Cardiac surgery beginning in the late morning is associated with a modest increase in cardiovascular mortality compared with other times of day.
This is according to a study led by researchers at the University of Manchester.
The study’s author now suggests that integrating body clock biology into the planning of heart surgery could support a more personalised, precision medicine approach.
The findings, based on the analysis of four linked national datasets comprising more than 24,000 patients in England, Wales and Northern Ireland, hold true even when accounting for differences in the complexity and duration of the surgery.
The data showed that late-morning surgery was linked to an 18% higher risk of death (almost one-fifth) from heart-related causes compared with early-morning surgery. And the most common surgical start time was 7.00am to 9.59am, accounting for 47% of all surgeries.
Although complication rates and readmissions were unaffected by time of day, the findings still raise questions about the best time to schedule heart surgery.
They also give an important insight into the potential influence of the body clock on surgery as a whole.
Lead author is Dr Gareth Kitchen, Clinical Senior Lecturer at the University of Manchester. He is also part of the Respiratory Theme and Co-Lead for Industry and Commercialisation at the NIHR Manchester BRC.
He said: ‘Given that over 25,000 heart operations are performed across the UK every year with around a 2.7% mortality, even small improvements in timing-related outcomes could have significant benefits to patients.
‘This research shows a slightly higher risk of heart-related mortality is likely to occur when heart surgery starts in the late morning. However, though the risk is statistically significant, it is relatively modest, and patients can be reassured that most people will almost certainly be unaffected. It is though, our duty as clinicians to ensure the best possible outcomes, and moderating timings is a potentially inexpensive method to achieve that.’
Given that over 25,000 heart operations are performed across the UK every year, with a mortality rate of around 2.7%, even small improvements in timing-related outcomes could have significant benefits for patients.
This research shows a slightly higher risk of heart-related mortality is likely to occur when heart surgery starts in in late morning
The researchers compared four starting times for the three-to-five operations:
• Early morning (07:00 to 09:59)
• Late morning (10:00 to 11:59)
• Early afternoon (12:00 to 13:59)
• Late afternoon (14:00 to 19:59).
The main outcomes they examined were the hazard of death from cardiovascular disease and the time to hospital readmission for heart attack or acute heart failure.
Secondary outcomes included duration of postoperative hospital stay, occurrence of major cardiovascular events and all-cause mortality.
The researchers accounted for potential bias by taking into account key mortality predictors, including age, sex, diabetes and the urgency of surgery.
Dr Kitchen added: ‘Integrating body clock biology into the planning of heart surgery could support a more personalised, precision medicine approach. As some people’s body clocks make them early birds and others make them night owls, it is worth exploring tailored operative times through further research.
‘With more understanding of how body clock biology varies between individuals, precision and personalised scheduling of cardiac surgery may one day allow us to achieve better patient outcomes.’
The study, supported by the National Institute for Health and Care Research (NIHR) Manchester Biomedical Research Centre (BRC), is published in the journal Anaesthesia.
