Manual Thrombectomy During PCI for STEMI Improves Survival: ATTEMPT

Fran Lowry

September 10, 2009

September 8, 2009(Barcelona, Spain) – Thrombectomy using manual but not mechanical thrombus-aspirating catheters significantly improved one-year survival in STEMI patients undergoing PCI in a pooled analysis of individual patient data from 11 randomized trials [1]. The positive effect of thrombectomy was enhanced by GP IIb/IIIa inhibitors, Dr Francesco Burzotta (Catholic University of the Sacred Heart, Rome, Italy) said at the European Society of Cardiology (ESC) 2009 Congress, where he presented the results of the Pooled Analysis of Trials on Thrombectomy in Acute Myocardial Infarction Based on Individual Patient Data (ATTEMPT).

The study was published simultaneously online September 2, 2009 in the European Heart Journal.

Although ATTEMPT has the typical limitations of a meta-analysis, it convincingly conveys three "simple, basic messages that we can apply to daily practice," discussant Dr Eric Eeckhout (Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland) told meeting attendees. "Thrombectomy during primary PCI improves one-year survival; the survival benefit is confined to manual thrombectomy only; and we need to add GP IIb/III antagonists to this treatment to further improve survival."

Dr Maria De Vita (Catholic University of the Sacred Heart, Rome, Italy), who coauthored the study, told heartwire that manual thrombectomy is easier to use and cheaper than mechanical-thrombectomy devices. "Mastering manual thrombectomy requires a learning curve, but that curve is not as steep as with mechanical thrombectomy," she said. "Young interventional cardiologists can learn to use this device in less time and after they have performed fewer primary PCI procedures."

Pooled analysis missing six trials

After doing a Medline search, the Italian investigators solicited the principal investigators (PIs) of 17 randomized trials comparing thrombectomy with standard PCI in STEMI patients. The PIs of 11 trials agreed to collaborate and provided information on their patients' pre-PCI characteristics and the longest clinical follow-up data that they had. ATTEMPT was able to collect information on a total of 2686 patients, with a median follow-up of 365 days, "which was significantly extended compared with the published follow-up of these patients, which was a median of 135 days," Burzotta noted.

The primary end point was all-cause mortality; secondary end points were MI, target vessel revascularization, composite of death or MI, and major adverse cardiac events (MACE).

The study found that randomization to thrombectomy was associated with significantly lower all-cause mortality (p=0.049) and significantly reduced MACE (p=0.011) and death or MI (p=0.015).

In a planned subanalysis of outcome according to the type of thrombectomy used, there was no difference in survival in patients receiving nonmanual thrombectomy; the survival benefit was confined to patients treated with manual thrombectomy (p=0.011).

The refusal of the principal investigators of six of the trials to participate might have skewed the results in favor of manual thrombectomy, Eeckhout suggested to heartwire . "Most of the trials that were missing were on nonmanual thrombectomy. My guess is these were refused by the sponsoring companies as they were all negative."

The ATTEMPT investigators also tried to determine which subgroups of patients might benefit more from thrombectomy. After analyzing the risk of death according to the presence or absence of diabetes, GP IIb/IIIa inhibitors, time to reperfusion, infarct-related artery, and TIMI flow, the researchers found that the only factor that was associated with improved survival was the use of GP IIb/IIIa inhibitors. The mortality rate in patients who received neither GP IIb/IIIa inhibitors nor thrombectomy was 7.4%; that of patients who received both was 3.3% (p=0.045).

Burzotta told heartwire that the results from ATTEMPT should convince more interventional cardiologists, including those from the US, to use thrombectomy. "I think our results will spread the use of thrombectomy. In the US, they are not so convinced. But this may be due to the fact that many interventional cath labs in the US are low volume, especially in emergency cases. The situation is quite different in Europe."

Need to know who will benefit

Dr Alfred A Bove (Temple University School of Medicine, Philadelphia, PA), who moderated the session at which ATTEMPT was presented, told heartwire that the results support the broad concept that a thrombus, as part of an acute-MI process, can complicate PCI procedures and that removing it can be beneficial. However, he suggested that it would have been very helpful if the investigators had managed to determine which patients would benefit from thrombectomy and which would not.

"The benefit is not in 100% of patients. If, for example, one out of 10 patients is going to benefit, and you can't figure out which one it is, the propensity is to do everyone and hope you are going to find the one. It would be nice to have some markers that would allow you to sort it out a little better than one in 10, but we don't. We need discrimination to figure out who are the beneficiaries, and we don't have that data."

Commenting on the finding that manual was better than mechanical thrombectomy, Bove, who is the current president of the American College of Cardiology, noted that this is a skill issue. "Some of the manual processes require more skill, some of the automated ones are a little easier to use. I'm not in the lab much anymore, but my sense is that we tend to do more automated procedures in the US. Manual is cheaper, and that may be more of a consideration in Europe, but in the US, we love machines. Still, a lot of the interventionalists go in and do the thrombectomy manually. You don't have to do just one or the other. The manual is always an option."