The choice of general anesthetic does not appear to influence the risk for myocardial infarction in patients undergoing noncardiac surgery, report researchers.
The finding emerges from a randomized controlled trial involving 385 patients at cardiovascular risk, the results of which are published in Circulation.
In an editorial accompanying the study, Judy Kersten (Medical College of Wisconsin, Milwaukee, USA) notes that the findings question current American College of Cardiology/American Heart Association guidelines, which recommend using volatile anesthetics in patients at cardiovascular risk who require noncardiac surgery.
The recommendation is based on preliminary but promising evidence for myocardial preconditioning and a reduced risk for ischemic complications in patients given volatile anesthetics for cardiac surgery.
But in the current study, the choice of general anesthetic had no impact on ischemic outcomes after noncardiac surgery, report Giovanna Lurati Buse (University Hospital Basel, Switzerland) and co-workers. Specifically, 40.8% and 40.3% of patients randomly assigned to receive sevoflurane and propofol, respectively, had myocardial ischemia within 48 hours of surgery, detected by continuous electrocardiogram and elevated troponin.
The rate of postoperative delirium was similar in the sevoflurane and propofol groups, at 11.4% and 14.4%, respectively, and longer-term outcomes were also unaffected, with a corresponding 7.6% and 8.5% having a major adverse cardiac event within 12 months of undergoing surgery.
The study was conducted across three centers. Anesthesia was induced with etomidate for all patients and maintained with the study drugs. Anesthesiologists were free to determine anesthetic doses, and use of other agents such as opioids, muscle relaxants, and vasopressors.
Kersten says that this study design would have made positive findings broadly applicable, but makes the actual negative finding difficult to interpret, because any effects of general anesthetic allocation on myocardial ischemia risk could be dose-dependent or obscured by use of opioids.
"Thus, it is unclear if the negative findings of the investigation indicate a lack of volatile anesthetic cardioprotection per se, or the influence of additional factors that also modulate the incidence of perioperative myocardial ischemia," she says.
She also cites research suggesting that that the skill of the anesthesiologist in managing intraoperative hemodynamics may in fact be the most important factor governing perioperative cardiac risk.
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