Every great story seems to begin with a snake: a case report of a huge right atrial thrombus during transcatheter mitral valve repair

Every great story seems to begin with a snake: a case report of a huge right atrial thrombus during transcatheter mitral valve repair | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Every great story seems to begin with a snake: a case report of a huge right atrial thrombus during transcatheter mitral valve repair Antonio Totaro, Vincenzo Ienco, Chiara Galuccio, Vincenzo Sacra, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6234800/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Jul, 2025 Read the published version in The Egyptian Heart Journal → Version 1 posted 8 You are reading this latest preprint version Abstract Background: TEER has revolutionized mitral regurgitation treatment, addressing clinical burden in aging patients. However, thrombotic complications may still occur. Case presentation: An 83-year-old man with severe mitral regurgitation underwent a MitraClip procedure. A huge molding thrombus was observed during the procedure. To prevent cerebral embolization, two carotid filters were placed. The procedure was successfully ended, and mitral regurgitation was reduced. The patient was stable during the procedure, with no evidence of pulmonary or cerebral embolism. Conclusions: The case highlights the importance of close observation and multidisciplinary decision-making in managing acute thrombus during TEER. Further research is needed to establish the potential role of cerebral protection devices and the effect of anticoagulation procedures on thrombus formation. Mitraclip Atrial thrombus TEER Carotid filter Figures Figure 1 Figure 2 Figure 3 Background The MitraClip procedure is a groundbreaking therapeutic approach that has revolutionized the treatment of mitral regurgitation. Mitral regurgitation poses a significant clinical burden, particularly in the aging population, and the development of transcatheter interventions has brought this once exclusively surgical domain to the attention of interventional cardiologists [ 1 ]. Access to the left atrium and sufficient anticoagulation are necessary for the procedure. However, thrombotic complications can still happen even with heparin treatment and the right activated clotting time (ACT). Case presentation An 83-years-old man with a past medical history of atrial fibrillation, type 2 diabetes and chronic heart failure (HFrEF) in ischemic cardiopathy, treated with previous percutaneous coronary intervention, previous ICD implantation, presented with a history of worsening dyspnea associated with ankle swelling. Transthoracic and transesophageal echocardiogram (TEE) showed severe mitral regurgitation with reduced left ventricular ejection fraction (EF 35%). The mitral valve presented a central prolapse of the posterior leaflet (P2) with chordal rupture and very eccentric regurgitant jet (video 1). The patient was considered to be at very high risk for open heart surgery by the Heart Team. He was therefore recommended for a MitraClip procedure (Abbott Vascular, Santa Clara, CA, USA). He underwent transcatheter edge-to-edge repair (TEER) under general anaesthesia and TEE guidance. Edoxaban 30 mg, which he was taking for atrial fibrillation, was stopped the day before the procedure as recommended in 2021 EHRA practical guidelines. For venous access, the right common femoral vein was utilized. An 8.5 F transeptal guiding introducer and BRK needle (St Jude Medical Little Canada, Minnesota) were used for the transeptal puncture, which was carried out under TEE guidance. As soon as the septal puncture was successful, 10,000 units of heparin were administered for anticoagulation. 281 seconds was the initial active clotting time (ACT) measured. The 0.035 × 260 cm Amplatz super stiff (Boston Scientific Marlborough, Massachusetts) was positioned into the left upper pulmonary vein via the 8.5 sheath, and a 24 F steerable guide catheter (SGC) was inserted into the left atrium. At the same time, a giant, very mobile echogenic mass (36 mm x 8 mm), compatible with molding thrombus was observed attached to SGC at the site of transseptal puncture on the right atrial side, straddling, in minimal part, in left atrium (7 mm) (Fig. 1 – 2 , video 2–3). Because of the possibility of pulmonary and systemic embolization of thrombus, SGC was not moved. To keep ACT > 300 s, heparin boluses were administered repeatedly. In consideration of the presence of a molding thrombus, which appeared suddendly during the insertion of SGC, there was a strong