 |
| From NFID Report |
#14,265
Over the past decade we've seen growing evidence that influenza (and other severe respiratory infections) can trigger other serious - and sometimes fatal - events, including heart attacks and strokes.
These adverse events may occur during, and up to several weeks after, infection. A few recent blogs on the topic include:
- In 2015, in UNSW: Flu Vaccine Provides Significant Protection Against Heart Attacks, we saw a study that found that if you are over 50 - getting the flu vaccine can cut your risk of a heart attack by up to 45%.
- And in May 2017, in Int. Med. J.: Triggering Of Acute M.I. By Respiratory Infection we looked at research from the University of Sydney that found the risk of a heart attack is increased 17-fold in the week following a respiratory infection such as influenza or pneumonia.
- And in 2018's NEJM: Acute Myocardial Infarction After Laboratory-Confirmed Influenza Infection, we saw a study that found a `significant association' between recent (lab confirmed) influenza infection and Myocardial Infarction.
Readers with long memories will recall that in 2010 we looked at a Study: EKG Abnormalities With Novel H1N1 Infection, that found unexpected electrical changes in the heart during H1N1 infection, even among patients without a history of cardiac problems.
The authors of the study (Akritidis N, Mastora M, Baxevanos G, et al.) wrote:
EXCERPT:
Of the 50 patients, 14 (28%) exhibited ECG changes on admission. Nine patients presented with T-wave inversions, while ST-segment depression was observed on the electrocardiograms of 6 patients.
The presence of ECG changes did not correlate with age, gender, co-morbidities, the laboratory profiles of the patients, or the coexistence of lower respiratory tract involvement.
(Continue . . . )
Fast forward to today, and we've a new open access research article published in PLoS One, that finds transient myocardial function changes among a small group of influenza patients studied.
Research Article
Transient depression of myocardial function after influenza virus infection: A study of echocardiographic tissue imaging
Takahide Ito ,Kanako Akamatsu , Shu-ichi Fujita , Yumiko Kanzaki, Akira Ukimura , Masaaki Hoshiga
Published: August 23, 2019 https://doi.org/10.1371/journal.pone.0221628
Abstract
Background
Influenza virus infection (IVI) was reported to be associated with minor cardiac changes, mostly those detected on electrocardiogram with and without elevated blood markers of myocardial injury; however, the characteristics of myocardial involvement in association with IVI are poorly understood. This study used echocardiographic tissue imaging (tissue Doppler, strain, and strain rate) to evaluate changes in left atrial (LA) and left ventricular (LV) myocardial function after IVI.
Methods and results
We examined 20 adult individuals (mean age, 43 years) at 2 and 4 weeks after diagnosis of IVI. For myocardial functional variables, we obtained LV global longitudinal strain (GLS), LV early diastolic strain rate (e'sr), LA strain, and LA stiffness (E/e’/LA strain), in addition to data on tissue Doppler (s’, e’, and a’) and myocardial performance index. Blood markers of myocardial injury were also examined.
During follow-up, there were no significant changes in global chamber function such as LV ejection fraction, E/e’, and LA volume. However, significant changes in myocardial function were observed, namely, in s’ (8.0 ± 1.6 cm/s to 9.3 ± 1.5 cm/s; p = 0.01), e’ (10.2 ± 2.8 cm/s to 11.4 ± 3.0 cm/s; p < 0.001), e’sr (1.43 ± 0.44 1/s to 1.59 ± 0.43 1/s; p = 0.005), and LA strain (35 ± 8% to 40 ± 12%; p = 0.025), and the myocardial performance index (0.52 ± 0.20 to 0.38 ± 0.09; p = 0.009), but not in a’, LA stiffness, or GLS. Cardiac troponin T and creatinine kinase isoenzyme MB were not elevated significantly at any examination.
Conclusions
Myocardial dysfunction during IVI recovery appeared to be transient particularly in the absence of myocardial injury. Echocardiographic tissue imaging may be useful to detect subclinical cardiac changes in association with IVI.
(Continue . . . )
This is admittedly a small study, and among its limited cohort the observed myocardial function changes were transient. A much larger study would be needed to evaluate the full range of cardiac involvement and outcomes associated with influenza virus infection (IVI).
It does, however, offer more evidence that influenza virus infection can, and does, affect cardiac function. And impacts that might prove benign in a healthy patient could conceivably pose a tipping point for someone with preexisting cardiac deficits.Despite providing only modest protection - particularly in the elderly - receipt of the flu vaccine has been linked to reduced cardiovascular events, and lower mortality. A few recent studies include:
- Three weeks ago, in Flu Vaccine May Lower Stroke Risk in Elderly ICU Patients, we saw a study that found influenza vaccinated ICU survivors had a lower 1-year risk of stroke and a lower 1-year risk of death than unvaccinated survivors.
- A 2019 Study of COPD patients found lower mortality rates, less critical illness, and a 38% reduction in influenza-related hospitalizations in vaccinated vs unvaccinated populations.
- A 2018 study appearing the American Heart Association's journal Circulation, found a substantial reduction in deaths among heart failure patients who received a yearly flu shot (see AHA: Study Shows Flu Shots Reduce Deaths From Heart Failure).
- A year ago, in CMAJ Research: Repeated Flu Vaccinations Reduce Severity of Illness In Elderly, a study found that repeated yearly flu vaccinations reduce the severity of illness in the elderly - usually the hardest hit segment of the population - even when it fails to prevent infection.
- In 2017 we saw a study published in the CID Journal: Flu Vaccine Reduces Severe Outcomes in Hospitalized Patients, that cited being vaccinated was associated with less severe illness, lower mortality, and shorter hospitalization stays.
All good enough reasons why I'll be rolling up my sleeve when the flu vaccine becomes available this fall. Hopefully you'll consider doing so as well.
