PRoximal Embolic Protection in Acute MI and Resolution of ST-Elevation - PREPARE


A number of studies have demonstrated the utility of adjunctive thrombectomy, especially of thrombus aspiration devices, over primary percutaneous coronary intervention (PCI) in patients presenting with ST-elevation myocardial infarction (STEMI). The PREPARE trial was designed to study the safety and efficacy of the Proxis device (combined thrombus aspiration and proximal embolic protection device) compared with primary PCI alone in patients presenting with STEMI within 6 hours of symptom onset.


Primary PCI, along with the use of the Proxis device, would be safe and efficacious compared with primary PCI alone in patients with STEMI.

Study Design

Patients Enrolled: 284
Mean Follow Up: 30 days
Mean Patient Age: 60 years
Female: 20
Mean Ejection Fraction: 51%

Patient Populations:

  • Consecutive STEMI patients ≤6 hours
  • ST-segment elevation ≥2 mm in ≥2 leads
  • TIMI flow grade 0 to 1 at first angiogram
  • Coronary anatomy suitable for Proxis
  • Electrocardiogram suitable for STR evaluation


  • Recurrence of MI in same area
  • Prior coronary artery bypass grafting or lytics

Primary Endpoints:

  • STR over time

Secondary Endpoints:

  • TIMI graded flow
  • Myocardial blush grade
  • Angiographic signs of distal embolization
  • Composite of death, MI, target vessel revascularization, and stroke at 30 days

Drug/Procedures Used:

Primary PCI with the Proxis device (combined thrombus aspiration and proximal embolic protection device) or primary PCI alone

Concomitant Medications:

Unfractionated heparin 70 U/kg, aspirin 300 mg, and clopidogrel 600 mg in all patients; glycoprotein IIb/IIIa inhibitors in 39%

Principal Findings:

A total of 284 patients were randomized, 141 to Proxis plus primary PCI, and 143 to primary PCI alone. Baseline characteristics were fairly similar between the two groups. About 8% of the patients had diabetes. The median duration of symptoms prior to PCI was about 161 minutes. Multivessel disease was noted in about 32% of the patients, and the right coronary artery was the culprit vessel in about 60% of the patients. About 98% of the patients had TIMI 0 or 1 flow on presentation.

The Proxis device could be successfully placed in 94% of the patients in that arm, and pathology confirmed thrombus in 75% of these patients. Additional thrombus aspiration was necessary in about 6% of the patients in both arms.

The incidence of >70% ST-resolution (STR) was significantly higher in the Proxis arm compared with the primary PCI alone arm only in the immediate post-PCI period (66% vs. 50%, p = 0.009). No difference was noted at 30 minutes (75% vs. 66%, p = 0.17), 90 minutes (81% vs. 74%, p = 0.23), or 120 minutes (78% vs. 76%, p = 0.88). Similarly, the mean % STR was higher in the Proxis arm only immediately post-PCI (73% vs. 63%, p = 0.009), but not at 30 minutes (p = 0.30), 90 minutes (p = 0.17), or 120 minutes (p = 0.48).

The incidence of post-PCI TIMI grade 3 flow was similar in both arms (93% vs. 87%, p = 0.06). Similarly, a myocardial blush grade of 3 was attained by 81% in the Proxis arm, compared with 83% in the primary PCI arm (p = 0.93). Despite the employment of the device, distal embolization occurred in 10% of the patients in the Proxis arm, compared with 14% in the primary PCI (no device) arm (p = 0.36). Major adverse cardiac events (MACE) at 30 days were similar between the two arms (4% vs. 7%), as were mortality, MI, and stroke.


The results of the PREPARE trial indicate that the use of the Proxis device in adjunct with PCI in patients with STEMI is associated with a higher incidence of >70% STR immediately post-PCI, compared with primary PCI alone. This difference was not noted thereafter up to 2 hours of follow-up. Similarly, there was no difference in myocardial blush grade or clinical outcomes at 30 days between the two arms.

This study is similar to other studies, which have indicated that of the mechanical thrombectomy devices, thrombus aspiration devices may be associated with a clinical benefit and more complete STR compared with primary PCI alone, whereas embolic protection devices have a neutral effect on these outcomes.

A significant limitation of these devices is that they can be deployed only if the anatomy is suitable for deployment. In this trial, more than 60% of the time, the right coronary artery was the culprit vessel, which is different than routine practice, where the left anterior descending artery is usually the culprit vessel.


Haeck JD, Koch KT, Gu YL, et al. Proximal embolic protection in patients undergoing primary angioplasty for acute myocardial infarction (PREPARE): core lab adjudicated angiographic outcomes of a randomised controlled trial. Neth Heart J. 2010 Nov;18(11):531-6.

Presented by Dr. Karel T. Koch at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2008), Washington, DC, October 2008.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Stable Ischemic Heart Disease, Aortic Surgery, Cardiac Surgery and SIHD

Keywords: Myocardial Infarction, Stroke, Follow-Up Studies, Embolic Protection Devices, Employment, Thrombectomy, Coronary Thrombosis, Electrocardiography, Coronary Vessels, Angioplasty, Balloon, Coronary, Diabetes Mellitus

< Back to Listings