Comparison of Invasive and Conservative Strategies After Treatment with Streptokinase in Acute Myocardial Infarction - SIAM


SIAM was a randomized, open-label, parellel-group clinical trial, which compared routine early coronary angiography with percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) to conservative strategy following fibrinolysis for ST-elevation myocardial infarction (STEMI).


Routine coronary angiography within 14-48 hours following fibrinolysis for STEMI will be associated with lower in-hospital mortality, lower rate of recurrent infarction, and a higher pre-discharge left ventricular ejection fraction (LVEF).

Study Design

Study Design:

Patients Enrolled: 324
Mean Ejection Fraction: Mean predischarge LVEF - 55%

Patient Populations:

Presentation with STEMI within 4 hours of symptom onset


Contraindications to fibrinolysis

Primary Endpoints:

In-hospital mortality, recurrent MI, pre-discharge LVEF

Drug/Procedures Used:

Patients were enrolled in 13 community hospitals in Germany if they presented with suspected STEMI within 4 hours of symptom onset. Patients were treated with intravenous streptokinase (1.5 million units over 1 hour), and then randomly assigned to invasive or conservative strategy groups.

Patients in the invasive group were transferred to a tertiary hospital, and underwent coronary angiography within 14-48 hours, with PCI/CABG if necessary, as well as a predischarge control coronary angiography. Those in the conservative group had no coronary angiography during the first 21 days, unless there was evidence of recurrent ischemia, with coronary angiography only prior to discharge.

Principal Findings:

A total of 324 patients were enrolled (166, conservative group; 158, invasive group), of whom 308 patients had a definite diagnosis of STEMI.

Recurrent infarction following PTCA was diagnosed in 1 patient in the conservative group and in 7 patients in the invasive group. Recurrent infarction without PTCA occurred in 27 patients in the conservative group and 11 patients in the invasive group. LVEF was 55±11% in the conservative group and 55±10% in the invasive group (p=NS). Ten patients died in the conservative group and 14 in the invasive group.


Following streptokinase fibrinolysis in patients with STEMI, invasive and conservative strategy were associated with similar rates of overall in-hospital mortality and recurrent MI, and with similar pre-discharge LVEF.

The results of this small early study mirror those of SWIFT and TIMI IIb trials, where conservative and invasive strategies were associated with similar overall outcomes following fibrinolysis for STEMI. However, a more contemporary GRACIA analysis demonstrated that the early invasive approach (routine angiography within 24 hours of fibrinolysis) was associated with a significantly lower 30-day incidence of death, recurrent MI or revascularization.


Ă–zbek C, Dyckmans J, Sen S, et al. Comparison of invasive and conservative strategies after treatment with streptokinase in acute myocardial infarction. Results of a randomised trial (SIAM). J Am Coll Cardiol 1990;15 Suppl A:63A

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Aortic Surgery, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Tertiary Care Centers, Myocardial Infarction, Hospital Mortality, Streptokinase, Coronary Angiography, Hospitals, Community, Stroke Volume, Germany, Fibrinolytic Agents, Coronary Artery Bypass, Percutaneous Coronary Intervention

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