Why are serious heart attacks more likely on a Monday?

According to new research presented at the British Cardiovascular Society (BCS) conference in Manchester, serious heart attacks are more likely to occur on a Monday compared to other days of the week.

The study, by doctors from the Belfast Health and Social Care Trust and the Royal College of Surgeons in Ireland, examined the records of 10,528 patients admitted to hospitals across the island of Ireland (including the Republic of Ireland and Northern Ireland).

These patients had been admitted between 2013 and 2018 for the most severe type of heart attack, known as an ST-segment elevation myocardial infarction (STEMI). This happens when a major coronary artery, which supplies blood to your heart, becomes completely blocked. Without emergency care, STEMIs can be fatal.

Each year in the UK, more than 30,000 people are admitted to hospital with a STEMI. They need immediate assessment and treatment to minimise damage to their hearts. This typically involves emergency angioplasty and stent(s), a procedure to reopen the blocked coronary artery and get blood flowing to the heart again.

The researchers found there was a notable increase in the rate of STEMI heart attacks at the start of the working week, with rates highest on a Monday (a 13 per cent increase). They also saw higher than expected rates of STEMI on Sundays.

The exact reason behind this “Blue Monday” effect isn’t yet known. Past studies showing a greater likelihood of heart attacks at the start of the week have suggested a link with the body's circadian rhythm, which governs our sleep and wake cycles.

What do the researchers say?

Cardiologist Dr Jack Laffan, who led the research at the Belfast Health and Social Care Trust, said: “We’ve found a strong statistical correlation between the start of the working week and the incidence of STEMI. This has been described before but remains a curiosity.”

He said there was likely to be more than one explanation for the findings: “The cause is likely multifactorial, however, based on what we know from previous studies, it is reasonable to presume a circadian element.”

The BHF verdict

Although STEMI heart attacks are more likely to occur on Mondays, this doesn’t mean they are unlikely to happen during the rest of the week. Whether it’s a Monday, Tuesday, or another day of the week, heart attacks are one of the most common medical emergencies.

• Learn all about the symptoms of a heart attack and what to do if you notice them

Professor Sir Nilesh Samani, Medical Director at the BHF, said: “Someone is admitted to hospital due to a life-threatening heart attack every five minutes in the UK, so it’s vital that research continues to shed light on how and why heart attacks happen.

“This study adds to evidence around the timing of particularly serious heart attacks, but we now need to unpick what it is about certain days of the week that makes them more likely. Doing so could help doctors better understand this deadly condition so we can save more lives in future.”

How good was the media coverage?

This research was covered in The Daily Mail, The Mirror and The Independent, among other media outlets. The coverage was largely accurate, with all three newspapers offering a balanced summary of the research and its key findings.

The headline used in The Mirror reads: “Warning as most common day to suffer a serious heart attack revealed”. However, this could risk causing unnecessary alarm as no official warning has been issued in light of the research.

It could also imply the need to take special care on a Monday, but the most sensible approach would be to take good care of your heart health throughout the week. This might include taking daily steps to address any risk factors for coronary heart disease, such as stopping smoking, eating healthily, staying active, and managing your stress.

Helpfully, The Daily Mail includes an extended quote from Dr Jack Laffan which sheds further light on the possible implications of this research: “We found a higher chance of having a serious heart attack on a Monday. This phenomenon has been described before across the Western world.

“We know that heart attacks are more likely to happen in winter and in the early hours of the morning. The same effect is seen in the event rate of strokes. Previous studies have also shown a higher rate of heart attacks in the days following the clocks going forward for daylight savings time.

“The exact mechanism for these variations is unknown but we presume it has something to do with how the circadian rhythm affects circulating hormones that can influence heart attacks and strokes.

“It is likely to be due to the stress of returning to work. Increased stress leads to rising levels of the stress hormone cortisol, which is linked to a higher risk of heart attack.”

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