6 ms·

Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection

Ice_cream_suit 9y ago
"CONCLUSIONS We found a significant association between respiratory infections, especially influenza, and acute myocardial infarction. RESULTS We identified 364 hospitalizations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza. Of these, 20 (20.0 admissions per week) occurred during the risk interval and 344 (3.3 admissions per week) occurred during the control interval. The incidence ratio of an admission for acute myocardial infarction during the risk interval as compared with the control interval was 6.05 (95% confidence interval [CI], 3.86 to 9.50). No increased incidence was observed after day 7. Incidence ratios for acute myocardial infarction within 7 days after detection of influenza B, influenza A, respiratory syncytial virus, and other viruses were 10.11 (95% CI, 4.37 to 23.38), 5.17 (95% CI, 3.02 to 8.84), 3.51 (95% CI, 1.11 to 11.12), and 2.77 (95% CI, 1.23 to 6.24), respectively."
- JoeAltmaier 9y ago
  Help me understand these 'incidence ratios'. Does this mean the chance of heart problems in the first week after influenza ranges from 3X to 10X the nominal rate for heart problems?
misnome 9y ago
I can't get to the full article here, but naively, I'd expect "Illness increasing stress on the bodily systems increases likelihood of heart attack" to be the unsurprising result. Is there some other reason that we'd expect this not to be the case? Are there other infections as agressive that don't increase the risk in similar ways? Or did we just suspect this and haven't had the data to back it up before? i.e. I'm not sure why this is interesting or revelatory? The free summary doesn't seem to answer this.
- rrmm 9y ago
  The first mechanism I could think of would be via inflammatory response. Here's an article from 2009 in the Lancet which performs a meta-analysis. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.490.1869&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.490... In their discussion they say: Influenza might act as an acute inflammatory and procoagulant stimulus transiently altering endothelial function. 58,59 Recent experimental studies in mice have explored the links between influenza infection and coronary artery remodelling. In one study, 60 inoculation of influenza A virus into a mouse atherosclerosis model of mice deficient in apolipoprotein E resulted in heavy infiltration of atherosclerotic plaques by inflammatory cells, as well as platelet aggregation and thrombosis— only the plaques and not normal sections of coronary arteries were disrupted. Evidence of influenza virus RNA has been found in human atherosclerotic plaques, although it is not known if this is clinically important. 61 Another study 62 revealed that infectious burden (measured by the presence of antibodies to influenza, hepatitis A virus, Chlamydophila pneumoniae , Helicobacter pylori, and cytomegalovirus in serum) was independently associated with angiographically-proven atherosclerosis.
stevespang 9y ago
Yet another PAYWALL scheme, what is not revealed in the abstract is whether this data was plotted versus age, which would reveal what I suspect is a strong correlation between age and incidence of MI. Likely patients over 60 or 65 much more likely to exhibit. . .
lawlessone 9y ago
I presume this was already suspected? The last time i had a virus i was warned by a doctor not to use gym for a while as it could cause heart problems.
- manmal 9y ago
  I once had the flu so bad that I could barely climb a couple of stairs without losing my breath. My heart was beating very hard afterwards.. I remember thinking to myself „Ok this is dangerous, I better lie down“, and I bet it was.
  - lawlessone 9y ago
    I had a viral chest infection once, a good bit of coughing but i was apart from that feeling fine, so i wanted to go back to them but was told not to.
- joncrane 9y ago
  I always heard that connective tissue can be weakened by the virus and thus high level athletes are more susceptible to injuries like tendon rupture post-virus.
- jhayward 9y ago
  This is probably referring to the danger of viral myocarditis, which is not the same thing as myocardial infarction (heart attack).
monkmartinez 9y ago
Age? Hx of cardiac problems? These would be good to know, but I assume they were controlled for.
tremendulo 9y ago
