Recent respiratory infection and the risk of myocardial infarction

Association between Influenza and COVID-19 Viruses and the Risk of Atherosclerosis: Meta-Analysis Study and Systematic Review

There is a lot of evidence to suggest that patients infected with the COVID-19 and influenza viruses are at risk of atherosclerosis. Additionally, there are heterogeneous studies on the risk of arthrosclerosis in patients infected with the influenza and COVID-19 viruses. We conducted a case−control and cross-sectional study and examined the association between the risk of atherosclerosis, and influenza virus (IV-A and IV-B) and COVID-19 infections in this study. We searched for keywords such as influenza virus, COVID-19 and atherosclerosis in English and Persian in well-known databases such as PubMed, SID, Magiran and Google Scholar. In this study, we analyzed the information using a meta-analysis, the random effect model, the I2 index and STAT (version 11.2). The results from the analysis of ten studies on influenza virus and nine studies on COVID-19 reviewed individually (totaling 6428 samples for influenza virus infections and 10,785 samples for COVID-19 infections) demonstrated a risk of arthrosclerosis in patients with influenza and COVID-19 infections, with an OR (odds ratio) = 0.45 ((95% CI): 0.25 to 0.64) and an OR (odds ratio) = 1.04 ((95% CI): 0.82 to 1.26), respectively. The present study provides new insights into the risk of atherosclerosis in patients infected with the COVID-19 and influenza viruses. Therefore, it seems necessary to consider different strategies for managing and eradicating viral infections among individuals.

Influenza Vaccination for the Prevention of Cardiovascular Disease in the Americas: Consensus document of the Inter-American Society of Cardiology and the Word Heart Federation

Background

Cardiovascular mortality is decreasing but remains the leading cause of death world-wide. Respiratory infections such as influenza significantly contribute to morbidity and mortality in patients with cardiovascular disease. Despite of proven benefits, influenza vaccination is not fully implemented, especially in Latin America.

Objective

The aim was to develop a regional consensus with recommendations regarding influenza vaccination and cardiovascular disease.

Methods

A multidisciplinary team composed by experts in the management and prevention of cardiovascular disease from the Americas, convened by the Inter-American Society of Cardiology (IASC) and the World Heart Federation (WHF), participated in the process and the formulation of statements. The modified RAND/UCLA methodology was used. This document was supported by a grant from the WHF.

Results

An extensive literature search was divided into seven questions, and a total of 23 conclusions and 29 recommendations were achieved. There was no disagreement among experts in the conclusions or recommendations.

Conclusions

There is a strong correlation between influenza and cardiovascular events. Influenza vaccination is not only safe and a proven strategy to reduce cardiovascular events, but it is also cost saving. We found several barriers for its global implementation and potential strategies to overcome them.

Human influenza A virus causes myocardial and cardiac-specific conduction system infections associated with early inflammation and premature death

AIMS

Human influenza A virus (hIAV) infection is associated with important cardiovascular complications, although cardiac infection pathophysiology is poorly understood. We aimed to study the ability of hIAV of different pathogenicity to infect the mouse heart, and establish the relationship between the infective capacity and the associated in vivo, cellular and molecular alterations.

METHODS AND RESULTS

We evaluated lung and heart viral titres in mice infected with either one of several hIAV strains inoculated intranasally. 3D reconstructions of infected cardiac tissue were used to identify viral proteins inside mouse cardiomyocytes, Purkinje cells, and cardiac vessels. Viral replication was measured in mouse cultured cardiomyocytes. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to confirm infection and study underlying molecular alterations associated with the in vivo electrophysiological phenotype. Pathogenic and attenuated hIAV strains infected and replicated in cardiomyocytes, Purkinje cells, and hiPSC-CMs. The infection was also present in cardiac endothelial cells. Remarkably, lung viral titres did not statistically correlate with viral titres in the mouse heart. The highly pathogenic human recombinant virus PAmut showed faster replication, higher level of inflammatory cytokines in cardiac tissue and higher viral titres in cardiac HL-1 mouse cells and hiPSC-CMs compared with PB2mut-attenuated virus. Correspondingly, cardiac conduction alterations were especially pronounced in PAmut-infected mice, associated with high mortality rates, compared with PB2mut-infected animals. Consistently, connexin43 and NaV1.5 expression decreased acutely in hiPSC-CMs infected with PAmut virus. YEM1L protease also decreased more rapidly and to lower levels in PAmut-infected hiPSC-CMs compared with PB2mut-infected cells, consistent with mitochondrial dysfunction. Human IAV infection did not increase myocardial fibrosis at 4-day post-infection, although PAmut-infected mice showed an early increase in mRNAs expression of lysyl oxidase.

