Effects of remote ischemic preconditioning in high-risk patients undergoing cardiac surgery (Remote IMPACT): a randomized controlled trial

Abstract

Background: Remote ischemic preconditioning is a simple therapy that may reduce cardiac and kidney injury. We undertook a randomized controlled trial to evaluate the effect of this therapy on markers of heart and kidney injury after cardiac surgery.

Methods: Patients at high risk of death within 30 days after cardiac surgery were randomly assigned to undergo remote ischemic preconditioning or a sham procedure after induction of anesthesia. The preconditioning therapy was three 5-minute cycles of thigh ischemia, with 5 minutes of reperfusion between cycles. The sham procedure was identical except that ischemia was not induced. The primary outcome was peak creatine kinase-myocardial band (CK-MB) within 24 hours after surgery (expressed as multiples of the upper limit of normal, with log transformation). The secondary outcome was change in creatinine level within 4 days after surgery (expressed as log-transformed micromoles per litre). Patient-important outcomes were assessed up to 6 months after randomization.

Results: We randomly assigned 128 patients to remote ischemic preconditioning and 130 to the sham therapy. There were no significant differences in postoperative CK-MB (absolute mean difference 0.15, 95% confidence interval [CI] -0.07 to 0.36) or creatinine (absolute mean difference 0.06, 95% CI -0.10 to 0.23). Other outcomes did not differ significantly for remote ischemic preconditioning relative to the sham therapy: for myocardial infarction, relative risk (RR) 1.35 (95% CI 0.85 to 2.17); for acute kidney injury, RR 1.10 (95% CI 0.68 to 1.78); for stroke, RR 1.02 (95% CI 0.34 to 3.07); and for death, RR 1.47 (95% CI 0.65 to 3.31).

Interpretation: Remote ischemic precnditioning did not reduce myocardial or kidney injury during cardiac surgery. This type of therapy is unlikely to substantially improve patient-important outcomes in cardiac surgery.

Trial registration: ClinicalTrials.gov, no. NCT01071265.

© 2016 Canadian Medical Association or its licensors.

Figures

Figure 1:

Flow chart for patients in the Remote IMPACT study of remote ischemic preconditioning (RIPC). CK-MB = creatine kinase–myocardial band, EuroSCORE = European System for Cardiac Operative Risk Evaluation.

Figure 2:

Serum creatine kinase–myocardial band (CK-MB), as multiples of the upper limit of normal, for patients in the remote ischemic preconditioning (RIPC) and sham therapy groups. For each data point, the central horizontal bar represents the median, the box shows the interquartile range (25th to 75th percentile), and the lower and upper whiskers represent the 2.5th and 97.5th percentiles, respectively.

Figure 3:

Serum creatinine levels in the remote ischemic preconditioning (RIPC) and sham therapy groups. For each data point, the central horizontal bar represents the median, the box shows the interquartile range (25th to 75th percentile), and the lower and upper whiskers represent the 2.5th and 97.5th percentiles, respectively.