medwireNews: A randomized, controlled trial provides the first strong evidence that remote ischemic preconditioning can reduce mortality among patients undergoing coronary artery bypass graft (CABG) surgery.
All-cause mortality was the main safety endpoint of the trial, as reported in The Lancet. By 1 year after surgery, 1.9% of 162 patients assigned to undergo remote ischemic preconditioning had died, compared with 6.9% of 167 patients in the control group.
Death rates at 30 days were also lower in the ischemic preconditioning versus control groups, but not significantly so, at 1.9% versus 3.6%, report Gerd Heusch (Universitätsklinikum Essen, Germany) and co-workers.
Also, as noted in an accompanying commentary by Nathan Mewton (Université Claude Bernard Lyon) and Michel Ovize (Hôpital Louis Pradel, Lyon, France), rates of noncardiac outcomes such as stroke and sepsis tended to be reduced among patients who underwent remote ischemic preconditioning.
“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,” they write.
The direct benefits for the heart were also clear, with significantly reduced rates of major cardiovascular events relative to control treatment and nonsignificantly reduced rates of cardiac death and repeat revascularization. Postoperative myocardial injury (the primary efficacy endpoint) was significantly reduced in the preconditioning group, with a geometric mean area under the curve for cardiac troponin I levels during the 72 hours after surgery of 266 ng/mL, compared with 321 ng/mL in the control group.
Patients in the ischemic preconditioning group received the intervention after induction of general anesthesia. A cuff on the upper left arm was inflated to 200 mmHg for 5 minutes (ischemia) and deflated for 5 minutes (reperfusion); this process was repeated three times. In the control group, the cuff was placed but not inflated.
“Thus, a simple and cheap method of inducing natural protection in various pathological settings might prove to have substantial clinical effects, possibly closer to those achieved pharmacologically than by focal ischaemic conditioning,” say Mewton and Ovize. “If such effects are genuine, whether additive benefit might be expected from the combination of different types of conditioning interventions in various clinical settings could be interesting to investigate.”