INFUSE-AMI: Bolus Abciximab Works, Thrombus Aspiration Doesn’t for Large STEMI

CHICAGO, IL—Intracoronary delivery of a bolus dose of the glycoprotein IIb/IIIa inhibitor abciximab reduces infarct size in patients receiving primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI). Unfortunately, according to results presented March 25, 2012, at the annual American College of Cardiology/i2 Scientific Session, manual aspiration thrombectomy provides no such benefits.

The results were simultaneously published online in the Journal of the American Medical Association.

For the INFUSE-AMI trial, researchers led by Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), randomized 452 STEMI patients with large, anterior infarcts to primary PCI plus bivalirudin anticoagulation with or without a bolus (0.25 mg/kg) of abciximab delivered via intracoronary catheter infusion at the site of the lesion. Patients were also randomized to treatment with or without manual aspiration thrombectomy. As a result of the 2 by 2 randomization, some patients received both treatments, some received neither treatment, and some received one or the other.

Different Treatments, Divergent Results

Neither abciximab nor thrombus aspiration made a difference in markers of reperfusion post PCI, such as corrected TIMI frame counts, myocardial blush grade, or ST-segment resolution at 60 minutes.

At 30 days, patients receiving abciximab (pooled from all patients) showed a reduction in the primary endpoint of infarct size (% of total LV mass) on cardiac MRI. Infarct mass was also reduced with abciximab, while other outcomes such as total LV mass and LVEF were equivalent (table 1).

Table 1. Cardiac MRI at 30 Days, Abciximab Results

 

Median Values

Intracoronary Abciximab

No Intracoronary Abciximab

P Value

Infarct Size

15.1%

17.9%

0.03

Total LV Myocardial Mass, g

128.6

130.4

0.55

Infarct Mass, g

18.7

24.0

0.03

Total Abnormal Wall Motion Score

7.0

8.0

0.08

LVEF

50.2%

48.9%

0.22

 

In the patients randomized with or without thrombectomy (pooled from all patients), there was no difference in cardiac MRI results between groups (table 2).

Table 2. Cardiac MRI at 30 Days, Thrombectomy Results

 

Median Values

Aspiration Thrombectomy

No Aspiration Thrombectomy

P Value

Infarct Size

17.0%

17.3%

0.51

Total LV Myocardial Mass, g

128.3

132.0

0.50

Infarct Mass, g

20.3

21.0

0.36

Total Abnormal Wall Motion Score

7.5

7.5

0.89

LVEF

49.6%

49.5%

0.66

 

In terms of clinical outcomes, 30-day rates of death, reinfarction, HF rehospitalization, definite/probable stent thrombosis, MACE, MACCE, and other endpoints were low and equivalent in patients with and without abciximab, as was bleeding according to several definitions. The same was true in patients with and without manual aspiration.

Interestingly, in an additional analysis, the researchers assessed 30-day infarct size according to the four separate patient groups: abciximab/aspiration, abciximab/no aspiration, no abciximab/aspiration, no abciximab/no aspiration. The patients who received both treatment modalities had a lower infarct size (14.7%) compared to the other 3 arms (17.6%; P = 0.03).

“Bolus intracoronary abciximab delivered to the infarct artery lesion site… resulted in a significant but modest reduction in infarct size at 30 days,” Dr. Stone said. However, “manual aspiration… did not reduce infarct size.”

He noted that the utility of combined aspiration plus local delivery of intracoronary abciximab deserves further study.

INFUSE-AMI Does Not Equal AIDA STEMI

Panelist Erik Magnus Ohman, MD, of Duke University School of Medicine (Durham, NC) asked Dr. Stone to reconcile his results with recent studies that did not find any benefit with intracoronary abciximab. For instance, the randomized AIDA STEMI trial, presented in November 2011 at the annual American Heart Association Scientific Session, showed no difference in outcomes between intracoronary vs. intravenous abciximab in STEMI patients.

“In [AIDA STEMI], the abciximab was given through the guide catheter, and therefore, you get systemic dilution of the abciximab,” Dr. Stone responded. “Using the technique we used ensures you’re getting a very high concentration of abciximab, so I don’t think you can generalize the results of AIDA STEMI to this study, but this does require an outcomes study for proof.”

In INFUSE-AMI, intracoronary abciximab was delivered using the ClearWay Rx catheter (Atrium Medical, Hudson, NH), a microporous PTFE balloon mounted on a rapid-exchange device.

Thrombus Aspiration Already Widespread

Panel co-chair Robert A. Harrington, MD, of Stanford University School of Medicine (Stanford, CA), commented that many clinicians are already using aspiration thrombectomy in AMI patients. “The guidelines certainly support doing that based on these single-center trials,” he said. “How do you put the whole thing together [in terms of advocating for a large outcomes trial]?”

“If you look at prior meta-analyses, the single center trials have been positive, but the multicenter trials have been negative,” Dr. Stone responded. “I think we need to have multicenter trials be positive. [INFUSE-AMI] is not an outcome trial.”

He noted, though, that 2 large outcome trials looking at manual aspiration—TOTAL and TASTE—are ongoing. “Although I will say in the largest MIs that presented early where you could expect to see a difference, if aspiration doesn’t reduce infarct size [as in INFUSE-AMI], I don’t understand why it might be beneficial,” Dr. Stone said. “So I would predict that these trials might not be positive, but of course if they are positive, that will carry the day.

Study Details

Manual aspiration was performed with a 6-Fr. Export catheter (Medtronic, Minneapolis, MN).

Note: Dr. Stone and several co-authors of the trial are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 

Source:

Stone GW, Maehara A, Witzenbichler B, et al. Intracoronary abciximab and aspiration thrombectomy in patients with large anterior myocardial infarction. The INFUSE-AMI randomized trial. JAMA. 2012;Epub ahead of print.

Disclosures:

  • The study was sponsored and funded by Atrium Medical.
  • Dr. Stone reports receiving consulting fees or honoraria from Abbott Vascular, Astra Zeneca, Atrium Medical, Boston Scientific, Bristol-Myers Squibb/Sanofi Aventis, Daiichi Sankyo, Eli Lilly, Janssen, and Medtronic.

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