Association of influenza vaccination and reduced risk of recurrent myocardial infarction

Influence of influenza vaccination on recurrent hospitalization in patients with heart failure

BACKGROUND

The current study aimed to evaluate the influence of regular annual influenza vaccinations on cardiovascular (CV) death and heart failure-related hospitalizations (HFrH) in stable outpatients with heart failure with reduced ejection fraction.

METHODS

The Turkish research team-HF (TREAT-HF) is a network undertaking multicenter, observational cohort studies in HF. This study is a subgroup analysis of TREAT-HF outpatient cohorts who completed a questionnaire on influenza vaccination status and for whom follow-up data were available. A total of 656 patients with available follow-up data for CV death and HFrH including recurrent hospitalization were included in the study. Patients were classified into two groups: those who received regular influenza vaccination (40 %) and those who did not receive vaccination.

RESULTS

During a mean follow-up of 15 ±6 months, 113 (18 %) patients had CV death and 471 (72 %) patients had at least one HFrH. The CV death rate was similar in both groups of patients (16 vs. 19 %, p = 0.37), whereas, HFrH and recurrent HFrH were significantly less frequently encountered in patients who received regular influenza vaccination than in those who did not receive vaccination (43 vs. 92 % and 16 vs. 66 %, p < 0.001, respectively). In a multivariate Cox proportional hazards model - in addition to a few clinical factors - vaccination status (HR = 0.30, 95 % CI = 0.17-0.51, p < 0.001) and graduation from university (HR = 0.35, 95 % CI = 0.17-0.72, p = 0.004) remained independently associated with the risk of recurrent HFrH.

CONCLUSION

Regular influenza vaccination does not influence CV deaths; however, it decreases HFrH including recurrent episodes of HFrH in outpatients with heart failure with reduced ejection fraction.

A Matched Influenza Vaccine Strain Was Effective in Reducing the Risk of Acute Myocardial Infarction in Elderly Persons: A Population-Based Study

The aim of this study was to explore whether matched or mismatched strains of influenza vaccines (IVs) are beneficial at reducing the risk of acute myocardial infarction (AMI) in elderly persons.Data were obtained from the Longitudinal Health Database 2005 (LHID 2005) which is maintained by the National Health Insurance Research Institute in Taiwan. The analytical data included individuals who were vaccinated with mismatched vaccines during the October 2007 to December 2007 season and individuals vaccinated with matched strains during the October 2008 to December 2008 season. All participants were 65 years of age and older. In this analysis, individuals were considered to be exposed if their records showed that they were vaccinated against influenza, and they were considered to be nonexposed if they were not vaccinated during these seasons. A Cox hazard model was used to estimate AMI hazard ratio.This study enrolled 93,051 exposed and 109,007 unexposed individuals. The AMI hazards ratios (HRs) for the men and women exposed to mismatched vaccine (in 2007) were 0.990 (95% confidence interval [CI], 0.745-1.316) and 1.102 (95% CI: 0.803-1.513), respectively. Men exposed to matched vaccines (in 2008) had significant HRs (HR: 0.681; 95% CI: 0.509-0.912) while the HRs in the women were barely significant (HR: 0.737; 95% CI: 0.527-1.029).AMI risk could be particularly reduced in men if the IV matches well with the circulating strains in elderly people 65 years of age and older.

Potential of a novel peptide P16-D from the membrane-proximal external region of human immunodeficiency virus type 1 to enhance retrovirus infection

A modified peptide nanofibril “networks” could capture and concentrate enveloped virus easily. Stronger immune response could be elicited by the captured virus implying a potential for P16-D to improve gene transfer rates and vaccine applications.

Acute myocardial infarction and influenza: a meta-analysis of case-control studies

OBJECTIVE

Acute myocardial infarction (AMI) is the leading cause of death and disability globally. There is increasing evidence from observational studies that influenza infection is associated with AMI. In patients with known coronary disease, influenza vaccination is associated with a lower risk of cardiovascular events. However, the effect of influenza vaccination on incident AMI across the entire population is less well established.

METHOD

The purpose of our systematic review of case-control studies is twofold: (1) to estimate the association between influenza infection and AMI and (2) to estimate the association between influenza vaccination and AMI. Cases included those conducted with first-time AMI or any AMI cases. Studies were appraised for quality and meta-analyses using random effects models for the influenza exposures of infection, and vaccination were conducted.

RESULTS

16 studies (8 on influenza vaccination, 10 on influenza infection and AMI) met the eligibility criteria, and were included in the review and meta-analysis. Recent influenza infection, influenza-like illness or respiratory tract infection was significantly more likely in AMI cases, with a pooled OR 2.01 (95% CI 1.47 to 2.76). Influenza vaccination was significantly associated with AMI, with a pooled OR of 0.71 (95% CI 0.56 to 0.91), equating to an estimated vaccine effectiveness of 29% (95% CI 9% to 44%) against AMI.

CONCLUSIONS

Our meta-analysis of case-control studies found a significant association between recent respiratory infection and AMI. The estimated vaccine effectiveness against AMI was comparable with the efficacy of currently accepted therapies for secondary prevention of AMI from clinical trial data. A large-scale randomised controlled trial is needed to provide robust evidence of the protective effect of influenza vaccination on AMI, including as primary prevention.

Influenza, influenza-like symptoms and their association with cardiovascular risks: a systematic review and meta-analysis of observational studies

AIMS

To synthesise the evidence relating influenza and influenza-like symptoms to the risks of myocardial infarction (MI), heart failure (HF) and stroke.

