• One stroke too many…are we underutilizing embolic protection devices during catheter and surgical intervention?

    Cardiovascular Revascularization Medicine, 2018-07-01, Volume 19, Issue 5, Pages 475-476, Copyright © 2018 Elsevier Inc.


     Embolic events during cardiovascular procedures can result in devastating complications with significant morbidly or mortality. I recently wrote a letter to the editor describing a patient who underwent elective aortic valve replacement and suffered a stroke [1]. He was basically a low risk patient and at the time, there was no protocol available allowing him to undergo transcatheter aortic valve replacement (TAVR). He underwent minimally invasive aortic valve replacement, and he woke up with hemiplegia and double vision which eventually resolved in two weeks. Not long ago, we treated a patient with atrial fibrillation and after an elective atrial fibrillation ablation; the patient suffered a devastating cerebellar embolic infarction. This 76 year old gentleman had known coronary disease and presented with permanent atrial fibrillation for RF ablation. The standard cryoablation technique was performed with pulmonary vein isolation, ablation of reentrant tachycardia coming from the left side and ablation of right sided arrhythmias. He was off anticoagulation for the procedure. Within 24 h the patient was noted to have headache, a visual defect, and with a CT imaging abnormality was begun on Heparin and was transferred for stroke intervention. He subsequently suffered a posterior fossa infarction, hemorrhagic transformation and neurologic decline eventually undergoing craniotomy for decompression and evacuation of a cerebellar hematoma. He also suffered left leg deep vein thrombosis, but was discharged three weeks later and although he has improved, he still is severely disabled.

    Both of these stroke procedures are done on a routine basis at many cardiovascular centers worldwide. With experience with TAVR, stroke rates have dropped to only 2%–11% [2]. It is possible that the rate may in fact be higher because few prospective trials are available with independent neurologic evaluation, and it appears stroke rates are no different in different risk groups. Even though the event rate has dropped, if a stroke occurs with TAVR, the mortality is increased three-and-one-half fold within the first 30 days of the procedure [3]. In addition to the Claret (Santa Rosa, California) SENTINEL™ device, there are other embolic protection devices being evaluated to prevent strokes with TAVR, including the TriGuard™ (Keystone Heart, Ltd., Caesarea, IL), Embrella™ (Embrella Cardiovascular, Inc., Wayne, Pennsylvania) Embo-X™ (Fluidx Medical Technology, LLC, Park City, Utah), Transverse Medical (TMI) Point-Guard™ (Golden, Colorado), Emblok (Innovative Cardiovascular Solutions, Grand Rapids, Michigan) and Emboliner™ (Emboline, Santa Cruz, California) devices. We know from the Kapadia data that by using an embolic protection device (the SENTINEL™) during the TAVR procedure, there can be new cerebral stroke reduction of 42% versus no embolic protection device ( P = 0.33) with a stroke incidence dropping 9.1%. to 5.6% (NS) at 30 days post procedure [ ]. A post hoc analysis of the SENTINEL which led to the clearance of the device in the US market, demonstrated that the use of the device significantly reduced the rate of peri-procedural stroke by 63% from 8.2% to 3% at 72 h ( p = 0.05%). [ ]. In this particular study, most filters had debris (99%) [ ]. The debris included bits of arterial wall and calcific particles as well as valve tissue and TAVR coating material. Although this study did not achieve statistical significance, on the basis of this trial and other data, the SENTINEL™ device was approved by the FDA to be utilized during the TAVR procedure. The transcatheter cerebral embolic protection (TCEP) placement takes about 9 min with inexperienced operators and about 3 min with experienced operators with TCEP. One of the most cogent aspects of this trial was that without TCEP, 1 out of 11 patients suffered with stroke. With updated data from other centers, we know that protected patients have a 1.4% incidence of stroke compared to 4.68% of unprotected patients ( p = 0.03) [ ]. Latib and Pagnpsi [ ], speculated that the defects that are shown on MRA could be related to memory loss, cognitive decline and dementia [ ]. They evaluated pooled data from 3 randomized trials of the SENTINEL™ device, suggesting that the device reduces new lesion volume by approximately 100 mm 3 of damaged brain which translates to approximately 8 million neurons and 450 million synapses [6].

    What about the role of these devices in routine open aortic valve surgery? One large study using suction based traction extraction or intra-aortic infiltration vs. standard care showed no difference in mortality or clinical stroke [8]. A prospective study at 129 post-op surgical aortic valve replacement (SAVR) patients when all of the patients underwent diffusion-weighted magnetic resonate imaging (DW-MRI), post-op reveals that 79 (46%) of patients had new cerebral embolic lesions. This trial confirmed the primary issue of stroke in open surgery is embolization [9].

