The safety and efficacy of inhalation of H2 gas during PCI in patients with acute myocardial infarction

INTERVENTION: H2 gas inhalation group: H2‐mixed gas (H2 1.3%, O2 26%, N2 74%) Patients who suspect that they are having an acute myocardial infarction at an emergency room start to inhale gas and continue to inhale gas during PCI procedure. Control group: control gas (O2 26%, N2 74%) Patients who suspect that they are having an acute myocardial infarction at an emergency room start to inhale gas and continue to inhale gas during PCI. CONDITION: Acute myocardial infarction PRIMARY OUTCOME: Evaluation of the extent of myocardial lethal ischemia‐reperfusion injury by cardiovascular magnetic resonance imaging 7 days after acute myocardial infarction SECONDARY OUTCOME: Angiographic assessment of reperfusion by TIMI flow grade and myocardial blush grade; Assessment of reperfusion by ST resolution; Assessment of infarct size by area under the curve‐creatine phosphokinase (CPK); Assessment of left ventricular failure by Killip classification; Evaluation of wall motion abnormalities and left ventricular ejection fraction by cine MRI 7 days after acute myocardial infarction; Evaluation of left ventricular ejection fraction and infarct size by cardiac MRI imaging INCLUSION CRITERIA: ST‐segment elevation myocardial infarction Within 24 hours following the onset of chest pain