suspicion that the thrombus had been dislocated by the 24 F SGC, when crossing an extensive deep abdominal vein thrombosis. For this reason, the idea of a contralateral or ipsilateral vein approach to reach the right atrium and to perform a thrombo-aspiration was excluded. To prevent cerebral embolization, two Emboshield NAV6 Embolic Protection System (Abbott Vascular, Santa Clara, CA, USA), via bilateral femoral artery access, were placed in the carotid artery to prevent cerebral embolization (Fig. 3 ). When a proper anticoagulation (ACT > 350 s) was obtained, the thrombus's size was shown to be reduced (video 4). Next, the Mitraclip was successfully placed in a central position, at A2/P2 scallop of mitral valve. Mitral regurgitation was reduced from severe to mild (video 5). At the end of procedure, thrombus partially disappeared but still partially entrapped between SGC and septum primum (video 6). In order to avoid an immediate paradoxical embolism, during SGC removal, or a future cerebral event due to the iatrogenic ASD, a Amplatzer Multifenestrated Septal Occluder 25/25 was placed while the SGC withdrawing (video 7). The patient was stable during the procedure, without evidence of right ventricular dysfunction or dilatation. He was extubated quickly. No evidence of pulmonary embolism was seen by a CT scan, while deep veins thrombosis (common iliac veins) was found (Fig. 4–5). Following the procedure, the patient was started on intravenous heparin before being switched to Coumadin. Five days later, he was discharged. The postoperative course was regular, and the patient continued his cardiological follow-up. Conclusions In this paper we describe a rare case of a huge molding right atrial thrombosis, occurring during TEER, resolved with medical therapy, without pulmonary or cerebral complications, thanks to double carotid filters and aggressive anticoagulant protocol during procedure. TEER is being increasingly used in patients with severe symptomatic mitral regurgitation who are not surgical candidates [ 1 ]. The risk of stroke or TIA during the MitraClip implantation reaches an incidence of 2.6% [ 2 ]. Generally, the patients, in a standard protocol, received an initial bolus of heparin (100 U/Kg) immediately after positioning the transseptal sheath in the left atrium. There have been no randomized studies on the optimal time of heparin administration prior to or immediately after transseptal puncture. However, due to the possibility of embolization and ischemic stroke, periprocedural thrombus formation on the MitraClip device is an uncommon but dreaded complication. The optimal management of acute thrombus during the MitraClip procedure is unknown. Frerker et al. suggested that the use of a cerebral protection device might be a reasonable strategy during the MitraClip implantation [ 3 ]. Huntgeburth et al. described a case of thrombus formed on SGC, despite adequate anticoagulation, which was successfully aspirated [ 4 ]. A similar solution was described by Mahmood et al., which successfully managed a right atrial thombus using aspiration thrombectomy [ 5 ]. Another approach was described by Wolff and colleagues, which used low-dose thrombolysis to treat left atrial thrombus during Mitraclip implantation [ 6 ]. Patients with a transient periprocedural thrombus had lower LVEF and tended to have worse right ventricular function and higher PASP than those without a thrombus [ 7 ]. One retrospective study of 100 patients undergoing the procedure showed that 9% of patients developed intracardiac thrombus. They were treated by flushing with heparinized saline after the transeptal sheath and needle were removed [ 7 ]. When manipulating the SGC, this technique carries the risk of systemic embolization through iatrogenic ASD. In our case, no thrombus was found in the right atrium before the procedure. Most likely the thrombus arrived in the atrium transported by the iliac veins through the SGC. This hypothesis is supported by the shape of the thrombus (molded) and the sudden appearance in the right atrium during the entry of the SGC into it. As a result, the idea of using a vein to access the right atrium and to perform a thrombo-aspiration was ruled out due to the high risk of bringing additional thrombus into the atrium. This finding was confirmed by CT scan performed after the procedure. The thrombolysis option was ruled out due to the patient's high bleeding risk. It was decided not to manipulate the SGC and to wait for the resolution of the thrombus while protecting the cerebral circulation in the meantime. A dedicated brain