LAA Closure With Thrombus: There is More To It Than Meets the Eye!

Dear Editors:

We have read the recent article by Sahiner et al¹ on left atrial appendage (LAA) occlusion in patients with thrombus in the LAA with great interest. The authors showed the safety of LAA closure by experienced operators in patients with resistant LAA thrombus. There were no ischemic cerebrovascular complications during follow-up. We would like to address some of our concerns. The absence of a minor or disabling stroke doesn’t rule out a thromboembolic event (transient ischemic attack) in this study, especially in patients under general anesthesia. The presence of silent brain infarction is well established, particularly in patients with atrial fibrillation and elderly age.² Cerebral magnetic resonance imaging (MRI) is the only way to diagnose these cases of asymptomatic stroke. Silent brain infarctions and white matter lesions can lead to cognitive dysfunction and dementia.³

It has been shown in transcatheter aortic valve replacement (TAVR) patients that the incidence of neurological injury (1.1% at 1 month) greatly differed from diffusion-weighted MRI-detected ischemic lesions (63% at 3 months).⁴ Although the mechanism of thromboembolism is different in TAVR and LAA closure, it emphasizes the discordance between obvious injury and silent infarction. 

As this procedure is increasingly being performed in patients with LAA thrombus, it would be advantageous to know the true incidence of embolic events. The role of cerebral protection devices will need to be defined accordingly.⁵ So, we would like to favor performing cerebral MRI in these patients who are at a high risk of cerebral embolism. This will give a true incidence of thromboembolism in these cases and will help us in guiding further management strategies in this subgroup of patients.

Sincerely,

Ashutosh Yadav, MD, DM, Consultant Cardiology, Fortis Hospital, Mohali, India; and Sourabh Agstam, MBBS, MD, Assistant Professor, VMMC and Safdarjung Hospital, New Delhi, India.

Address for correspondence: Sourabh Agstam, MBBS, MD, Assistant Professor, Department of Cardiology, VMMC and Safdarjung Hospital, New Delhi, India 110029. Email: sourabhagstam@gmail.com

Authors’ Response:

We have read the letter to the editor with great interest and gratitude. As we know, percutaneous cardiovascular interventions can cause silent thromboembolic events.^1,2 For percutaneous LAA closure, the embolization of thrombus from LAA is the primary cause of the increased risk of procedure-related ischemic events. On the other hand, endothelial damage of the aorta or main branches of the aorta is the main reason for most of the embolic events related to cardiovascular interventions.³ Therefore, the preventative methods for procedure-related thromboembolic events can be different.

In our study, we had several precautions against embolic events. First, defining the localization of thrombus formation in LAA is essential. So, we classified the thrombus in the LAA according to its localization and excluded the patients with type 0 LAA thrombus. Second, periprocedural intravenous anticoagulation infusion with activated clotting time monitoring is another significant prevention. Third, we suggest an individualized postprocedural antithrombotic regimen for protection from periprocedural thromboembolic events. And last, we utilize interventional radiologists who are experienced and capable of on-site intervention (such as embolectomy) at our hospital.

The importance of silent brain infarction is still under investigation.⁴ Also, silent ischemic events were reported in patients with atrial fibrillation, even in patients who had received an oral anticoagulant drug.^5,6 So, based on the insights of previous studies, we assume that our study population could have undiagnosed silent brain infarction history, and postprocedural cranial imaging might be insufficient to detect brain infarction related to the procedure.

Cerebral protection devices are being used for the prevention of thromboembolic events related to the TAVR procedure. Although the efficiency of cerebral protection devices has been shown, using them is not obligatory for all patients,² because the impact of silent brain infarction on the neurocognitive prognosis is not clear. Likewise, the significance of cerebral protection device usage and its cost effectiveness in the LAA closure procedure remain uncertain. In our opinion, cerebral protection device usage should be limited to high-risk patients during the LAA closure procedure. In our series, we defined patients who had a history of one-sided carotid artery occlusion, patients with fresh thrombus in the LAA, and patients who could not tolerate heparin infusion during the therapy as high-risk patients. Consequently, we did not use CPDs in our study.

Sincerely,

Levent Sahiner, MD; Cem Coteli, MD;  Ergun Baris Kaya, MD;  Ahmet Ates, MD;  Gul Sinem Kilic, MD;  Hikmet Yorgun, MD;  Kudret Aytemir, MD

Address for correspondence: Cem Coteli, MD, Ankara City Hospital, Cardiology, Üniversiteler Mahallesi Bilkent Cad. No:1 Çankaya/ANKARA, Ankara, Çankaya 06800, Turkey. Email: cemcoteli@hacettepe.edu.tr

1. Sahiner L,  Coteli C,  Kaya EB, et al. Left atrial appendage occlusion in patients with thrombus in left atrial appendage. J Invasive Cardiol. 2020;32:222-227. Epub 2020 April 24.
2. Kempster PA, Gerraty RP, Gates PC. Asymptomatic cerebral infarction in patients with chronic atrial fibrillation. Stroke. 1988;19:955-957.
3. Gupta A, Giambrone AE, Gialdini G, et al. Silent brain infarction and risk of future stroke: a systematic review and meta-analysis. Stroke. 2016;47:719-725.
4. Alassar A, Soppa G, Edsell M, et al. Incidence and mechanisms of cerebral ischemia after transcatheter aortic valve implantation compared with surgical aortic valve replacement. Ann Thorac Surg. 2015;99:802-808. 
5. Tarantini G, D’Amico G, Latib A, et al. Percutaneous left atrial appendage occlusion in patients with atrial fibrillation and left appendage thrombus: feasibility, safety and clinical efficacy. EuroIntervention. 2018;13:1595-1602.

Author Response References

1. Grabert S, Lange R, Bleiziffer S. Incidence and causes of silent and symptomatic stroke following surgical and transcatheter aortic valve replacement: a comprehensive review. Interact Cardiovasc Thorac Surg. 2016;23:469-476.
2. Demir OM, Iannopollo G, Mangieri A, et al. The role of cerebral embolic protection devices during transcatheter aortic valve replacement. Front Cardiovasc Med. 2018;5:150.
3. Khatri P, Kasner SE. Ischemic strokes after cardiac catheterization: opportune thrombolysis candidates? Arch Neurol. 2006;63:817-821.
4. Fanning JP, Wong AA, Fraser JF. The epidemiology of silent brain infarction: a systematic review of population-based cohorts. BMC Med. 2014;12:119.
5. Escudero-Martínez I, Ocete RF, Mancha F, et al. Prevalence and risk factors of silent brain infarcts in patients with AF detected by 3T-MRI. J Neurol. 2020 May 14 (Epub ahead of print).
6. Patel MR, Mahaffey KW, Garg J, et al. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med. 2011;365:883-891.