Inhaled, IV Anesthestics Even in Cardiac Surgery Survival

Inhaled anesthesia may be safer for the heart than infusion agents, but that didn’t lead to better survival in patients undergoing coronary artery bypass grafting (CABG) surgery in the MYRIAD trial.

Those randomized to inhaled anesthesia had the same likelihood of mortality at 1 year as peers who got IV general anesthesia-only (2.8% vs 3.0%, RR 0.94, 95% CI 0.69-1.29). Deaths at 30 days were also virtually a dead heat (1.4% vs 1.3%, RR 1.11, 95% CI 0.70-1.76), according to investigators led by Giovanni Landoni, MD, of IRCCS San Raffaele Scientific Institute in Milan, Italy.

“There were no significant differences between the groups in any of the secondary outcomes or in the incidence of prespecified adverse events, including MI,” Landoni’s group noted. Neither group experienced any propofol infusion syndrome or malignant hyperthermia.

Data from the study were presented at the International Symposium on Intensive Care and Emergency Medicine and also published online in the New England Journal of Medicine.

“Previous preclinical studies, observational studies, moderate-sized randomized, controlled trials, meta-analyses of randomized, controlled trials, and consensus opinion had all suggested that the use of volatile anesthetics during cardiac surgery, and especially during CABG, would enhance myocardial protection and reduce the risk of perioperative MI, myocardial dysfunction, and death,” according to Landoni and colleagues.

Importantly, their trial had been stopped early for futility after interim analyses indicated that final results wouldn’t show a difference.

MYRIAD included 5,400 patients undergoing CABG at 36 centers in 13 countries. Randomization resulted in two well-matched groups at baseline. There was a 2.3% rate of crossovers.

Surgeries were performed on-pump in 64% of patients, with cardiopulmonary bypass lasting 79 minutes on average.

Particular protocols weren’t required, but some were recommended to enhance the cardioprotective effect of inhalation agents, typically sevoflurane (83.2%). Patients in that arm could also receive infused anesthetics, and nearly all did, as this is standard in routine practice.

Controls getting only IV anesthesia received propofol (87.7%) and/or midazolam (32.2%). They were not allowed to receive any volatile agents.

No specific drug protocol was given because the trial was meant to be “pragmatic” and “aimed at replicating a real-life environment,” according to Landoni’s group.

“For the same reason, we did not compare total IV anesthesia with total inhalational anesthesia because the latter strategy is seldom used in adult surgery, and previous trials also allowed for administration of IV anesthetics in the volatile anesthetics group.”