Intracoronary Thrombectomy During Percutaneous Coronary Intervention in Acute Myocardial Infarction – Technology Showcase or True Need?

Abstract

1 Reference Section a report by D r D a r i u s z D u d e k , D r J a c e k L e g u t k o , R o m a n W o j d y l a , W a l d e m a r M i e l e c k i and K r z y s z t o f Z m u d k a Thrombectomy for patients with ST elevation myocardial infarction (STEMI) is an evolving issue. Randomised studies on suction and thrombectomy devices in a whole spectrum of STEMI patients provide conflicting results. New European Society of Cardiology (ESC) percutaneous coronary intervention (PCI) guidelines do not give definitive recommendations regarding the use of embolic protection devices for this group of patients. More randomised trials are needed; however, many operators expect beneficial clinical impact of easy-to-use manual thrombectomy devices in selected STEMI patients. D i s t a l E m b o l i s a t i o n o f E p i c a r d i a l A r t e r y T h r o m b u s D u r i n g P r i m a r y P C I m a y b e a M a j o r C o n t r i b u t o r t o S u b o p t i m a l P e r f u s i o n In recent years it has been demonstrated that restoration of normal coronary flow in the infarct-related artery is not equivalent to the restoration of myocardial perfusion through cardiac microcirculation. After conventional primary PCI with stent implantation and IIb/IIIa blockade, the normal myocardial perfusion expressed on angiography by the tissue myocardial perfusion grade three (tMPG-3) is seen in one-third of patients. In the other two-thirds of cases, impaired microcirculatory perfusion is observed (tMPG-2 to tMPG-0), accompanied by only partial (30% to 70%) or no resolution (less than 30%) of ST segment elevation in electrocardiography (ECG). Conversely, it is recognised that complete resolution of ST segment elevation (more than 70%) in resting ECG is a good indicator of the restoration of myocardial perfusion. Accordingly, patients with impaired microperfusion have increased early and late mortality, larger irreversible myocardial injury and consequently higher incidence of adverse remodelling of the left ventricle (LV), leading to heart failure (HF). One of the main causes of inadequate myocardial reperfusion despite restoration of epicardial flow in the infarct-related artery is embolisation of distal artery, side branches and/or microcirculation by embolic material consisted of fragmented thrombus, fragmented plaque, lipids released from the plaque core as well as platelet and platelet-leukocyte aggregates released from the culprit lesion in the course of fibrinolytic therapy and/or primary PCI. Other reasons include increased microcirculatory resistance due to neutrophile obstruction of microcirculation and/or constriction of arterioles, progressing myocardial oedema and myocardial damage following reperfusion. In extreme cases these phenomena may amount to abrogation of epicardial flow despite removal of mechanical obstruction in the infarct-related artery (no reflow). D i s t a l P r o t e c t i o n S y s t e m s i n P r i m a r y P C I f o r A c u t e M y o c a r d i a l I n f a r c t i o n (A M I) Two distal protection devices (GuardWire and Filter WireEX) have proven to be clinically beneficial for the PCI of saphenous vein graft (SVG) lesions. The hope that the distal protection may improve results of primary PCI for STEMI is based on the fact that the PercuSurge GuardWire system provides protection from distal embolisation during each balloon inflation while thrombectomy is performed only before stent implantation. Consequently, intracoronary thrombectomy does not prevent distal embolisation from the material shed during stent implantation or following postdilatations. Promising initial results with PercuSurge GuardWire have not yet been confirmed by the larger randomised studies, such as the Enhanced Myocardial Efficacy and Removal by Aspiration of Liberated Debris (EMERALD). Despite the fact that thrombotic and plaque debris were found in aspirates of 76% of patients, no differences were found between studied groups in angiographically assessed myocardial reperfusion, ST segment elevation resolution or infarct size measured by isotope scan at 30 days. The results of the EMERALD trial have seriously impeached the concept of mechanical cardio-protection of microcirculation during primary PCI for AMI. The PercuSurge GuardWire system has important limitations. Aspiration of thromboembolic material is performed via an ordinary perfusion