Despite DEDICATION, Filter Protection Fails Again in STEMI

Shelley Wood

March 27, 2007

March 27, 2007 (New Orleans, LA) - Yet another distal-protection trial has failed its primary end point, showing no differences in infarct size between a strategy of filter-based distal protection and stenting vs no distal protection in stenting.

"Our study does not support routine use of filterwire [devices] during primary PCI for ST-segment elevation myocardial infarction," Dr Leif Thuesen (Aarhus University Hospital, Denmark) concluded. Thuesen presented the DEDICATION trial results during the i2 Summit late-breaking clinical-trials session here at the American College of Cardiology 2007 Scientific Sessions.

The DEDICATION trial randomized 626 STEMI patients either to stenting plus distal protection or to stenting alone. The EZ Filterwire (Boston Scientific, Natick, MA) was used in 85% of cases, while the Spider RX filter system (ev3 Inc, Plymouth, MN) was used in the remainder. For the primary end point of the study--ST resolution on ECG at 30 to 90 minutes--investigators saw no difference in infarct size between the two groups, as measured by the proportion of patients with ST resolution of 70% or greater within 30 to 90 minutes. No differences were seen for secondary end points of changes in cardiac biomarker elevation or LV function, as measured by wall-motion index at the time of hospital discharge. Tracking events to 30 days, Thuesen et al saw no differences in the composite end point of major adverse cardiovascular or cerebrovascular events or for any components of that end point.

The only postprocedural difference between the two groups was in TIMI III flow, which was 95% in the distal-protection group and 88% in the group not treated with distal-protection. During his presentation, Thuesen suggested that this finding should be investigated further in case this difference translated into clinical benefits later on but added the caveat that TIMI III flow was operator assessed, "so there may be some bias there," he cautioned.

Primary and secondary outcomes in DEDICATION

Outcome Distal-protection group Conventional-treatment group p
ST-segment resolution >70% (%) 76 72 0.27
Wall-motion index (score) 1.6 1.6 NS
CK-MB (mg/L) 236 238 NS
Troponin-T (mg/L) 6.72 6.69 NS
30-day MACCE (%) 5.4 4.1 NS

MACCE=Major adverse cardiac and cerebral events

 

"A bit disappointingly, we have to conclude that routine use of a protection device can not be supported by our data," Thuesen told a press conference following the presentation.

Commenting on the results, Dr William O'Neill (University of Miami, FL) emphasized that despite being one of the best-designed studies of its kind, DEDICATION joins a long list of failed distal-protection studies.

"There really hasn't been any proof, in this study, using very good devices, that preventing a distal embolization during an intervention for an STE infarct does any good at all. There's no decrease in the size of the heart attack and no improvement in untoward events that occur afterward. I think, on a routine basis, this story is almost done. I don’t think we need to look at this question anymore."

Thuesen, for his part, says he is "a little less pessimistic."

"This is a subset of patients who are extremely difficult to treat. . . . Anyone working a lot in the lab knows that something is going on when you stent the vessel, and I think we still need to figure out how to improve our procedures. Sometimes you can be quite convinced that you may be doing some harm to a patient by stenting him, so we need to go on in this direction, somehow," to find ways of minimizing harm, Thuesen said.

In an interview with heartwire , Thuesen pointed to the numerically higher rates of ST resolution in the distal-protection group and the TIMI findings. "Clearly our study was negative, but there was still a trend in the right direction for the ST resolution." He believes the way forward is to decrease the size of the filter pores, such that smaller debris can be captured, and to improve the ability of the filter devices to cross the lesion. In the current study, operators failed to cross the lesion with the filters 20% of the time.

"That's too high a number," Thuesen said.

The complete contents of Heartwire , a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.

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