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31 Aug 2008

Polish-Italian-Hungarian Randomized Thrombectomy Trial (PIHRATE trial). 

Clinical Trial Update I

Session number: 979-980
Session title: Clinical Trial Update I
Authors: Dudek, Dariusz & De Feyter, Pim J
Objectives : International multi-center randomized trial investigating whether simple thrombus aspiration followed by direct stenting in infarct related arteries with large thrombus burden during primary percutaneous coronary intervention (PPCI) may reduce distal embolization and improve myocardial reperfusion.



Discussant report:

Dudek, Dariusz (Poland)


Background
:  It has been demonstrated that primary percutaneous coronary intervention (PPCI) is the best treatment strategy for ST-Elevation Myocardial Infarction (STEMI) (1). PPCI is highly effective in epicardial flow restoration, but restoration of  optimal coronary flow in the infarct-related artery is not equivalent to the restoration of myocardial perfusion through cardiac microcirculation. Normal myocardial perfusion expressed on angiography by the Myocardial Blush Grade (MBG) 3 is seen in one third of patients after conventional PPCI with stent implantation and even with glycoprotein (GP) IIb/IIIa inhibitors administration.
Slides available

In the other two-thirds of cases, impaired microcirculatory perfusion is observed (MBG grade 0 to 2), accompanied by partial (30–70%) or no (<30%) ST-segment elevation resolution (STR) in electrocardiogram (ECG). Patients with impaired microperfusion have increased early and late mortality, larger irreversible myocardial injury, and consequently, a higher incidence of adverse remodeling of the left ventricle leading to heart failure (3). It seems that the main reason for impaired myocardial reperfusion is embolization by thrombus and plaque debris. Recent trials have demonstrated that thrombectomy can improve angiographic results of PCCI.  The aim of our study was to compare the new method of PPCI based on simple aspiration thrombectomy (Diver CE, Invatec, Italy), instead of balloon predilatation followed by direct stenting.
Methods: 196 consecutive patients (pts) with STEMI <6 hours and occluded infarct related artery (TIMI grade flow 0 to 1) at baseline angiography were randomized to two groups: easy-to-use aspiration thrombectomy (Diver CE, Invatec, Italy) followed by direct stenting (thrombectomy group) or standard balloon predilatation followed by stent implantation (control group). The primary end point of the PIHRATE trial was ECG ST-segment elevation resolution (STR) after PPCI. Secondary end points included: direct stenting rate, final TIMI grade 3 flow, corrected TIMI Frame Count (cTFC), final MBG grade 3, periprocedural angiographic complications, combination of STR≥70% and MBG 3 (optimal myocardial reperfusion), and  in-hospital major adverse cardiac events (MACE).

Results: Enrollment of 100 pts in the thrombectomy group and 96 pts in the control group at 10 PPCI centers in Poland, Italy and Hungary was completed in July 2007. Aspiration thrombectomy was successful in 91% of cases (passing lesion with thrombus reduction and flow restoration). Direct stenting was performed in 75% of cases in the thrombectomy group versus 5.2% in the control group (p<0.0001). TIMI thrombus scale rate after wiring was similar in both groups, but strong evidence of thrombus burden was present only in 68.4% of patients in group A and 66.2% in group B (p=0.76).  STR≥70% directly after the procedure was significantly better in the group with thrombectomy (41.4 vs. 25.9, p=0.037) but at 60 minutes after procedure, only a trend was observed (53.7% vs. 35.1%, p=0.29). There was no difference in final TIMI grade 3 flow (87.8% vs. 81.3%, p=0.36, group A vs. group B) but the final cTFC was significantly better in group A (28±15 vs. 33±19, p=0.027). Also, MBG rates were significantly better in group A (MBG grade 3 76.1% vs. 57.8%, p=0.026). The combined angiographic end point of TIMI grade 3 flow + MBG grade 3 was significantly better in the thrombectomy group 72.7% vs. 54.2%, p=0.012) as well as STR≥70% + MBG grade 3 (35.1% vs. 11.8%, p<0.0001). There was a trend towards a decrease of periprocedural angiographic complication rates in the thrombectomy group (16% vs. 24.2, p=0.15). However, nitroprusside sodium or adenosine were less frequently used in the thrombectomy group (3% vs. 10%, p<0.05) due to slow/no reflow phenomenon. The study groups did not differ in the stenting rate, stent length, or maximal stent deployment pressure, except for the direct stenting rate which was higher in the thrombectomy group (75% vs. 5.2%, p<0.0001). There was no difference in 6 months follow up in terms of death (4.0% vs 3.1%) and  reMI (1.0% vs 3.1%, p=NS).

