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Table of Contents

• Focus of Research for Clinicians
• Background Information
• Conclusion
• Clinical Bottom Line
• Glossary of Terms
• Gaps in Knowledge
• Figure 1. Explanation of Thrombectomy and Embolic Protection Devices Studied
• Ordering Information
• Source

Focus of Research for Clinicians

A systematic review of 175 clinical studies published between January 1996 and March 2011 sought to determine the comparative effectiveness, benefits, and adverse effects of adjunctive devices to remove thrombi or protect against embolization in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI) of native vessels. This summary is provided to assist in decisionmaking along with consideration of a patient’s values and preferences. Reviews of evidence should not be construed to represent clinical recommendations or guidelines. The full report is available at www.effectivehealthcare.ahrq.gov/thrombusacs.cfm.

Background Information

Outcomes of PCI have improved with the use of coronary stents and adjunctive pharmacologic agents. However, distal embolization caused by the dislodgement of atherothrombotic material from coronary lesions during PCI can lead to the “no-reflow phenomenon,” which results in significantly higher morbidity and mortality for patients with ACS. Several adjunctive devices have been developed to remove thrombi and to protect against distal embolization during PCI (Figure 1). They are classified into catheter aspiration thrombectomy, mechanical thrombectomy, and embolic protection devices. The comparative effectiveness and the risk differences between these devices in patients with ACS undergoing PCI for native coronary arteries are not well established.

Conclusion

Catheter aspiration thrombectomy reduces the occurrence of major adverse cardiovascular events, distal embolization, and no reflow and improves ST-segment elevation resolution and coronary flow when used as an adjunctive therapy for patients with ST-segment elevation myocardial infarction (STEMI) who are undergoing primary PCI. Evidence does not support benefits from mechanical thrombectomy or embolic protection devices, which appear to prolong procedure time. Current evidence is too limited to permit conclusions about the comparative benefits and harms of these devices with respect to final health outcomes and adverse events.

Clinical Bottom Line

Devices to remove thrombi or protect against distal embolization in patients with ACS who were undergoing PCI of native vessels were compared with standard PCI.

Strength of Evidence Scale

High:
There are consistent results from good-quality studies. Further research is very unlikely to change the conclusions.

Moderate:
Findings are supported, but further research could change the conclusions.

Low:
There are very few studies, or existing studies are flawed.

Insufficient:
Research is either unavailable or does not permit estimation of a treatment effect.

Glossary of Terms

Myocardial blush grade (MBG): An angiographic method of grading myocardial tissue perfusion ranging from grade 0 to grade 3.

Thrombolysis in myocardial infarction (TIMI) blood flow: An angiographic method of grading blood flow in an epicardial coronary artery with a range from grade 0 to grade 3.

Gaps in Knowledge

• Direct comparative randomized controlled trials are needed that compare one thrombectomy or embolic protection device with another and evaluate final health outcomes.
• Studies examining final health outcomes and using longer followup data are needed to fully determine the comparative effectiveness, benefits, and harms of adjunctive thrombectomy and embolic protection devices in patients with ACS who are undergoing PCI.

Figure 1. Explanation of Thrombectomy and Embolic Protection Devices Studied

Figure 1. Explanation of Thrombectomy and Embolic Protection Devices Studied. Numerous adjunctive devices have been developed to help improve clinical outcomes by removing thrombi and to protect against distal embolization during PCI. These devices utilize different technologies and are broadly classified as catheter aspiration, mechanical thrombectomy, or embolic protection devices (i.e., distal or proximal embolic balloon or distal filter protection devices).

(A) Catheter aspiration thrombectomy uses a catheter that is advanced over a guidewire to the thrombus where manual syringe suction is used to aspirate the debris.

(B) Mechanical thrombectomy devices apply energy through saline jets or a rotating catheter head to facilitate breakup of the thrombus before its active aspiration.

(C) Proximal embolic protection devices employ an occlusion balloon advanced over a guidewire proximal to the thrombus to trap and aspirate thrombotic debris released during angioplasty and stenting procedures.

(D and E) Distal embolic protection devices are similar to proximal devices, except they employ an occlusion balloon (D) or filter (E) advanced over a guidewire distal to the thrombus to trap and aspirate (balloon devices) or capture and retrieve (filter devices) thrombotic debris released during angioplasty and stenting procedures.

Ordering Information

For electronic copies of this clinician research summary and the full systematic review, visit www.effectivehealthcare.ahrq.gov/thrombusacs.cfm. To order free print copies, call the AHRQ Publications Clearinghouse at 800-358-9295.

Source

The information in this summary is based on Adjunctive Devices for Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention, Comparative Effectiveness Review No. 42, prepared by the University of Connecticut/Hartford Hospital Evidence-based Practice Center under Contract No. 290-2007-10067-I for the Agency for Healthcare Research and Quality (AHRQ), December 2011. Available at www.effectivehealthcare.ahrq.gov/thrombusacs.cfm. 

This summary was prepared by the John M. Eisenberg Center for Clinical Decisions and Communications Science at Baylor College of Medicine, Houston, TX.

It was written by Andrea Humphries, Thomas Workman, Hani Jneid, and Michael Fordis. 

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