Which Early ST-elevation myocardial infarction Therapy - WEST

Jul 11, 2006
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Date Published:
01/01/2006
Date Updated:
07/11/2006
Original Posted Date:
07/11/2006
References

Description:

The goal of the trial was to evaluate whether early (prehospital if possible) optimal pharmacologic therapy was noninferior to primary percutaneous coronary intervention (PCI) among patients with ST elevation myocardial infarction (STEMI).

Study Design

Study Design:

Patients Enrolled: 304
Mean Follow Up: 30 days
Mean Patient Age: Median age 58 years
Female: 20

Patient Populations:

Patients with STEMI with symptoms ≥20 minutes and high-risk ECG criteria in whom reperfusion therapy (primary PCI, fibrinolysis, or transfer for rescue PCI) was feasible within 3 hours of randomization

Exclusions:

Primary PCI available within 1 hour of diagnosis, contraindications to fibrinolysis, prior coronary bypass grafting, or glycoprotein IIb/IIIa inhibitor use within 7 days

Primary Endpoints:

Death, reinfarction, refractory ischemia, congestive heart failure, cardiogenic shock or major ventricular arrhythmia by 30 days, or evaluated for noninferiority of the TNK groups relative to the primary PCI group

Secondary Endpoints:

ST-resolution at 90 and 180 minutes; infarct size

Drug/Procedures Used:

Patients were randomized to either: 1) tenecteplase (TNK) and usual care (n = 100), 2) TNK and mandatory invasive study within 24 hours and rescue PCI if failed reperfusion (n = 104), or 3) primary PCI with 300 mg loading dose of clopidogrel (n = 100).

Concomitant Medications:

Aspirin and subcutaneous enoxaparin (1 mg/kg)

Principal Findings:

Anterior MI was present in 40% of patients, 12.5% had a prior MI, and 14% were diabetic. Prehospital randomization was performed in 40% of patients. The median time from symptom onset to first study drug was 113 minutes in the TNK group and 130 minutes in the TNK + invasive study group. Median time from symptom onset to PCI was 176 minutes in the primary PCI group and 425 minutes in the 81 patients in the TNK + invasive study group who underwent PCI.

Complete ST resolution (≥70%) at 180 minutes was present in 60.8% of the TNK group, 69.4% of the TNK + invasive study group, and 55.7% of the primary PCI group. Median peak CK levels were 1199, 1590, and 1833, respectively (p = 0.045). NT-pro-B-type natriuretic peptide levels were significantly higher in the primary PCI group compared to the TNK group (p = 0.019).

The primary composite endpoint at 30 days occurred in 25% of the TNK group, 24% of the TNK + invasive study group, and 23% of the primary PCI group, meeting the noninferiority criteria. Death or recurrent MI occurred in 13.0%, 6.7%, and 4.0%, respectively (p = 0.021 for TNK alone vs. primary PCI; p = 0.378 for TNK + invasive study group vs. primary PCI). There were no intracranial hemorrhages in the trial. Major bleeding occurred in 1.0% of the TNK group, 1.9% of the TNK + invasive study group, and 1.0% of the primary PCI group.

Interpretation:

Among patients with STEMI, early reperfusion therapy with TNK, aspirin, and enoxaparin or TNK plus routine invasive strategy was noninferior to primary PCI for the 30-day composite endpoint of death, MI, refractory ischemia, heart failure, cardiogenic shock, or major ventricular arrhythmia in this pilot study.

In the present trial, STEMI was diagnosed early and treatment was initiated early, with 40% of patients receiving prehospital randomization. The rapid diagnosis and treatment may explain in part some of the differences between the results of the present trial and other STEMI trials comparing medical management with primary PCI.

Unlike the ASSENT-4 PCI trial, TNK with an invasive strategy was not associated with an in-hospital mortality or stroke hazard, possibly because the time from TNK administration to PCI was longer in the present trial.

References:

Armstrong PW, on behalf of the WEST Steering Committee. A comparison of pharmacologic therapy with/without timely coronary intervention vs. primary percutaneous intervention early after ST-elevation myocardial infarction: the WEST (Which Early ST-elevation myocardial infarction Therapy) study. Eur Heart J 2006;27:1530–8.

Keywords: Stroke, Hospital Mortality, Ticlopidine, Electrocardiography, Fibrinolytic Agents, Stents, Percutaneous Coronary Intervention, Shock, Cardiogenic, Intracranial Hemorrhages, Enoxaparin, Fibrinolysis, Heart Failure, Tissue Plasminogen Activator, Diabetes Mellitus, Natriuretic Peptide, Brain


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