Remote ischemic preconditioning improves myocardial salvage after PCI
MedWire News: Researchers report that remote ischemic preconditioning, by the induction of intermittent upper-arm ischemia, before primary percutaneous coronary intervention (PCI) reduces reperfusion injury and thereby increases myocardial salvage in patients with evolving myocardial infarction (MI).
The effect seems to be strongest in patients with totally occluded vessels and with infarcts in the left anterior descending artery, they say. Reporting their findings in The Lancet, Hans Erik Bøtker (Aarhus University Hospital, Denmark) and colleagues call for further research to investigate the impact of the approach on clinical outcomes.
The study involved 333 consecutive patients with suspected first acute MI who were randomly assigned to receive PCI with or without remote ischemic preconditioning, which was induced through four cycles of 5-min inflation and 5-min deflation of a blood-pressure cuff and started while the patients were being transported to hospital.
The primary endpoint of myocardial salvage index at 30 days after primary PCI, measured by myocardial perfusion imaging (single photon emission computed tomography), was calculated as the proportion of the area at risk salvaged by treatment.
Bøtker and colleagues report that 82 patients were excluded on arrival at hospital because the diagnosis of MI could not be confirmed, or the patient had had a previous MI or coronary artery bypass graft or onset of chest pain 12 hours earlier or more. A further 32 patients were lost to follow-up and 77 did not complete follow-up with data for salvage index.
In per-protocol analysis of the remainder, the salvage index was significantly higher in the 73 patients who received the remote preconditioning than in the 69 patients who did not, at a median of 0.75 versus 0.55 (p=0.0333). The area at risk correlated with final infarct size in both the intervention and control groups. But the slope of the regression line was lower in the intervention than control group, suggesting that smaller infarcts developed for a given area at risk with intervention, the authors note.
Per-protocol analysis of the primary endpoint in patient subgroups revealed that remote preconditioning was associated with a higher myocardial salvage index in patients with an occluded artery on admission, at 0.74 compared with 0.53 in the intervention versus control groups (p=0.0313), whereas no significant difference was seen between treatment groups for patients without vessel occlusion.
Similarly, remote preconditioning was associated with increased salvage index, although the difference did not reach significance, and significantly reduced final infarct size (8% vs 16%, p=0.0108) in patients with infarct in the left anterior descending artery. However, the interaction of remote preconditioning with vessel occlusion or infarct location was not significant for increase in salvage index.
“At a time of major difficulties in supporting the cost of our healthcare systems, Bøtker and colleagues have shown that a non-invasive, simple, safe, and cheap intervention, possibly done by a paramedic before hospital admission, can significantly increase myocardial salvage; they have also shown the benefit of an integrated prehospital and inhospital therapeutic strategy,” say Michel Oviz (University Lyon, France) and Eric Bonnefoy (INSERM, Lyon, France) in an accompanying commentary.
They add that the study “confirms proof-of-concept clinical studies and suggests that lethal reperfusion injury is the next major target for the treatment of patients with acute MI.”
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By Caroline Price