Heart Health

Updated 29 January 2018

You are more likely to die if this attack happens at night

The odds of surviving cardiac arrest outside peak hours are lower than for people who have cardiac arrest in the daytime during the week.

In the case of cardiac arrest, an irregular heart rhythm causes the heart to stop beating. This causes sudden cardiac death if the patient doesn't receive treatment quickly.

A new study has found that survival rates are rising for people who have cardiac arrest while in hospital.

But if cardiac arrest happens at night or on a weekend, you're more likely to die than if it happens on a weekday.

Cardiac arrest vs. heart attack

The odds of surviving an "off-hours" cardiac arrest are nearly 4% lower than for people who have cardiac arrest in the daytime during the week, the study found.

The study was published in the Journal of the American College of Cardiology.

According to a previous Health24 article, cardiac arrest occurs when your heart function suddenly and unexpectedly stops, you lose consciousness and stop breathing. Your heart either stops completely or the rhythm becomes erratic, which prevents it from pumping blood effectively.

A heart attack, on the other hand, occurs when the flow of blood and oxygen to the heart is blocked by a clot for example, causing damage to the heart muscle. If the clot partially blocks the flow of blood in the arteries of the heart, it can cause a lack of oxygen to the heart muscle tissue called ischemia. If the clot completely stops the blood flow, then a heart attack develops.

The new study findings came from an analysis of data from 2000 through 2014 on more than 151 000 adults who had a cardiac arrest while hospitalised in the United States.

Sudden cardiac death claims the lives of as many as 2 000 young South Africans per year who are seemingly healthy, show no signs of heart disease, and who are unaware that they have an existing heart condition.

Improving survival

In that time period (2000–2014), in the US, overall rates of survival at least until discharge from the hospital increased from 16% to 25% for those who had cardiac arrest on a weekday. Survival also improved for those with an off-hours cardiac arrest, from nearly 12% to 22%. However, that was 3.8% lower than patients whose cardiac arrest occurred during a weekday, the researchers noted.

Each year, about 200 000 people experience cardiac arrest while in a US hospital, according to the study authors.

"Nearly 50% of in-hospital cardiac arrests take place during off-hours. By determining how survival has changed in recent years, we may be able to identify opportunities for quality improvement efforts," the study's lead author, Dr Uchenna Ofoma, said in a news release from the American College of Cardiology.

"If we can improve survival for cardiac arrests that occur during off-hours, it could impact a substantial number of patients," said Dr Ofoma.

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