According to a study conducted by the British Heart Foundation, heart attacks are more likely to kill heart patients in the winter than in the summer.

Cardiologists at Leeds General Infirmary compared information from 4,056 people who received treatment for a heart attack in four separate years and found the most severe heart attacks were more deadly in the coldest six months, compared to the warmest. The overall number of heart attacks was roughly the same in the coldest half of the year, compared to the warmer months (52 percent between November and April), with the most serious heart attacks leading to cardiac arrest and cardiogenic shock.

The risk of dying within 30 days of a severe heart attack was nearly 50 percent higher in the six coldest months, compared to the six warmest months (28 percent vs 20 percent). Cardiac arrest is when the heart suddenly stops pumping blood around the body, while cardiogenic shock is when the heart can't pump enough blood to meet the body's needs. Both conditions are often caused by a severe heart attack, but not everyone who has a heart attack has a cardiac arrest or cardiogenic shock.

Arvin Krishnamurthy, who led the research from Leeds, said, "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. The next step is to find out if this trend is seen nationwide".

"Potential explanations could include longer time to treatment, prolonged hospitalisation and delays to discharge, and increased prevalence of winter-associated infections, which in the sickest patients, could be potentially lethal", continued Krishnamurthy. "Further studies interrogating the association between time of admission and outcomes, especially in the sickest and most vulnerable patients, are certainly warranted".

Researcher Metin Avkiran 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. It's vital we carry out more research to find out why there are these differences, as well as continuing to do all we can to stop people having heart attacks in the first place". "Although we've made huge strides in the last 50 years, we must urgently fund more research to continue to drive down the number of heart attacks and ensure more people can live full lives even after a heart attack." The study was presented at the British Cardiovascular Society Conference 2018 in Manchester.