METHODS

We conducted a systematic review and meta-analysis of the evidence relating influenza and influenza-like symptoms to the risks of MI, HF and stroke. We systematically searched all MEDLINE and EMBASE entries up to August 2014 for studies of influenza vs. the cardiovascular outcomes above. We conducted random effects meta-analysis using inverse variance method for pooled odds ratios (OR) and evaluated statistical heterogeneity using the I(2) statistic.

RESULTS

We identified 12 studies with a total of 84,003 participants. The pooled OR for risk of MI vs. influenza (serologically confirmed) was 1.27 (95% CI, confidence interval 0.54-2.95), I(2)  = 47%, which was significant for the only study that adjusted for confounders (OR 5.50, 95% CI 1.31-23.13). The pooled OR for risk of MI vs. influenza-like symptoms was 2.17 (95% CI 1.68-2.80), I(2)  = 0%, which was significant for both unadjusted (OR 2.23, 95% CI 1.65-3.01, five studies) and adjusted studies (OR 2.01, 95% CI 1.24-3.27, two studies). We found one study that evaluated stroke risk, one study in patients with HF, and one that evaluated mortality from MI - all of these studies suggested increased risks of events with influenza-like symptoms.

CONCLUSIONS

There is an association between influenza-like illness and cardiovascular events, but the relationship is less clear with serologically diagnosed influenza. We recommend renewed efforts to apply current clinical guidelines and maximise the uptake of annual influenza immunisation among patients with cardiovascular diseases, to decrease their risks of MI and stroke.

Gene Expression Profiles Link Respiratory Viral Infection, Platelet Response to Aspirin, and Acute Myocardial Infarction

Background

Influenza infection is associated with myocardial infarction (MI), suggesting that respiratory viral infection may induce biologic pathways that contribute to MI. We tested the hypotheses that 1) a validated blood gene expression signature of respiratory viral infection (viral GES) was associated with MI and 2) respiratory viral exposure changes levels of a validated platelet gene expression signature (platelet GES) of platelet function in response to aspirin that is associated with MI.

Methods

A previously defined viral GES was projected into blood RNA data from 594 patients undergoing elective cardiac catheterization and used to classify patients as having evidence of viral infection or not and tested for association with acute MI using logistic regression. A previously defined platelet GES was projected into blood RNA data from 81 healthy subjects before and after exposure to four respiratory viruses: Respiratory Syncytial Virus (RSV) (n=20), Human Rhinovirus (HRV) (n=20), Influenza A virus subtype H1N1 (H1N1) (n=24), Influenza A Virus subtype H3N2 (H3N2) (n=17). We tested for the change in platelet GES with viral exposure using linear mixed-effects regression and by symptom status.

Results

In the catheterization cohort, 32 patients had evidence of viral infection based upon the viral GES, of which 25% (8/32) had MI versus 12.2% (69/567) among those without evidence of viral infection (OR 2.3; CI [1.03-5.5], p=0.04). In the infection cohorts, only H1N1 exposure increased platelet GES over time (time course p-value = 1e-04).

Conclusions

A viral GES of non-specific, respiratory viral infection was associated with acute MI; 18% of the top 49 genes in the viral GES are involved with hemostasis and/or platelet aggregation. Separately, H1N1 exposure, but not exposure to other respiratory viruses, increased a platelet GES previously shown to be associated with MI. Together, these results highlight specific genes and pathways that link viral infection, platelet activation, and MI especially in the case of H1N1 influenza infection.

Influenza vaccines for preventing cardiovascular disease

BACKGROUND

This is an update of the original review published in 2008. The risk of adverse cardiovascular outcomes is increased with influenza-like infection, and vaccination against influenza may improve cardiovascular outcomes.

OBJECTIVES

To assess the potential benefits of influenza vaccination for primary and secondary prevention of cardiovascular disease.

SEARCH METHODS

We searched the following electronic databases on 18 October 2013: The Cochrane Library (including Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Economic Evaluation Database (EED) and Health Technology Assessment database (HTA)), MEDLINE, EMBASE, Science Citation Index Expanded, Conference Proceedings Citation Index - Science and ongoing trials registers (www.controlled-trials.com/ and www.clinicaltrials.gov). We examined reference lists of relevant primary studies and systematic reviews. We performed a limited PubMed search on 20 February 2015, just before publication.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of influenza vaccination compared with placebo or no treatment in participants with or without cardiovascular disease, assessing cardiovascular death or non-fatal cardiovascular events.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by The Cochrane Collaboration. We carried out meta-analyses only for cardiovascular death, as other outcomes were reported too infrequently. We expressed effect sizes as risk ratios (RRs), and we used random-effects models.

MAIN RESULTS

We included eight trials of influenza vaccination compared with placebo or no vaccination, with 12,029 participants receiving at least one vaccination or control treatment. We included six new studies (n = 11,251), in addition to the two included in the previous version of the review. Four of these trials (n = 10,347) focused on prevention of influenza in the general or elderly population and reported cardiovascular outcomes among their safety analyses; four trials (n = 1682) focused on prevention of cardiovascular events in patients with established coronary heart disease. These populations were analysed separately. Follow-up continued between 42 days and one year. Five RCTs showed deficits in at least three of the risk of bias criteria assessed. When reported (seven studies), vaccination provided adequate immunogenicity or protection against influenza. Cardiovascular mortality was reported by four secondary prevention trials and was significantly reduced by influenza vaccination overall (risk ratio (RR) 0.45, 95% confidence interval (CI) 0.26 to 0.76; P value 0.003) with no significant heterogeneity between studies, and by three trials reporting cardiovascular mortality as part of their safety analyses when the numbers of events were too small to permit conclusions. In studies of patients with coronary heart disease, composite outcomes of cardiovascular events tended to be decreased with influenza vaccination compared with placebo. Generally no significant difference was found between comparison groups regarding individual outcomes such as myocardial infarction.

