BlueCross and BlueShield of Montana Medical Policy/Codes
Mechanical Embolectomy for Treatment of Acute Stroke
Chapter: Medicine: Treatments
Current Effective Date: April 18, 2013
Original Effective Date: April 18, 2013
Publish Date: January 18, 2013

The majority of strokes are caused by thrombotic or embolic occlusion, and these frequently present as acute neurologic emergencies.  Tissue plasminogen activator (tPA), given intravenously within three hours of symptom onset, is approved by the U.S. Food and Drug Administration (FDA) for treatment of acute ischemic strokes.  Mechanical embolectomy is being studied as another method of stroke treatment.

The acute brain injury of stroke has two major types: ischemic and hemorrhagic.  Of patients with stroke presenting to the emergency department, approximately 80% will be diagnosed with ischemic brain injury.  Distinguishing between these types of stroke is important because the established treatments for each are significantly different.  The focus of treatment in ischemic stroke is reperfusion of hypoxic brain tissue, while the focus in hemorrhagic stroke is correction of the condition which led to bleeding.  If the underlying cause of ischemia is systemic hypotension, this must be corrected.  Far more commonly, however, a clot occluding an intracranial vessel is the cause of ischemic stroke.  Recanalization of the vessel, particularly in the first few hours after occlusion, has been shown to reduce rates of disability and death.

While spontaneous thrombolysis does occur, treatment of ischemic stroke has focused on the use of intravenous tPA to promote dissolution of the clot and subsequent restoration of blood flow to the ischemic area of the brain.  Reperfusion benefits decrease over time; infarcted brain tissue will not recover.  Because tPA is associated with an increased risk of intracranial bleeding, it is contraindicated in hemorrhagic stroke and in some ischemic stroke patients in which the risk of bleeding outweighs potential benefit, such as those with mild or resolving symptoms, hypocoagulable state, or advanced age.

Intravenous tPA has improved outcomes for many, but not all, ischemic stroke patients.  Researchers have studied intra-arterial tPA, transcranial ultrasound energy, and mechanical clot destruction or clot removal (mechanical embolectomy) as an alternative, or second line, to the established intravenous tPA therapy.  Clots can be defined as located in large or small vessels.  Large intracranial arteries include the internal carotid, Circle of Willis and the first two branches of the anterior (A1 and A2), middle (M1 and M2), and posterior (P1 and P2) cerebral arteries.  These can be accessed with a catheter; further branches of the cerebral circulation are defined as small vessels and are too tortuous to be mechanically accessed with available technology.  Two devices are discussed in this medical policy, the Merci® Retriever and Penumbra System®.  With the Merci® device, a microcatheter is passed through the thrombus from a larger, percutaneous catheter positioned proximal to the occlusion.  A helical snare is deployed, and the catheter and clot are withdrawn together.  With the Penumbra® device, an opening at the tip of the percutaneous catheter utilizes suction to extract the clot.

In August 2004, “The Merci® Retriever” (Concentric Medical, Mountainview, CA) was cleared by the FDA through the 510(k) process.  This device was judged equivalent to a predicate device, the Concentric Retriever which was indicated for endovascular foreign body removal.  The FDA clearance indicated that the MERCI Clinical Study established that no new issues of safety and effectiveness exist when the Merci Retriever is used for thrombus removal versus foreign body removal from the neurovasculature.  A modified Merci Retriever also manufactured by Concentric Medical, Inc., received 510(k) clearance from the FDA in May 2006.  The clearance notes that the Modified Merci Retriever is intended to restore blood flow in the neurovasculature by removing thrombi in patients experiencing ischemic stroke.  Patients who are ineligible for intravenous tPA or who fail intravenous tPA therapy are candidates for treatment.  The device also has clearance for retrieval of foreign bodies misplaced during interventional radiologic procedures in the neuro, peripheral, and coronary vasculature.

