Our hypothesis is that bivalirudin, compared with UFH, may provide significant benefits in term of bleeding in the selected population of patients deemed at high risk of bleeding. Our aim is thus to prove, in a double-centres, randomized, blind controlled trial enrolling patients undergoing PCI via the femoral approach, the efficacy in term of haemorrhagic events and, secondarily, the effectiveness and safety of bivalirudin by means of the study drug vs UFH.