Hearts attacks which happen in winter are more deadly than those suffered in summer, a UK study involving thousands of patients has found.
Cardiologists looked at the 30-day mortality rate for patients suffering from the most serious heart attacks and found the risk of dying in the six coldest months was almost 50 per cent higher than the warmest.
The study involved 4,056 patients at Leeds General Infirmary over four years and the findings are being presented at the British Cardiovascular Society Conference in Manchester.
It found 28 per cent of patients died within 30 days over the winter months, but that fell to 20 per cent in the summer.
Dr Arvin Krishnamurthy, who led the research said possible causes for the difference needed further study.
In colder weather, the body has to work harder to keep warm, causing blood pressure to rise.
Another possible issue was blood clots forming more easily in the cold, and illnesses like flu being more prevalent.
"There is no physical reason why a heart attack, even the most severe, should be more deadly in winter than in summer so we must do further research to find the cause of this difference and remedy it," he said.
Professor Metin Avkiran, associate medical director at the British Heart Foundation, said: "You obviously can't choose when you have a major heart attack, but it shouldn't have such an impact on your chances of surviving."
Meanwhile, a separate UK study being presented at the conference says it is taking some heart attack patients an average of 25 minutes longer to arrive at hospital than in 2011.
Researchers at Portsmouth Hospitals NHS Trust studied 1,347 cases going back six years from 2017 and found the average time from an emergency call being made to the patient arriving at hospital has gone up from 53 minutes to 78 minutes.
