Percutaneous coronary intervention (PCI) has become the default therapy for obstructive coronary artery disease and invariably involves coronary stenting. Currently, stenting with a drug-eluting stent (DES) has become the default method for intervention, with few exceptions.1 The major drawback of this strategy is both acute and subacute stent thrombosis. The DES type, positioning, and lesion complexity may all contribute to stent thrombosis, the mechanisms of which are still under investigation.2 While there may be some debate as to the absolute occurrence of stent thrombosis, the complications are often more severe, with larger infarct size and higher mortality than that which occurs from non-stent-initiated ST-elevation myocardial infarction (STEMI). Iakovou reported a case fatality rate of stent thrombosis at 45%.3 In the current issue, Lemesle et al examine the use of thrombus aspiration prior to intervention in patients presenting with acute stent thrombosis.4
Intuitively, decreasing the thrombus burden prior to stenting makes logical sense, and physiologic studies of epicardial blood flow and ST resolution have demonstrated benefit.5 Despite early promise, larger thrombectomy and distal protection trials (both filter and balloon occlusion) have failed to demonstrate positive results in hard clinical endpoints (EMERALD6, AMI7). The largest mechanical thrombectomy trial, AiMI, which evaluated the AngioJet device (Possis Medical, Inc, Minneapolis, Minnesota,) demonstrated an increase in periprocedural myocardial infarction and had a detrimental impact on outcomes compared with primary intervention without antecedent thrombectomy.8 Additionally, a recent meta-analysis of thrombectomy and embolic protection devices did not demonstrate any statistically significant advantage over primary stenting.9 Although these initial trials had mixed results, there now is growing evidence to support routine thrombectomy in acute STEMI, and in particular, stent thrombosis.
Most notably, the TAPAS trial showed positive results from antecedent manual thrombectomy prior to percutaneous intervention.10 TAPAS demonstrated benefit of manual thrombectomy at 1 year, with significant reductions in cardiac death and reinfarction. Additionally, when pooled with eight other trials and evaluated through meta-analysis, aspiration thrombectomy improved myocardial blush grade, thrombolysis in myocardial infarction (TIMI) 3 flow, and 30-day mortality.11 It is in this environment that routine thrombectomy in the setting of STEMI is being reevaluated.
The current manuscript demonstrated a reduction in the combined endpoint of death, recurrent myocardial infarction and recurrent stent thrombosis at 30 days by 25% (47.2% to 22.2%) with the use of aspiration thrombectomy prior to intervention in patients with acute in stent thrombosis. These results are consistent with the benefit demonstrated in TAPAS and as such expand the body of evidence favoring thrombectomy to the arena of acute stent thrombosis. The authors should be congratulated on the randomization of patients in this challenging area. While variability must obviously exist in the operator's judgment of initial angiographic appearance, lesion area, vessel size, TIMI flow and the potential need for continued medical therapy, the two groups remained well matched. Additionally, more patients in the thrombectomy group presented with ST elevation, which may have biased the results against this group. The outcomes, however, still supported the use of thrombectomy in this difficult patient population.
Several issues are raised by this manuscript that should be discussed, the first of which is treatment selection. Although lesion descriptions were well balanced between aspiration and nonaspiration groups, a number of factors were not recorded that may have influenced the interventionalist at the time of the procedure. These include the appearance of the artery, time elapse between symptom onset and presentation, the presence of continued chest pain and the presence or resolution of ST changes. The group randomization can be affected by any of these variables.
Second, and this point follows from the first, generalization of this type of information is inherently difficult. Just as the randomization may be altered by these variables, these unreported factors make it difficult to generalize the results to all patients, hence one cannot advocate for routine thrombectomy. Should another trial be conducted, it would be helpful to include these parameters in order to gain more objective data as to who would benefit from thrombectomy.
Third, the trial is a small retrospective study and so is inherently limited. However, the positive results of the trial are compelling and, at the very least, warrant a prospective trial.
Finally, the complication rates were not reported. Aspiration thrombectomy has been shown to have a minimal effect on door-to-balloon time, but it would be useful to know other possible drawbacks such as risk of dissection. In addition, The European Heart Journal’s meta analysis of thrombus aspiration trials, while favorable, did raise the concern for increased risk of stroke.11 Any further trials should address this question.
This study continues along the same line of interest that was established by the TAPAS trial and expands the context to STEMIs resulting from acute thrombosis of DES. Despite these limitations and relatively small study size, the current manuscript does suggest what many have suspected: that antecedent thrombus aspiration is a useful adjunct to treating a highly difficult patient population that present with acute stent thrombosis.
1. Smith SC Jr, Feldman TE, Hirshfeld JW Jr, et al. ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention, 2005 by the American College of Cardiology Foundation and the American Heart Association, Inc. Circulation 2006;21;113:e166–e286.
2. Joner M, Finn A. Farb A, et al. Pathology of drug-eluting stents in humans: Delayed healing and late thrombotic risk. J Am Coll Cardiol 2006;48:193–202.
3. Iakovou I, Schmidt T, Bonizzoni E, et al. Incidence, predictors, and outcome of thrombosis after successful implantation of drug-eluting stents. JAMA 2005;293:2126–2130.
4. Lemesle G, de Labriolle A, Bonello L, et al. Impact of thrombus aspiration use for the treatment of stent thrombosis on early patient outcome. J Invasive Cardiol 2009;21:210–214.
5. Beran G, Lang I, Schreiber W, et al. Intracoronary thrombectomy with the X-sizer catheter system improves epicardial flow and accelerates ST-segment resolution in patients with acute coronary syndrome: A prospective, randomized, controlled study. Circulation 2002;105:2355.
6. Stone GW, Webb J, Cox DA, et al. Enhanced Myocardial Efficacy and Recovery by Aspiration of Liberated Debris (EMERALD) investigators. Distal microcirculatory protection during percutaneous coronary intervention in acute ST-segment elevation myocardial infarction: Randomized controlled trial. JAMA 2005;293:1063–1072.
7. Ali A, Cox D, Dib N, et al. Rheolytic thrombectomy with percutaneous coronary intervention for infarct size reduction in acute myocardial infarction: 30-Day results from a multicenter randomized study. J Am Coll Cardiol 2006;48:244–252.
8. Ali A, Cox D, Dib N, et al. Rheolytic thrombectomy with percutaneous coronary intervention for infarct size reduction in acute myocardial infarction: 30-Day results from a multicenter randomized study. J Am Coll Cardiol 2006;48:244–252.
9. Bavry AA, Kumbhani DJ, Bhatt DL. Role of adjunctive thrombectomy and embolic protection devices in acute myocardial infarction: A comprehensive meta-analysis or randomized trial. Eur Heart J 2008;29:2989–3001.
10. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med 2008;358:557–567.
11. De Luca G, Dudek D, Sardella G, et al. Adjunctive manual thrombectomy improves myocardial perfusion and mortality in patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction: A meta-analysis of randomized trials. Eur Heart J 2008;29:3002–3010.