    When procedures are performed on the mitral valve, many patients have disease in the left atrium as well as thrombus. Is this a population that requires embolic protection? Transient ischemic attacks or CVAs during the MitraClip® (Abbott, Abbott Park, Illinois) procedure occur in 0.2% to 2.6% [10 11 12]. In a prospective trial evaluating 27 patients before and after the MitraClip® procedure, 85.7% of patients had new diffusion-weighted MRI defects [13 ]. Trials using the SENTINEL™ device during the MitraClip® procedure reveal in almost all cases, debris is found including acute thrombus, small fragments of foreign materials, organizing thrombus, valve tissue or atrial tissue, and in a small number of cases, even myocardial material [ ]. In a 14 patient prospective study by Frerker with over 8 month follow-up, no patient had a neurologic event when the SENTINEL™ device was used during the procedure [14].

    It is important to remember that overt and covert cerebral injury occurs in up to 7% and 80% respectively in the MitraClip® procedure and it remains poorly defined until future studies delineate this risk more clearly. Studies reflect that device placement time during MitraClip® is the only independent predictor or risk factor for new cerebral embolic lesions [13].

    Endovascular treatment of thoracic aortic aneurysm (TEVAR) can be complicated by stroke that has been speculated to be of embolic ideology. In a single center prospective analysis looking at the incidence of success, perioperative mortality, spinal cord ischemia and TEVAR aortic repair with/without arch involvement the following were found: 86.7% vs. 94.4%, 4.2% vs. 2.4%, 2.1% vs. 3.6%, 2.8% vs. 1.2% []. Others have described the incidence of stroke in TEVAR as 2%–6% and stroke is clearly associated with post-op mortality [ ]. They also theorized that this was an embolic phenomenon. In another prospective study of TEVAR, 19 patients had DW-MRI at baseline and at 5 days. Twenty-nine new foci were seen in 19 (63%) of TEVAR patients. None of these patients had a clinical event that was documented [17]. As mentioned earlier, stroke rates are not neurologist assessed and may be higher.

    Interventional left atrial appendage occlusion (iLAAO) is a procedure being performed on more and more patients with atrial fibrillation. The primary reason you do this is to prevent strokes instead of warfarin therapy, but early on strokes occurring during the iLAAO procedure were found to be extremely devastating. Meincke, et al., did a small study in 5 consecutive patients where the SENTINEL™ device was placed and debris was found in all of these patients [17]. Although the incidence of stroke after left atrial appendage occlusion is low 0.7%–1.1% [18]. Filtered material found in this small study included acute thrombus in 3, organizing thrombus in 4, endocardial or myocardial tissue in 2 [17].

    Atrial ablation has grown in use over the last 20 years and some studies show that it may be superior to medical therapy in some patients. If one evaluates patients for silent cerebral events, as was done by Deneke, et al., they find that over 60% of atrial fib patients had asymptomatic cerebral lesions to begin with [21]. Left atrial dilation and patient age appears to increase the risk of silent cerebral events as judged by DW-MRI. The pulmonary vein ablation catheter (PVAC®) (Medtronic, Minneapolis, Minnesota) utilized for out of phase ablation may lead to higher current densities with more silent cerebral events. This common procedure may have some specific procedural characteristics that put patients at higher risk for at least silent cerebral events if not overt cerebral events like our patient described. Those include intermittent low intra-procedure ACT, intra-procedure cardioversion, contrast echo pre-ablation, and ablation of complex fractionated electrograms as independent predictors of silent clinical events. The authors speculate that perhaps continued oral anticoagulation during the procedure may be somewhat protective. In Siklody's study of 74 patients with neurologic exams as well as DW-MRI, they felt that these silent cerebral events were most likely an embolic phenomenon [22]. Their group also looked at the use of multi-electrode phased RF PVAC®, which seemed to result in a significantly higher incidence of DW-MRI embolic events.

    Stroke is the second leading cause of death worldwide after cardiovascular disease. With cardiovascular disease being treated with cholesterol lowering medications and aggressive preventive measures, perhaps stroke will overcome cardiovascular disease as a leading cause of death. As the two cases I have described, the results can be temporary and relatively benign or permanent and devastating. With the cost of stroke care at $73 billion annually in the United States, if a simple device that could be placed via the brachial or radial artery, can prevent visible embolization, perhaps we need to think about its utilization in common procedures such as surgical aortic valve replacement, transcutaneous aortic valve replacement, mitral valve percutaneous therapy, endoluminal grafting of the thoracic aorta, as well as during left atrial exclusion and perhaps in high risk atrial fibrillation ablation procedures. Clearly further studies are necessary to see the role of these new, safe embolic protection devices in these applications.

    Conflicts of Interest: The author holds equity in Claret Medical

    Source:

    References

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