Conclusions: In patients with STEMI and occluded infarct related artery, simple thrombectomy and direct stenting provides better myocardial reperfusion than standard balloon predilatation followed by stent implantation. Death and reMI rates were similar in both groups after 6 months follow-up.
 

Discussant report:

De Feyter, Pim J (Rotterdam, Netherlands)


The aim of this study is to demonstrate that thrombectomy improves myocardial perfusion during primary PCI
Slides available

 

Study : Prospective multicentre non-blinded randomized trial comparing thrombectomy + PCI versus conventional PCI.

Device : Thrombo-aspirator DIVER CE (invatec Brescia)

  • Patients: acute ST-segment elevation myocardial infarction within 6 hours of onset, and TIMI 0 or 1
  • Primary Endpoint: ST-segment resolution (STR) > 70% at 60 minutes
  • Secondary Endpoints were Efficacy of thrombectomy, cTFC, MBG 3, STR >70% immediately after PCI.
  • Angiographic adverse events were distal embolization, no reflow, Final TIMI <3,
    Pharmacological bail-out.
  • MCE : 30 days, 6 months

 Results:

  • No difference in baseline clinical or angiographic characteristics

Similar PCI technical stent procedures:

-    Thrombus removal :              93%

-    Periprocedural compl            16%   -   vs   23%   -    0.22

-    No, slow flow                       10%   -   vs   16%    -   0.18

-    TIMI 3 final                           88%   -   vs   82%   -    0.4

-    CTFC final                           8 ± 15  - vs    32 ± 19  - 0.036

-    MBG                                   3 %    -  vs    59%     -  0.023

-    STR > 70% (immediate) :      41%       vs    27%        0.037
 
-    MBG 3 + TIMI 3 + STR at 60 min :   38%      vs    22%        0.07

-    Primary endpoint : STR > 70% at 60 min:   50%       vs    40%,       0.28

-    Death/re-MI 6 months:           5.0%      vs    6.2%,      0.70


PIHRATE – TRIAL

Strengths                                                         Weaknesses

randomized                                                      small sized

multicentre                                                       not based on primary

exper. Investigators                                          clinical endpoint

device : safe easy                                            limited to low risk MI

effective                                                          patients (Killip I : 80-90%)

non-invasive endpoint                                       and TIMI 0,1

STR     >70%                                                  GP 2b/3a : ≈ 60%

Conclusion:
Thrombus aspiration in primary PCI is safe, and effective to retrieve thrombus.
Improvement in coronary flow and myocardial perfusion as witnessed by cTFC, MBG3.
No difference in primary endpoint : STR >70% at 60 min.
No difference in death/re-MI at 6 months.

The PIHRATE-trial partially confirms previous randomized trials investigating the efficacy of thrombectomy in primary PCI which demonstrated (meta-analyses)

- Improved myocardial blush grade
- Improved ST-segment resolution
- Less angiographic distal embolization
- No difference in clinical outcome (30 days)

Importantly, PIHRATE confirms the lack of impact on mortality and re-myocardial infarction. Only one large scale trial (the TAPAS trial) demonstrated improved myocardial flow and perfusion which translated into less cardiac mortality and less combined death/re-MI.

 

Conclusion Although intuitively thrombectomy during PCI should be effective, and available data demonstrate a beneficial effect  on coronary flow and myocardial perfusion, only few data show a positive effect on cardiac mortality and re-infarction. To date, there is limited evidence to recommend generalized use of thrombectomy during primary PCI.


Notes to editor
This congress report accompanies a presentation given at the ESC Congress 2008. 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.