Effect of METOprolol in CARDioproteCtioN During an Acute Myocardial InfarCtion. The METOCARD-CNIC Trial.

• Infarct size evaluated primarily by area of delayed enhancement on cardiac magnetic resonance imaging. [ Time Frame: 5-7 days after reperfusion ] [ Designated as safety issue: No ]
  

• Infarct size evaluated primarily by the area under the curve of CK, CK-MB and troponin release over the first 72 hours of reperfusion. [ Time Frame: over the first 72 hours of reperfusion. ] [ Designated as safety issue: No ]
  
• Infarct size evaluated by area of delayed enhancement on cardiac magnetic resonance imaging. [ Time Frame: at month 6 ] [ Designated as safety issue: No ]
  
• Infarct size evaluated by area of delayed enhancement on cardiac magnetic resonance imaging in patients with coronary TIMI flow 0-1 of culprit coronary artery. [ Time Frame: 5-7 days after reperfusion. ] [ Designated as safety issue: No ]
  
• Percent salvaged myocardium evaluated by cardiac magnetic resonance imaging. [ Time Frame: 5-7 days after reperfusion ] [ Designated as safety issue: No ]
  
• Recovery of myocardial contraction assessed by magnetic resonance imaging and echocardiography. [ Time Frame: at month 6 ] [ Designated as safety issue: No ]
  
• Myocardial perfusion evaluated by magnetic resonance imaging. [ Time Frame: 5-7 days post-reperfusion. ] [ Designated as safety issue: No ]
  
• Composite of death, malignant ventricular arrhythmias, reinfarction or admission due to heart failure [ Time Frame: hospital discharge, 1, 6 and 12 months post-reperfusion. ] [ Designated as safety issue: No ]
  
• Major cardiovascular events (death, malignant ventricular arrhythmias, AV block, cardiogenic shock, reinfarction). [ Time Frame: within first 24 hr post-reperfusion. ] [ Designated as safety issue: Yes ]
  

Acute myocardial infarction (AMI) is a chief cause of death worldwide. The best strategy to limit myocardial damage is to perform an early coronary reperfusion. However, despite reperfusion, the size of infarctions is many times large. Infarct size has been recently shown to be a strong predictor of future cardiovascular events and mortality. Therefore interventions aimed at reducing infarct size are the matter of intense research; but despite great efforts, no therapy has been shown to consistently limit infarct size.

ß-blockers are a class of drugs that have been used to treat cardiovascular conditions for several decades. β-blockers reduce mortality when administered after an AMI, and are a class IA indication in this context. What remains unclear is what timing and route of β-blocker administration gives the maximum cardioprotective effect. In particular, whether early β-blocker administration is able to reduce infarct size is a subject of debate. Recent experimental data suggest that the β1 selective blocker metoprolol is able to limit the area of necrosis only when administered before reperfusion.

The objective of this trial is to determine whether the administration of intravenous pre-reperfusion metoprolol might reduce infarct size.