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ATTEMPT: Clinical outcome after thrombectomy or standard angioplasty in patients with ST elevation myocardial infarction

Clinical Trial Update III

Acute Coronary Syndromes (ACS)



Presenter | see Discussant report

Francesco Burzotta, FESC (Italy)

Presentation webcast

Presentation slides

List of Investigators:
Francesco Burzotta, Maria De Vita (Co-first investigator), Youlan Gu, Takaaki Isshiki, Thierry Lefèvre, Anne Kaltoft, Dariusz Dudek, Gennaro Sardella, Pedro Silva Orrego, David Antoniucci, Leonardo De Luca, Giuseppe GL Biondi-Zoccai, Filippo Crea, Felix Zijlstra.

Abstract:

BACKGROUND
Trials on thrombectomy in patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI) have shown favourable impact on myocardial reperfusion. However, no published study was adequately powered to asses the impact of thrombectomy on long term clinical outcome. Thus, we conducted a collaborative individual patient-data pooled analysis aimed to assess the long-term clinical outcome in STEMI patients randomized to percutaneous coronary intervention (PCI) with or without thrombectomy (study acronym: ATTEMPT, registration number on clinicaltrial.org website: NCT00766740).

METHODS
Principal investigators of randomized trials comparing thrombectomy with standard PCI in patients with STEMI were contacted. Agreeing investigators constituted the ATTEMPT Investigators (SEE APPENDIX) and provided a series of key pre-PCI data as well as the longest available clinical outcome of the patients enrolled in the corresponding trial. Primary end-point was all-cause mortality during the follow-up. Secondary end-points were major adverse cardiac events (MACE: all-cause death and/or target lesion/vessel revascularization (TLR/TVR) and/or myocardial infarction (MI)), MI, all-cause death + MI and TLR/TVR. Moreover, the effect of thrombectomy on clinical outcome was assessed in a series of predefined patient subgroups.

FINDINGS
Individual data of 2686 patients enrolled in 11 trials entered the pooled analysis. Clinical follow-up was available in 2674 (99.6%) patients at a median of 365 days.

- Primary end-point
Kaplan-Meier analysis at the longest available follow-up showed that allocation to thrombectomy was associated with reduced all-cause mortality (log-rank p=0.049) (figure 1).

- Secondary end-points
Kaplan-Meier analyses at the longest follow-up available, either crude or stratified by study (which provided similar results for direction and magnitude of statistical significance), showed that allocation to thrombectomy was associated with significantly fewer MACE (log-rank p=0.011) and death+MI (log-rank p=0.015), but non-significant differences in MI (log-rank p=0.126) or in TLR/TVR (log-rank p=0.126).

Subgroups analysis

  • - Type of thrombectomy device

The ATTEMPT study population was divided in two groups considering the type of thrombectomy device used: manual thrombectomy group (1815 patients enrolled in trials with use of Diver CE, Pronto and Export catheters) and non-manual thrombectomy group (871 patients enrolled in trials with use of X-Sizer, Angiojet, Rescue and TVAC devices). In the manual thrombectomy group Kaplan-Meier analyses at the longest follow-up available showed that allocation to thrombectomy was associated with significantly fewer deaths (log-rank p=0.011; estimated number needed to treat to save 1 life: 34) while in the non-manual thrombectomy group the allocation to thrombectomy was associated to similar mortality compared to standard PCI (log-rank p=0.481) (figure 2).

  • - Clinical and angiographic subgroups

There was no difference in mortality when splitting the study population according to the presence or absence of diabetes, to shorter, intermediate or longer time-to-reperfusion, to type of culprit artery (left anterior descending or circumflex artery or right coronary artery) and to pre-PCI TIMI flow (0-1 or 2-3). Conversely, a significant benefit of thrombectomy in terms of survival was present in the subgroup of patients treated with GP IIb/IIIa inhibitors (1787 patients; log-rank p=0.045; HR 0.61, 95%CI 0.38- 0.90) and not in those not receiving this drugs (899 patients; log-rank p=0.843; HR 0.93, 95%CI 0.48-1.80). Interestingly, in a post-hoc analysis stratified according to thrombectomy use and IIb/IIIa inhibitor administration, patients treated by both thrombectomy and IIb/IIIa inhibitors had the lowest mortality rate, those who had none of these treatments had the highest mortality rate, and patients receiving only one of these therapies showed intermediate outcome (figure 3).

