Myocardial Conditioning

Abstract

Myocardial conditioning is an endogenous cardioprotective phenomenon that profoundly limits infarct size in experimental models. The current challenge is to translate this paradigm from the laboratory to the clinic. Accordingly, our goal in this review is to provide a critical summary of the progress toward, opportunities for, and caveats to, the successful clinical translation of postconditioning and remote conditioning, the 2 conditioning strategies considered to have the broadest applicability for real-world patient care. In the majority of phase II studies published to date, postconditioning evoked a ≈35% reduction of infarct size in ST-segment–elevation myocardial infarction patients. Essential criteria for the successful implementation of postconditioning include the appropriate choice of patients (ie, those with large risk regions and negligible collateral flow), timely application of the postconditioning stimulus (immediately on reperfusion), together with proper choice of end points (infarct size, with concomitant assessment of risk region). Remote conditioning has been applied in planned ischemic events (including cardiac surgery and elective percutaneous coronary intervention) and in ST-segment–elevation myocardial infarction patients during hospital transport. Controversies with regard to efficacy have emerged, particularly among surgical trials. These disparate outcomes in all likelihood reflect the remarkable heterogeneity within and among studies, together with a deficit in our understanding of the impact of these variations on the infarct-sparing effect of remote conditioning. Ongoing phase III trials will provide critical insight into the future role of postconditioning and remote conditioning as clinically relevant cardioprotective strategies.