Aortic Valve Replacement: Afternoon Surgery Linked to Fewer Adverse Events

By Kelly Young

Edited by André Sofair, MD, MPH, and William E. Chavey, MD, MS

Having cardiac surgery in the afternoon rather than the morning is linked to better outcomes, suggests a Lancet study.

First, researchers studied consecutive patients who underwent on-pump cardiac surgery for aortic valve replacement: 300 patients who had surgery in the morning were matched to 300 who had surgery in the afternoon. During roughly 17 months' follow-up, the rate of major adverse cardiac events was significantly lower with afternoon versus morning surgery (hazard ratio, 0.5). For every 11 patients who had afternoon surgery, one major cardiac event was averted. This difference was driven by lower rates of perioperative myocardial infarction and acute heart failure.

Then, 88 patients undergoing aortic valve replacement were randomized to morning or afternoon surgery. Postoperative cardiac troponin T levels were significantly lower in the afternoon group. A separate analysis of human myocardium biopsy samples found that time of day affected the expression of nearly 300 genes.

Commentators write: "Even before we have drugs available to regulate the circadian clock, one might propose that high-risk patients should preferentially be operated on in the afternoon."

Dr. Harlan Krumholz of NEJM Journal Watch Cardiology offered his take: "Before everyone rushes to schedule their surgery in the afternoon, it will be good to understand how well this replicates across systems and whether this is related to biology, quality of care, or some other factors."