Fig 5.

Refined hypothesis of potential mechanisms contributing to perioperative myocardial injury. This figure summarises our microRNA findings and their potential roles in cardioprotection. Trop I, troponin I; Trop C, troponin C; Trop T, troponin T; NCX, sodium–calcium exchanger. Adrenergic stress is a common feature of the perioperative period, leading to the release of microRNA from cardiac cells, which may be cardiomyocytes, fibroblasts, or other cell types. In individuals at highest risk of elevated troponin after surgery (e.g. older patients, patients with cardiac failure, diabetes mellitus, renal disease), pre-existing (preoperative), or acquired, loss of cardioprotective signalling mechanisms promotes the likelihood of calcium overload from adrenergic stress, resulting in mitochondrial dysfunction, bioenergetic compromise and myocardial injury manifest clinically by the measurement (at low concentrations) of troponin T in plasma/serum.