Remote Ischaemic PrEconditioning of Human Myocardium (RIPE): study protocol for a double-blinded randomised controlled trial

Abstract

A b s t r a c tBackground: Remote preconditioning has been shown to be a potent protective phenomenon in many animals. Several studies aimed to demonstrate it was feasible in humans by trying to show its protective effect during cardiac surgery. Of these, some small studies and one larger trial were positive while two other bigger studies showed no effectiveness of remote preconditioning as assessed by levels of postoperatively released cardiac markers. Recently, two large clinical trials also failed to prove the benefit of remote preconditioning in cardiac surgery. No study showed that remote preconditioning actually increases resistance of human myocardium to standardised ischaemic and reperfusion stimulus in experimental settings. In animal studies, remote preconditioning was shown to improve mitochondrial function and structure, but such data on human myocardium are scarce. Aim:The aim of the study is to determine whether remote preconditioning protects human myocardium against ischaemia-reperfusion injury in both in vivo and in vitro conditions. Methods:The trial is designed as a single-centre, double-blinded, sham-controlled trial of 120 patients. We randomise (1:1) patients referred for coronary artery bypass grafting for stable coronary artery disease to remote preconditioning or "sham" intervention. The remote preconditioning is obtained by three cycles of 5 min inflation and 5 min deflation of a blood pressure cuff on the right arm. Postoperative course including myocardial enzymes profile will be analysed. Moreover, in the in-vitro arm the clinically preconditioned myocardium will be assessed for function, mitochondria structure, and mitochondria-dependent apoptosis. The informed consent of all patients is obtained before enrolment into the study by the investigator. The study conforms to the spirit and the letter of the declaration of Helsinki. Results and conclusions:In case the effect of remote preconditioning is not measurable in ex-vivo assessment, any future attempt at implementing this phenomenon in clinical practice may be futile and should not be continued until the effect can be confirmed in a controlled experimental setting. The study might therefore indicate future directions in trials of clinical implementation of remote preconditioning. INTRODUCTIONNo experimental study showed that human myocardium can be remotely preconditioned against standardised ischaemic/hypoxic insult. We aim to remove this major knowledge gap by applying remote preconditioning to the patient and studying ex-vivo the myocardium obtained thereafter. We assume that we will be able to show that remote preconditioning by brief periods of ischaemia of the arm protects segments of human right atrial appendage myocardium subjected to simulated hypoxia and reoxygenation in-vitro.This proof of principle is crucial. In case the effect of remote preconditioning is not measurable in ex-vivo assessment, any future attempt at implementing this phenomenon in clinical practice may be futile and should not be continued until the e...

Optimizing cardiac ischemic preconditioning and postconditioning via epitranscriptional regulation

“…Thus, investigators have exploited the phenomenon of remote preconditioning/postconditioning, wherein ischemia rendered in a distant organ or tissue promotes cardioprotection (13,14). The results of this study reinforce the conclusion that the effect of remote preconditioning cannot be measured through ex-vivo experimentation, and therefore, further advancements are needed before the clinical implementation of such procedures (15).…”