protection system was not used due to its unavailability. The procedure was completed without complications, and, to prevent embolization of residual thrombus in the right atrium, an Amplatzer Multifenestrated Septal Occluder was positioned to treat the iatrogenic ASD. This case report emphasizes the unusual and significant finding of a large, molded right atrial thrombus formed during transcatheter edge-to-edge repair of a severe mitral regurgitation. In spite of the large thrombotic burden with potentially catastrophic complications, the patient did well with medical therapy only. Such a result was likely facilitated by the use of carotid double filters given preventively, thus decreasing the risk of cerebral embolization. TEER is a successful therapeutic option for many patients, but it is associated with inherent complications, including risk for thrombus formation. Interestingly, while the optimal management of acute thrombus during TEER is still under investigation, this case teaches the importance of close observation and consideration of a multidisciplinary decision-making process. More investigation is needed regarding the incidence, risk factors, and best practices for managing periprocedural thrombus formation during TEER. Further research is needed to establish the range of potential role of cerebral protection devices and the effect of anticoagulation procedures on thrombus formation. Abbreviations TEER transcatheter edge to edge repair TEE transesophageal echocardiography SGC steerable guide catheter ASD atrial septal defect Declarations Ethics approval and consent to participate This study does not require institutional review board approval. Consent for publication Written informed consent for publication of their details was obtained from the patient. Funding Dr Totaro was co-funded by Next Generation EU, in the context of the National Recovery and Resilience Plan, Investment PE8 – Project Age-It: “Ageing Well in an Ageing Society”. This resource was co-financed by the Next Generation EU [DM 1557 11.10.2022]. The views and opinions expressed are only those of the authors and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. Author Contribution AT: Conceptualization, Supervision, Investigation, Writing – Original Draft.VI: Investigation.CG: Writing – Original Draft.VS: Writing – Original DraftAP: Investigation, Supervision.NT: Investigation.GT: Supervision.CS: Investigation, Supervision.All authors read and approved the final manuscript. References Feldman, T., et al., Percutaneous repair or surgery for mitral regurgitation . N Engl J Med, 2011. 364(15): p. 1395–406. Glower, D.D., et al., Percutaneous mitral valve repair for mitral regurgitation in high-risk patients: results of the EVEREST II study . J Am Coll Cardiol, 2014. 64(2): p. 172–81. Frerker, C., et al., Cerebral Protection During MitraClip Implantation: Initial Experience at 2 Centers . JACC Cardiovasc Interv, 2016. 9(2): p. 171–9. Huntgeburth, M., et al., Thrombus formation at the MitraClip system during percutaneous mitral valve repair . JACC Cardiovasc Interv, 2014. 7(9): p. e111-2. Mahmood, M., et al., Management of Right Atrial Thrombus During MitraClip Implantation: A Case Report and Review of Literature . Cardiovasc Revasc Med, 2023. 47: p. 97–99. Wolff, G., et al., Low-Dose Thrombolysis for the Management of Left Atrial Thrombus Formation During Percutaneous Mitral Valve Repair . JACC Cardiovasc Interv, 2019. 12(2): p. e9-e10. Pregowski, J., et al., Incidence, clinical correlates, timing, and consequences of acute thrombus formation in patients undergoing the MitraClip procedure . Kardiol Pol, 2020. 78(1): p. 45–50. Additional Declarations No competing interests reported. Supplementary Files 1.mp4 Video 1 – 3D color transesophageal echocardiography: surgical mitral view. Leaflet lesion and regurgitation jet. 2.mp4 Video 2 – 2D transesophageal echocardiography: ME AV SAX view. Molding thrombus attached to SGC at the site of transseptal puncture on the right atrial side, straddling, in minimal part, in left atrium (7 mm) 3.mp4 Video 3 – 3D transesophageal echocardiography. Molding thrombus. 4.mp4 Video 4 – 2D transesophageal echocardiography: ME bicaval view. Molding thrombus. 5.mp4 Video 5 – 2D color transesophageal echocardiography: Final result after Mitraclip implantation. 6.mp4 Video 6 – 2D transesophageal echocardiography: ME 4 chamber view. Residual thrombus at the end of procedure. 