For the past 10 years, an ongoing attempt has been made to improve primary PCI outcomes by optimizing the thrombus management in these patients. The introduction of thrombus aspiration devices and catheters showed enormous promise at first, but the overall data derived from the clinical trials were not conclusive. The two major studies in the field, TAPAS and TASTE, left us in a confused state regarding the benefit and clinical utility of thrombus aspiration devices for the treatment of STEMI patients.

The Thrombus Aspiration During Percutaneous Coronary Intervention in Acute Myocardial Infarction (TAPAS) study is a single-center, randomized study that compared stenting (bare metal stent only) for acute STEMI with or without the prior use of Medtronic’s Export® AP Aspiration Catheter . In TAPAS, 1071 patients with acute STEMI were randomized, prior to angiography, either to stenting preceded by thrombus aspiration (and predilatation as necessary) or to stenting preceded by balloon inflation . TAPAS demonstrated better reperfusion with thrombus aspiration, which was accompanied by significantly better resolution of ST-segment changes. Interestingly and unexpectedly, the study suggested a survival benefit with thrombus aspiration among patients with STEMI as a secondary end point. The study changed clinical practice since its publication in February 2008, to a broader use of thrombus aspiration in patients presenting with STEMI, especially in those with visual thrombus on angiogram.

In September 2013, the results of The Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia (TASTE) trial became available; outcomes contradicted the results of TAPAS. TASTE had a novel study design; it was a multicenter, prospective, open-label, randomized, controlled clinical trial that used the infrastructure of a population-based registry to facilitate patient enrollment and data collection. In TASTE, a total of 7244 patients with STEMI were randomized, with 3623 randomized to PCI only and 3621 randomized to the thrombus aspiration arm. Overall, death from any cause at 30 days occurred in 2.8% of patients in the thrombus aspiration group and in 3.0% of patients who received PCI without thrombus aspiration, a non-significant difference. Furthermore, there was no significant effect of thrombus aspiration on any of the pre-specified secondary end points. However, there were trends toward reduction in the risk of hospitalization for recurrent MI at 30 days and the risk of stent thrombosis with thrombus aspiration, but these differences also failed to achieve statistical significance.

In the current issue of CRM you will find an interesting, observational study looking at the clinical utility of thrombus aspiration in patients presenting with STEMI complicated by cardiogenic shock. The investigators, led by Dr. Tomassini, report that while there was improvement in ST resolution with the use of thrombus aspiration, aspiration was not an independent predictor of in-hospital and long-term survival. For the interventionalist who performs primary PCI, what will he/she make of these data?

Although the totality of the data available today does not indicate any harm in using thrombus aspiration devices, the data do not support the routine use of these devices to save lives. Study limitations, including those in TAPAS and TASTE, are substantial and prohibit us from drawing conclusive recommendations regarding the role of thrombus aspiration in patients presenting with STEMI.

Further, studies like TASTE look into hard clinical end points, such as reduction in mortality, MI, and stent thrombosis. Even if the benefits of thrombus aspiration are limited to either improved visualization of the lesion after aspiration or improved reperfusion and myocardial salvage, should its use be justified despite the lack of survival benefit and reduced stent thrombosis rates? It should be noted that with the declining rates of mortality (< 3%) and stent thrombosis (< 1%), it is challenging to design a definitive clinical trial in this field. Further, the heterogeneity of the patients who present with STEMI adds to the complexity of these trials and to the interpretation of their results. Surrogate end points should perhaps be considered when designing future trials to evaluate the clinical utility of thrombus aspiration devices. The results of the ongoing Trial of Routine Aspiration Thrombectomy With Percutaneous Coronary Intervention versus PCI alone in patients with STEMI undergoing primary PCI (TOTAL) may or may not shed more light on whether we should routinely use or abandon thrombus aspiration devices . Given the limitations of the preceding studies, we may need to readjust our expectation levels and instead of looking into p values, use simple common sense regarding when, where and how these devices are used.