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

Effect of METOprolol in CARDioproteCtioN During an Acute Myocardial InfarCtion. The ME"Effect of METOprolol in CARDioproteCtioN During an Acute Myocardial InfarCtion" (METOCARD-CNIC): A Randomized, Controlled Parallel-group, Observer-blinded Clinical Trial of Early Pre-reperfusion Metoprolol Administration in ST-segment Elevation Myocardial infarctionTOCARD-CNIC Trial.

The purpose of this study is to test whether early pre-reperfusion metoprolol administration in patients suffering and acute myocardial infarction might reduce the size of myocardial necrosis.

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.

Inclusion Criteria:

1. Confirmed* acute anterior wall myocardial infarction (ST segment elevation ≥ 2mm in ≥ 2 contiguous leads [one of which should be V2, V3, or V4]).

2. Killip class I or II on diagnosis.

   • Cases of non-confirmed infarction by enzymatic release (above 2 standard deviations from upper limit of CK and Troponin) are excluded from efficacy analysis but kept in the safety analysis.

Exclusion Criteria:

1. COPD or asthma on active bronchodilator therapy
2. Active treatment with beta blockers
3. Left bundle branch block or pacemaker.
4. Systolic blood pressure <120 mmHg, Heart rate <60 bpm, or AV block (PR˃240 mS or superior) on diagnosis.