Comparison of Angiojet Rheolytic Thrombectomy before direct infarct artery stenting with direct stenting alone in patients with Acute Myocardial Infarction

Alfredo E. Rodriguez

    BACKGROUND: Occlusive thrombus complicating a ruptured atherosclerotic plaque is the most common physiopathological pathway of acute myocardial infarction (AMI) and primary percutaneous intervention (PCI) is the first choice for the acute treatment of this pathology. One of the most frequent complications of this technique is the distal atherothrombotic embolization, resulting in a failed myocardial reperfusion. There are several randomized trials assessing the efficacy of embolic protection or thrombectomy devices in improving myocardial reperfusion and metanalyses derived from them have conflicting results, however only two studies used the rheolytic thrombectomy (RT) device with contradictory outcomes.

    OBJECTIVE: The purpose of this trial was to determine whether RT before direct stenting (DS) alone results in an improved reperfusion and clinical outcome in patients with AMI.

    METHODS: This is a randomized, multicenter, international, two-arm, prospective study sponsored by Medrad Interventional/ Possis (Minneapolis, Minnesota). All patients with ST elevation myocardial infarction and evidence of thrombus grade 3 to 5 with reference vessel diameter > 2.5 mm were eligible without restrictions based of age or clinical status at presentation. Clinical exclusion criteria were thrombolysis for current AMI; major surgery < 6 weeks; stroke; <30 days or any history of hemorrhagic stroke; comorbidities with expected survival < 1 year and participation in another study. Primary endpoints were early ST segment resolution thirty minutes after PCI and 99 Tcsestamibi infarct size measurements a month after randomization. An alpha value=0.05 achieved by either both coprimary surrogate endpoints or an alpha value= 0.025 for a single primary surrogate end point would be considered evindence of statistical significance. Other surrogate end points were thrombolysis in myocardial infarction (TIMI) flow grade 3, corrected TIMI frame count, and TIMI grade 3 blush. All angiographic markers of reperfusion and quantitative coronary angiographic analysis were performed at central core laboratory by physicians not involved in the study. Clinical secondary end points were composite of major adverse cardiovascular events (MACE) at 1, 6 and 12 months.

    RESULTS: From December 2005 to September 2009, 501 patients were randomly assigned to RT before DS or to DS alone. Mean age was 63.7 +/- 11.9 years, 38% patients had anterior AMI and 4% were in cardiogenic shock due to left ventricular failure at admission. ST segment resolution was more frequent in the RT arm as compared with the DS alone arm (85.8% vs 78.8%, P=0.043) while no differences were shown in the other surrogate end points. No major procedural complications occurred in the RT arm, whereas 1 patient in DS alone arm had a coronary perforation. One month MACE rate was 3.1% in RT arm vs. 6.9% in DS arm (P=0.05) and this difference between groups increases at 6 months (11.2% vs. 19.4%, P=0.01) and maintained at 12 months (14.9% vs 22.7%, P=0.03). One year Kaplan Meier analysis for freedom from MACE were 85.2 +/- 2.3% for the RT arm, and 75 +/- 3.1% for the DS alone arm (P=0.009).

    CONCLUSIONS: Although the primary efficacy end points were not met, the results of this study support the use of RT before infarct artery stenting in patients with AMI and evidence of coronary thrombus, however the routine use in AMI should be confirmed by larger trials. Complete one year clinical results will be available at the time of this presentation.