In December 2007, “The Penumbra System®” (Penumbra Inc., Alameda, CA) was cleared through the 510(k) process.  The FDA determined that this device was substantially equivalent to existing devices for use in the revascularization of patients with acute ischemic stroke secondary to intracranial large vessel occlusive disease (in the internal carotid, middle cerebral - Ml and M2 segments, basilar, and vertebral arteries) within eight hours of symptom onset.



Blue Cross and Blue Shield of Montana considers mechanical embolectomy experimental, investigational and unproven for the treatment of acute stroke.

Federal Mandate

Federal mandate prohibits denial of any drug, device or biological product fully approved by the FDA as investigational for the Federal Employee Program (FEP). In these instances coverage of these FDA-approved technologies are reviewed on the basis of medical necessity alone.

Rationale for Benefit Administration

This medical policy was developed through consideration of peer reviewed medical literature, FDA approval status, accepted standards of medical practice in Montana, Technology Evaluation Center evaluations, and the concept of medical necessity. BCBSMT reserves the right to make exceptions to policy that benefit the member when advances in technology or new medical information become available.

The purpose of medical policy is to guide coverage decisions and is not intended to influence treatment decisions. Providers are expected to make treatment decisions based on their medical judgment. BCBSMT recognizes the rapidly changing nature of technological development and welcomes provider feedback on all medical policies.

When using this policy to determine whether a service, supply or device will be covered, please note that member contract language will take precedence over medical policy when there is a conflict.


Baker et al. published a systematic review of neurothrombectomy devices for the treatment of acute ischemic stroke in 2011.  This review included any human studies that reported on outcomes following thrombectomy.  A total of 87 articles met the inclusion criteria, 62 of these were case series or case reports, 18 were prospective single-arm studies and seven were retrospective single-arm studies.  The rate of successful recanalization, defined as Thrombolysis in Myocardial Infarction (TIMI) flow grade of two or two, ranged from 43-100% across all studies.  Higher rates of recanalization were reported with the Penumbra System (83-100%) compared to either the Merci Retriever (43-78%) or other devices (50-90%).  Clinical effectiveness was determined by a post-treatment Rankin score of 0-2, a measure that was available in 17/25 studies.  There was a wide range of clinical effectiveness, from 15% to 60% of treated patients.  The most common adverse events from treatment were intracranial hemorrhage, and vessel perforation/dissection.  The rate of symptomatic intracranial hemorrhage ranged from 0-25%, and the rate of asymptomatic intracranial hemorrhage ranged from 1-43%.  Target vessel perforation or dissection was reported by less than half the studies, with rates ranging from 0-7%.

In 2008, Stead and colleagues conducted a systematic review and meta-analysis of percutaneous clot removal devices.  Of note, the authors were unable to obtain individual patient data for the Mechanical Embolus Removal in Cerebral Ischemia (Merci) trial described below; those 151 patients were not included in the meta-analysis.  The authors identified 14 case series and 8 case reports with a total of 147 patients.  The Merci® Retriever was utilized for 17 patients; a variety of mechanical embolectomy devices (with coronary or peripheral vascular indications) were used in other studies.  Patients were similar in that they were diagnosed with large vessel disease but were otherwise heterogeneous.  Emboli were accessible in 85% of patients.  In all studies, post-procedural blood flow was measured using the TIMI grade.  A flow rate representing full recanalization was achieved in 67 of 146 patients (45.6%).  Partial or full recanalization was achieved in 101 of 146 patients (68.7%).  When embolectomy methods were compared, superiority of one device over others was not demonstrated in accessing the lesion, retrieving the clot, or in clinical outcome.  Pooled data were compared to the placebo arm and intra-arterial thrombolysis arm of the PROACT II (Prolyse in Acute Cerebral Thromboembolism II) study, comparing intravenous and intra-arterial tPA use.  Partial or full

recanalization rate in the placebo group was 18%; the rate was 66% in the intra-arterial group.  However, the authors acknowledge that 81 patients (55.1%) in the meta-analysis also received thrombolytics, and the comparative role of thrombolytics against mechanical thrombectomy is unknown.  The authors concluded that there was a modest survival benefit in the mechanical thrombectomy patients compared to historical controls, while recognizing the limitation of small study sizes and non-randomized comparator groups.

