Thrombectomy during PCI for acute myocardial infarction: are the randomized controlled trial data relevant to the patients who really need this technique?

Macro and microembolization during percutaneous coronary intervention (PCI) in ST elevation acute myocardial infarction (STEAMI) is frequent and may result in obstruction of the microvascular network with subsequent reduction in efficacy of reperfusion. Numerous mechanistic studies have shown that the presence and size of the culprit thrombus is the most powerful predictor of incidence of embolization and slow flow/no reflow. Techniques that have been used to reduce the incidence of these events include thrombectomy devices and embolic protection devices. Although numerous prospective randomized clinical trials have been performed to evaluate the role of thrombectomy devices in patients with STEAMI, the results of these trials are conflicting and they speak to both sides of the controversy. The Achilles heal of the majority of these trials is the premise that thrombectomy devices should be routinely used in all patients presenting with STEAMI even irrespective of the presence and size of the thrombus. Such a hypothesis is naively optimistic and it ignores the basic knowledge available to us regarding the relationship between thrombus burden and embolization. Nonetheless, clinicians are faced every day with the reality of making difficult decisions on how to best treat patients presenting with STEAMI and large thrombus burden. The current available "evidence-based medicine" cannot and should not be generalized to these patients because only a minority of these patients was included in these randomized clinical trials. In these patients, thrombectomy devices should be strongly considered as an integral part of the armamentarium available to reduce thrombus burden prior to definitive treatment. Whether a future clinical trial will provide a definitive answer in terms of clinical outcome difference is doubtful because such a trial will need to include large number of selected patients with STEAMI who both have large amount of myocardium at jeopardy and large thrombus burden, a difficult and possibly undoable study.
(2008 Wiley-Liss, Inc.)