Another chapter in the story of thrombectomy in ST-elevation myocardial infarction: a story not yet finished.

Microvascular perfusion after primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI) has been clearly linked to mortality. It seems logical that by removing thrombus prior to PCI, thrombectomy could prevent distal embolization, improve microvascular perfusion and improve outcomes in STEMI. The early small randomized clinical trials of distal protection devices combined with aspiration failed to show improvements in surrogate outcomes of ST segment resolution or infarct size. As a result, many questioned the concept that by preventing distal embolization during primary PCI, one could improve clinical outcomes. The concept gained new momentum with the publication of the TAPAS trial, a single-centre trial comparing thrombectomy with the Export catheter (Medtronic CardioVascular, Santa Rosa, CA, USA) vs. PCI alone in STEMI (n 1⁄4 1072). This trial showed not only an improvement in the primary outcome of myocardial blush grade but a nearly 50% reduction in mortality at 1 year. Subsequent meta-analyses of small trials that were dominated by the TAPAS trial showed similar findings. This single-centre trial influenced guidelines in Europe and North America, and manual aspiration became a class IIa recommendation in the guidelines. Given this evidence, some believed that manual thrombectomy was the most important advance in STEMI since the advent of fibrinolytic therapy or primary PCI itself. The use of thrombectomy has rapidly grown. Manual thrombectomy provides immediate feedback to the operator, when visible thrombus is removed from the artery and visualized in the basket. More recently, two multicentre randomized trials, INFUSE AMI (n 1⁄4 452) and MUSTELA (n 1⁄4 208), did not show differences in the surrogate outcome of magentic resonance imaging (MRI) determined infarct size with thrombectomy compared with PCI alone. These conflicting findings have left many wondering what the true clinical effect of thrombectomy in STEMI is. Finally, there are now two large multicentre randomized trials powered for clinical outcomes, TOTAL (NCT01149044) and TASTE (NCT01093404), that combined will enrol . 10 000 patients to answer this question definitively. Onuma and colleagues have now randomized 154 patients with STEMI to thrombectomy with the Eliminate catheter (Terumo, Japan) vs. PCI alone in a multicentre trial. The primary outcome was flow area as measured by optical frequency domain imaging (OFDI; Terumo, Japan). Flow area was defined as stent area – area of atherothrombotic material protruding through or within the stent. The hypothesis of the study is that removal of thrombus would increase the flow area in patients receiving thrombectomy compared with PCI alone. The TROFI study demonstrated no difference in the primary outcome of flow area. Of interest, . 50% of patients in either group had prolapse of material/thrombus through the stent into the vessel lumen. In a post-hoc analysis, there was a benefit of thrombectomy for the outcome of flow area in patients with the highest thrombus burden [thrombolysis in myocardial infarction (TIMI) grade 4 or 5].