Southwest German Interventional Study in Acute Myocardial Infarction - SIAM III


The goal of the SIAM III trial was to evaluate the efficacy of immediate stenting after thrombolysis versus a more conservative treatment regimen in patients with acute myocardial infarction (MI).

Study Design

Study Design:

Patients Enrolled: 163
Mean Follow Up: Six months (mean 287 days)
Mean Patient Age: Mean age 63 years
Female: 21
Mean Ejection Fraction: Mean baseline left ventricular ejection fraction 54.7%

Patient Populations:

Age >18 years; symptoms of MI present for <12 h; ST-segment elevation of ≥1 mm in ≥2 limb leads, ST-segment elevation of ≥2 mm in the precordial leads, or new bundle branch block; eligible for thrombolysis, meaning no history of stroke or central nervous system damage, recent major surgery, systolic blood pressure >200 mm Hg, or diastolic blood pressure >110 mm Hg at any time after arrival, no recent noncompressible vascular puncture, or concomitant use of an oral anticoagulant with an international normalized ratio >2; no secondary or iatrogenic infarction; and no chronic renal insufficiency requiring dialysis

Secondary angiographic inclusion criteria: indication for angioplasty independent of the study; and infarct-related lesion in a native coronary artery >2.5 mm with diameter stenosis of ≥70% or TIMI flow


Secondary angiographic exclusion criteria: coronary anatomy unsuitable for stent placement; anticipated indication for surgical coronary revascularization within six months; previous MI in the area of the infarct-related vessel; or infarct-related lesion not clearly defined

Primary Endpoints:

Composite of death, reinfarction, ischemic events, and TLR at six months

Drug/Procedures Used:

All patients were enrolled at community hospitals without on-site catheterization laboratories. Patients received reteplase (two boluses of 10 MU 30 minutes apart) and were randomized to immediate transfer (within six hours of thrombolysis) to a larger facility for coronary angiography, including stenting of the infarct-related artery (IRA) (n=82) or elective coronary angiography two weeks after thrombolysis with stenting of the IRA (n=81).

Concomitant Medications:

Aspirin intravenously (250 mg) and heparin (bolus of 5000 IU + infusion of 1000 IU/h)

Principal Findings:

TIMI 3 flow rates at two-week angiography were 98% in the immediate stent arm versus 59% in the delayed stent arm (p<0.001). The primary composite endpoint of ischemic events, death, reinfarction, and target lesion revascularization (TLR) was significantly lower in the immediate stenting arm compared with the delayed stenting arm (25.6% vs. 50.6%, p=0.001). The reduction was driven primarily by the reduction in ischemic events (4.9% vs. 28.4%, p=0.01).

There was no difference in reinfarction (2.4% vs. 2.5%, p=0.685) or TLR (19.5% vs. 23.5%, p=0.336), but mortality was non-significantly lower in the immediate stenting arm (4.9% vs. 11.1%, p=0.119). Similar results were observed in an intention-to-treat basis (composite 29.8% vs. 53.4%, p=0.001). Patients with and without reperfusion after thrombolysis undergoing immediate stenting showed similar outcomes (composite 24.6% vs. 29.4%) in contrast with those patients with delayed stenting (composite 44.4% vs. 72.2%, p=0.001).

Ejection fraction was improved in the immediate stenting arm compared with delayed angiography both at two-weeks (56.7% vs. 52.5%, p=0.037) and six months (61.5% vs. 56.4%, p=0.018). There was no difference in major bleeding between the immediate stent group or the delayed angiography group (9.8% vs. 7.4%, p=0.400).


Among patients with acute MI, treatment with an immediate facilitated percutaneous coronary intervention (PCI) strategy was associated with a reduction in the primary composite endpoint of death, reinfarction, ischemic events, and TLR at six-month follow-up compared with patients treated with thrombolysis and a two-week delay in PCI.

Findings are unlike trials in the 1980s, which did not show a benefit with thrombolysis and angioplasty, but did show increased bleeding. While primary PCI has been associated with improved outcomes in several trials, the availability of facilities with on-site catheterization labs is limited.

Additionally, transfer to such facilities routinely takes >1 hour in the United States, according to a recent National Registry of MI study. Given the importance of initiating early reperfusion therapy, data from the present trial suggest a combination of thrombolysis followed by early transfer for stenting may be optimal, both in patients with patent and occluded vessels at angiography. Further studies are warranted.


Scheller B, Hennen B, Hammer B, et al., for the SIAM III Study Group. Beneficial effects of immediate stenting after thrombolysis in acute myocardial infarction. J Am Coll Cardiol 2003;42:634–41.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, EP Basic Science, Lipid Metabolism, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Myocardial Infarction, Stroke, Follow-Up Studies, Hospitals, Community, Blood Pressure, Fibrinolytic Agents, Constriction, Pathologic, Angioplasty, Stents, Percutaneous Coronary Intervention, International Normalized Ratio, Renal Dialysis, Coronary Angiography, Catheterization, Bundle-Branch Block, Recombinant Proteins, Coronary Vessels, Tissue Plasminogen Activator, Renal Insufficiency, Chronic

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