Heart surgery may be safer in the afternoon, study reports

Researchers have found that the body's internal clock could make afternoon heart surgery safer than morning procedures.
By Jeremy Morrow | Oct 28, 2017
The body's internal clock may make heart surgery safer in the afternoon than in the morning, a new study published in The Lancet reports.

Our internal clock -- also known as circadian rhythm -- drives large changes in the way the body works. It is the reason we sleep at night, and it also drives certain biological changes throughout the day.In the new study, a group of researchers fromthe Institut Pasteur de Lille also proved that it could make the heart stronger and more able to withstand surgery during the afternoon.

In order to perform operations on the heart, doctors typically need to stop the organ. This reduces oxygen flow to the tissue and puts the heart under an enormous amount of stress.

To get an idea of how that stress is linked to time, the team looked at how complications -- including heart attacks, heart failure, or death after surgery -- changed from morning to afternoon to night. This showed that 54 out of 298 morning patients had adverse events, compared to just 28 out of 298 afternoon patients. In addition, patients who went into surgery during the afternoon had half the risk of complications.

While the team does not want to discourage people from having life-saving surgery, they do hope to make doctors more aware of the best times to operate.

"If we can identify patients at highest risk, they will definitely benefit from being pushed into the afternoon and that would be reasonable," study co-author Bart Staels, a researcher at the Institut Pasteur de Lille, told BBC News.

Previous research has already shown that heart health fluctuates throughout the day. The risk of a heart attack or stroke is highest first thing in the morning, while the heart and lungs work at their peak in the afternoon.

While some people speculate that surgeons being tired in the morning is the reason for those differences, the team showed that was not the cause. Not only did they analyze DNA samples to show different genes changed throughout the day, but they alsoaltered the activity of one of those genes in mice, which reduced the risk of death.

However, while this is compelling evidence, more research needs to be done before the link between heart surgery and time of day can be confirmed. There are many factors at play and scientists hope they can better narrow it down for future study.

"What this research suggests is that an intrinsic body clock within cells of the heart may render these cells more susceptible to injury during cardiac surgery in the morning versus the afternoon," saidBryan Williams, chair of medicine at University College London who was not involved in the study, according toThe Guardian."This would be needed to change practice because the logistical implications of doing so would be huge and require definitive proof that there is a real benefit."

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