Systematic influenza screening in cardiac intensive care units during the influenza season: A prospective study in Spain

BACKGROUND

Little is known about the incidence of influenza among admissions to the cardiac intensive care unit (C-ICU), accuracy of clinical suspicion, and influenza vaccination uptake. We evaluated the incidence of influenza at C-ICU admission during the influenza season, potential underdiagnosis, and vaccination uptake.

METHODS

Prospective study at five C-ICUs during the 2017-2020 influenza seasons. A nasopharyngeal swab was collected at admission from patients who consented (n = 788). Testing was with Xpert®XpressFlu/RSV.

RESULTS

Influenza was detected in 43 patients (5.5%) (40 FluA; 3 FluB) and clinically suspected in 27 (62.8%). Compared to patients without influenza, patients with influenza more frequently had heart failure (37.2% vs 22.8%, P = 0.031), previous contact with relatives with influenza-like illnesses (23.3% vs 12.5%, P = 0.042), antimicrobial use (67.4% vs 23.2%, P <0.01), and need for mechanical ventilation (25.6% vs 14.5%, P = 0.048). Patients received oseltamivir promptly. We found no differences in mortality (11.6% vs 5.2%, P = 0.076). Patients with influenza more frequently had myocarditis (9.3% vs 0.9%, P <0.01) and pericarditis (7.0% vs 0.8%, P = 0.01). Overall, 43.0% of patients (339/788) were vaccinated (51.9% of those with a clear indication [303/584]).

CONCLUSION

Influenza seems to be a frequently underdiagnosed underlying condition in admissions to the C-ICU. Influenza should be screened for at C-ICU admission during influenza epidemics.

AMPK protects endothelial cells against HSV-1 replication via inhibition of mTORC1 and ACC1

Herpes simplex virus type 1 (HSV-1) is a widespread contagious pathogen, mostly causing mild symptoms on the mucosal entry side. However, systemic distribution, in particular upon reactivation of the virus in immunocompromised patients, may trigger an innate immune response and induce damage of organs. In these conditions, HSV-1 may infect vascular endothelial cells, but little is known about the regulation of HSV-1 replication and possible defense mechanisms in these cells. The current study addresses the question of whether the host cell protein AMP-activated protein kinase (AMPK), an important metabolic sensor, can control HSV-1 replication in endothelial cells. We show that downregulation of the catalytic subunits AMPKα1 and/or AMPKα2 increased HSV-1 replication as monitored by TCID50 titrations, while a potent AMPK agonist, MK-8722, strongly inhibited it. MK-8722 induced a persistent phosphorylation of the AMPK downstream targets acetyl-CoA carboxylase (ACC) and the rapamycin-sensitive adaptor protein of mTOR (Raptor) and, related to this, impairment of ACC1-mediated lipid synthesis and the mechanistic target of the rapamycin complex-1 (mTORC1) pathway. Since blockade of mTOR by Torin-2 as well as downregulation of ACC1 by siRNA also decreased HSV-1 replication, MK-8722 is likely to exert its anti-viral effect via mTORC1 and ACC1 inhibition. Importantly, MK-8722 was able to reduce virus replication even when added after HSV-1. Together, our data highlight the importance of endothelial cells as host cells for HSV-1 replication upon systemic infection and identify AMPK, a metabolic host cell protein, as a potential target for antiviral strategies against HSV-1 infection and its severe consequences. IMPORTANCE Herpes simplex virus type 1 (HSV-1) is a common pathogen that causes blisters or cold sores in humans. It remains latent in infected individuals and can be reactivated multiple times. In adverse conditions, for instance, in immunocompromised patients, HSV-1 can lead to serious complications such as encephalitis, meningitis, or blindness. In these situations, infection of endothelial cells lining the surface of blood vessels may contribute to the manifestation of disease. Here, we describe the role of AMP-activated protein kinase (AMPK), a potent regulator of cellular energy metabolism, in HSV-1 replication in endothelial cells. While downregulation of AMPK potentiates HSV-1 replication, pharmacological AMPK activation inhibits it by limiting the availability of required host cell macromolecules such as proteins or fatty acids. These data highlight the role of metabolic host cell proteins as antiviral targets and reveal activation of endothelial AMPK as a potential strategy to protect from severe consequences of HSV-1 infection.

Interaction between bacteria and cholesterol crystals: Implications for endocarditis and atherosclerosis

Background

The interaction between pathogenic bacteria and cholesterol crystals (CCs) has not been investigated. However, CCs are found extensively in atherosclerotic plaques and sclerotic cardiac valves. Interactions between pathogenic bacteria and CCs could provide insights into destabilization of atherosclerotic plaques and bacterial adhesion to cardiac valves.

Methods

Staphylococcus aureus and Pseudomonas aeruginosa were used to assess in vitro bacterial adhesion to CCs and proliferation in the presence of CCs compared to plastic microspheres and glass shards as controls. Ex vivo studies evaluated bacterial adhesion to atherosclerotic rabbit arteries compared to normal arteries and human atherosclerotic carotid plaques compared to normal carotid arteries. Scanning electron microscopy (SEM) was used to visualize bacterial adhesion to CCs and confocal microscopy was used to detect cholesterol binding to bacteria grown in the presence or absence of CCs.