INTERPRETATION
The present large pooled analysis of randomized trials suggests that thrombectomy, when performed by manual thrombus-aspirating catheters, significantly improves survival in patients with STEMI undergoing mechanical reperfusion and that its effect may be additional to that of IIb/IIIa inhibitors.

 


 Discussant | see Presenter abstract

Eric Eeckhout, FESC (Switzerland)

Presentation webcast

Presentation slides

Report:

Primary percutaneous coronary intervention (PCI) has received the highest level of recommendation and evidence for practice by our 2008 Society Guidelines on the management of patients with ST-segment elevation myocardial infarction. At present, primary PCI is a daily activity in most catheterization laboratories around the world.

Over time, primary PCI practice has taught us that the classical TIMI flow is not an adequate marker to judge the quality of reperfusion at the level of the myocardium. The no - reflow phenomenon has been defined as the inability to restore perfusion at tissue level despite the absence of epicardial mechanical obstruction. No – reflow is particularly frequent during primary PCI (up to 40% of cases) and is partially explained by distal embolization of thrombus from the instrumented infarct – related artery. No – reflow during primary PCI has a prognostic impact and its prevention is a major objective during primary PCI. From a techical point of view, manual thrombus aspiration prior to stenting has emerged as a simple and very effective tool to prevent no reflow. Indeed, this has been demonstrated by the large (single –center) TAPAS trial which further showed survival benefit at 1 year follow-up.

During the clinical trial update III, Burzotta et al present a meta-analysis of randomized controlled trials on thrombectomy during primary PCI (ATTEMPT). This meta-analysis was able to include 11 out of 17 studies identified after a careful MEDLINE search. A total of 2686 individual patient data were available for a pooled analysis. The primary end point was all cause mortality and a subgroup analysis was predefined on the type of thrombectomy technique and the administration of IIb/IIIa antagonists. The investigators were requested to provide the longest follow-up available.

The main conclusions of the ATTEMPT study are the following : systematic thrombectomy during primary PCI improves survival at 1 year ; survival benefit is observed after manual thrombectomy only; an additional benefit is obtained in patients treated with IIb/IIIa antagonists.

Conclusion:

What are the positive features of this study? This is a pooled analysis of individual patient data on a relevant and practical question. The analysis was performed by individual investigators without financial support. In order to check for heterogeneity, internal validity and publication bias a complex statistical analysis was performed. Finally, the follow-up of each study was updated and significantly extended. As usual, a meta-analysis raises a few points of concern. The role of the secondary end points is unclear in view of such a hard positive end point as mortality. They are particularly vulnerable to error in interpretation. Furthermore, the predefined subgroups (other than thrombectomy type and the use of IIb/IIIa antagonists) are underpowered to make any reasonable conclusions. Finally, the absence of 6 out of 17 trials is certainly the major limitation of ATTEMPT. The majority involves non manual thrombectomy trials and, even if these studies have revealed negative results, the global analysis imbalances further in favour of manual thrombectomy.

Still, these limitations do not counterweight the merit of the ATTEMPT study. Manual thrombectomy should be standard practice during primary PCI.

References


5021-5022

SessionTitle:

Clinical outcome after thrombectomy or standard angioplasty in patients with ST elevation myocardial infarction: individual patient-data pooled analysis of 11 randomized trials. ATTEMPT

Notes to editor


This congress report accompanies a presentation given at the ESC Congress 2009. Written by the author himself/herself, this report does not necessarily reflect the opinion of the European Society of Cardiology.

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.