Having heart surgery is much better in the afternoon, major new study finds

If you must have heart surgery, then it's a good idea to make sure it happens at the right time

Lisa was handed her heart four days after the surgery (AFP/Getty Images)

Nobody wants to have open heart surgery. But if you do, you want to have it in that afternoon.

That's the conclusion of a major new study that found there is a significantly higher risk of damage for people having surgery in the morning.

And it's all because of the body clock, or circadian rhythms, which help keep us regulated through the day. It decides when we wake up, sleep and eat – and how ready we are to recover from major surgery.

The new study, published in the Lancet, found that there are almost 300 genes that link the body clock to heart damage.

And it found that there is a link between a person's body clock and how at risk they are of undergoing heart damage and major events like heart attacks after having heart surgery.

Study author Professor David Montaigne, University of Lille, France, 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.

"As a result, moving heart surgery to the afternoon may help to reduce a person's risk of heart damage after surgery."

Researchers looked at the medical records of 596 people who had heart valve replacement surgery including half who had surgery in the morning, half in the afternoon.

They checked for any major cardiac events such as a heart attack, heart failure or death from heart disease in this research which took place between January 2009 to December 2015.

They found that 28 out of 298 afternoon patients had adverse events while 54 out of 298 morning patients experienced such events.

The researchers suggest this could equate to one major event being avoided for every 11 patients who have afternoon surgery and that people who had surgery in the afternoon had a 50% lower risk of a major cardiac event, compared with people who had surgery in the morning.

The team also tracked the health of 88 patients who were randomly scheduled for heart valve replacement surgery in the morning or afternoon between January 2016 to February 2017.

Those who had afternoon surgery had lower levels of heart tissue damage after surgery, compared with morning surgery patients, according to the researchers.

Tests on heart tissue samples from 30 of the patients - including 14 who had morning surgery and 16 from the afternoon surgery group - showed that the afternoon surgery samples more quickly regained their ability to contract when put in conditions similar to the heart refilling with blood.

Genetic analysis of these samples also showed that 287 genes linked to the circadian clock were more active in the afternoon surgery sample.

The researchers believe this suggests the heart is subject to the body's circadian clock and the post-surgery results highlight that the heart is maybe weaker at repairing in the morning than in the afternoon.

Larger trials are need to test the findings.

Professor Michel Ovize, Hopital Louis Pradel, France, said the scientists have "clearly shown that circadian rhythm is of clinical importance in aortic valve replacement surgery" but that more research is needed.

He added: "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."

Additional reporting by agencies