CONCLUSION

Human IAV can infect the heart and cardiac-specific conduction system, which may contribute to cardiac complications and premature death.

Outbreak of SARS-CoV2: Pathogenesis of infection and cardiovascular involvement

Since the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) has emerged from China, the infection (novel corona virus disease-2019, COVID-19) has affected many countries and led to many deaths worldwide. Like SARS-CoV, angiotencin converting enzyme (ACE)2 as a functional receptor for SARS-CoV2 is essential for the virus to make an entry into the cell. ACE2 is a part of Renin-Angiotensin-Aldosterone System, which is expressed in several organs that opposes the angiotensin (Ang) II functions by converting Ang II to Ang (1-7), the one with vasodilation effects. The death rate of COVID-19 is estimated to be approximately 3.4%; however, some comorbid conditions like underlying cardiovascular disease, hypertension, and diabetes increase the risk of mortality. In addition, cardiovascular involvement as a complication of SARS-CoV2 could be direct through either ACE2 receptors that are expressed tremendously in the heart, or by the surge of different cytokines or by acute respiratory distress syndrome-induced hypoxia. Traditional risk factors could aggravate the process of COVID-19 infection that urges the triage of these high-risk patients for SARS-CoV2. Currently, there is no effective, proven treatment or vaccination for COVID-19, but many investigators are struggling to find a treatment strategy as soon as possible. Some potential medications like chloroquine by itself or in combination with azithromycin and some protease inhibitors used for the treatment of COVID-19 have cardiovascular adverse effects, which should be kept in mind while the patients taking these medications are being closely monitored.

Influenza coverage rates in subjects with chronic heart diseases: results obtained in four consecutive immunisation seasons in the Local Health Unit of Ferrara (North Italy)"

Background

Seasonal influenza epidemics yearly affects 5–15% of the world’s population, resulting in 3–5 million serious cases and up to 650,000 deaths. According to the 2017–2019 Italian National Immunisation Plan, free immunisation is offered to the categories at increased risk of experience the complications of the infection (over 65 years old subjects, pregnant women and individuals with underlying conditions, including chronic heart diseases). Rising evidence suggests that influenza can trigger adverse cardiovascular events therefore the vaccination is recommended for secondary prevention of cardiovascular diseases. Despite this, the influenza coverage rate in subjects with chronic heart disease is underestimated.

Methods

The study investigated the coverage rate in four consecutive influenza seasons (from 2011/2012 to 2014/2015) in subjects that benefit from exemption from paying healthcare costs for chronic heart disease living in Local Health Unit (LHU) of Ferrara (Italy), comparing the databases of exemptions and immunisations.

Results

The levels of influenza vaccine uptake were unstable, reaching the 50.3% in 2011/2012 immunisation season and falling to 42.2% in the following year. Coverage rates increased with increasing age, without achieving the 75% target, neither in over 65 years old subjects. The logistic regression analysis showed that influenza coverage rates were statistically significant different (p < 0.0001, 0.003 only for category of disease in 2011/2012 immunisation season) according to age, district of residence, category of chronic heart disease and length of exemption, but not influenced by gender.

Conclusions

The recommendation of influenza immunisation was weakly followed in individuals with chronic heart diseases. A collaboration between cardiologists, GPs, scientific societies and patient associations could successfully support influenza vaccine uptake.

Cardiovascular Manifestations of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the cause of COVID-19, was first reported in Wuhan, China. SARS-CoV-2 especially involves alveolar epithelial cells, which results in respiratory symptoms more severe in patients with cardiovascular disease (CVD) probably linked with increased secretion of angiotensin-converting enzyme 2 in these patients compared with healthy individuals. Cardiac manifestations may contribute to overall mortality and even be the primary cause of death in many of these patients. A higher prevalence of hypertension (HTN) followed by diabetes mellitus and CVD was observed in COVID-19 patients. A higher case-fatality rate was seen among patients with pre-existing comorbid conditions, such as diabetes, chronic respiratory disease, HTN, and cancer, compared to a lesser rate in the entire population. Cardiovascular (CV) manifestations of COVID-19 encompass a wide spectrum, including myocardial injury, infarction, myocarditis-simulating ST-segment elevation myocardial infarction, nonischemic cardiomyopathy, coronary vasospasm, pericarditis, or stress (takotsubo) cardiomyopathy. This review is intended to summarize our current understanding of the CV manifestations of COVID-19 and also to study the relationship between SARS-CoV-2 and CVDs and discuss possible mechanisms of action behind SARS-CoV-2 infection-induced damage to the CV system.

