TROFI Published: No Clear Benefit of Thrombectomy in STEMI Patients Undergoing PCI

Thrombectomy does not appear to reduce thrombus burden in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI), according to results from a multicenter randomized trial published online February 8, 2013, ahead of print in the European Heart Journal. The findings were originally presented in May 2012 at EuroPCR in Paris, France.

For the TROFI trial, Patrick W. Serruys, MD, PhD, of Erasmus Medical Center (Rotterdam, The Netherlands), and colleagues randomized 141 STEMI patients at 5 European centers to primary PCI with (n = 71) or without (n = 70) thrombectomy between November 2010 and October 2011. Thrombectomy was performed using the Eliminate device (Terumo Clinical Supply, Gifu, Japan), and all patients received a Nobori biolimus-A9-eluting stent with biodegradable polymer (Terumo). High-resolution optical frequency domain imaging (OFDI) was used to measure flow area.

No Real Difference

After treatment, minimal lumen diameter and reference vessel diameter were larger in the thrombectomy group compared with the non-thrombectomy group. However, the minimum flow area (primary endpoint) and stent area were similar between the groups (table 1).

Table 1. Postprocedure Imaging

TIMI flow grade postprocedure remained comparable between groups, as did the 3 individual components of minimal flow area (protrusion, intraluminal defect area, and incomplete stent apposition).

However, post-hoc analysis evaluating the impact of pre-procedural thrombus grade on minimum flow area suggested that thrombolysis is more effective in patients with larger thrombus burden. For example, in those with a thrombus grade of 4 or 5, minimal flow area was 6.52 ± 1.97 mm² without thrombectomy and 7.54 ± 2.30 mm² with thrombectomy (P = 0.043). In those with lower thrombus grades, there was virtually no difference between the thrombectomy and non-thrombectomy arms (P = 0.81; P for interaction = 0.09).

In terms of clinical outcomes, there were no differences between groups for cardiac death, re-infarction in the territory of the infarction-related vessel, clinically driven TVR, TVF, all-cause death, stroke, definite stent thrombosis, or non-target vessel revascularization.

Non-Documented Treatment Effects?

According to the study authors, although some all-comer studies have suggested that ACS and STEMI are independent predictors of acute/subacute or late stent thrombosis, the TROFI results indicate that in-stent protrusion/thrombus “is small and might not be associated with stent thrombosis.”

In addition, they say thrombectomy may impart “non-documented treatment effects.”

“Thrombectomy not only aspirates particulated debris but also soluble vasoconstrictors, thrombogenic, and inflammatory mediators released during plaque rupture and contributing to microcirculatory impairment,” they write. These include endothelin, serotonin, thromboxane, and tumor necrosis factor alpha, none of which were measured in the study.

“Ideally, in future studies, quantitative assessment of OFDI prior to [thrombectomy] and immediately post-[thrombectomy] as well as post-stenting should be performed to quantify changes in vasomotor tone,” Dr. Surreys and colleagues conclude.

Awaiting Randomized Trial Data

In a telephone interview with TCTMD, Sunil V. Rao, MD, of the Duke Clinical Research Institute (Durham, NC), said while TROFI is a small study with surrogate endpoints, it is interesting. nonetheless.

“There is a lot of enthusiasm for thrombectomy right now based on the results of the TAPAS trial, which showed a reduction in mortality [with thrombectomy] that had not previously been shown,” he said. “But the mechanism by which this mortality benefit was conveyed really wasn’t and isn’t clear.”

Dr. Rao said the real value of TROFI lies in the careful documentation of the thrombectomy procedures and the ongoing understanding of why, and for whom, thrombectomy might be important in the first place.

“You want to clean up the thrombus and prevent embolization, and you want to make sure you get your stent well apposed,” he said. “This study, even though it’s relatively small, is important because it’s showing that some of those goals are not being achieved and that the utility of thrombectomy is not resolved.”

In order to optimize technique and narrow down patient populations that may derive the greatest benefit from thrombectomy, adequately powered randomized trials are needed, Dr. Rao added. Two such trials, TASTE and TOTAL, are ongoing and are powered for clinical outcomes.

“I think one other important thing to remember when we talk about [these devices] is that not all of them are going to be for routine use in the cath lab,” Dr. Rao said. “I equate thrombectomy a little bit to rotational atherectomy because there are clearly situations in which you need it, but you are not going to use it in everyone.”

Study Details

Baseline characteristics and procedural details were similar between the 2 groups, although there were trends in the non-thrombectomy arm for increased glycoprotein IIb/IIIa inhibitor use (P = 0.09) as well as increased transradial PCI (P = 0.06). Five patients (7%) who initially were randomized to receive standard PCI crossed over to the thrombectomy arm.

 

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Source:
Onuma Y, Thuesen L, van Geuns R-J, et al. Randomized study to assess the effect of thrombus aspiration on flow area in patients with ST-elevation myocardial infarction: An optical frequency domain imaging study—TROFI trial. Eur Heart J. 2013;Epub ahead of print.

 

 

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