Distal Protection During Primary Percutaneous Coronary Intervention for ST-elevation Myocardial Infarction

Primary percutaneous coronary intervention (PCI) is the standard treatment strategy for patients with ST-elevation myocardial infarction (STEMI). However, despite the early restoration of epicardial artery flow, microvascular obstruction and reduced myocardial perfusion may occur. The " no-reflow " phenomenon is associated with a large infarct size and poor outcomes. The pathogenesis of no-reflow phenomenon is multi-factorial, which includes distal embolization, ischemia-reperfusion injury, and ischemic insult. There have been several attempts to prevent the no-reflow phenomenon. An early reperfusion to shorten the isch-emic time is pivotal to attenuate the ischemic insult and prevent no-reflow; however, the role of adjunctive pharmacological intervention, such as human atrial natriuretic peptide, or mechanical intervention, such as remote-/post-conditioning, in preventing the reper-fusion injury remains inconclusive. During PCI, intracoronary thrombus and ath-erosclerotic plaques are crushed and streamed down the coronary artery. The atherothrombotic debris can be detected as high-intensity transient signals using a Doppler guide wire, immediately after the balloon deflation 1). No-reflow phenomenon may occur, if the size and number of emboli are large enough to obstruct the coronary microcirculation. A thrombus aspiration device was developed to reduce the throm-bus burden that has the potency to become the source of emboli. Thrombus aspiration during PCI in Acute myocardial infarction Study (TAPAS) randomized 1,071 patients with STEMI to aspiration before stent-ing and conventional PCI. It was reported in 2008 that thrombus aspiration improved the myocardial perfusion after PCI and reduced the rate of 1-year cardiac death or re-infarction 2). The ACC/AHA 2011 PCI guidelines and 2013 STEMI guidelines recommended thrombus aspiration as belonging to Class a 3, 4). However, in 2015 the Trial of Routine Aspiration Thrombectomy with PCI versus PCI Alone in Patients with STEMI (TOTAL) that randomized patients with 10,732 failed to show any clinical benefits of aspiration thrombectomy and rather showed higher incidences of stroke in the thrombectomy group 5). The 2015 STEMI guidelines modified the recommendations for aspiration thrombectomy, i.e., routine aspiration was classified as Class and selec-tive/bailout aspiration as Class b 6). Distal protection prevents embolization of ath-erothrombotic debris during PCI. Filter-based devices are currently used, as they maintain perfusion during the procedure and have shown to be safe and effective in comparison to the balloon occlusion devices. PCI of saphenous vein graft (SVG) carries a significant risk of no-reflow, periprocedural MI, and adverse clinical events as the degenerated SVG lesions contain friable lipid-rich plaques. Saphenous vein graft Angioplasty Free of Emboli …