AUTHORS' CONCLUSIONS

In patients with cardiovascular disease, influenza vaccination may reduce cardiovascular mortality and combined cardiovascular events. However, studies had some risk of bias, and results were not always consistent, so additional higher-quality evidence is necessary to confirm these findings. Not enough evidence was available to establish whether influenza vaccination has a role to play in the primary prevention of cardiovascular disease.

Influenza virus aggravates the ox-LDL-induced apoptosis of human endothelial cells via promoting p53 signaling

Oxidized low-density lipoprotein (ox-LDL) is well recognized to play a key role in the development of atherosclerosis. And influenza virus infection has been also recognized to promote the atherosclerosis onset and progressing. However, little is known about the mechanism into it. In present study, we investigated the infection of A/Porto Rico/8/1934 (H1N1) (PR8) influenza virus in human endothelial Eahy926 cells, and determined the induction of apoptosis by the virus infection in the cell. Then we investigated the apoptosis induced by ox-LDL in Eahy926 cells, determined the influence of influenza virus infection on the ox-LDL-induced apoptosis in Eahy926 cells. Results demonstrated that PR8 virus infected human endothelial Eahy926 cells, forming plaques and replicated efficiently in the cell. And the virus infection promoted apoptosis in the cell, upregulated cytchrome c release, activated caspase 3. And what's more, we found that combined PR8 virus infection and ox-LDL treatment promoted higher level of apoptosis and higher level of the activation of apoptosis-associated molecules. Further examination indicated that the p53 signaling was more significantly promoted by both treatments. Therefore, present study confirmed that influenza virus aggravated the ox-LDL-induced apoptosis of human endothelial Eahy926 cells via promoting p53 signaling.

Global burden of influenza as a cause of cardiopulmonary morbidity and mortality

Severe acute respiratory infections, including influenza, are a leading cause of cardiopulmonary morbidity and mortality worldwide. Until recently, the epidemiology of influenza was limited to resource-rich countries. Emerging epidemiological reports characterizing the 2009 H1N1 pandemic, however, suggest that influenza exerts an even greater toll in low-income, resource-constrained environments where it is the cause of 5% to 27% of all severe acute respiratory infections. The increased burden of disease in this setting is multifactorial and likely is the result of higher rates of comorbidities such as human immunodeficiency virus, decreased access to health care, including vaccinations and antiviral medications, and limited healthcare infrastructure, including oxygen therapy or critical care support. Improved global epidemiology of influenza is desperately needed to guide allocation of life-saving resources, including vaccines, antiviral medications, and direct the improvement of basic health care to mitigate the impact of influenza infection on the most vulnerable populations.

Vaccine responsiveness in the elderly: best practice for the clinic

The success of vaccines developed since the beginning of the 20th century, has enabled the conquest of several childhood diseases preventing death and or disability for millions of children. But, globally, the number of children will soon be surpassed by the number of adults over the age of 65. The active lifestyle of these older individuals, coupled with a degree of immune deficiency recognised within this population will lead to a change in the profile of diseases affecting the elderly. The challenge for policy makers and also those involved in primary healthcare is how to protect this population from communicable diseases and keep them healthy, autonomous and independent when vaccines in the main have been developed for use on children and young adults.

Influenza vaccination reduces hospitalization for acute coronary syndrome in elderly patients with chronic obstructive pulmonary disease: a population-based cohort study

BACKGROUND

Elderly patients with chronic obstructive pulmonary disease (COPD) are at a higher risk of hospitalization for cardiovascular complications, especially during respiratory infections. Previous studies showed that vaccination for influenza may reduce the risk of recurrent major cardiovascular events in patients with acute coronary syndrome (ACS). The purpose of this study was to evaluate the hypothesis that influenza vaccination could reduce hospitalizations for ACS in elderly patients with COPD.

METHOD

Using the Taiwan Longitudinal Health Insurance Database 1996-2008, this cohort study comprised elderly patients (≥ 55 years old) with a recorded diagnosis of COPD (n=7722) between January 1, 2000 and December 31, 2007. Each patient was followed until the end of 2007. A propensity score was derived by using a logistic regression model to reduce vaccine therapy selection bias. The hazard ratio (HR) and 95% confidence interval (CI) for the association between the influenza vaccination and the occurrence of first hospitalization for ACS in elderly COPD patients was examined by Cox proportional hazards regression analysis. In addition, we categorized the patients into four groups according to vaccination status (unvaccinated, total number of vaccinations: 1, 2-3, and ≥ 4).

RESULTS

We found that elderly patients with COPD receiving influenza vaccination had a lower risk of hospitalization for ACS (adjusted HR=0.46, 95% CI (0.39-0.55), p < 0.001). We observed similar protective effects in both sexes and all age groups (55-64, 65-74, ≥ 75) regardless of influenza seasonality. When the patients were stratified according to the total number of vaccinations, the adjusted HRs for hospitalization because of ACS were 0.48 (0.38-0.62) and 0.20 (0.14-0.28) for patients who received 2-3 and ≥ 4 vaccinations during the follow-up period.