Two single-arm studies were published in 2011 that made comparisons with historical controls.  Alexandrov et al. treated 125 patients presenting with acute stroke with the Penumbra System.  Outcomes of embolectomy were compared with historical controls that were treated with IV tPA in a previous clinical trial.  Embolectomy patients had a similar stroke severity score, but were younger and had a longer time from onset of treatment to symptoms.  The rate of recanalization was 82% for the embolectomy patients; this was higher than the 40% recanalization rate reported with TPA.  However, mortality at three months was higher in the embolectomy group compared to TPA (32.8% vs. 14.1%, p=0.008), and the rate of favorable functional outcome was lower (25% vs. 39%, p=0.046).

Taschner et al. treated 22 consecutive patients with acute ischemic stroke and a National Institutes of Health (NIH) stroke scale score of at least seven with the Penumbra system.  Outcomes from this group of patients were compared to patients treated with TPA who were matched for stroke score and location. Recanalization with embolectomy was successful in 25/32 target vessels (78%) compared to 17/32 (53%) with TPA.  A favorable outcome, defined as a stroke score of 0-1 or an improvement of at least ten points, was present in 2/20 (10%) of patients treated with embolectomy, compared with 7/20 (35%) treated with TPA.

In 2005, Smith and colleagues reported the results of the MERCI trial.  This was a multicenter (25 centers), prospective nonrandomized trial of this device for patients with symptoms of acute stroke for less than eight hours who were not candidates for thrombolytic therapy, either because of contraindications (approximately 25%) or because symptoms were present for more than three hours.  A total of 1,809 patients were screened to identify the 151 patients enrolled in the trial.  Chief reasons for exclusion were NIHSS (National Institutes of Health [NIH] stroke score) too low or improving, intracranial hemorrhage, or inability to obtain consent.  Of the 151 patients, 141 had the device deployed.  Recanalization was achieved in 46% (69/151) of patients on an intent-to-treat analysis and in 48% (68/141) of patients in whom the device was employed.  (One patient had “spontaneous” recanalization.)  The status of vessels distal to the treatable vessel was not considered in the recanalization rate.  Clinically significant procedural complications occurred in 10 patients (7.1%), and symptomatic intracranial hemorrhages were observed in eleven (7.8%).  Good neurological outcomes were more frequent at 90 days in those with successful recanalization compared to those with unsuccessful recanalization (46% vs. 10%, respectively; p<0.0001) and mortality was less (32% vs. 54%, respectively; p=0.01).  Of note, in the study, up to six passes could be made to remove the clot, and at least two devices were used in each patient in the MERCI trial.  The MERCI investigators compared their patients to the placebo arm of the PROACT II study to determine safety and efficacy of mechanical embolectomy.

In 2008, Smith and colleagues reported the results of the Multi MERCI trial, a prospective, international, multicenter, single-arm study.  As with the MERCI trial, patients were eligible if they presented with eight hours of onset of symptoms from large-vessel stroke.  In addition to the MERCI indications, patients were eligible if they received intravenous tPA but failed to completely recanalize their occluded vessel.  A total of 1,088 patients were screened to enroll 177 patients.  Of these, 164 patients had the device deployed.  A newer generation device was available for 131 of the 164 patients, and patients could be treated with adjuvant intra-arterial tPA, depending on the operator.  Recanalization was achieved in 55% (90/164) on intention-to-treat analysis, and in 58% (88/151) in the per-protocol analysis.  Two patients recanalized spontaneously.  Procedural complications occurred in nine patients (5.5%), and symptomatic intracranial hemorrhage was observed in 16 (9.8%).  In comparison with patients who did not recanalize, 90-day neurological outcomes favored patients in whom flow was restored (49% vs. 10%, respectively; p=0.001).  An average of three attempts was made on each patient.  This report also compares their results to the placebo arm of the PROACT II trial.

