Washington, DC - The use of a paclitaxel-eluting stent is associated with wider luminal diameter and less late loss than the use of a bare-metal stent among patients with ST-elevation MI (STEMI) undergoing PCI, a new study has shown. There was a trend toward less target vessel revascularization (TVR) in the drug-eluting-stent arm, although the study was not powered to look at clinical events.

These are the findings of the Helsinki Area Acute Myocardial Infarction Treatment Reevaluation (HAAMU-STENT) study, an angiographic comparison of bare-metal and drug-eluting stents in STEMI patients undergoing PCI, presented this week at the TCT 2006 meeting. Patients were part of the larger HAAMU trial that compared abciximab-facilitated PCI with thrombolysis.

"It seems the strategy of using the paclitaxel-eluting stent in ST-segment elevation MI appears to be safe and feasible in the short term, within the first year, but more data are needed on its long-term effects," said lead investigator Dr Ilkka Tierala (Helsinki University Central Hospital, Finland).

Single-center, investigator-driven trial

The HAAMU-STENT trial was a single-center, investigator-initiated study enrolling 165 patients presenting with STEMI <12 hours after symptom onset. After PCI, patients were treated with a 300- to 600-mg loading dose of clopidogrel, followed by clopidogrel 75 mg daily for one year.

At nine months, the in-stent mean lumen diameter was significantly larger in patients treated with the paclitaxel-eluting stent. In addition, late loss, binary restenosis, and in-stent percent diameter stenosis were significantly larger in patients treated with the bare-metal stent. Underpowered for clinical events, the composite of death, MI, or TVR event rate was statistically similar in the two arms.

HAAMU-STENT: Angiographic findings at nine months

Angiographic end point	Bare-metal-stent group (n=75)	Paclitaxel-eluting-stent group (n=70)	p
In-stent mean luminal diameter (mm)	2.0	2.5	<0.001
In-stent percent diameter stenosis (%)	34	24	<0.001
Late loss (mm)	0.73	0.26	<0.001

Overall, there were 12 deaths, eight in the paclitaxel-eluting-stent arm, although Tierala said these were not related to the stent. Nine of the 12 deaths occurred during the primary hospital stay, five of which were the result of cardiac failure caused by a large infarct. There were three cases of stent thrombosis in the bare-metal-stent group and one in the paclitaxel-eluting-stent group.

Dr David Faxon (University of Chicago, IL), who commented on the results of the study during the late-breaking clinical-trials session, pointed out that more patients in the drug-eluting-stent arm had diabetes mellitus and prior PCI, which means that the angiographic findings might be more robust than the results suggest. Faxon noted, however, that the existing trials of drug-eluting stents in MI patients—STRATEGY, PASSION, TYPHOON, and HAAMU-STENT—all had very different trial designs and end points, and although there are data "to support the use of drug-eluting stents in this setting," only 1670 patients have been studied so far. None of the trials showed an increase in stent thrombosis, but numbers are still very low, he said.

During a discussion of the study, Dr Spencer King (Piedmont Hospital, Atlanta, GA) wondered whether clinicians might not be "chasing a nonexistent problem." King told the TCT audience that in an Atlanta registry used by his hospital, a review of MI patients treated with bare-metal stents revealed low rates of target lesion revascularization. "All we're really after in acute infarction angioplasty and stenting is to stop the infarct," he said.