CONCLUSION

Our data showed that there was a lower risk of ACS hospitalization in elderly patients with COPD receiving annual influenza vaccination.

The role of infection and immunity in atherosclerosis

Cardiovascular diseases account for 20% of deaths worldwide, rising to 50% in developed countries. Current understanding of atherosclerosis derives from a combination of research in animals and cell cultures, analysis of human lesions, clinical investigations of patients with acute coronary syndromes and epidemiological studies of coronary artery disease. By measuring serologic titers in the serum of patients after cardiovascular events, it was observed that the greater the infectious exposure of a patient, the larger the atherosclerotic lesion extension. In addition, gene targeting or pharmacological inhibition of certain cytokines aggravates atherosclerosis in animal experiments. Other animal experiments have succeeded in proving that B cells play a protective role in atherosclerosis through induced immunity against oxidized low-density lipoprotein and other epitopes. Molecular mimicry might respond to the question of how infection may trigger vulnerability in previously stable atherosclerotic lesions. The FLU Vaccination Acute Coronary Syndromes trial enhanced the debate on atherosclerosis prevention by the application of antiflu vaccine. So far, antibiotics have failed to reduce cardiovascular risk, as recent trials could not demonstrate a statistically significant risk reduction. Having assumed atherosclerosis to be an inflammatory disease, the WHO considered the possible role of secondary prevention with antiflu vaccine.

Investigating the association between influenza vaccination and reduced stroke risk

Acute infections, mainly of the respiratory tract, have consistently been demonstrated to considerably increase the risk of stroke. At present, prospective interventional trials are lacking and there is no proof of the effectiveness of any therapeutic anti-infective strategy in stroke prevention. However, some new evidence from observational studies lends support to the idea that influenza vaccination may contribute importantly to fighting stroke. Although final proof of efficacy is still missing, patients with previous cerebral ischemia and subjects of any age at high risk of stroke should be encouraged to receive annual influenza vaccination.

Vaccination for atherosclerosis: a novel therapeutic paradigm

Numerous studies have identified a role for the innate and adaptive immune response in atherosclerosis; both pro- and antiatherogenic roles for the immune responses have been demonstrated. Common autoantigens against which an immune response has been identified in experimental and human models of atherosclerosis include oxidized low-density lipopoteins, beta2 glycoprotein 1 and heat shock protein 60. Activation of atheroprotective adaptive immune responses have been demonstrated for oxidized low-density lipoprotein-related antigens. Conversely, atheroprotection has been demonstrated with the induction of immune tolerance through activation of mucosal immunity to heat shock protein 65/60 and beta2 glycoprotein 1. Recent identification of specific immunoreactive antigenic epitopes in the apolipoprotein B-100 component of low density lipoproetin and early experimental observations have provided proof of concept that active vaccination using specific apolipoprotein B-100-related antigens may emerge as a novel immunomodulating atheroprotective strategy.

Influenza vaccine and survival in acute heart failure

AIMS

Influenza vaccine is a well-recommended secondary prevention measure for improving survival in patients with coronary artery disease, but it has generally been less studied in heart failure. We ask whether having influenza vaccination is associated with survival among patients with acute heart failure (HF).

METHODS AND RESULTS

This was a prospective population-based cohort study accompanied by an analysis of two cross-sectional population samples for external validation of baseline characteristics differences. We analysed all 1964 ambulatory patients with acute HF aged ≥50 years who were admitted to the Heart Failure Survey in Israel (HFSIS). We used the Israel Health Survey (IHS) 2009 and the Behavioural Risk Factor Surveillance System (BRFSS) 2003-2004 surveys (274 535 participants) for external validation. In the HFSIS, the multivariate-adjusted hazard ratios for in-hospital, 1 and 4 year mortality outcomes of influenza-vaccinated patients were 0.71 (P = 0.19), 0.81 (P = 0.04), and 0.83 (P = 0.006), respectively. In the IHS validation sample, a recent physician visit [odds ratio (OR) 1.61; 95% confidence interval (CI) 1.43-1.80] or having supplementary health insurance (OR 1.39; 95% CI 1.19-1.61) were associated with higher likelihood of being vaccinated against influenza. In the BRFSS validation sample, having > 1 healthcare providers (OR 2.31; 95% CI 2.22-2.40) or having any healthcare coverage were associated with higher likelihood of being vaccinated (OR 1.59; 95% CI 1.54-1.65).

CONCLUSIONS

Influenza vaccine might improve survival among patients with acute HF. This association, however, could be affected by unmeasured confounding and bias due to baseline medical surveillance and socioeconomic differences between vaccinated and non-vaccinated patients.

