People living in the mountains, or fighting a winter storm, may be more likely to have a heart attack, according to a new study by Philippe Amouyel and colleagues at the Institut Pasteur de Lille, France. The group, reporting in the journal
There have long been reports of an association between deaths from heart attacks and temperature – the colder the weather, the more deaths occur. But these studies didn't usually take into account people who had heart attacks and survived. Furthermore, they were often complicated by other causes of death during the winter months – such as the 'flu – which made it hard to be sure what a person had died from.
Amouyel and colleagues set out to look more comprehensively at the possible relationship between temperature and heart attacks. They collected ten years' worth of data (1985-1994) on 257,000 men in the Nord district in northern France, and found a direct relationship between air temperature and the number of heart attacks. The researchers calculated that a 10°C decrease in daily temperature was associated with a 13% increase in the rate of heart attacks in the population. Other researchers have reported that very high temperatures can also cause an increase in heart-attack rate. This study could not fully examine that possibility because average daily temperatures in the Nord rarely climb above 25 °C.
As well as looking at correlations with temperature, the group also examined the relationship between atmospheric pressure and heart attacks – an association that few people have examined previously. These results were not quite so straightforward: there was a 'V'-shaped association between pressure and incidence of heart attacks. In other words, there was a best atmospheric pressure to be at – 1,016 millibars – and people at either higher or lower pressures were at an increased risk. For every 10-millibar increase or decrease in pressure, the rate of heart attacks increased by 11-12%.
The people in the study were broken up into groups by age (25-44, 45-54 and 55-64). Not surprisingly, the trends were weakest for those men in the youngest age group and strongest for those in the highest.
Another study has found that the association between more deaths and lower temperatures was, in fact, more prominent in warmer parts of Europe than in colder regions. The authors speculate that this may be because people who live in very cold climates tend to be better protected against the weather. They make the straightforward conclusion that "individual prevention with clothes suited to cold weather in winter and collective prevention with the improvement of heat insulation of living quarters may be implemented."