International Circulation International diabetes idiabetes
2024-07-31 19:07 Beijing
The link between influenza infection and an increased short-term risk of acute myocardial infarction (MI) was reaffirmed in a recent study that showed that the risk appeared to be higher in individuals without a prior diagnosis of coronary artery disease, results published in NEJM Evidence. Dr. Patricia Bruijning-Verhagen, senior author of the study at Utrecht University Medical Center in the Netherlands, said: "Our findings confirm previous findings that there is an increased risk of myocardial infarction during or subsequent acute severe influenza infection and raise the idea of prophylactic anticoagulation in these patients."
About the study
This observational, self-controlled case series linked laboratory records of PCR testing for respiratory viruses from 16 laboratories in Netherlands to national mortality, hospitalizations, medications, and official registration. The investigators compared the incidence of acute myocardial infarction in the risk period (1~7 days) after influenza infection and the control group (1 year before the risk period and 51 weeks after the risk period).
The researchers found that 26,221 cases of influenza PCR tests were positive, constituting 23,405 unique cases of influenza illness. Among the acute myocardial infarction episodes that occurred 1 year before or 1 year after the confirmed influenza infection and were included in the analysis, 25 cases of acute myocardial infarction occurred 1~7 days after influenza infection, and 394 cases occurred in the control period. Compared with the control group, the adjusted relative incidence of acute myocardial infarction in the risk period was 6.16 (95%CI: 4.11~9.24).
The relative incidence of acute myocardial infarction was 16.60 (95%CI: 10.45~26.37) in patients who had not been hospitalized for coronary artery disease, and 1.43 (95%CI: 0.53~3.84) in patients who had been hospitalized for coronary artery disease.
Several previous studies have reported a temporary increase in the risk of myocardial infarction. A 2018 study conducted by Kwong et al., in Canada, showed a 6-fold increased risk of acute myocardial infarction after influenza infection, which was subsequently confirmed in studies in United States, Denmark, and Scotland.
In this study, Patricia Bruijning-Verhagen and her colleagues aimed to further quantify the link between laboratory-confirmed influenza infection and acute myocardial infarction and to study specific subpopulations that have the potential to guide a more individualized approach to prevention. They repeated the Canada study, using a self-controlled case series design, correcting for confounding factors that do not change over time, and found very similar results: a six-fold increased risk of acute myocardial infarction in the first week after laboratory-confirmed influenza infection.
"In fact, it is now becoming increasingly clear that we found similar results to Kwong et al. that strongly support the finding that acute influenza infection is associated with an increased risk of myocardial infarction," she said. It also shows that this impact can be generalized to other countries".
People without cardiovascular disease are at higher risk
The researchers also explored whether there was a difference in risk between people with influenza who already had cardiovascular disease and those who did not, driving the development of this area.
Most previous studies on influenza and myocardial infarction have not stratified people with and without cardiovascular disease. Studies have shown that patients with acute influenza infection without known cardiovascular disease are at higher risk of myocardial infarction, but this is uncertain.
Current studies show a large difference between the two groups, with a much higher risk of influenza-related myocardial infarction in individuals without any known cardiovascular disease.
Patricia Bruijning-Verhagen said: "Previously, it might have been thought that patients with cardiovascular disease were at greater risk of myocardial infarction after contracting the flu, but the results of this study are surprising. I think the results are real. There is a big difference between these two groups." She noted that influenza can lead to a hypercoagulable state, systemic inflammation, and vascular changes that can lead to myocardial infarction, even in patients previously thought to be at risk. This is because acute infection can lead to an increased workload on the heart.
She added that patients who already have cardiovascular disease may be protected to some extent by the cardiovascular medications they are taking. These results could justify the use of short-term anticoagulants to survive the high-risk period in patients with severe influenza infection. Just as doctors give short-term anticoagulation to patients undergoing surgery as a preventative measure, this approach must be tested, and clinical studies of this strategy are currently underway.
A flu shot is necessary
This result reinforces the need for influenza vaccination. Patricia Bruijning-Verhagen noted: "These results should add extra weight to the message of getting a flu shot. Even if you don't think you're at risk of cardiovascular disease, our research shows that there is still an increased risk of myocardial infarction due to severe flu infection."
In many countries, influenza vaccination is recommended for people aged 60 years or older, as well as young people with a history of cardiovascular disease. She said there were no data on flu vaccination in the current study, but the average age of people infected with the flu was 74, so most patients could be vaccinated. In the study conducted in Netherlands, it was recommended that people over 60 years old receive the flu vaccine, and the vaccination rate is about 60%.
"There will be some cases in young people, but the number of people who need to be vaccinated to show benefit is higher in young people, which may not be cost-effective", reports Patricia Bruijning-Verhagen. Influenza vaccination policies vary around the world, and there are many factors to consider, with some countries already advocating for universal vaccination every year.
Promote influenza vaccine to prevent acute respiratory syndrome
Raina MacIntyre, MBo, Zubair Akhtar, MPH, and Aye Moa, MPH, from the University of New South Wales in Australia, wrote in an editorial that the study "furthers policymakers to review and update guidelines for the prevention of acute coronary syndrome (ACS)". "Although many countries recommend and fund vaccination against influenza in people aged 65 years and older, the additional benefits of preventing ACS have not been universally incorporated into policy and practice, and it is not recommended that ACS prevention be considered in people aged 50~64 years," they added. For people who are at risk of acute myocardial infarction but have not yet had their first episode, vaccination is readily available. It's time for us to consider the flu vaccine, along with statins, blood pressure control, and smoking cessation, as routine preventive measures for patients with ACS and risk factors for coronary artery disease."
Dr. Lori Dodd of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health in Bethesda, Maryland, United States, noted whether the link between an increased risk of myocardial infarction and severe influenza infection may be a result of myocardial infarction being more likely to be detected in patients hospitalized with severe influenza infection, who still need to be thoroughly examined.
参考文献：Flu and MI Risk: A Sixfold Increase, More If No CVD History - Medscape - July 18, 2024