Ischemic Preconditioning Ineffectual Before Cardiac Surgery

A new study suggests that cycles of upper arm remote ischemic preconditioning (RIPC) before heart surgery has no effect on outcomes.

Researchers at University Hospital Frankfurt (Germany), University Hospital Göttingen (Germany) and other institutions in Germany conducted a prospective, randomized trial involving 1,385 adults (692 study cohort and 693 shams) scheduled for elective cardiac surgery requiring cardiopulmonary bypass. The primary end point was a composite of death, myocardial infarction (MI), stroke, or acute renal failure up to hospital discharge. Secondary end points included the occurrence of any individual component of the primary end point by day 90.

The results showed no significant between-group difference in the rate of the composite primary end point, or of any of the individual components; the results were similar in the per-protocol analysis, and no treatment effect was found in any subgroup analysis. No significant differences between the RIPC group and the sham-RIPC group were seen in level of troponin release, duration of mechanical ventilation, length of stay in the ICU or the hospital, new onset of atrial fibrillation, and incidence of postoperative delirium. No RIPC-related adverse events were observed. The study was published on October 8, 2015, in the New England Journal of Medicine (NEJM).

“The preconditioning protocol had no impact on the primary composite endpoint of death, MI, stroke, or acute renal failure up to the time of hospital discharge, compared with sham conditioning before elective cardiac surgery requiring cardiopulmonary bypass,” concluded lead author Patrick Meybohm, MD, of University Hospital Frankfurt, and colleagues. “Negative findings did not rule out a possible benefit from other remote ischemic preconditioning protocols, such as those done on lower limbs, with a longer duration of ischemia, or more cycles of preconditioning.”

RIPC involves repetitive cycles of transient ischemia of non-vital tissue to help remote vital organs withstand a subsequent prolonged ischemic event and the eventual reperfusion. It usually consists of 3¬–4 five-minute cycles of right upper arm ischemia, induced by an automated cuff inflated to 200 mmHg, with an intervening five minutes of reperfusion during which the cuff is deflated.

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University Hospital Frankfurt
University Hospital Göttingen