Remote ischemic preconditioning may improve clinical outcomes after CABG procedure

August 23, 2007 By Katherine Ogando[mailto:kogando@perfuse.org]

London, England: Coronary bypass patients may experience better outcomes following surgery thanks to remote ischemic preconditioning, a technique which induces ischemia and reperfusion in a distant region from the heart and may reduce the risk of myocardial injury after coronary artery bypass graft surgery.

According to a randomized controlled trial recently published in [http://www.thelancet.com/ The Lancet, remote ischemic preconditioning offered a significant improvement in clinical outcomes of patients who underwent elective coronary artery bypass graft surgery. The study included a total of 57 adult patients, 30 of which were randomly assigned to the control group and 27 to the remote ischemic preconditioning group. Remote ischemic preconditioning was performed by restricting blood flow to the right arm in three 5-minute cycles by inflating an arm cuff to 200 mmHg, and reperfusing the arm by deflating the arm cuff.

Troponin-T, a perioperative cardiac enzyme, was used as an indicator of the outcome of the procedure. Since high levels of serum troponin-T following an intervention have been associated with an increased risk of morbidity and mortality, the authors suggest positive clinical outcomes may result from the significant decrease of 43% in serum troponin-T, from 36.12 μg/L in the control to 20.58 μg/L in the experimental group at 6, 12, 24, and 48 hours after surgery. Measurements at 72 hours did not show a significant reduction in troponin-T.

The authors hypothesize that remote ischemic preconditioning triggers a protective mechanism in the heart, which may consequently reduce the size and damage of a subsequent myocardial infarction following surgery. Despite the fact that the exact method in which this protective mechanism works is still uncertain, Hausenloy et al. are optimistic of the potential of remote ischemic preconditioning, stating in their published article, “One might expect that in high-risk patients for whom serum troponin-T concentrations are substantially greater, remote ischemic preconditioning might confer an even greater reduction in myocardial injury.”

Larger trials would be needed to further validate these findings and to determine if the biomarker reduction would translate into improved clinical outcomes.

References

D Hausenloy, P K Mwamure, V Venugopal, J Harris, M Barnard, E Grundy, E Ashley, S Vichare, C DiSalvo, S Kovekar, M Hayward, B Keogh, R J MacAllister, D M Yellon. Effect of remote ischaemic preconditioning on myocardial injury in patients undergoing coronary artery bypass graft surgery: A randomised controlled trial. The Lancet 2007; 370: 575-79.