Heart operations are safer in afternoons

UNDERGOING heart surgery in the afternoon may be far safer than in the morning because it syncs up with the body’s circadian rhythm, a study has suggested.

A review by French researchers of nearly 600 people who underwent heart valve replacements found that people who had morning operations were twice as likely to suffer a major cardiac event in the following 500 days. Only nine per cent of afternoon patients suffered a heart attack, heart failure, or death from heart disease, in the follow-up period, in contrast to 18 per cent of morning patients, the study in The Lancet showed.

Study author Professor David Montaigne, of the University of Lille, said: “Our study found that post-surgery heart damage is more common among people who have heart surgery in the morning, compared to the afternoon. Our findings suggest this is because part of the biological mechanism behind the damage is affected by a person’s circadian clock and the underlying genes that control it.”

The researchers tested 30 heart tissue samples. A genetic analysis showed that 287 genes linked to the circadian clock were more active in the afternoon surgery samples, compared to the morning surgery samples. This suggests that the heart is subject to the body’s circadian clock, reflecting the heart’s poorer ability to repair in the morning.

Tim Chico, consultant cardiologist at the University of Sheffield, said the findings could have “major implications” on operation schedules, but added many other factors could explain them.