Cardiovascular Outcomes after a Respiratory Tract Infection among Adults with Non-Cystic Fibrosis Bronchiectasis: A General Population-based Study

RATIONALE

Studies suggest that adults with bronchiectasis are at increased risk of cardiovascular comorbidities.

OBJECTIVES

We aimed to quantify the relative risk of incident cardiovascular events after a respiratory tract infection among adults with bronchiectasis.

METHODS

Using UK electronic primary care records, we conducted a within-person comparison using the self-controlled case series method. We calculated the relative risk of first-time cardiovascular events (either first myocardial infarction or stroke) after a respiratory tract infection compared with the individual's baseline risk.

RESULTS

Our cohort consisted of 895 adult men and women with non-cystic fibrosis bronchiectasis with a first myocardial infarction or stroke and at least one respiratory tract infection. There was an increased rate of first-time cardiovascular events in the 91-day period after a respiratory tract infection (incidence rate ratio, 1.56; 95% confidence interval, 1.20-2.02). The rate of a first cardiovascular event was highest in the first 3 days after a respiratory tract infection (incidence rate ratio, 2.73; 95% confidence interval, 1.41-5.27).

CONCLUSIONS

These data suggest that respiratory tract infections are strongly associated with a transient increased risk of first-time myocardial infarction or stroke among people with bronchiectasis. As respiratory tract infections are six times more common in people with bronchiectasis than the general population, the increased risk has a disproportionately greater impact in these individuals. These findings may have implications for including cardiovascular risk modifications in airway infection treatment pathways in this population.

Extreme influenza epidemics and out-of-hospital cardiac arrest

INTRODUCTION

There is compelling evidence for an association between influenza epidemics and major adverse cardiovascular events. However, the role of extreme influenza epidemics as a trigger of out-of-hospital cardiac arrest (OHCA) is unclear. Thus, we evaluated the potential association between extreme influenza epidemics and incidence of OHCA.

METHODS

We used a quasi-experimental design with time-series analysis of national registry data for cases of OHCA from all 47 prefectures of Japan during influenza seasons between 2005 and 2014. A Poisson regression time-series model with a distributed lag non-linear model was used to estimate prefecture-specific effects of influenza epidemics on OHCA. A multivariate meta-analysis was conducted for nationally pooled estimates.

RESULTS

In total, 481,516 OHCAs of presumed cardiac origin were reported during the study period. The minimum morbidity percentile (MMP) was estimated as the 0th percentile for influenza incidence. The overall cumulative relative risk versus the MMP was 1.25 (95% confidence interval, 1.16-1.34) for extreme influenza epidemics (at the 99th percentile of influenza incidence). The effect of extreme influenza epidemics was significant for lag periods of 1.5-7.1 and 17.9-21 days. Multivariate random-effects meta-analysis indicated significant spatial heterogeneity among prefectures (Cochran Q test, p = 0.011; I² = 23.2%).

CONCLUSION

Extreme influenza epidemics are associated with higher risk of OHCA. Our findings suggest that several weeks' prevention for extreme influenza infections should be implemented to reduce the risk of OHCA.

Seasonal Influenza Infections and Cardiovascular Disease Mortality

IMPORTANCE

Cardiovascular deaths and influenza epidemics peak during winter in temperate regions.

OBJECTIVES

To quantify the temporal association between population increases in seasonal influenza infections and mortality due to cardiovascular causes and to test if influenza incidence indicators are predictive of cardiovascular mortality during the influenza season.

DESIGN, SETTING, AND PARTICIPANTS

Time-series analysis of vital statistics records and emergency department visits in New York City, among cardiovascular deaths that occurred during influenza seasons between January 1, 2006, and December 31, 2012. The 2009 novel influenza A(H1N1) pandemic period was excluded from temporal analyses.

EXPOSURES

Emergency department visits for influenza-like illness, grouped by age (≥0 years and ≥65 years) and scaled by laboratory surveillance data for viral types and subtypes, in the previous 28 days.

MAIN OUTCOMES AND MEASURES

Mortality due to cardiovascular disease, ischemic heart disease, and myocardial infarction.