To determine if this treatment improves net outcomes (considers both benefits and risk) in stroke, there must be a comparison with an appropriate control group.  It is not clear what the recanalization rate would have been without embolectomy in those patients who had successful clot removal.  Concurrent control groups are also important to evaluate possible unexpected events when intravascular devices are used that may damage arterial endothelium.

Concerns have been raised about using the patients from the PROACT II study as historic controls.  These concerns include the fact that the MERCI trial included patients with different types of occlusions; PROACT II had M1 and M2 occlusions while the MERCI trial also included internal carotid and vertebral basilar systems.  Questions have also been raised about the outcome measure of recanalization since the MERCI study did not look for distal emboli.  Also, there are concerns about the reliability of the TIMI perfusion score as reported in this trial, and thus questions about whether the recanalization rates can be compared among studies.

In 2010, Shi and colleagues published a retrospective subgroup analysis of data from the MERCI and Multi MERCI trials, comparing patients with middle cerebral artery occlusions of the first (M1) or second (M2) large vessel branch.  The relatively smaller M2 occlusions were associated with higher recanalization rates.  Recanalization was also improved in patients who had received intravenous tPA.  However, an accompanying editorial points out that no difference in 90-day morbidity or mortality was noted.  Molina further comments that in published literature of patients undergoing mechanical embolectomy, recanalization is often achieved without improvement in clinical outcomes at three months post-procedure.  Rates of “futile” recanalization range from 26% to 51% in various studies.

In 2007, Flint and colleagues reported on a study of 80 patients who had use of the MERCI device for occlusion of the intracranial internal carotid artery.  Forty-seven of these patients were from the MERCI trial, and 33 were from the Multi-MERCI study, which included patients who had been previously treated with intravenous tPA.  Of these 80 patients, 53% had internal carotid artery (ICA) recanalization with the MERCI device and 63% had ICA recanalization with the MERCI device and adjunctive treatment.  Successful clinical outcomes as defined by the study were more common in study patients who had successful recanalization than in study patients for whom recanalization was not successful.  As noted above, this was a single-arm study.

In 2009, Lin and colleagues reported on a case series of 75 patients with internal carotid artery terminus occlusion.  The team performed a retrospective analysis of ischemic stroke patients at their institution who received a variety of treatment options, alone or in combination.  Primary outcome measure was recanalization rate.  Lowest recanalization rate was observed with intra-arterial thrombolytics alone at 17.6% (3/17), while Merci embolectomy with intra-arterial thrombolytics was associated with the highest recanalization rate at 85.7% (18/21).  The small sample sizes, as well as non-randomized and retrospective design preclude definitive conclusions from these results.

Published articles identified report small (approximately 25 patients) non-comparative results from single centers: University of California at Los Angeles (UCLA) and University of Tennessee.  The published evidence continues to describe case series and often includes only intermediate outcomes, such as vessel recanalization.  In addition, results from a trial using the Penumbra System® on 23 enrolled patients (21 target vessels) are available.

An ongoing trial, the Magnetic Resonance and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE) study, being sponsored through the National Institutes of Neurological Disorders and Stroke, is underway.  This study randomly assigns patients with stroke seen within eight hours to either medical therapy or embolectomy.  This trial should provide important comparative data.

Practice Guidelines and Position Statements

The 2007 guideline for early management of ischemic stroke from the American Heart Association and others gives a class II B recommendation (usefulness/effectiveness is uncertain) to the use of the mechanical embolectomy devices.  This guideline notes that the utility of the devices in improving outcomes after stroke is unclear.  This position was reiterated in 2009 in a scientific statement from the American Heart Association.  In this scientific statement the following recommendations are made:

  • Although the Concentric Merci device can be useful for extraction of intra-arterial thrombi in appropriately selected patients, the utility of the device in improving outcomes after stroke remains unclear (Class IIb, Level of Evidence B).
  • The usefulness of other endovascular devices is not yet established, but they may be beneficial (Class IIb, Level of Evidence C).


