The Current Role of AngioJet Rheolytic Thrombectomy in Acute Myocardial Infarction

Acute myocardial infarction is often due to complete coronary occlusion and large thrombus burden. This is associated with poor clinical outcomes due to distal embolization, no-reflow, major adverse events, and death after angioplasty.^1,2 Many small studies have looked at the use of different devices to either remove the thrombus or to protect the distal artery from thrombus embolization. This is in hopes to improve clinical outcomes for the patient experiencing an acute myocardial infarction.

To remove thrombus from the coronary artery there are manual aspiration catheters as well as mechanical thrombectomy catheters. One such mechanical thrombectomy device is the AngioJet Rheolytic Thrombectomy System (Medrad Interventional/Possis, Minneapolis, Minnesota). This device injects pressurized saline into the coronary catheter through its distal tip, causing a low-pressure zone via the Bernoulli effect, which subsequently macerates and removes the thrombus. The saline and the macerated clot are then sucked back into the lumen and removed from the system.

Because the data on the benefit of thrombectomy in acute MI have been inconclusive, the use of thrombectomy devices is not routinely used in the acute MI population. In 2008, Grines et al performed a Bayesian meta-analysis to compare AngioJet thrombectomy to percutaneous coronary intervention (PCI) alone in patients presenting with acute myocardial infarction (MI). Given the mixed results seen in multiple small studies, they set out to examine the role of thrombectomy in acute MI. This paper is a summary of this meta-analysis and review of the data on AngioJet thrombectomy in acute MI.

Results of the Meta-Analysis

Grines et al reviewed the literature and found 125 publications that met inclusion criteria, 114 were studies looking at PCI alone in acute MI and 11 were the AngioJet experience in acute MI.³ There were 2 randomized controlled trials (RCT) and 9 non-RCT studies involving patients in the AngioJet literature and 81 studies in the PCI-alone literature. Included studies involved patients with at least 30 minutes but less than 24 hours of chest pain, ST-segment elevation, and either primary or rescue PCI with or without AngioJet. Glycoprotein IIb/IIIa inhibitors and thrombolytics were adjunctive medicines. Papers exclusively dealing with elderly patients > 75 years of age or cardiogenic shock were excluded.

The largest RCT on AngioJet, the AngioJet rheolytic thrombectomy in patients undergoing primary angioplasty for acute myocardial infarction (AiMI) study, involved 480 patients.⁴ Thrombus burden was not a criterion in this study. In this trial, AngioJet thrombectomy did not reduce infarct size, and there seemed to be a higher 30-day mortality rate and major adverse cardiac events (MACE) rate compared to PCI alone. Researchers speculated that this was due to the extremely low mortality rate seen in the PCI-only arm of this trial, and not due to increased mortality in the AngioJet arm, which was 4.6%.

However, the procedure for thrombectomy in this study was to cross the lesion first and then turn on the thrombectomy device and pull back. Some have suggested that this technique may be associated with more distal embolization and is not the current method of choice. However, Antoniucci et al showed in a smaller RCT of 100 patients that rheolytic thrombectomy before stenting the infarct related artery was efficacious.⁵ Myocardial perfusion was improved as evidenced by more frequent ST resolution, lower TIMI frame counts, and smaller infarct size.

Grines et al’s meta-analysis found that the AngioJet group as a whole were higher-risk than the primary PCI group; more likely to need rescue procedures for failed thrombolysis; more likely to have been experiencing ongoing symptoms longer than the primary-only group; and were inevitably treated beyond 12 hours with AngioJet versus

Short-term MACE rates (defined as death, recurrent MI, stroke, or target-vessel revascularization) were similar between the 2 groups. Grines et al concluded that, even though the AngioJet group was a higher risk group (higher thrombus burden, more rescue PCI, longer symptom duration), it had similar outcomes to the primary-PCI group with regards to MACE rates, short-term mortality, and post-procedural TIMI 3 flow. In the PCI subgroup that required rescue due to failed thrombolytics, AngioJet performed better than primary PCI, exhibiting reduced mortality and increased TIMI 3 flow post-procedure.

