anterior ECG leads. Coronary angiography showed a hazy, mid left anterior descending artery lesion, at the site of a single BVS implanted two years prior (3.0 x 18 mm, post dilated with 3.25 non-compliant balloon at 18 atm). Optical coherence tomography of the lesion (Video 2) revealed partially resorbed scaffold struts appropriate for the ‘‘resorption phase’’, neointimal hyperplasia in the distal scaffold segment, and areas of neoatherosclerosis (Figure 1, panel E). Uncovered and malapposed struts were identified in the proximal segment with overlapping struts associated with in-scaffold red thrombus (Figure 1, panel F). No plaque
rupture was identified. The scaffold was successfully embedded in the arterial wall with a metallic drug-eluting stent (3.0 x 24 mm Promus Premier, post dilated with 3.5 noncompliant balloon at 16 atm).
Discussion The mechanism of stent thrombosis is often complex and multifactorial. The most striking feature of the two cases of late scaffold thrombosis presented here is the finding of malapposed and poorly endothelialised struts within the lumen associated with thrombus at 20 months and 2 years respectively. No OCT or IVUS imaging had been performed at the initial implantation leaving us to speculate whether the late malappostion was due to undersizing of scaffolds at implantation or early / late malapposition (positive remodelling) in the period following implatation. The association with a side branch in the first case may be another mechanism for strut malapposition. We propose that as resorption of BVS progresses, struts which are unrestrained by re-endothelialisation or neointima formation, may lose their structural integrity and collapse into the lumen, disrupting laminar flow and increasing the risk of in-situ thrombus formation.
Figure 1 Bioresorbable vascular scaffold associated acute coronary syndrome (A) Angiography in case 1, showing a mid right coronary artery thrombotic lesion at the site of previous overlapping bioresorbable vascular scaffolds (o=overlap). B-C represent their respective panels showing serial OCT frames suggestive of scaffold struts in the lumen not attached to the vessel wall (arrows) covered with extensive red thrombus (T), and a malapposed strut (M). (D) Angiography in case 2 showing mid LAD hazy lesion at the site of previous bioabsorbable vascular scaffold, letters E-F represent their respective panels. (E) OCT showing partially resorbed scaffold struts covered by neointimal layer with areas of neoatherosclerosis (N). (F) OCT showing overlapping strut (arrow) and red thrombus (T). Please cite this article in press as: Asrar ul Haq M, et al. Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.09.008
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Late strut fracture within a partially resorbed BVS
This raises an important question of whether this device may be more susceptible to intermediate-late failure in the context of the scaffold’s architectural degradation. This may increase the risk of late stent thrombosis in a malapposed scaffold as compared to a metallic stent that retains its mechanical strength. A ‘‘resorption fracture’’ of BVS therefore, when not fully endothelialised and incorporated into the vessel wall by a covering tissue layer, may result in dislodgment of the scaffold fragments in the lumen and cause ACS. Excellent scaffold-to-vessel wall apposition of the entire scaffold to promote endothelialisation and embedding the scaffold into the vessel wall may avoid this complication. Longer term dual antiplatelet therapy may be of benefit however cannot be recommended routinely with the current level of evidence. We would encourage the strategy of post dilating the scaffold meticulously and a low threshold for intracoronary imaging. These cases further highlight the importance of minimising early and late malapposition by correct sizing, optimal postdilatation, and possibly avoiding large side-branches. These strategies will likely help achieve the improved late clinical outcomes proposed with this technology.
Funding Sources Nil
Disclosures None
Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.hlc. 2016.09.008.
References [1] Onuma Y, Serruys PW, Perkins LE, Okamura T, Gonzalo N, Garcia-Garcia HM, et al. Intracoronary optical coherence tomography and histology at 1 month and 2, 3, and 4 years after implantation of everolimus-eluting bioresorbable vascular scaffolds in a porcine coronary artery model: an attempt to decipher the human optical coherence tomography images in the ABSORB trial. Circulation 2010;122(22):2288–300. [2] Serruys PW, Ormiston JA, Onuma Y, Regar E, Gonzalo N, Garcia-Garcia HM, et al. A bioabsorbable everolimus-eluting coronary stent system (ABSORB): 2-year outcomes and results from multiple imaging methods. Lancet 2009;373(9667):897–910. [3] Serruys PW, Onuma Y, Dudek D, Smits PC, Koolen J, Chevalier B, et al. Evaluation of the second generation of a bioresorbable everolimus-eluting vascular scaffold for the treatment of de novo coronary artery stenosis: 12-month clinical and imaging outcomes. J Am Coll Cardiol 2011;58 (15):1578–88. [4] Ellis SG, Kereiakes DJ, Metzger DC, Caputo RP, Rizik DG, Teirstein PS, et al. Investigators AI. Everolimus-Eluting Bioresorbable Scaffolds for Coronary Artery Disease. N Engl J Med 2015;373(20):1905–15.
Please cite this article in press as: Asrar ul Haq M, et al. Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome. Heart, Lung and Circulation (2016), http://dx.doi.org/10.1016/j.hlc.2016.09.008