The scientific evidence does not permit conclusions concerning the effect of mechanical embolectomy on patient outcomes.  The existing observational data are not sufficient to determine whether this approach improves net health outcomes.  Single-arm studies report a high rate of recanalization of the infarcted vessel, however only a subset of patients with successful recanalization achieves good functional outcomes.  Comparison with historical controls receiving thrombolysis suggests higher rates of recanalization with embolectomy, but lower rates of good functional outcomes.  Given the lack of controlled studies to assess the impact of this treatment compared with alternatives, the use of embolectomy devices for acute stroke is considered experimental, investigational and unproven.


Disclaimer for coding information on Medical Policies

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy.  They may not be all-inclusive.

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers.  Only the written coverage position in a medical policy should be used for such determinations.

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps. 

ICD-9 Codes
I63.00-I63.9, 03CG3ZZ, 03CG4ZZ, 03CH3ZZ, 03CH4ZZ, 03CJ3ZZ, 03CJ4ZZ, 03CK3ZZ, 03CK4ZZ, 03CL3ZZ, 03CL4ZZ, 03CM3ZZ, 03CM4ZZ, 03CN3ZZ, 03CN4ZZ, 03CP3ZZ, 03CP4ZZ, 03CQ3ZZ, 03CQ4ZZ, 03CR3ZZ, 03CR4ZZ, 03CS3ZZ, 03CS4ZZ, 03CT3ZZ, 03CT4ZZ, 03CU3ZZ, 03CU4ZZ, 03CV3ZZ, 03CV4ZZ
ICD-10 Codes
I63.00-I63.9, 03CG3ZZ, 03CG4ZZ, 03CH3ZZ, 03CH4ZZ, 03CJ3ZZ, 03CJ4ZZ, 03CK3ZZ, 03CK4ZZ, 03CL3ZZ, 03CL4ZZ, 03CM3ZZ, 03CM4ZZ, 03CN3ZZ, 03CN4ZZ, 03CP3ZZ, 03CP4ZZ, 03CQ3ZZ, 03CQ4ZZ, 03CR3ZZ, 03CR4ZZ, 03CS3ZZ, 03CS4ZZ, 03CT3ZZ, 03CT4ZZ, 03CU3ZZ, 03CU4ZZ, 03CV3ZZ, 03CV4ZZ
Procedural Codes: 37799
  1. Furlan, A., Higashida, R., et al.  Intra-arterial prourokinase for acute ischemic stroke. The PROACT II study: a randomized controlled trial. Journal of American Medical Association (1999) 282(21):2003-11.
  2. Smith, W.S., Sung, G., et al.  Safety and efficacy of mechanical embolectomy in acute ischemic stroke: Results of the MERCI trial. Stroke (2005) 36(7):1432-8.
  3. Becker, K.J., Brott, T.G.  Approval of the MERCI clot retriever: a critical view. Stroke (2005) 36(2):400-3.
  4. FDA – 510K Summary for Merci® Retriever.  Food and Drug Administration (2006). Available at   (accessed – 2009 January).
  5. Tomsick, T.A.  Mechanical embolus removal: a new day dawning. Stroke (2005) 36(7):1439-40.
  6. Kim, D., Jahan, R., et al.  Endovascular mechanical clot retrieval in a broad ischemic stroke cohort. AJNR American Journal of Neuroradiology (2006) 27(10):2048-52.
  7. Devlin, T.G., Baxter, B.W., et al.  The Merci Retrieval System for acute stroke: the Southeast Regional Stroke Center experience. Neurocritical Care (2007) 6(1):11-21.
  8. Flint, A.C., Duckwiler, G.R., et al. Mechanical thrombectomy of intracranial internal carotid occlusion: pooled results of the MERCI and Multi MERCI Part I trials. Stroke (2007) 38(4):1274-80.
  9. Adams HP, Jr., del Zoppo G, Alberts MJ et al. Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: The American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists.  Circulation 2007; 115(20):e478-534.
  10. Smith WS, Sung G, Saver J et al. Mechanical thrombectomy for acute ischemic stroke: final results of the Multi MERCI trial. Stroke 2008; 39(4):1205-12.
