New UK research has found that those who have had flu or pneumonia can be six times more likely to suffer from a heart attack or stroke in the days and weeks following infection.
Carried out by researchers from University College London (UCL), the School of Mathematics and Statistics, Open University, Milton Keynes, and Health Protection Scotland, the study is largest to date to look at the effect of specific respiratory infections on the risk of heart attack and stroke, with the findings following a particularly virulent flu season.
For the research the team looked at data from the Scottish Morbidity Record and identified 1,227 adults with a first heart attack and 762 with a first stroke, who had also had a respiratory virus or bacteria infection at any time between 2004 and 2014.
The team then looked at the rate of heart attacks and strokes in the days and weeks immediately after a respiratory infection, and then compared this to the rate of heart and strokes in other periods of time in the same people.
The results showed that having a respiratory infection made people six times more likely to have a heart attack or stroke for three days after infection, with the increased risk of having a heart attack remaining for up to a week after infection, and the increased risk of stroke increased for up to one month.
The findings also showed that although several different organisms that cause respiratory infections increased the risk, the S.pneumoniae bacteria and the influenza virus were found to have the biggest impact.
Perhaps surprisingly, the risk of heart attack and stroke was actually found to be higher for those age 65 and under, with the researchers suggesting that as those aged 65 and over are more likely to be vaccinated against infections.
The researchers emphasize that the findings highlight the importance of vaccinations against respiratory disease for the elderly as well as other at-risk individuals in an effort to prevent not only infections such as the flu, but also reduce the risk of heart attack and stroke.
“For most young, healthy people, the risk of heart attacks and strokes occurring after a respiratory infection is low. This research is particularly relevant for those over the age of 65, as well as people with pre-existing heart diseases, as these groups are at higher risk of heart attacks and strokes,” commented lead researcher Dr Charlotte Warren-Gash.
“These groups are already recommended to have vaccinations against influenza and S.pneumoniae — the two bugs we found to be linked to the highest cardiovascular risk — but we know that vaccine uptake is not high among younger people with heart problems. Understanding that there is a link between these bugs and heart attacks and strokes is an added incentive to get those vaccinations.”
The findings can be found published online in the European Respiratory Journal.