Cardioprotective and Prognostic Effects of Remote Ischaemic Preconditioning in Patients Undergoing Coronary Artery Bypass Surgery: A Single-Centre Randomised, Double-Blind, Controlled Trial

Study Questions:

What is the safety and efficacy of remote ischemic preconditioning in patients undergoing coronary artery bypass graft (CABG) surgery?

Methods:

Eligible patients were those scheduled to undergo elective isolated first-time CABG surgery under cold crystalloid cardioplegia and cardiopulmonary bypass at the West-German Heart Centre, Essen, Germany, between April 2008, and October 2012. Patients were prospectively randomized to receive remote ischemic preconditioning (three cycles of 5 minutes of ischemia and 5 minutes of reperfusion in the left upper arm after induction of anesthesia) or no ischemic preconditioning (control). The primary endpoint was myocardial injury, as reflected by the geometric mean area under the curve (AUC) for perioperative concentrations of cardiac troponin I (cTnI) in serum in the first 72 hours after CABG. Mortality was the main safety endpoint. Analysis was done in intention-to-treat and per-protocol populations.

Results:

A total of 329 patients were enrolled. Baseline characteristics and perioperative data did not differ between groups. cTnI AUC was 266 ng/ml over 72 hours (95% confidence interval [CI], 237-298) in the remote ischemic preconditioning group and 321 ng/ml (287-360) in the control group. In the intention-to-treat population, the ratio of remote ischemic preconditioning to control for cTnI AUC was 0.83 (95% CI, 0.70-0.97; p = 0.022). cTnI release remained lower in the per-protocol analysis (ratio, 0.79; 99% CI, 0.66-0.94; p = 0.001). All-cause mortality was assessed over 1.54 (standard deviation, 1.22) years, and was lower with remote ischemic preconditioning than without (ratio, 0.27; 95% CI, 0.08-0.98; p = 0.046).

Conclusions:

The authors concluded that remote ischemic preconditioning provided perioperative myocardial protection and improved the prognosis of patients undergoing elective CABG surgery.

Perspective:

Ischemic preconditioning with walking exercise has been shown to reduce claudication and angina at a given workload. Small studies have shown that remote ischemic preconditioning improves outcome with PCI and other vascular procedures. This is the first randomized controlled study demonstrating that remote ischemic preconditioning reduces postoperative release of cTnI, which remarkably is associated with a decrease in long-term all-cause mortality. If this relatively simple protocol for improving long-term outcome in patients undergoing coronary surgery can be validated in a much larger trial, remote ischemic preconditioning may become a standard of care.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Prognosis, Biological Markers, Troponin I, Standard of Care, Germany, Coronary Artery Bypass, Ischemic Preconditioning


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