Upper-limb RIPC performed while patients were under propofol-induced anesthesia did not show a relevant benefit among patients undergoing elective cardiac surgery. (Funded by the German Research Foundation; RIPHeart ClinicalTrials.gov number, NCT01067703.).

BackgroundRemote ischemic preconditioning (RIPC) has been suggested to protect against certain forms of organ injury after cardiac surgery. Previously, we reported the main results of RIPHeart (Remote Ischemic Preconditioning for Heart Surgery) Study, a multicenter trial randomizing 1403 cardiac surgery patients receiving either RIPC or sham‐RIPC.Methods and ResultsIn this follow‐up paper, we present 1‐year follow‐up of the composite primary end point and its individual components (all‐cause mortality, myocardial infarction, stroke and acute renal failure), in a sub‐group of patients, intraoperative myocardial dysfunction assessed by transesophageal echocardiography and the incidence of postoperative neurocognitive dysfunction 5 to 7 days and 3 months after surgery. RIPC neither showed any beneficial effect on the 1‐year composite primary end point (RIPC versus sham‐RIPC 16.4% versus 16.9%) and its individual components (all‐cause mortality [3.4% versus 2.5%], myocardial infarction [7.0% versus 9.4%], stroke [2.2% versus 3.1%], acute renal failure [7.0% versus 5.7%]) nor improved intraoperative myocardial dysfunction or incidence of postoperative neurocognitive dysfunction 5 to 7 days (67 [47.5%] versus 71 [53.8%] patients) and 3 months after surgery (17 [27.9%] versus 18 [27.7%] patients), respectively.ConclusionsSimilar to our main study, RIPC had no effect on intraoperative myocardial dysfunction, neurocognitive function and long‐term outcome in cardiac surgery patients undergoing propofol anesthesia.Clinical Trial RegistrationURL: https://www.clinicaltrials.gov. Unique identifier: NCT01067703.

These data suggest that desflurane-induced APC is mediated in part by activation of mitochondrial large-conductance K(Ca) channels, and that activation of these channels by desflurane is mediated by PKA.

The results demonstrate that anesthetic preconditioning is mediated by the beta1-adrenergic pathway, whereas this pathway is not essential for ischemic preconditioning. These results indicate important differences in the mechanisms of anesthetic and ischemic preconditioning.