Results

In vitro, S. aureus and P. aeruginosa displayed significantly greater adhesion, 36% (p<0.0001) and 89% (p<0.0001), respectively, and growth upon exposure to CCs compared to microspheres or glass shards. Rabbit and human atherosclerotic arteries contained significantly greater bacterial burdens compared to controls (4× (p<0.0004); 3× (p<0.019), respectively. SEM demonstrated that bacteria adhered and appeared to degrade CCs. Consistent with this, confocal microscopy indicated increased cholesterol bound to the bacterial cells.

Conclusions

This study is the first to demonstrate an interaction between bacteria and CCs showing that bacteria dissolve and bind to CCs. This interaction helps to elucidate adhesion of bacteria to sclerotic valves and atherosclerotic plaques that may contribute to endocarditis and plaque destabilization.

Prognostic Implications of Influenza Virus Infection in a Cardiac Intensive Care Unit: Potential Impact of a Screening Program

Objectives: Our goal was to determine the presentation and prognosis of influenza in an intensive cardiac care unit and to analyze the impact of an active surveillance program in the diagnosis. Methods: We performed a prospective registry during the flu season in a coronary unit. In the first phase, no systematic screening was performed. Systematic influenza A and B detection was performed in a second phase for all patients admitted. Results: From 227 patients, we identified 17 (7.5%) with influenza. Influenza patients were more likely to have a non-ischemic cause of admission (14 patients [82.4%] vs. 48 patients [40.3%], p = 0.002), fever (8 patients [47.1%] vs. 3 patients [2.6%], p < 0.001), and respiratory failure (7 patients [41.2%] vs. 8 patients [7%], p = 0.001). Influenza infection was an independent predictor of mortality (odds ratio 12.0, 95% confidence interval 1.9–13.6, p < 0.001). The incidence of influenza was 6.6% (6 patients) when no active screening was performed and 7.9% (11 patients) when systematic detection was performed (p = 0.005). The time to diagnosis was shorter in the systematic screening phase (0.92 ± 1.6 vs. 5.2 ± 3.8 days, p = 0.01). Conclusions: Influenza affects approximately 8% of patients admitted to an intensive cardiac care unit during the flu season, with a high mortality rate. An active surveillance program improves early detection.

HLA, infections and inflammation in early stages of atherosclerosis in children with type 1 diabetes

AIMS

This prospective study focuses on risk factors for arterial damage in children with type 1 diabetes (T1D).

METHODS

Eighty children and adolescents with T1D were investigated twice, approximately 2 years apart, for carotid artery intima-media thickness (cIMT) and compliance (CAC), flow-mediated dilatation (FMD) of the brachial artery, and plasma levels of matrix metalloproteinase (MMP)-8. All subjects were genotyped for HLA. The number of respiratory tract infections (RTI) during the past year was obtained by a questionnaire in 56 patients.

RESULTS

cIMT progression, defined as percentage (%) change of cIMT from baseline, correlated inversely with the % changes of both CAC (p = 0.04, r = - 0.3; n = 62) and FMD (p = 0.03, r = - 0.3; n = 47). In multivariate analysis, RTI frequency correlated significantly with cIMT progression irrespective of age, diabetes duration, BMI, and HbA1c (p = 0.03, r = 0.3). When patients were divided in relation to RTI, the association of DQ2/8 with cIMT progression remained significant in patients with over three infections/year (p = 0.04, r = 0.3). During follow-up, the group of DQ2/8 patients with hsCRP > 1 mg/l showed significantly higher levels of plasma MMP-8 than the non-DQ2/8 group.

CONCLUSIONS

The diabetes-risk genotype DQ2/8 and systemic inflammation contribute to pro-atherosclerotic vascular changes in children and adolescents with T1D.

Herpes Simplex Virus Type 1 and Type 2 Infection Increases Atherosclerosis Risk: Evidence Based on a Meta-Analysis

Objective. The aim of our study was to evaluate the relation of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) infection with the risk of atherosclerosis (AS). Methods. A systematic literature search was performed through three electronic databases. The pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were used to assess the effect of HSV-1 and HSV-2 infection on AS risk. Results. 17 studies were available for meta-analysis of HSV-1 infection and AS risk and seven studies for meta-analysis of HSV-2 infection and AS risk. Subjects exposed to HSV-1 infection exhibited an increased risk of AS (OR = 1.77; 95% CI: 1.40-2.23; P < 0.001). And consistent elevated AS risks for HSV-1 positive subjects were found in all subgroup analysis of disease type, region, male proportion, and age. HSV-2 positive subjects demonstrated significantly increased AS risk (OR = 1.37; 95% CI: 1.13-1.67; P < 0.005). In subgroup analysis, elevated AS risks were only observed in myocardial ischemia group, male proportion >60% group, and age ≤60-year-old group. Conclusion. Our meta-analysis indicated that HSV-1 and HSV-2 infection could increase the risk of contracting AS.

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.