7.mp4 Video 7 – 2D transesophageal echocardiography: ME bicaval view. Amplatzer Multifenestrated Septal Occluder. CAREchecklistEnglish2013.pdf Cite Share Download PDF Status: Published Journal Publication published 01 Jul, 2025 Read the published version in The Egyptian Heart Journal → Version 1 posted Editorial decision: Revision requested 23 May, 2025 Reviews received at journal 23 May, 2025 Reviewers agreed at journal 14 May, 2025 Reviews received at journal 06 May, 2025 Reviewers agreed at journal 06 May, 2025 Reviewers invited by journal 29 Mar, 2025 Submission checks completed at journal 26 Mar, 2025 First submitted to journal 25 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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B: Transesophageal echocardiography, ME bicaval view. LA: left atrium, RA: right atrium, Ao: aorta, * streerable guidance catheter, arrow: thrombus.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/13164573609026f3261feb83.jpg"},{"id":81021442,"identity":"61ca9777-70a6-4d27-bb55-05e9976a98ef","added_by":"auto","created_at":"2025-04-21 09:52:55","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":172664,"visible":true,"origin":"","legend":"\u003cp\u003eFluoroscopy image of the deployed carotid filters inserted into the carotid arteries (arrow).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/54c6c36e336ca10d9c95c147.jpg"},{"id":81023719,"identity":"8dea6f1e-abef-4bee-97c8-6d1dcc08ab07","added_by":"auto","created_at":"2025-04-21 10:08:56","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":90885,"visible":true,"origin":"","legend":"\u003cp\u003eA: CT scan: pulmonary artery. B: CT scan: parietal thrombosis of common iliac vein (arrow).\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/6c15423aa36aad0fa08d1deb.jpg"},{"id":86179054,"identity":"ea0efe56-a87d-402f-95a1-066fc788b051","added_by":"auto","created_at":"2025-07-07 16:15:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":736879,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/1cc10d2c-bbf0-4bfe-b1ff-aa1e0cce23e1.pdf"},{"id":81021446,"identity":"10d20798-0995-43c9-be76-beaa2e3b461d","added_by":"auto","created_at":"2025-04-21 09:52:56","extension":"mp4","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2541786,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 1 – 3D color transesophageal echocardiography: surgical mitral view. Leaflet lesion and regurgitation jet.\u003c/p\u003e","description":"","filename":"1.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/835cd09a8f7cdd30a7cf0fae.mp4"},{"id":81023721,"identity":"d415f05a-539a-4987-8cf4-741bb94cb1f6","added_by":"auto","created_at":"2025-04-21 10:08:56","extension":"mp4","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":3022152,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 2 – 2D transesophageal echocardiography: ME AV SAX view. Molding thrombus attached to SGC at the site of transseptal puncture on the right atrial side, straddling, in minimal part, in left atrium (7 mm)\u003c/p\u003e","description":"","filename":"2.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/7175393dea63304a502d6e51.mp4"},{"id":81024358,"identity":"fa4caf17-66ad-41a1-b54b-688bdcce3b1c","added_by":"auto","created_at":"2025-04-21 10:16:56","extension":"mp4","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":2933780,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 3 – 3D transesophageal echocardiography. Molding thrombus.\u003c/p\u003e","description":"","filename":"3.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/4bbec55d6dec1e21ffd8fe53.mp4"},{"id":81021451,"identity":"f368c3d6-eff4-4a1c-90bc-a4e4175b5156","added_by":"auto","created_at":"2025-04-21 09:52:56","extension":"mp4","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":2889094,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 4 – 2D transesophageal echocardiography: ME bicaval view. Molding thrombus.\u003c/p\u003e","description":"","filename":"4.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/7deb3561c50f443622d7b5fd.mp4"},{"id":81021459,"identity":"ff360de8-795d-4fb1-85d3-a18ab76a15db","added_by":"auto","created_at":"2025-04-21 09:52:56","extension":"mp4","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":2866872,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 5 – 2D color transesophageal echocardiography: Final result after Mitraclip implantation.\u003c/p\u003e","description":"","filename":"5.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/a4971a80327d0210ecc8afaf.mp4"},{"id":81022571,"identity":"d9380870-b5c4-4ddb-8c5a-4ef1ea1c6d32","added_by":"auto","created_at":"2025-04-21 10:00:56","extension":"mp4","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":3197562,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 6 – 2D transesophageal echocardiography: ME 4 chamber view. Residual thrombus at the end of procedure.