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Filters, extractors and other devices in acute myocardial infarction
  1. Charles J Knight
  1. Correspondence to Dr Charles J Knight, The London Chest Hospital, Barts and the London NHS Trust, Bonner Road, London E2 9JX, UK; charles.knight{at}

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The principal cause of acute ST segment elevation myocardial infarction (STEMI) is intracoronary plaque rupture with associated occlusive thrombus. Primary percutaneous coronary intervention (PCI) is now established as the optimum treatment for STEMI and for the majority of patients treated in this fashion coronary flow in the infarct-related vessel is restored and myocardial damage limited. However, despite the effective treatment of epicardial coronary obstruction, adequate flow is not restored in a minority of patients—the no-reflow phenomenon. This is perhaps not surprising given the inevitable plaque disruption consequent upon the intracoronary passage of wire, balloon and stent with the potential for embolisation of thrombotic and atherosclerotic debris. The no-reflow phenomenon is, as one would expect, a poor prognostic sign.1 As distal embolisation is an important contributor to the development of no-reflow it is therefore logical to try to reduce the risk of the phenomenon with thrombectomy (mechanical and manual) and distal protection (distal occlusion and filters) as adjuncts to primary PCI. It should be recognised that effective protection against distal embolisation will not prevent all cases of no-reflow as the pathology of the syndrome also includes ischaemia-reperfusion injury and microcirculatory injury. A combination of both pharmacological and physical measures stands the best chance of reducing the adverse prognostic impact of the phenomenon. Accepting this limitation, what do we know of the efficacy of thrombectomy and distal protection in patients as adjunctive treatments during primary PCI in patients presenting with STEMI?

Initial studies were not encouraging. Two large trials published in 2005–6 showed that neither a distal occlusive protection device2 nor a mechanical thrombectomy device3 were effective in reducing infarct size or improving clinical outcomes in patients undergoing primary/rescue PCI. Other …

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  • Competing interests None.

  • Provenance and peer review Commissioned; not externally peer reviewed.