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10/5/2000

MI Damage Less with Stent Plus Abciximab

Kate Traynor

Patients suffer less extensive heart damage after an acute myocardial infarction when treated with a coronary stent and the platelet-receptor blocker abciximab instead of the tissue plasminogen activator alteplase alone, according to a recent study in Germany.

 

Ten days after treatment with a stent and abciximab, the infarct in half of the patients occupied no more than 14.3 percent of the area of the left ventricle, the researchers found. Half of the patients given alteplase alone, however, had an infarct constituting as much as 19.4 percent of the left ventricle.

In the study, which appeared in the Aug. 10 New England Journal of Medicine, the researchers used scintigraphy to assess the extent of damage to each patient’s left ventricle. This technique allowed the researchers to calculate the size of the original "perfusion defect" and the final infarct size approximately 10 days later.

The researchers also compared the incidence of death, stroke, and repeat infarction between the two groups, though the authors cautioned that their small study lacked the statistical power to properly evaluate these clinical outcomes.

Within six months of treatment, 10.0 percent of the stent recipients needed therapy to re-open the affected artery, compared with 34.9 percent of patients in the alteplase group. People in the alteplase group were 31 percent more likely to die within six months of the initial treatment than those in the stent group. None of the patients had a stroke during the follow-up period.

The study was conducted between December 1997 and August 1999. Eligible patients had had 20 or more minutes of chest pain and sought treatment within 12 hours of symptom onset. The diagnosis of acute myocardial infarction was confirmed with an electrocardiogram.

People with a recent history of stroke or surgery were excluded from the study. Other ineligible patients included people who used oral coumarin products, were actively bleeding, or had uncontrolled hypertension.

Of the 140 eligible patients, 71were randomly assigned to the stent treatment group and 69 were selected for alteplase treatment. The median patient age was 57.8 years in the stent group and 60.9 years in the alteplase group. About a quarter of the patients in each treatment group were women.

While in the emergency room, each study participant received 500 mg of aspirin and 5,000 units of intravenous (i.v.) heparin. Technetium Tc 99m sestamibi, a diagnostic aid, was injected into each patient in preparation for baseline scintigraphy, which was performed on 127 study participants. Follow-up scintigraphy was done approximately 10 days later for 63 patients in the stent group and 60 in the alteplase group.

Scintigraphic imaging showed that the initial infarct sizes were similar in the alteplase and stent groups.

People in the alteplase group were given a 15-mg bolus dose of the drug. Accelerated alteplase perfusion followed, with each patient receiving a maximum of 50 mg delivered at 0.75 mg/kg for 30 minutes, then up to 35 mg delivered at 0.5 mg/kg for 60 minutes.

Patients given alteplase also received i.v. heparin for 48 hours at an initial dose of 1,000 units/hour. Bleeding tendency was tested by measuring activated partial thromboplastin time (APTT), and heparin dosages were modified to achieve APTT values between 60 and 85 seconds.

Patients assigned to the stent group received an intra-arterial dose of heparin during the procedure. Abciximab, a monoclonal antibody that inhibits clot formation by blocking platelet glycoprotein IIb/IIIa receptors, was given as a 0.25-mg/kg bolus dose, then infused at 10 mcg/minute for 12 hours. After surgery, these patients received 250 mg of ticlopidine twice daily for four weeks.

Patients assigned to the stent group started treatment about half an hour later than those in the alteplase group, who started receiving the drug a median of 30 minutes after admission to the hospital. No other significant differences were noted between the two groups at the start of treatment.

All patients in the study began taking 100 of mg aspirin twice daily, to continue indefinitely. In both groups, over 86 percent of the enrollees started beta-blocker therapy, over 87 percent used an angiotensin-converting-enzyme inhibitor, and over 83 percent received a statin.

Within 30 days of treatment, three stent recipients and five patients in the alteplase group died. Two stent recipients and four people in the alteplase group survived a new myocardial infarction during this time. One patient from each group required coronary artery bypass surgery. Major bleeding occurred in three patients with stents and two patients in the alteplase group.

The Actilyse brand of alteplase used in this study was obtained from Boehringer Ingelheim Pharma. Abciximab, known by the brand name ReoPro, was obtained from Lilly Deutschland. The study was funded in part with grants from Boehringer and Lilly.

According to the authors, the hospitals that participated in this study had "high volumes of interventional procedures" and may not be representative of all community hospitals.