\u003c/p\u003e","description":"","filename":"6.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/08211d5cf9ff9fb0b2715a2d.mp4"},{"id":81022573,"identity":"cef562aa-7e84-4e13-af7c-c6e1c1415004","added_by":"auto","created_at":"2025-04-21 10:00:56","extension":"mp4","order_by":7,"title":"","display":"","copyAsset":false,"role":"supplement","size":3315977,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 7 – 2D transesophageal echocardiography: ME bicaval view. Amplatzer Multifenestrated Septal Occluder.\u003c/p\u003e","description":"","filename":"7.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/ae95c83ab0db115f145396ba.mp4"},{"id":81021460,"identity":"22d845ea-688b-4145-8558-126c026858b1","added_by":"auto","created_at":"2025-04-21 09:52:56","extension":"pdf","order_by":8,"title":"","display":"","copyAsset":false,"role":"supplement","size":818688,"visible":true,"origin":"","legend":"","description":"","filename":"CAREchecklistEnglish2013.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6234800/v1/bd24a881838d8ee247bb054d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEvery great story seems to begin with a snake: a case report of a huge right atrial thrombus during transcatheter mitral valve repair\u003c/p\u003e","fulltext":[{"header":"Background","content":"\u003cp\u003eThe MitraClip procedure is a groundbreaking therapeutic approach that has revolutionized the treatment of mitral regurgitation. Mitral regurgitation poses a significant clinical burden, particularly in the aging population, and the development of transcatheter interventions has brought this once exclusively surgical domain to the attention of interventional cardiologists [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAccess to the left atrium and sufficient anticoagulation are necessary for the procedure. However, thrombotic complications can still happen even with heparin treatment and the right activated clotting time (ACT).\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003eAn 83-years-old man with a past medical history of atrial fibrillation, type 2 diabetes and chronic heart failure (HFrEF) in ischemic cardiopathy, treated with previous percutaneous coronary intervention, previous ICD implantation, presented with a history of worsening dyspnea associated with ankle swelling.\u003c/p\u003e \u003cp\u003eTransthoracic and transesophageal echocardiogram (TEE) showed severe mitral regurgitation with reduced left ventricular ejection fraction (EF 35%). The mitral valve presented a central prolapse of the posterior leaflet (P2) with chordal rupture and very eccentric regurgitant jet (video 1).\u003c/p\u003e \u003cp\u003eThe patient was considered to be at very high risk for open heart surgery by the Heart Team. He was therefore recommended for a MitraClip procedure (Abbott Vascular, Santa Clara, CA, USA).\u003c/p\u003e \u003cp\u003eHe underwent transcatheter edge-to-edge repair (TEER) under general anaesthesia and TEE guidance. Edoxaban 30 mg, which he was taking for atrial fibrillation, was stopped the day before the procedure as recommended in 2021 EHRA practical guidelines.\u003c/p\u003e \u003cp\u003eFor venous access, the right common femoral vein was utilized. An 8.5 F transeptal guiding introducer and BRK needle (St Jude Medical Little Canada, Minnesota) were used for the transeptal puncture, which was carried out under TEE guidance. As soon as the septal puncture was successful, 10,000 units of heparin were administered for anticoagulation. 281 seconds was the initial active clotting time (ACT) measured. The 0.035 \u0026times; 260 cm Amplatz super stiff (Boston Scientific Marlborough, Massachusetts) was positioned into the left upper pulmonary vein via the 8.5 sheath, and a 24 F steerable guide catheter (SGC) was inserted into the left atrium. At the same time, a giant, very mobile echogenic mass (36 mm x 8 mm), compatible with molding thrombus was observed attached to SGC at the site of transseptal puncture on the right atrial side, straddling, in minimal part, in left atrium (7 mm) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, video 2\u0026ndash;3). Because of the possibility of pulmonary and systemic embolization of thrombus, SGC was not moved. To keep ACT\u0026thinsp;\u0026gt;\u0026thinsp;300 s, heparin boluses were administered repeatedly.