Cardiopulmonary Protection of Modified Remote Ischemic Preconditioning in Mitral Valve Replacement Surgery: A...

Background: Remote ischemic preconditioning (RIPC) is reported to have early-phase and delayed-phase organ-protective effects. Previous studies have focused on the organ protection of a single RIPC protocol, and the clinical outcomes remain uncertain. Whether the modified RIPC (mRIPC) protocol performed repeatedly provides cardiopulmonary protection is still uncertain. Methods: In this single-center, randomized, controlled trial, 86 patients undergoing elective mitral valve replacement (MVR) surgery were randomized 1:1 to receive either mRIPC or no ischemic preconditioning (control). Three cycles of 5 min ischemia and 5 min reperfusion induced by a blood pressure cuff served as the RIPC stimulus. mRIPC was induced at the following three time points: 24 h, 12 h, and 1 h before surgery. Blood samples were withdrawn at 10 min after intubation (T0), at 1 h after aortic declamping (T1), and at 6 h (T2), 12 h (T3), and 24 h (T4) after surgery to measure the serum concentrations of myocardial enzymes and other biomarkers, including cardiac troponin I (cTnI), which was the primary endpoint of this study. Creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH), inotropic score (IS), and inflammatory mediators were also measured. Blood gas analysis was conducted to calculate the PaO₂/FiO₂ ratio and A-aDO₂, and the incidence of acute lung injury (ALI) was also recorded. Results: mRIPC significantly decreased the serum concentrations of cTnI, CK-MB, and LDH at T2, T3, and T4 (p < 0.01), and the IS decreased compared with that in the control group (12.0 ± 1.0 vs. 14.2 ± 1.1, p < 0.01). In addition, the incidence of ALI in the mRIPC group was decreased (32.6% vs. 51.2%, p = 0.039), and the PaO₂/FiO₂ was higher at T4 (p < 0.05). Compared with those in the control group, the levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were decreased at T1, T2, T3, and T4 (p < 0.05) in the mRIPC group, and the level of IL-10 increased at the same time. Conclusions: mRIPC decreased the incidence of myocardial and lung injury in MVR surgery, providing new evidence for the clinical application of RIPC in valve surgery. Trial Registration: ClinicalTrials.gov (NCT01406678).