Heart surgery safer in the afternoon than in the morning, says study

LONDON: People who undergo heart surgery in the morning are twice as likely to suffer a major cardiac event, compared to those who get operated in the afternoon, according to a study published in The Lancet journal.

Researchers, including those from the University of Lille in France, reviewed nearly 600 people who underwent heart valve replacements.

They found that people who had morning operations were twice as likely to suffer a major cardiac event, in the following 500 days.

The study found that 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.

"Our study found that post-surgery heart damage is more common among people who have heart surgery in the morning, compared to the afternoon," David Montaigne, professor at University of Lille told 'The Telegraph'.

"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," Montaigne said.

Researchers tested 30 heart tissue samples from people who took part in the study.

A genetic analysis of these samples also 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, and the surgical outcomes reflect the heart's poorer ability to repair in the morning than in the afternoon, researchers said.

"In the morning, just after we have woken up, the cardiovascular system is not yet at peak performance, which partly explains why heart attacks and strokes are occur more frequently in the morning," researchers said.