 Beyond its immunosuppressive properties, ciclosporine A CsA can also inhibit the opening of a mitochondrial mega-channel called the permeability transition pore mPTP. Opening of the mPTP plays a key role in cardiomyocyte death during reperfusion following a prolonged ischemic insult. Ciclosporin A has been shown to reduce infarct size when administered at reperfusion in experimental models. The objective of the present study is to determine whether administration of CsA at reperfusion in patients with ongoing acute myocardial infarction treated by coronary angioplasty might reduce infarct size. 