Effectiveness of the influenza vaccine at preventing hospitalization due to acute exacerbation of cardiopulmonary disease in Korea from 2011 to 2012

There is a lack of targeted studies to validate the effectiveness of influenza vaccination on the reduction in influenza-related hospitalizations among patients with co-morbidities. In this study, we estimate the effectiveness of influenza vaccination on preventing hospitalizations in persons with cardiopulmonary disease and establish an evidence base for recommendations on influenza vaccination in this population. During the influenza epidemic in 2011-2012, we performed a multicenter, retrospective case-control study. Cases were patients hospitalized due to acute exacerbation of asthma, COPD, ischemic heart disease (IHD), and congestive heart failure (CHF). Controls were selected from outpatients who visited study hospitals but who were not hospitalized. Cases and controls were matched 1:1 based on age, gender, and date of hospital visit. Conditional logistic regression analyses were used to determine the effectiveness of vaccination. Between 25 December 2011 and 5 May 2012, 828 of each hospitalized and control subjects were identified. The influenza vaccination rate of the hospitalized and non-hospitalized patients was 54.2% and 60.4%, respectively (P = 0.006). The overall vaccine effectiveness for preventing hospitalization was 33.7% (95% confidence interval [CI] 14.0-49.0%; P = 0.002). Conditional logistic regression analysis showed that influenza vaccination significantly reduced the risk of hospitalization, especially due to acute exacerbation of IHD and CHF, in patients aged 65 y and older. The estimated vaccine effectiveness in these patients was 56.0% (95% CI 32.1-71.4%, P = 0.002). Influenza vaccination was associated with a reduction in the risk of hospitalization due to acute exacerbation of cardiopulmonary disease. We recommend the vaccine be given primarily to patients with underlying cardiovascular disease, particularly those 65 y of age and older.

Ischaemic heart disease, influenza and influenza vaccination: a prospective case control study

Background

Abundant, indirect epidemiological evidence indicates that influenza contributes to all-cause mortality and cardiovascular hospitalisations with studies showing increases in acute myocardial infarction (AMI) and death during the influenza season.

Objective

To investigate whether influenza is a significant and unrecognised underlying precipitant of AMI.

Design

Case-control study.

Setting

Tertiary referral hospital in Sydney, Australia, during 2008 to 2010.

Patients

Cases were inpatients with AMI and controls were outpatients without AMI at a hospital in Sydney, Australia.

Main outcome measures

Primary outcome was laboratory evidence of influenza. Secondary outcome was baseline self-reported acute respiratory tract infection.

Results

Of 559 participants, 34/275 (12.4%) cases and 19/284 (6.7%) controls had influenza (OR 1.97, 95% CI 1.09 to 3.54); half were vaccinated. None were recognised as having influenza during their clinical encounter. After adjustment, influenza infection was no longer a significant predictor of recent AMI. However, influenza vaccination was significantly protective (OR 0.55, 95% CI 0.35 to 0.85), with a vaccine effectiveness of 45% (95% CI 15% to 65%).

Conclusions

Recent influenza infection was an unrecognised comorbidity in almost 10% of hospital patients. Influenza did not predict AMI, but vaccination was significantly protective but underused. The potential population health impact of influenza vaccination, particularly in the age group 50–64 years, who are at risk for AMI but not targeted for vaccination, should be further explored. Our data should inform vaccination policy and cardiologists should be aware of missed opportunities to vaccinate individuals with ischaemic heart disease against influenza.

Influenza vaccination and reduction in risk of ischemic heart disease among chronic obstructive pulmonary elderly

COPD estimates the third leading cause of death by 2020. To reduce its complications becomes an important issue. The purpose of this study is to investigate the influenza vaccine effect for IHD occurrence with secondary to COPD. We used 11 years Taiwan National Health Insurance cohort research database and analyzed the relationships between vaccination and incident of IHD for COPD patients stratified by age. Total 29,178 COPD patients, 703 patients got vaccination out of 1464 who have developed IHD and 6010 patients vaccinated out of 27,714 that did not developed IHD. Major findings we observed: vaccination was associated with a reduced risk of IHD (OR, 0.746; 95% CI, 0.595-0.937) in elderly COPD patients. Influenza vaccination was associated with a reduced risk for IHD only in elderly COPD patients. Moreover, COPD patients with IHD had higher vaccination rate than without IHD.

[Early and late mortality of patients with community acquired pneumonia]

Community acquired pneumonia is the most frequent infective cause of severe sepsis and death. The risk of mortality in community acquired pneumonia is predictable by the "pneumonia severity index" and various biomarkers (e.g., procalcitonin, troponin-I). Quantitative testing of pneumococcal load (DNA) in blood has also become possible recently. Early death due to acute myocardial infarction is more frequent among patients with previous community acquired pneumonia. The 1-year and the 5-6 year survival is shorter among these patients. Pro-inflammatory cytokines synthesized during community acquired pneumonia accelerate chronic inflammation ongoing in atherosclerotic plaques. The pro-thrombotic condition present in atherosclerosis is also potentiated by community acquired pneumonia. These pathophysiological mechanisms may explain the epidemiologic fact that community acquired pneumonia is an independent risk factor of cardiovascular mortality.

Association of influenza virus infection and inflammatory cytokines with acute myocardial infarction

OBJECTIVE

To explore the potential relationship between previous influenza virus (IV) infection and acute myocardial infarction (AMI), and the mechanism of atherosclerosis, we conducted a case-control study and examined inflammatory cytokines to assess the association of previous IV infection and AMI.

METHODS

A questionnaire-based survey was conducted to collect information about demographic characteristics and heart disease risk factors. Fasting blood samples were obtained to measure immunoglobulin (Ig) G antibodies to influenza virus A (IV-A), influenza virus B (IV-B), cytomegalovirus, herpes simplex virus type-1 and type-2, adenovirus, rubella virus and Chlamydia pneumoniae, and to measure the level of certain biochemistry markers: interleukin-2, 6, 10 and 18 (IL-2, 6, 10 and 18), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), endothelin-1 (ET-1), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1).

