Paramedics at London Ambulance Service are urging Londoners to learn life-saving skills and how to use a defibrillator as the number of cardiac arrests rise sharply during the winter months.
London Ambulance Service data released to coincide with the annual ‘Restart a Heart Day’ this week (16 October) shows that there were 3,400 cardiac arrests during winter 2025/26 – 488 more incidents than summer 2025 and a 17% increase.
The trend was even more pronounced the previous year. Winter 2024/25 saw 3,643 cardiac arrests, compared with 2,965 during summer 2024 – an increase of 678 incidents (23%).
The figures mean London experienced 20% more cardiac arrests during winter compared to the summer months across both years.
Dr Fenella Wrigley MBE, Chief Medical Officer at London Ambulance Service, said:
“These figures paint a stark picture about the significant impact colder weather can have on heart health.
“Cold weather puts additional pressure on the heart and make it work harder to pump blood around the body. This can increase the risk of cardiac arrest particularly in patients with known heart conditions.
“As we expect to see an increase in cardiac arrests during the winter months, it’s vital that as many Londoners as possible feel confident to start chest compressions and use a defibrillator before an ambulance crew arrives.
“Every minute without chest compressions and defibrillation reduces a person’s chance of survival, so early intervention is absolutely crucial.
“These skills take only minutes to learn and more than doubles a person’s chance of surviving.”
As part of the Restart a Heart campaign – an annual initiative led by Resuscitation Council UK – paramedics at London Ambulance Service are also offering free sessions to teach people what to do if someone suffers a cardiac arrest.
Since September 2021, the Service’s London Lifesavers campaign has trained over 63,000 Londoners as part of its aim to make the capital a city of lifesavers.
The London Ambulance Charity’s Heart Starters campaign is also installing defibrillators in the neighbourhoods in London where there is no or little access to one of these life-saving devices.
Help us to help people in the capital by becoming a London Lifesaver or by donating to the Heart Starters campaign.