1. Home>
2. Specialties>
3. Emergency Medicine>
4. Summary and Comment

Reperfusion Decreases Infarct Size in Late Presentation STEMI

Patients with ST-segment-elevation MI who present more than 12 hours after symptom onset benefit from mechanical reperfusion.

Patients with acute ST-segment–elevation myocardial infarction (STEMI) who present 12 or more hours after symptom onset pose a particular challenge because the efficacy of thrombolysis is substantially reduced and clinical outcomes are poor. In an international, multicenter, open-label, randomized, controlled trial, an invasive treatment strategy was compared with a conservative strategy in 365 patients, ages 18 to 80, who were diagnosed with STEMI 12 to 48 hours after symptom onset and were symptom-free at presentation. Patients in the invasive-strategy group received immediate coronary catheterization followed by percutaneous coronary intervention plus abciximab or coronary artery bypass graft surgery; patients in the conservative-strategy group received intravenous unfractionated heparin or subcutaneous low-molecular–weight heparin for at least 1 day. All patients received aspirin plus clopidogrel or ticlopidine and an IV bolus of heparin (70 U/kg up to 5000 U).

The primary outcome measure, left ventricular infarct size, was determined by single-photon emission computed tomography scan performed 5 to 10 days after randomization. Left ventricular infarct size was significantly smaller in the invasive-strategy cohort than in the conservative-strategy cohort (median infarct size, 8.0% vs. 13.0%; mean difference, 6.8%). Rates of the secondary outcome measure, a composite of death, recurrent MI, or stroke at 30 days, did not differ significantly between the two groups (4.4% and 6.6%, respectively).

Comment: These data are the first to support mechanical reperfusion in patients who present with STEMI more than 12 hours after symptom onset. Factors such as ischemic preconditioning, persistence of residual blood flow in the infarct-related artery, and recruitment of collateral flow may explain the presence of viable myocardium 12 hours after coronary occlusion. In this study, glycoprotein IIb/IIIa inhibitors may have contributed to the effectiveness of mechanical recanalization.

— John A. Marx, MD, FACEP

Published in Journal Watch Emergency Medicine September 14, 2005

Citation(s):

Schömig A et al. Mechanical reperfusion in patients with acute myocardial infarction presenting more than 12 hours from symptom onset: A randomized controlled trial. JAMA 2005 Jun 15; 293:2865-72.

• Original article (Subscription may be required)
• Medline abstract (Free)

Gibbons RJ and Grines CL. Acute PCI for ST-segment elevation myocardial infarction: Is later better than never? JAMA 2005 Jun 15; 293:2930-2.

• Original article (Subscription may be required)
• Medline abstract (Free)