RESULTS

Compared with the controls, the cases were more likely to have positive IgG antibodies to IV-A and IV-B [IV-A: odds ratio (OR): 3.1, 95% confidence interval (CI): 1.5-6.4; IV-B: OR: 10.2, 95% CI: 5.7-20.0]. After adjustment for potential confounding variables, the risk of AMI was still associated with the presence of IgG antibodies to IV-A (adjusted OR: 5.5, 95% CI: 1.3-23.0) and IV-B (adjusted OR: 20.3, 95% CI: 5.6-40.8). The levels of IL-2, 6, 10 and18, TNF-α, IFN-γ, ET-1, sICAM-1 and sVCAM-1 in patients with AMI were significantly higher than those of the controls (P < 0.01).

CONCLUSIONS

Our study supports the hypothesis that previous IV infection is associated with AMI. Inflammatory cytokines may take part in the development of atherosclerosis and trigger the occurrence of AMI.

Influenza vaccination and cardiovascular morbidity and mortality: analysis of 292,383 patients

Studies have documented an association between influenza vaccination and risk reduction in myocardial infarction, all-cause mortality, and major adverse cardiac events. This meta-analysis pooled data from 5 trials with a total of 292 383 patients. Influenza vaccination was found to be associated with significant reductions in myocardial infarction, all-cause mortality, and major adverse cardiac events. The risk reduction afforded by vaccination and the lack of major adverse events related to the influenza vaccination makes it particularly important to vaccinate those with a known cardiovascular disease or those at high risk of developing cardiovascular disease.

Pathogens and atherosclerosis: update on the potential contribution of multiple infectious organisms to the pathogenesis of atherosclerosis

It is currently unclear what causes the chronic inflammation within atherosclerotic plaques. One emerging paradigm suggests that infection with bacteria and/or viruses can contribute to the pathogenesis of atherosclerosis either via direct infection of vascular cells or via the indirect effects of cytokines or acute phase proteins induced by infection at non-vascular sites. This paradigm has been supported by multiple epidemiological studies that have established positive associations between the risk of cardiovascular disease morbidity and mortality and markers of infection. It has also been supported by experimental studies showing an acceleration of the development of atherosclerosis following infection of hyperlipidaemic animal models. There are now a large number of different infectious agents that have been linked with an increased risk of cardiovascular disease. These include: Chlamydia pneumoniae, Porphyromonas gingivalis, Helicobacter pylori , influenza A virus, hepatitis C virus, cytomegalovirus, and human immunodeficiency virus. However, there are significant differences in the strength of the data supporting their association with cardiovascular disease pathogenesis. In some cases, the infectious agents are found within the plaques and viable organisms can be isolated suggesting a direct effect. In other cases, the association is entirely based on biomarkers. In the following review, we evaluate the strength of the data for individual or groups of pathogens with regard to atherosclerosis pathogenesis and their potential contribution by direct or indirect mechanisms and discuss whether the established associations are supportive of the infectious disease paradigm. We also discuss the failure of antibiotic trials and the question of persistent infection.

Influenza vaccination promotes stable atherosclerotic plaques in apoE knockout mice

OBJECTIVE

Current evidence suggests a relationship between seasonal Influenza viral infection and cardiovascular disease (CVD). Experimental animals inoculated with Influenza A virus have shown to develop thrombotic complications similar to those seen in humans. Conversely, several epidemiological studies and clinical trials have suggested that Influenza vaccination may have a protective effect on CVD. However, the potential mechanisms behind this protective effect remain unstudied. We aimed to study the effect of Influenza vaccination on atherosclerotic plaque development in apoE(-/-) mice.

METHODS AND RESULTS

The effect of immunization with increasing doses of Influenza vaccine (0.38, 1.8, 9 and 45 μg/0.5 mL Vaxigrip®, Sanofi-Aventis) on atherogenesis was compared with that of animals immunized with Pneumo23® (pneumococcus vaccine, Sanofi-Aventis) and control group inoculated with phosphate buffered saline (PBS). Animals vaccinated with 45 μg/0.5 mL Vaxigrip®, (the same dose used to immunize humans adults against Influenza) developed smaller atherosclerotic lesions with lower lipid content but richer in smooth muscle cells and collagen when compared with control animals. Concomitantly, they showed lower levels of interferon gamma (IFNγ), interleukin (IL)-2 and tumor necrosis factor alpha (TNFα) but higher levels of IL-4. Furthermore, we found increased levels of anti-Influenza immunoglobulin (Ig) G1 or anti-Pneumo23® IgM specific antibodies in a time and dose dependent fashion in animals immunized with these vaccines.

CONCLUSIONS

These results indicate that vaccination against Influenza may protect against the development of CVD by promoting smaller and stable atherosclerotic plaques and by inducing atheroprotective immune responses.

Influenza vaccination reduces cardiovascular events in patients with acute coronary syndrome

AIMS

Influenza infection has been shown to accentuate the progression of atherosclerosis and precipitate the occurrence of acute coronary syndrome (ACS). However, the protective effects of the influenza vaccine on cardiovascular events are still inconclusive.

