ACC: Drug-Eluting Stent Safety for Acute MI Seen in Real World Practice

By Crystal Phend
CHICAGO, March 31 -- For acute MI patients, drug-eluting stents hold no more risk than bare-metal devices, researchers said here.
An observational study of all acute MI patients in Massachusetts for 18 months revealed only benefits at two years in rates of mortality, heart attack, and revascularization for drug-eluting stents compared with bare-metal devices, reported Laura Mauri, M.D., of Brigham and Women's Hospital in Boston, and colleagues, at the American College of Cardiology meeting.
The findings may help settle some of the disagreements over the appropriate choice of stents for acute MI, she said. "In particular in ST-elevation MI, there have been concerns that the presence of thrombus might impact outcomes related to drug-eluting stents."
The reassuring results may also increase use of drug-eluting stents in acute MI from the relatively low 40% penetration, said William Knopf, M.D., of Saint Joseph's Hospital in Atlanta, who moderated a press conference at which the findings were discussed.
However, it may be too early to make the jump from bare-metal stents, said Bruce R. Brodie, M.D., of the Moses Cone Heart and Vascular Center in Greensboro, N.C., who was a discussant for the study at a late-breaking clinical trials session.
Healing may be inhibited by stents in patients with ruptured versus stable plaques, he said. "We should wait for HORIZONS AMI."
Early outcomes from that trial made waves at the Transcatheter Cardiovascular Therapeutics meeting last October by showing bivalirudin (Angiomax), a direct thrombin inhibitor, improved major cardiovascular adverse events over abciximab (ReoPro) and heparin (See: HORIZONS AMI Verdict: Bivalirudin (Angiomax) a Winner).
But that trial also randomized patients to drug-eluting or bare-metal stents, an ongoing component that could provide more guidance in acute MI.
Aside from HORIZONS AMI, acute MI patients have typically been excluded from randomized trials comparing stent types, Dr. Mauri said.
So to expand the evidence, her group studied outcomes for all patients who had two years of follow-up after percutaneous coronary intervention for ST- or non-ST-segment elevation MI in Massachusetts hospitals from April 2003 through September 2004.
Overall, 3,200 patients were given bare-metal stents while 4,016 patients had drug-eluting stents, 2,849 of them sirolimus (Rapamune)-eluting stents.
There was a clear selection bias, Dr. Mauri said. Those with more complex lesions were more likely to get drug-eluting stents, whereas those with more comorbidities tended to get bare-metal stents.
So for analysis of thrombosis outcomes, the researchers used propensity matching on 63 patient, procedural, and hospital variables to select 2,629 pairs of patients with similar risk factors.
Dr. Mauri said her group set out to see whether there was a signal of harm from drug-eluting stents but was surprised to find that all outcomes favored drug-eluting stents in the matched MI patient groups at two years.
In the overall cohort, mortality risk was 2.7% lower with drug-eluting than bare-metal stents (10.6% versus 13.4%, P=0.002) while recurrent MI tended to be 1.5% less common with drug-eluting stents (P=0.08).
STEMI patients had an even greater benefit in mortality with drug-eluting versus bare-metal stents (3.1% lower risk, P=0.009), whereas non-STEMI patients had a lesser benefit which was not significant (1.9% lower risk, P=0.18).
Recurrent MI tended to be less common among drug-eluting stent patients compared with bare-metal stent patients (risk difference -1.5% overall, -2.4% for non-STEMI, and -1.6% for STEMI, P=NS for all).
The largest benefits, though, were a reduction in need for revascularization or target-vessel revascularization (5.3% and 3.6% lower risk with drug-eluting stents overall, respectively, both P<0.001). Both STEMI and non-STEMI patient subgroups had significant advantages as well.
The reduction in revascularization "to us means that the randomized trial benefits that have been documented for drug-eluting stents in preventing restenosis translate into actual benefits in practice," Dr. Mauri said.
She said the group plans to continue to follow this cohort of patients. Monitoring late-stent thrombosis will be important, Dr. Brodie said. Data are needed on early and late subacute thrombosis as well, Dr. Knopf said.
Dr. Mauri reported receiving honoraria from Abbott, Boston Scientific, Cordis, and Medtronic. Co-authors reported employment or research funding from the Massachusetts Department of Public Health. Dr. Knopf reported no conflicts of interest. Dr. Brodie provided no information on conflicts of interest.
Primary source: American College of Cardiology meetingSource reference:Mauri L, et al "Long-term clinical outcomes following drug-eluting and bare-metal stenting for acute myocardial infarction in Massachusetts" ACC meeting 2008; Abstract 2404-2.