  11. Bose A, Henkes H, Alfke K et al. The Penumbra System: a mechanical device for the treatment of acute stroke due to thromboembolism. AJNR Am J Neuroradiol 2008; 29(7):1409-13.
  12. Stead LG, Gilmore RM, Bellolio MF et al. Percutaneous clot removal devices in acute ischemic stroke: a systematic review and meta-analysis. Arch Neurol 2008; 65(8):1024-30.
  13. Lin R, Vora N, Zaidi S et al. Mechanical approaches combined with intra-arterial pharmacological therapy are associated with higher recanalization rates than either intervention alone in revascularization of acute carotid terminus occlusion. Stroke 2009; 40(6):2092-7.
  14. Restrepo L, Bang OY, Ovbiagele B et al. Impact of hyperlipidemia and statins on ischemic stroke outcomes after intra-arterial fibrinolysis and percutaneous mechanical embolectomy.
  15. Cerebrovasc Dis 2009; 28(4):384-90.
  16. Meyers PM, Schumacher HC, Higashida RT et al. Indications for the performance of intracranial endovascular neurointerventional procedures: a scientific statement from the American Heart Association Council on Cardiovascular Radiology and Intervention, Stroke Council, Council on Cardiovascular Surgery and Anesthesia, Interdisciplinary Council on Peripheral Vascular Disease, and Interdisciplinary Council on Quality of Care and Outcomes Research. Circulation 2009; 119(16):2235-49.
  17. Abou-Chebl A. Endovascular treatment of acute ischemic stroke may be safely performed with no time window limit in appropriately selected patients. Stroke 2010; 41(9):1996-2000.
  18. Castano C, Dorado L, Guerrero C et al. Mechanical thrombectomy with the Solitaire AB device in large artery occlusions of the anterior circulation: a pilot study. Stroke 2010; 41(8):1836-40.
  19. Abelson M, Roos J. Mechanical embolectomy for large vessel ischemic strokes: A cardiologist's experience. Catheter Cardiovasc Interv 2010.
  20. Shi ZS, Loh Y, Walker G et al. Clinical outcomes in middle cerebral artery trunk occlusions versus secondary division occlusions after mechanical thrombectomy: pooled analysis of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) and Multi MERCI trials. Stroke 2010; 41(5):953-60.
  21. Molina CA. Futile recanalization in mechanical embolectomy trials: a call to improve selection of patients for revascularization. Stroke 2010; 41(5):842-3.
  22. Baker WL, Colby JA, Tongbram V et al. Neurothrombectomy devices for the treatment of acute ischemic stroke: state of the evidence. Ann Intern Med 2011; 154(4):243-52.
  23. Alexandrov AV, Schellinger PD, Saqqur M et al. Reperfusion and outcomes in Penumbra vs. systemic tissue plasminogen activator clinical trials. Int J Stroke 2011; 6(2):118-22.
  24. Taschner CA, Treier M, Schumacher M et al. Mechanical thrombectomy with the Penumbra recanalization device in acute ischemic stroke. J Neuroradiol 2011; 38(1):47-52.
  25. Mechanical Embolectomy for Treatment of Acute Stroke.  Chicago, Illinois: Blue Cross Blue Shield Association Medical Policy Reference Manual (2011 September) Medicine 2.01.76.
January 2013 New 2013 BCBSMT medical policy.  Considered investigational.
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Mechanical Embolectomy for Treatment of Acute Stroke