METHODS AND RESULTS

The study was a prospective randomized open with blinded endpoint (PROBE) study. The 439 patients who had been admitted due to ACS within 8 weeks were enrolled and randomly allocated to receive inactivated influenza vaccine in the vaccine group and no treatment in the control group. All patients were treated with the standard therapy including revascularization according to primary cardiologists. The primary endpoint, which was the combined major cardiovascular events, including death, hospitalization from ACS, hospitalization from heart failure, and hospitalization from stroke, occurred less frequently in the vaccine group than the control group [9.5 vs. 19.3%, unadjusted HR 0.70 (0.57-0.86), P = 0.004]. There was no significant difference in the incidence of cardiovascular death between the vaccine and control groups [2.3 vs. 5.5%, unadjusted HR 0.39 (0.14-1.12), P = 0.088].

CONCLUSION

The influenza vaccine reduced major cardiovascular events in patients with ACS. Therefore, it should be encouraged as a secondary prevention in this group of patients.

Inflammation-related effects of adjuvant influenza A vaccination on platelet activation and cardiac autonomic function

BACKGROUND

Inflammation, platelet reactivity and cardiac autonomic dysfunction increase the risk of cardiovascular events, but the relationships between these prognostic markers are poorly defined. In this study, we investigated the effect of an inflammatory stimulus (influenza A vaccine) on platelet activation and cardiac autonomic function.

METHODS

We measured serum C-reactive protein (CRP) and interleukin-6 levels, monocyte-platelet aggregates (MPAs) and monocyte/platelet receptor expression before and after adjuvant influenza A vaccination in 28 patients with type II diabetes (mean age 62.1 ± 8 years, 18 men). Twenty-four-hour Holter electrocardiogram was recorded 24 h before and after vaccination; heart rate variability (HRV) was assessed as a measure of cardiac autonomic function.

RESULTS

Inflammatory cytokines, MPA formation and monocyte/platelet receptor expression increased after vaccination. CRP was 2.6 ± 2.8 and 7.1 ± 5.7 mg L⁻¹ 48 h before and after vaccination, respectively (P < 0.0001). HRV parameters decreased after vaccination compared to baseline, with very low-frequency amplitude showing the most significant change (34.6 ± 11.8 and 31.0 ± 10.2 ms 48 h before and after vaccination, respectively; P = 0.002). A significant correlation was found between percentage changes in CRP levels and in most HRV variables, with the most significant correlations between changes in CRP levels and changes in standard deviation of all normal RR intervals (r = 0.43; P = 0.02).

CONCLUSIONS

Together with an inflammatory reaction, influenza A vaccine induced platelet activation and sympathovagal imbalance towards adrenergic predominance. Significant correlations were found between CRP levels and HRV parameters, suggesting a pathophysiological link between inflammation and cardiac autonomic regulation. The vaccine-related platelet activation and cardiac autonomic dysfunction may transiently increase the risk of cardiovascular events.

The effect of influenza vaccination on risk of acute myocardial infarction: self-controlled case-series study

Acute myocardial infarction (AMI) peaks in winter months, partly linked to epidemic influenza. This implies that influenza vaccination may prevent some cases of AMI. This study investigated the association between influenza vaccination and AMI using the self-controlled case-series method. We identified 8180 cases of first AMI aged 40 years and over at time of diagnosis. The incidence of AMI was significantly reduced in the 60 days following vaccination (compared with the baseline period), ranging from a reduction of 32% (IRR 0.68; 95% CI 0.60-0.78) at 1-14 days after vaccination, to 18% (IRR 0.82; 95% CI 0.75-0.90) at 29-59 days after vaccination. Reductions in AMI incidence were more pronounced for early seasonal vaccinations before mid-November.

Evaluation of inter-pandemic influenza vaccine effectiveness during eight consecutive winter seasons in England and Wales in patients with cardiovascular risk factors

We evaluated the effectiveness of inactivated influenza vaccine in persons aged ≥45 years with co-morbidities (including essential hypertension) likely to have prompted consideration of prophylactic statin therapy. Using case-control analyses, we measured the impact of vaccination on General Practitioner (GP) reported new episodes of illness for clinically diagnosed influenza-like illness (ILI) and total acute respiratory infection (TARI) during eight consecutive winters, adjusting for potential confounders using multivariable techniques. Although the study failed to demonstrate the effectiveness of influenza vaccine, we identified important potential confounding related to a greater likelihood of vaccinees than non-vaccinees to consult with a GP for respiratory infections. Future researchers should consider and account for this phenomenon.

Influenza vaccination, pneumococcal vaccination and risk of acute myocardial infarction: matched case-control study

BACKGROUND

Previous studies have shown an association between acute myocardial infarction and preceding respiratory infection. Contradictory evidence exists on the influence of influenza vaccination and pneumococcal vaccination in preventing cardiovascular disease. We aimed to investigate the possible association of influenza vaccination and pneumococcal vaccination with acute myocardial infarction.

METHODS

We used a matched case-control design with data from the United Kingdom General Practice Research Database. Cases were patients who were at least 40 years of age at diagnosis of first acute myocardial infarction recorded from Nov.1, 2001, to May 31, 2007, and were matched for sex, general practice, age and calendar time (i.e., month corresponding to index date of acute myocardial infarction), with up to four controls each. Data were analyzed using conditional logistic regression, adjusted for vaccination target groups, cardiovascular risk factors, treatment medications and attendances at a general practice.

RESULTS

We included 78 706 patients, of whom 16 012 were cases and 62 694 were matched controls. Influenza vaccination had been received in the previous year by 8472 cases (52.9%) and 32 081 controls (51.2%) and was associated with a 19% reduction in the rate of acute myocardial infarction (adjusted odds ratio [OR] 0.81, 95% confidence interval [CI] 0.77-0.85). Early seasonal influenza vaccination was associated with a lower rate of acute myocardial infarction (adjusted OR 0.79, 95% CI 0.75-0.83) than vaccination after mid-November (adjusted OR 0.88, 95% CI 0.79-0.97). Pneumococcal vaccination was not associated with a reduction in the rate of acute myocardial infarction (adjusted OR 0.96, 95% CI 0.91-1.02).