\u003c/p\u003e \u003cp\u003eIn consideration of the presence of a molding thrombus, which appeared suddendly during the insertion of SGC, there was a strong suspicion that the thrombus had been dislocated by the 24 F SGC, when crossing an extensive deep abdominal vein thrombosis. For this reason, the idea of a contralateral or ipsilateral vein approach to reach the right atrium and to perform a thrombo-aspiration was excluded.\u003c/p\u003e \u003cp\u003eTo prevent cerebral embolization, two Emboshield NAV6 Embolic Protection System (Abbott Vascular, Santa Clara, CA, USA), via bilateral femoral artery access, were placed in the carotid artery to prevent cerebral embolization (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhen a proper anticoagulation (ACT\u0026thinsp;\u0026gt;\u0026thinsp;350 s) was obtained, the thrombus's size was shown to be reduced (video 4).\u003c/p\u003e \u003cp\u003eNext, the Mitraclip was successfully placed in a central position, at A2/P2 scallop of mitral valve. Mitral regurgitation was reduced from severe to mild (video 5).\u003c/p\u003e \u003cp\u003eAt the end of procedure, thrombus partially disappeared but still partially entrapped between SGC and septum primum (video 6). In order to avoid an immediate paradoxical embolism, during SGC removal, or a future cerebral event due to the iatrogenic ASD, a Amplatzer Multifenestrated Septal Occluder 25/25 was placed while the SGC withdrawing (video 7).\u003c/p\u003e \u003cp\u003eThe patient was stable during the procedure, without evidence of right ventricular dysfunction or dilatation. He was extubated quickly. No evidence of pulmonary embolism was seen by a CT scan, while deep veins thrombosis (common iliac veins) was found (Fig.\u0026nbsp;4\u0026ndash;5). Following the procedure, the patient was started on intravenous heparin before being switched to Coumadin. Five days later, he was discharged. The postoperative course was regular, and the patient continued his cardiological follow-up.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn this paper we describe a rare case of a huge molding right atrial thrombosis, occurring during TEER, resolved with medical therapy, without pulmonary or cerebral complications, thanks to double carotid filters and aggressive anticoagulant protocol during procedure.\u003c/p\u003e \u003cp\u003eTEER is being increasingly used in patients with severe symptomatic mitral regurgitation who are not surgical candidates [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The risk of stroke or TIA during the MitraClip implantation reaches an incidence of 2.6% [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Generally, the patients, in a standard protocol, received an initial bolus of heparin (100 U/Kg) immediately after positioning the transseptal sheath in the left atrium. There have been no randomized studies on the optimal time of heparin administration prior to or immediately after transseptal puncture. However, due to the possibility of embolization and ischemic stroke, periprocedural thrombus formation on the MitraClip device is an uncommon but dreaded complication.\u003c/p\u003e \u003cp\u003eThe optimal management of acute thrombus during the MitraClip procedure is unknown. Frerker et al. suggested that the use of a cerebral protection device might be a reasonable strategy during the MitraClip implantation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Huntgeburth et al. described a case of thrombus formed on SGC, despite adequate anticoagulation, which was successfully aspirated [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. A similar solution was described by Mahmood et al., which successfully managed a right atrial thombus using aspiration thrombectomy [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Another approach was described by Wolff and colleagues, which used low-dose thrombolysis to treat left atrial thrombus during Mitraclip implantation [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Patients with a transient periprocedural thrombus had lower LVEF and tended to have worse right ventricular function and higher PASP than those without a thrombus [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOne retrospective study of 100 patients undergoing the procedure showed that 9% of patients developed intracardiac thrombus. They were treated by flushing with heparinized saline after the transeptal sheath and needle were removed [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. When manipulating the SGC, this technique carries the risk of systemic embolization through iatrogenic ASD.