No reduction in risk of death with ischemic conditioning
medwireNews: Ischemic conditioning has no effect on the risk of all-cause mortality in patients undergoing invasive procedures, results of a meta-analysis suggest.
“Adoption of ischaemic conditioning cannot be recommended for routine use unless further high quality and well powered evidence shows benefit,” write Martin Gallagher (University of Sydney, New South Wales, Australia) and co-authors.
As reported in The BMJ, the team analyzed results from 68 randomized controlled comparisons, and found that 205 out of 5678 patients undergoing ischemic conditioning died, compared with 219 of 5646 in the control group (risk ratio [RR]=0.96).
The authors explain that ischemic conditioning “has been advocated as a means of mitigating the effects of injury including myocardial ischaemia, acute kidney injury, and stroke,” and that some guidelines support its use during coronary bypass surgery.
However, the results of the present meta-analysis “raise questions about [its] true effects on clinical outcomes” and therefore “current evidence does not warrant adoption into routine clinical practice,” they add.
Over two-thirds of a total of 89 studies included in the meta-analysis were cardiac trials, including adult cardiac surgery (38%), pediatric cardiac surgery (10%), and percutaneous coronary intervention (24%). Ischemic preconditioning was investigated in 76% of trials, and post-conditioning in 24%.
There was no significant reduction in the risk of combined cardiovascular events – a composite of myocardial infarction, stroke, and cardiovascular death, or as defined by study authors – in patients undergoing ischemic conditioning versus controls, with corresponding rates of 21.6% and 23.1% (RR=0.88). Similarly, ischemic conditioning did not reduce the risk of myocardial infarction.
Gallagher and colleagues identified low-quality evidence suggesting that ischemic conditioning could reduce the risk of stroke and acute kidney injury. Stroke occurred in 2.1% of patients undergoing ischemic conditioning versus 2.9% in the control group (RR=0.72), and acute kidney injury in 16.1% versus 18.4%, respectively (RR=0.83).
“Doubt remains, however, about the clinical validity of these results, arising from the incongruous lack of benefit seen for the better powered combined cardiovascular events endpoint, the restriction of benefit for acute kidney injury to mild cases, and the restriction of the stroke and acute kidney injury effects to non-operative settings,” write the authors.
They add that further high-quality trials should investigate “the effect of ischaemic conditioning on myocardial ischaemia, stroke, and acute kidney injury, particularly in non-surgical settings.”
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