Assuming you've already caught the flu, what are some ways you can reduce the risk to the heart?
- AstralStorm 9y ago
  As with any infarctions. Take a clotting reducing agent. Non-aspirin anti-inflammatory should do the trick. (Prostaglandin system is fun.) Aspirin is ok too if you can live with the tiny risk of Reye's syndrome. Disclaimer: not an MD.
  - widerporst 9y ago
    Not sure if I understand you correctly, but what anti-inflammatory medications except for aspirin are you talking about? To my knowledge, NSAIDs such as ibuprofen or naproxen actually promote platelet aggregation and therefore increase the risk of cardiovascular events.
    - 35bge57dtjku 9y ago
      Can you cite that? Doctors recommend it for blood thinning/interfering with clotting, a half dose/baby aspirin/80mg.
      - widerporst 9y ago
        I'm not a medical professional, so I'm unsure about the details. Aspirin is, to my knowledge, the only NSAID that works as an anticoagulant due to some mechanism other than affecting prostaglandins and is therefore recommended by doctors. Other NSAIDs, however, consistently increase the risk of MI, for instance: http://www.bmj.com/content/357/bmj.j1909 http://www.bmj.com/content/357/bmj.j1909
  - nonbel 9y ago
    No, NSAIDs are actually supposed increase the risk of heart attacks. See the second source in my other post: "It is generally accepted that oral non-steroidal anti-inflammatory drugs (NSAIDs) can increase the risk of acute myocardial infarction." https://news.ycombinator.com/item?id=16239642 https://news.ycombinator.com/item?id=16239642 Why would you tell someone that?
jnordwick 9y ago
> We identified 364 hospitalizations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza. Can somebody explain why they looked at hospitalizations for MI before having the flu as well as after? if the theory is that the flu causes heart issues why wouldn't they just look at MIs after hospitalizations?It seems to remove any explanatory ability.
- nonbel 9y ago
  Look at fig 1. They compared the number of people who had heart attacks from 1 -7 days after getting a positive lab test for influenza, and people who got heart attacks at any other time +/- 1 yr of the positive lab test. They saw that out of these people who had both a positive flu test and heart attack, there were more heart attacks in the 7 days subsequent to the positive lab test than at 8+ days after or beforehand. That abrupt cutoff at 7 days makes it sound like these people were being advised some kind of treatment that was increasing heart attack risk. This was in Ontario... they advise: >"-stay home and get plenty of rest -drink lots of fluids -avoid caffeine -speak to your doctor or nurse practitioner about over-the-counter medications that can help you feel better (basic pain or fever relievers), but do not give acetylsalicylic acid (ASA or Aspirin®) to children or teenagers under the age of 18 -treat muscle pain using a hot water bottle or heating pad — apply heat for short periods of time -take a warm bath -gargle with a glass of warm salt water or suck on hard candy or lozenges -use spray or saline drops for a stuffy nose -avoid alcohol and tobacco" https://www.ontario.ca/page/flu-facts#section-4 https://www.ontario.ca/page/flu-facts#section-4 My first guess would be ibuprofin: https://en.wikipedia.org/wiki/Ibuprofen#Cardiovascular_risk https://en.wikipedia.org/wiki/Ibuprofen#Cardiovascular_risk EDIT: More on the NSAID possibility (apparently it is not supposed to only be chronic use): "Taking any dose of NSAIDs for one week, one month, or more than a month was associated with an increased risk of myocardial infarction." http://www.bmj.com/content/357/bmj.j1909 http://www.bmj.com/content/357/bmj.j1909
  - djbelieny 9y ago
    This may be a highly simplistic view but from your list the salt water gargle seemed like a simple explanation to me. ie. Excessive consumption/gargle of Salt Water leading to Elevated Blood Pressure leading to heart attack. could this be it ?
nradov 9y ago
Another good reason to get a flu vaccine every year. Although it isn't completely effective it improves your odds. https://www.cdc.gov/flu/prevent/index.html https://www.cdc.gov/flu/prevent/index.html
vannevar 9y ago
I wonder what the AMI risk is for people in respiratory distress in general, and whether the flu risk is distinguishable.