\u003c/p\u003e \u003cp\u003eIn our case, no thrombus was found in the right atrium before the procedure. Most likely the thrombus arrived in the atrium transported by the iliac veins through the SGC. This hypothesis is supported by the shape of the thrombus (molded) and the sudden appearance in the right atrium during the entry of the SGC into it. As a result, the idea of using a vein to access the right atrium and to perform a thrombo-aspiration was ruled out due to the high risk of bringing additional thrombus into the atrium. This finding was confirmed by CT scan performed after the procedure. The thrombolysis option was ruled out due to the patient's high bleeding risk. It was decided not to manipulate the SGC and to wait for the resolution of the thrombus while protecting the cerebral circulation in the meantime. A dedicated brain protection system was not used due to its unavailability. The procedure was completed without complications, and, to prevent embolization of residual thrombus in the right atrium, an Amplatzer Multifenestrated Septal Occluder was positioned to treat the iatrogenic ASD.\u003c/p\u003e \u003cp\u003eThis case report emphasizes the unusual and significant finding of a large, molded right atrial thrombus formed\u0026ensp;during transcatheter edge-to-edge repair of a severe mitral regurgitation. In spite of\u0026ensp;the large thrombotic burden with potentially catastrophic complications, the patient did well with medical therapy only. Such a result was likely facilitated by the use of\u0026ensp;carotid double filters given preventively, thus decreasing the risk of cerebral embolization.\u003c/p\u003e \u003cp\u003eTEER\u0026ensp;is a successful therapeutic option for many patients, but it is associated with inherent complications, including risk for thrombus formation. Interestingly, while the optimal\u0026ensp;management of acute thrombus during TEER is still under investigation, this case teaches the importance of close observation and consideration of a multidisciplinary decision-making process.\u003c/p\u003e \u003cp\u003eMore investigation is needed regarding the incidence, risk factors, and best practices for managing periprocedural\u0026ensp;thrombus formation during TEER. Further research is needed to establish\u0026ensp;the range of potential role of cerebral protection devices and the effect of anticoagulation procedures on thrombus formation.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTEER\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003etranscatheter edge to edge repair\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTEE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003etransesophageal echocardiography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSGC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003esteerable guide catheter\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eASD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eatrial septal defect\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eThis study does not require institutional review board approval.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003e Written informed consent for publication of their details was obtained from the patient.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eDr Totaro was co-funded by Next Generation EU, in the context of the National Recovery and Resilience Plan, Investment PE8 \u0026ndash; Project Age-It: \u0026ldquo;Ageing Well in an Ageing Society\u0026rdquo;. This resource was co-financed by the Next Generation EU [DM 1557 11.10.2022]. The views and opinions expressed are only those of the authors and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAT: Conceptualization, Supervision, Investigation, Writing \u0026ndash; Original Draft.VI: Investigation.CG: Writing \u0026ndash; Original Draft.VS: Writing \u0026ndash; Original DraftAP: Investigation, Supervision.NT: Investigation.GT: Supervision.CS: Investigation, Supervision.All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFeldman, T., et al., \u003cem\u003ePercutaneous repair or surgery for mitral regurgitation\u003c/em\u003e. N Engl J Med, 2011. 364(15): p. 1395\u0026ndash;406.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGlower, D.D., et al., \u003cem\u003ePercutaneous mitral valve repair for mitral regurgitation in high-risk patients: results of the EVEREST II study\u003c/em\u003e. J Am Coll Cardiol, 2014. 64(2): p. 172\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFrerker, C., et al., \u003cem\u003eCerebral Protection During MitraClip Implantation: Initial Experience at 2 Centers\u003c/em\u003e. JACC Cardiovasc Interv, 2016. 