The cardiovascular manifestations of influenza: a systematic review

Influenza accounts for 3 to 5 million cases of severe illness and up to 300,000 deaths annually, presenting a considerable burden to healthcare services. A spectrum of cardiovascular complications has been reported in association with influenza infection. This can occur through direct effects of the virus on the myocardium or through exacerbation of existing cardiovascular disease. Direct myocardial involvement presenting as myocarditis is not uncommon during influenza infection. Clinical presentation may vary from asymptomatic to fulminant myocarditis resulting in cardiogenic shock and death. Cardiovascular mortality is also increased during influenza epidemics in patients with pre-existing coronary artery disease. Rates of myocardial infarction have been shown to increase following influenza outbreaks, whilst decreases in cardiovascular mortality have been demonstrated following influenza vaccination in high risk patients. The purpose of this review is to provide an overview of cardiovascular complications, their presentation, clinical course and the management options available following influenza infection.

Circulating influenza virus, climatic factors, and acute myocardial infarction: a time series study in England and Wales and Hong Kong

BACKGROUND

Previous studies identifying associations between influenza and acute cardiac events may have been confounded by climatic factors. Differing seasonal patterns of influenza activity in Hong Kong and England and Wales provide a natural experiment to examine associations with myocardial infarction (MI) independent of cold weather effects.

METHODS

Weekly clinical and laboratory influenza surveillance data, environmental temperature and humidity data, and counts of MI-associated hospitalizations and deaths were obtained for England and Wales and for Hong Kong for the period 1998-2008. We used Poisson regression models that included environmental and seasonal variables to investigate the relationship between influenza and MI.

RESULTS

There were ≥1.2 million MI-associated hospitalizations and 410,204 MI-associated deaths in England and Wales, with a marked peak in the winter season. In Hong Kong, the incidence of MI, on the basis of 65,108 hospitalizations and 18,780 deaths, had a large winter and smaller summer peak, mirroring patterns of influenza activity. There was strong evidence for a link between influenza and MI both in England and Wales, where 3.1%-3.4% of MI-associated deaths (P < .001) and 0.7%-1.2% of MI-associated hospitalizations (P < .001) were attributable to influenza, and in Hong Kong, where the corresponding figures were 3.9%-5.6% (P = .018) and 3.0%-3.3% (P = .002).

CONCLUSIONS

Influenza was associated with an increase in MI-associated deaths and hospitalizations in 2 contrasting settings.

Relation between common allergic symptoms and coronary heart disease among NHANES III participants

We investigated whether there is an increased risk of coronary heart diseases (CHD) in those with common allergic symptoms using the NHANES III, which is a representative sample of the United States population in 1988 to 1994. CHD was defined by Rose questionnaire and history of heart attack. Allergic symptoms were categorized into no symptoms (NO), rhinoconjunctivitis without wheezing (RC), and wheezing (WZ) based on symptoms. Multivariate logistic regression was used to obtain odds ratios (ORs) of CHD. Eight thousand six hundred fifty-three nonpregnant subjects ≥20 years old with overnight fasting ≥8 hours were included. CHD was present in 5.9% of the population; 36.5% did not have allergic symptoms (NO), 45.9% had RC, and 17.6% had WZ. The prevalence of CHD was 3.9% in NO, 4.8% in RC, and 12.8% in WZ (p <0.001). Compared to NO, unadjusted ORs of CHD were 1.24 (95% confidence interval 0.94 to 1.62) in RC and 3.58 (2.68 to 4.78) in WZ and ORs adjusted for sociodemographic factors and co-morbidities were 1.40 (1.02 to 1.92) in RC and 2.64 (1.79 to 3.90) in WZ. Only the group of women <50 years of age had significantly increased ORs in RC and WZ. In conclusion, common allergic symptoms were significantly associated with an increased risk of CHD.

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.

Influenza as a trigger for acute myocardial infarction or death from cardiovascular disease: a systematic review

Cardiac complications of influenza infection, such as myocarditis, are well recognised, but the role of influenza as a trigger of acute myocardial infarction is less clear. We did a systematic review of the evidence that influenza (including influenza-like illness and acute respiratory infection) triggers acute myocardial infarction or cardiovascular death. We examined the effectiveness of influenza vaccines at protecting against cardiac events and did a meta-analysis of data from randomised controlled trials. 42 publications describing 39 studies were identified. Many observational studies in different settings with a range of methods reported consistent associations between influenza and acute myocardial infarction. There was weaker evidence of an association with cardiovascular death. Two small randomised trials assessed the protection provided by influenza vaccine against cardiac events in people with existing cardiovascular disease. Whereas one trial found that influenza vaccination gave significant protection against cardiovascular death, the other trial was inconclusive. A pooled estimate from a random-effects model suggests a protective, though non-significant, effect (relative risk 0.51, 95% CI 0.15-1.76). We believe influenza vaccination should be encouraged wherever indicated, especially in people with existing cardiovascular disease, among whom there is often suboptimum vaccine uptake. Further evidence is needed on the effectiveness of influenza vaccines to reduce the risk of cardiac events in people without established vascular disease.