"CONCLUSIONS We found a significant association between respiratory infections, especially influenza, and acute myocardial infarction. RESULTS We identified 364 hospitalizations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza. Of these, 20 (20.0 admissions per week) occurred during the risk interval and 344 (3.3 admissions per week) occurred during the control interval. The incidence ratio of an admission for acute myocardial infarction during the risk interval as compared with the control interval was 6.05 (95% confidence interval [CI], 3.86 to 9.50). No increased incidence was observed after day 7. Incidence ratios for acute myocardial infarction within 7 days after detection of influenza B, influenza A, respiratory syncytial virus, and other viruses were 10.11 (95% CI, 4.37 to 23.38), 5.17 (95% CI, 3.02 to 8.84), 3.51 (95% CI, 1.11 to 11.12), and 2.77 (95% CI, 1.23 to 6.24), respectively."

JoeAltmaier 9y ago
Help me understand these 'incidence ratios'. Does this mean the chance of heart problems in the first week after influenza ranges from 3X to 10X the nominal rate for heart problems?

misnome 9y ago

I can't get to the full article here, but naively, I'd expect "Illness increasing stress on the bodily systems increases likelihood of heart attack" to be the unsurprising result. Is there some other reason that we'd expect this not to be the case? Are there other infections as agressive that don't increase the risk in similar ways? Or did we just suspect this and haven't had the data to back it up before? i.e. I'm not sure why this is interesting or revelatory? The free summary doesn't seem to answer this.

rrmm 9y ago
The first mechanism I could think of would be via inflammatory response. Here's an article from 2009 in the Lancet which performs a meta-analysis. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.490.1869&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.490... In their discussion they say: Influenza might act as an acute inflammatory and procoagulant stimulus transiently altering endothelial function. 58,59 Recent experimental studies in mice have explored the links between influenza infection and coronary artery remodelling. In one study, 60 inoculation of influenza A virus into a mouse atherosclerosis model of mice deficient in apolipoprotein E resulted in heavy infiltration of atherosclerotic plaques by inflammatory cells, as well as platelet aggregation and thrombosis— only the plaques and not normal sections of coronary arteries were disrupted. Evidence of influenza virus RNA has been found in human atherosclerotic plaques, although it is not known if this is clinically important. 61 Another study 62 revealed that infectious burden (measured by the presence of antibodies to influenza, hepatitis A virus, Chlamydophila pneumoniae , Helicobacter pylori, and cytomegalovirus in serum) was independently associated with angiographically-proven atherosclerosis.

stevespang 9y ago

Yet another PAYWALL scheme, what is not revealed in the abstract is whether this data was plotted versus age, which would reveal what I suspect is a strong correlation between age and incidence of MI. Likely patients over 60 or 65 much more likely to exhibit. . .

lawlessone 9y ago

I presume this was already suspected? The last time i had a virus i was warned by a doctor not to use gym for a while as it could cause heart problems.

manmal 9y ago
I once had the flu so bad that I could barely climb a couple of stairs without losing my breath. My heart was beating very hard afterwards.. I remember thinking to myself „Ok this is dangerous, I better lie down“, and I bet it was.
- lawlessone 9y ago
  I had a viral chest infection once, a good bit of coughing but i was apart from that feeling fine, so i wanted to go back to them but was told not to.
joncrane 9y ago
I always heard that connective tissue can be weakened by the virus and thus high level athletes are more susceptible to injuries like tendon rupture post-virus.
jhayward 9y ago
This is probably referring to the danger of viral myocarditis, which is not the same thing as myocardial infarction (heart attack).

monkmartinez 9y ago

Age? Hx of cardiac problems? These would be good to know, but I assume they were controlled for.

tremendulo 9y ago

Assuming you've already caught the flu, what are some ways you can reduce the risk to the heart?