9(2): p. 171\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuntgeburth, M., et al., \u003cem\u003eThrombus formation at the MitraClip system during percutaneous mitral valve repair\u003c/em\u003e. JACC Cardiovasc Interv, 2014. 7(9): p. e111-2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMahmood, M., et al., \u003cem\u003eManagement of Right Atrial Thrombus During MitraClip Implantation: A Case Report and Review of Literature\u003c/em\u003e. Cardiovasc Revasc Med, 2023. 47: p. 97\u0026ndash;99.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWolff, G., et al., \u003cem\u003eLow-Dose Thrombolysis for the Management of Left Atrial Thrombus Formation During Percutaneous Mitral Valve Repair\u003c/em\u003e. JACC Cardiovasc Interv, 2019. 12(2): p. e9-e10.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePregowski, J., et al., \u003cem\u003eIncidence, clinical correlates, timing, and consequences of acute thrombus formation in patients undergoing the MitraClip procedure\u003c/em\u003e. Kardiol Pol, 2020. 78(1): p. 45\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"the-egyptian-heart-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tehj","sideBox":"Learn more about [The Egyptian Heart Journal](https://tehj.springeropen.com)","snPcode":"43044","submissionUrl":"https://submission.springernature.com/new-submission/43044/3","title":"The Egyptian Heart Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Mitraclip, Atrial thrombus, TEER, Carotid filter,","lastPublishedDoi":"10.21203/rs.3.rs-6234800/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6234800/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBackground: TEER has revolutionized mitral regurgitation treatment, addressing clinical burden in aging patients. However, thrombotic complications may still occur.\u003c/p\u003e\n\u003cp\u003eCase presentation: An 83-year-old man with severe mitral regurgitation underwent a MitraClip procedure. A huge molding thrombus was observed during the procedure. To prevent cerebral embolization, two carotid filters were placed. The procedure was successfully ended, and mitral regurgitation was reduced. The patient was stable during the procedure, with no evidence of pulmonary or cerebral embolism.\u003c/p\u003e\n\u003cp\u003eConclusions: The case highlights the importance of close observation and multidisciplinary decision-making in managing acute thrombus during TEER. Further research is needed to establish the potential role of cerebral protection devices and the effect of anticoagulation procedures on thrombus formation.\u003c/p\u003e","manuscriptTitle":"Every great story seems to begin with a snake: a case report of a huge right atrial thrombus during transcatheter mitral valve repair","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-21 09:52:51","doi":"10.21203/rs.3.rs-6234800/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-23T22:31:16+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-23T22:24:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"30087087441856958498337159272442527684","date":"2025-05-14T10:09:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-06T16:21:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"301303936287479476987426953325782745854","date":"2025-05-06T16:14:52+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-30T03:13:57+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-26T07:25:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"The Egyptian Heart Journal","date":"2025-03-25T22:05:08+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"the-egyptian-heart-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tehj","sideBox":"Learn more about [The Egyptian Heart Journal](https://tehj.springeropen.com)","snPcode":"43044","submissionUrl":"https://submission.springernature.com/new-submission/43044/3","title":"The Egyptian Heart Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a640153d-e8f9-4f52-90ff-a79702cae976","owner":[],"postedDate":"April 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-07T16:03:52+00:00","versionOfRecord":{"articleIdentity":"rs-6234800","link":"https://doi.org/10.1186/s43044-025-00661-z","journal":{"identity":"the-egyptian-heart-journal","isVorOnly":false,"title":"The Egyptian Heart Journal"},"publishedOn":"2025-07-01 15:57:47","publishedOnDateReadable":"July 1st, 2025"},"versionCreatedAt":"2025-04-21 09:52:51","video":"","vorDoi":"10.1186/s43044-025-00661-z","vorDoiUrl":"https://doi.org/10.1186/s43044-025-00661-z","workflowStages":[]},"version":"v1","identity":"rs-6234800","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6234800","identity":"rs-6234800","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}