What time heart surgery is performed has a huge impact on success

Glen Mclaughlin
October 29, 2017

The circadian clock governs the body's day-night cycles, thus influencing sleep patterns, the release of hormones, and even body temperature.

Researchers say patients have an increased chance of surviving open heart surgery if done in the afternoon.

Earlier this month, the Nobel Prize for medicine was awarded to three United States scientists who pioneered our understanding of how the circadian clock ticks.

The researchers said that the study will need to be replicated in larger trials to fully understand the association between the circadian clock and damage after heart surgery, and to confirm their findings.

A review by French researchers of almost 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.

Previous research has suggested that heart attacks, cardiovascular events, which occur in the morning may be associated with a higher risk of the damage, compared to afternoon events, but reasons have remained unclear.

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 researchers suggested that our hearts may be better equipped to deal with surgery in the afternoon as they may be stronger this time of day due to the impact of our body clock.

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Those who had surgery in the afternoon had a 50 per cent lower risk of a major cardiac event, compared to people who had surgery in the morning.

During year-long trials that ended in February 88 patients were randomly scheduled for heart valve replacement surgery in the morning or afternoon and monitored until they left hospital.

Nobody wants to have open heart surgery.

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

"The authors have clearly shown that circadian rhythm is of clinical importance", commented Michel Ovize, a cardiologist from Louis Pradel Hospital, outside Lyon, France.

"If we can identify patients at highest risk, they will definitely benefit from being pushed into the afternoon and that would be reasonable", he said.

Heart health is known to fluctuate over the course of one day.

However, John O'Neill from the Medical Research Council Laboratory of Molecular Biology in Cambridge, said the discrepancy between morning and afternoon operations could also be explained by the varying abilities of the surgeons at different times of day.

Other reports by MaliBehiribAe

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