AstralStorm 9y ago
As with any infarctions. Take a clotting reducing agent. Non-aspirin anti-inflammatory should do the trick. (Prostaglandin system is fun.) Aspirin is ok too if you can live with the tiny risk of Reye's syndrome. Disclaimer: not an MD.
- widerporst 9y ago
  Not sure if I understand you correctly, but what anti-inflammatory medications except for aspirin are you talking about? To my knowledge, NSAIDs such as ibuprofen or naproxen actually promote platelet aggregation and therefore increase the risk of cardiovascular events.
  - 35bge57dtjku 9y ago
    Can you cite that? Doctors recommend it for blood thinning/interfering with clotting, a half dose/baby aspirin/80mg.
    - widerporst 9y ago
      I'm not a medical professional, so I'm unsure about the details. Aspirin is, to my knowledge, the only NSAID that works as an anticoagulant due to some mechanism other than affecting prostaglandins and is therefore recommended by doctors. Other NSAIDs, however, consistently increase the risk of MI, for instance: http://www.bmj.com/content/357/bmj.j1909 http://www.bmj.com/content/357/bmj.j1909
- nonbel 9y ago
  No, NSAIDs are actually supposed increase the risk of heart attacks. See the second source in my other post: "It is generally accepted that oral non-steroidal anti-inflammatory drugs (NSAIDs) can increase the risk of acute myocardial infarction." https://news.ycombinator.com/item?id=16239642 https://news.ycombinator.com/item?id=16239642 Why would you tell someone that?

jnordwick 9y ago

> We identified 364 hospitalizations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza. Can somebody explain why they looked at hospitalizations for MI before having the flu as well as after? if the theory is that the flu causes heart issues why wouldn't they just look at MIs after hospitalizations?It seems to remove any explanatory ability.

nonbel 9y ago
Look at fig 1. They compared the number of people who had heart attacks from 1 -7 days after getting a positive lab test for influenza, and people who got heart attacks at any other time +/- 1 yr of the positive lab test. They saw that out of these people who had both a positive flu test and heart attack, there were more heart attacks in the 7 days subsequent to the positive lab test than at 8+ days after or beforehand. That abrupt cutoff at 7 days makes it sound like these people were being advised some kind of treatment that was increasing heart attack risk. This was in Ontario... they advise: >"-stay home and get plenty of rest -drink lots of fluids -avoid caffeine -speak to your doctor or nurse practitioner about over-the-counter medications that can help you feel better (basic pain or fever relievers), but do not give acetylsalicylic acid (ASA or Aspirin®) to children or teenagers under the age of 18 -treat muscle pain using a hot water bottle or heating pad — apply heat for short periods of time -take a warm bath -gargle with a glass of warm salt water or suck on hard candy or lozenges -use spray or saline drops for a stuffy nose -avoid alcohol and tobacco" https://www.ontario.ca/page/flu-facts#section-4 https://www.ontario.ca/page/flu-facts#section-4 My first guess would be ibuprofin: https://en.wikipedia.org/wiki/Ibuprofen#Cardiovascular_risk https://en.wikipedia.org/wiki/Ibuprofen#Cardiovascular_risk EDIT: More on the NSAID possibility (apparently it is not supposed to only be chronic use): "Taking any dose of NSAIDs for one week, one month, or more than a month was associated with an increased risk of myocardial infarction." http://www.bmj.com/content/357/bmj.j1909 http://www.bmj.com/content/357/bmj.j1909
- djbelieny 9y ago
  This may be a highly simplistic view but from your list the salt water gargle seemed like a simple explanation to me. ie. Excessive consumption/gargle of Salt Water leading to Elevated Blood Pressure leading to heart attack. could this be it ?

nradov 9y ago

Another good reason to get a flu vaccine every year. Although it isn't completely effective it improves your odds. https://www.cdc.gov/flu/prevent/index.html https://www.cdc.gov/flu/prevent/index.html

vannevar 9y ago

I wonder what the AMI risk is for people in respiratory distress in general, and whether the flu risk is distinguishable.