Frey UH, et al. - Researchers intended to determine the mechanisms underlying the cardioprotective effect of remote ischaemic preconditioning (RIPC), therefore, they investigated whether RIPC in anaesthetized patients undergoing coronary artery bypass (CABG) surgery triggers the release of extracellular vesicles (EVs) from the ischaemic/reperfused arm into the blood stream harbouring cardioprotective microRNAs (miRNAs). This study included 58 patients. Parallel right radial artery and regional (left subclavian) venous blood sampling was performed before (awake) and 5 and 60 minutes after randomization to RIPC (three 5/5 minutes episodes of left arm ischaemia/reperfusion by suprasystolic blood pressure cuff inflations/deflations) or Sham during isoflurane/sufentanil anaesthesia. Using polymer-based precipitation methods, they extracted EVs and assessed levels and miRNA signature of these. Findings revealed a rise in serum EV concentrations as a result of RIPC, this happened most likely by early EV release from the patients’ left (RIPC) arm. Also, RIPC altered miRNA signature of EVs and was related to myocardial protection. Overall, the RIPC effect could be mediated by an increased EV concentration with an altered miR-signature.