INTERPRETATION

Influenza vaccination but not pneumococcal vaccination is associated with a reduced rate of first acute myocardial infarction. This association and the potential benefit of early seasonal vaccination need to be considered in future experimental studies.

A cluster of deaths following influenza vaccination, Israel, 2006

When four deaths occurred in one week among influenza vaccine recipients, the Israeli Health Ministry suspended its 2006 influenza vaccination campaign pending investigation of the causes of death. Medical histories of the deceased vaccinees, quality control reports, and laboratory test results were examined. Prior vaccine use that season and a risk assessment of the vaccinated population were also considered. All four decedents had been treated for cardiac and other chronic diseases, and none had experienced post-injection symptoms suggesting adverse reaction to influenza vaccine. Quality control and laboratory reports confirmed vaccine batch safety, and no adverse effects had been reported among any other vaccine recipients. Investigators found no causal connection between the deaths and the vaccine, and the Health Ministry resumed the campaign. Israeli public health officials viewed the investigation as vital to maintaining broad confidence in the public health system, and in future vaccination campaigns.

Vaccination for atherosclerosis

Atherosclerosis is an inflammatory disease, and several antigens have been shown to activate the immune response and affect the development of atherogenesis. This suggests that modulation of the immune system could represent a useful approach to prevent and/or treat this disorder. A vaccination approach might be a useful, effective tool in the modern arsenal of cardiovascular therapy and could possibly be used on a large scale at a low cost. Several modalities of vaccines have been tested against lipoproteins, cholesterol, molecules involved in cholesterol metabolism, atherosclerosis-associated microorganisms, and other molecules (heat shock protein, CD99, vascular endothelial growth factor-receptor, interleukin-2), with promising results. Nevertheless, a deeper understanding of the role of immunization in atherosclerosis will be essential to the use of vaccines in clinical medicine.

Pathways to further boost treatment rates and clinical outcomes in hospitalized stroke patients

Inpatient quality improvement initiatives have been associated with impressive improvements in evidence-based discharge treatment rates in hospitalized stroke patients. However, these programs have generally focused only on optimizing recurrent stroke prevention strategies among ischemic stroke patients. Many patients hospitalized with recent symptomatic cerebral ischemia are also at risk for future ischemic episodes emanating from other vascular beds, and the inpatient setting could represent an opportunity to screen and appropriately manage such patients who harbor cross-vascular risk. The stroke hospitalization may also be ideal for identifying stroke patients susceptible to a highly preventable yet common trigger of vascular events and poor clinical outcomes like influenza infection. Finally, several hospital-based prevention measures are underutilized in patients hospitalized with intracerebral hemorrhage (ICH) compared with those with ischemic stroke or transient ischemic attack, and so protocols geared at enhancing prevention of ICH recurrence, are certainly warranted. This article presents pathways (algorithms, pocket cards, preprinted orders) developed from expert consensus prevention guidelines and implemented within a broader stroke inpatient quality improvement program, which target patients highly vulnerable to future coronary events, poor clinical outcomes following influenza infection, and recurrent ICH.

Secondary prevention strategies for coronary heart disease

Patients with established coronary heart disease (CHD) have a high risk of subsequent cardiovascular events, including myocardial infarction (MI), stroke, and death from cardiovascular disease. Adherence to evidence-based secondary prevention therapies for CHD has improved in recent years but still remains suboptimal. Mortality from CHD in the United States (US) has decreased substantially in recent decades. The decline in US deaths from CHD from 1980 through 2000 has been attributed to reductions in major risk factors and utilization of evidence-based medical therapies. It has been estimated that optimization of secondary prevention strategies could save as many as 80,000 more lives per year in the US. The American College of Cardiology (ACC) and American Heart Association (AHA) updated its guidelines for secondary prevention for patients with atherosclerotic vascular disease in 2006. The guidelines emphasize evidence-based developments in the field of CHD secondary prevention and also reinforce the need to implement these recommendations in actual clinical practice through programs such as the ACC's Guidelines Applied to Practice and the AHA's Get With The Guidelines. This review will discuss the epidemiology and risk assessment of CHD, current pharmacologic and nonpharmacologic strategies available for the secondary prevention of CHD, and summarize the guidelines and evidence that support these treatment options. There will be an emphasis on antiplatelet therapy given the important role of thrombosis in clinical cardiovascular events.

Role of acute infection in triggering acute coronary syndromes

Acute coronary syndromes are a leading cause of morbidity and mortality worldwide. The mechanisms underlying the triggering of these events are diverse and include increased coronary and systemic inflammatory activity, dominant prothrombotic conditions, increased biomechanical stress on coronary arteries, variations in the coronary arterial tone, disturbed haemodynamic homoeostasis, and altered myocardial metabolic balance. There is experimental evidence that acute infections can promote the development of acute coronary syndromes, and clinical data strongly support a role for acute infections in triggering these events. In our Review, we summarise the pathogenesis of coronary artery disease and present the evidence linking acute infections with the development of acute coronary syndromes. Greater awareness of this association is likely to encourage research into ways of protecting patients who are at high risk.