Remote ischemic preconditioning before CABG reduced myocardial injury

Research published in The Lancet found that performing remote ischemic preconditioning on patients about to undergo CABG was associated with reduced risk for myocardial injury and improved long-term prognosis.

The purpose of the prospective, single-center, double blind, randomized controlled trial was to verify previous research indicating that remote ischemic preconditioning reduces myocardial injury and to investigate the effect on long-term survival and other clinical outcomes.

A simple process

In this study, remote ischemic preconditioning was performed using a BP cuff on the upper left arm.

Matthias Thielmann, MD, and colleagues recruited 329 patients with triple-vessel CAD scheduled for elective CABG at West-German Heart Center, Essen, Germany, between April 2008 and October 2012. After anesthesia but before surgery, the intervention group (n=162) had a BP cuff inflated on the upper left arm for 5 minutes, followed by reperfusion for 5 minutes, with the cycle repeated three times. The control group (n=167) did not have remote ischemic preconditioning. Blood samples from all participants were taken before surgery and at 1, 6, 12, 24, 48 and 72 hours after surgery.

The primary endpoint was perioperative myocardial injury, as indicated by the concentration of cardiac troponin I (cTnI) in a patient’s blood. Secondary endpoints were all-cause mortality, major adverse cardiac and cerebrovascular events, and repeat revascularization. Mean follow-up was 1.54 years.

The cTnI geometric mean area under the curve was 266 ng/mL over 72 hours (95% CI, 237-298) in the intervention group vs. 321 ng/mL over 72 hours (95% CI, 287-360) in the control group. After 72 hours, patients in the intervention group had average cTnI concentrations that were 17% lower than those in the control group (95% CI, 3-30).

At the end of follow-up, three deaths (1.9%) had occurred in the intervention group vs. 11 (6.9%) in the control group (HR=0.27; 95% CI, 0.08-0.98); the association with remote ischemic preconditioning became weaker when deaths from sepsis were excluded. The intervention group had lower rates of major adverse cardiac and cerebrovascular events than the control group (13.9% vs. 18.9%; HR=0.32; 95% CI, 0.14-0.71).

Rate of repeat revascularization did not differ between the two groups. There were no adverse events related to remote ischemic preconditioning.

Cardioprotection provided

“At this point, causal relations between cardioprotection and improved clinical outcome must remain speculative,” Thielmann and colleagues wrote. “Nevertheless, our findings indicate that remote ischemic preconditioning is a safe perioperative method that provides cardioprotection and improves prognosis in patients undergoing elective CABG surgery.”

In a related editorial, Nathan Mewton, MD, PhD, and Michel Ovize, MD, PhD, both of the Louis Pradel Hospital, Lyon, France, wrote that because the rates of events not related to the heart were lower in the treatment group vs. the control group, “these findings suggest that the effect on the heart might be only one aspect of a much wider effect, and that remote conditioning, unlike local conditioning, might lead to persistent protection.”

For more information:

Mewton N. Lancet. 2013;382:579-580.

Theilmann M. Lancet. 2013;382:597-604.

Disclosure: The researchers, Mewton and Ovize report no relevant financial disclosures.