The ERIC-PPCI is a 2000 patient 30 UK site randomised controlled double-blind clinical trial which will investigate whether remote ischemic conditioning (RIC) can reduce cardiac death and hospitalization for heart failure at 12 months in patients presenting with a ST-elevation myocardial infarction (STEMI) and treated by percutaneous coronary intervention (PPCI). It also includes 2 sub-studies. The Biomarker sub-study will investigate the enzymatic infarct size at 6 months. The Cardiac Magnetic Resonance (CMR) sub-study will investigate infarct size at 6 months. This study is a research collaboration with Aarhus University in Denmark (CONDI2 trial ClinicalTrials.gov Identifier:NCT01857414).