Further Evidence

Since the publication of this meta-analysis, there have been 2 more meta-analyses on thrombectomy devices in general, the first of which is a review of the literature. The second is a prospective study comparing acute-MI patients with high thrombus burden who were treated with AngioJet thrombectomy and PTCA with acute-MI patients who were treated with PTCA only before the institution’s obtaining the AngioJet device.^6–9 In addition, the long-awaited JETSTENT trial was recently published; the data in its results were favorable toward the benefit of AngioJet thrombectomy in acute MI patients with large thrombus burden (see JETSTENT Trial Results: Impact on ST-Segment Elevation Myocardial Infarction Interventions on p. 24B).¹⁰

Burzotta et al looked at thrombectomy devices in general and only included the Antoniucci et al study on AngioJet. They concluded that the adjunct use of thrombectomy devices (especially manual aspiration) improved long-term clinical outcomes, especially if glycoprotein IIb/IIIa inhibitors were used.

The meta-analysis performed by Bavry et al included both RCT studies of AngioJet thrombectomy and concluded that mechanical thrombectomy may be harmful. However, the researchers did concede that this was based largely on the AiMI study which, as previously mentioned, had many limitations, including an unexpected low mortality rate in the control group.

The prospective study performed by Srinivasan et al was very encouraging as this was the first 1-year follow-up study looking at patients who had large thrombus burden during an acute MI and were treated with AngioJet thrombectomy and PCI. The AngioJet group had significantly reduced MACE, all-cause death, and cardiac death when compared to the PCI-only group. The AngioJet group also exhibited a decreased need for revascularization as compared to the PCI-alone group.

Conclusion

In our opinion, AngioJet thrombectomy has a place in the acute MI treatment armamentarium. Though it is not for all patients with acute MI, patients who are higher risk with large thrombus burden and treated with AngioJet, have at least comparable rates of MACE, mortality and TIMI-3 flow as those treated with PCI alone. This is most likely due to decreased embolization and better perfusion in the microvasculature. There also may be a benefit in long-term outcomes of AngioJet thrombectomy over PCI alone. The results of JETSTENT will hopefully further solidify the use of AngioJet in this patient population.

References

1. Gibson CM, Cannon CP, Murphy SA, et al. Relationship of the TIMI myocardial perfusion grades, flow grades, frame count, and percutaneous coronary intervention to long-term outcomes after thrombolytic administration in acute myocardial infarction. Circulation 2002;105:1909–1913.
2. Henriques JP, Zijlstra F, Ottervanger JP, et al. Incidence and clinical significance of distal embolization during primary angioplasty for acute myocardial infarction. Eur Heart J 2002;23:1112–1117.
3. Grines CL, Nelson TR, Safian RD, Hanzel G, Goldstein JA, Dixon S. A Bayesian meta-analysis comparing AngioJet thrombectomy to percutaneous coronary intervention alone in acute myocardial infarction. J Interv Cardiol 2008;21:459–482.
4. Ali A, Cox D, Dib N, et al. Rheolytic thrombectomy with percutaneous coronary intervention for infarct size reduction in acute myocardial infarction: 30-day results from a multicenter randomized study. J Am Coll Cardiol 2006;48:244–252.
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6. Bavry AA, Kumbhani DJ, Bhatt DL. Role of adjunctive thrombectomy and embolic protection devices in acute myocardial infarction: a comprehensive meta-analysis of randomized trials. Eur Heart J 2008;29:2989–3001.
7. Burzotta F, De Vita M, Gu YL, et al. Clinical impact of thrombectomy in acute ST-elevation myocardial infarction: an individual patient-data pooled analysis of 11 trials. Eur Heart J 2009;30:2193–2203.
8. De Rosa S, Cirillo P, De Luca G, et al. Rheolytic thrombectomy during percutaneous coronary intervention improves long-term outcome in high-risk patients with acute myocardial infarction. J Interv Cardiol 2007;20:292–298.
9. Srinivasan M, Rihal C, Holmes DR, Prasad A. Adjunctive thrombectomy and distal protection in primary percutaneous coronary intervention: impact on microvascular perfusion and outcomes. Circulation 2009;119:1311–1319.
10. Migliorini A, Stabile A, Rodriguez EA, et al. Comparison of angiojet rheolytic thrombectomy before direct infarct artery stenting with direct stenting alone in patients with acute myocardial infarction: the JETSTENT trial. J Am Coll Cardiol 2010 Jul 29. [Epub ahead of print]