RESULTS

Among adults 65 years and older, who accounted for 83.0% (73 363 deaths) of nonpandemic cardiovascular mortality during influenza seasons, seasonal average influenza incidence was correlated year to year with excess cardiovascular mortality (Pearson correlation coefficients ≥0.75, P ≤ .05 for 4 different influenza indicators). In daily time-series analyses using 4 different influenza metrics, interquartile range increases in influenza incidence during the previous 21 days were associated with an increase between 2.3% (95% CI, 0.7%-3.9%) and 6.3% (95% CI, 3.7%-8.9%) for cardiovascular disease mortality and between 2.4% (95% CI, 1.1%-3.6%) and 6.9% (95% CI, 4.0%-9.9%) for ischemic heart disease mortality among adults 65 years and older. The associations were most acute and strongest for myocardial infarction mortality, with each interquartile range increase in influenza incidence during the previous 14 days associated with mortality increases between 5.8% (95% CI, 2.5%-9.1%) and 13.1% (95% CI, 5.3%-20.9%). Out-of-sample prediction of cardiovascular mortality among adults 65 years and older during the 2009-2010 influenza season yielded average estimates with 94.0% accuracy using 4 different influenza metrics.

CONCLUSIONS AND RELEVANCE

Emergency department visits for influenza-like illness were associated with and predictive of cardiovascular disease mortality. Retrospective estimation of influenza-attributable cardiovascular mortality burden combined with accurate and reliable influenza forecasts could predict the timing and burden of seasonal increases in cardiovascular mortality.

Triggering of acute myocardial infarction by respiratory infection

BACKGROUND

Respiratory infection has been associated with an increased short-term risk of myocardial infarction (MI). However, previous studies have predominantly been conducted without angiographic confirmation of MI. The possibility can therefore not be excluded that raised troponin levels or electrocardiogram abnormalities that may be seen with respiratory infections are due to non-ischaemic causes.

AIMS

To investigate the association between respiratory infection and angiographically confirmed MI.

METHODS

Interviews were conducted within 4 days of hospitalisation in 578 patients with angiographically confirmed MI, to assess for recent exposure to respiratory infection symptoms and the usual annual frequency of these symptoms. Using case-crossover methodology, exposure to respiratory infection prior to the onset of MI was compared against the usual frequency of exposure in the past year.

RESULTS

Symptoms of respiratory infection were reported by 100 (17%) and 123 (21%) within 7 and 35 days, respectively, prior to MI. The relative risk (RR) for MI occurring within 1-7 days after respiratory infection symptoms was 17.0 (95% confidence interval (CI) 13.2-21.8), and declined with subsequent time periods. In a subgroup analysis, the RR tended to be lower in groups taking regular cardiac medications. For those who reported milder, upper respiratory tract infection symptoms, the RR for the 1-7-day time period was 13.5 (95% CI 10.2-17.7).

CONCLUSION

These findings confirm that respiratory infection can trigger MI. Further study is indicated to identify treatment strategies to decrease this risk, particularly in individuals who may have increased susceptibility.

Influenza vaccine as a coronary intervention for prevention of myocardial infarction

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality globally. Influenza is one of the leading infectious causes of morbidity and mortality globally, and evidence is accumulating that it can precipitate acute myocardial infarction (AMI). This is thought to be due to a range of factors including inflammatory release of cytokines, disruption of atherosclerotic plaques and thrombogenesis, which may acutely occlude a coronary artery. There is a large body of observational and clinical trial evidence that shows that influenza vaccine protects against AMI. Estimates of the efficacy of influenza vaccine in preventing AMI range from 15% to 45%. This is a similar range of efficacy compared with the accepted routine coronary prevention measures such as smoking cessation (32-43%), statins (19-30%) and antihypertensive therapy (17-25%). Influenza vaccine should be considered as an integral part of CVD management and prevention. While it is recommended in many guidelines for patients with CVD, rates of vaccination in risk groups aged <65 years are very low, in the range of 30%. The incorporation of vaccination into routine CVD prevention in patient care requires a clinical practice paradigm change.

Lung exposure to lipopolysaccharide causes atherosclerotic plaque destabilisation

Epidemiological studies have implicated lung inflammation as a risk factor for acute cardiovascular events, but the underlying mechanisms linking lung injury with cardiovascular events are largely unknown.

Our objective was to develop a novel murine model of acute atheromatous plaque rupture related to lung inflammation and to investigate the role of neutrophils in this process.

Lipopolysaccharide (LPS; 3 mg·kg−1) or saline (control) was instilled directly into the lungs of male apolipoprotein E-null C57BL/6J mice following 8 weeks of a Western-type diet. 24 h later, atheromas in the right brachiocephalic trunk were assessed for stability ex vivo using high-resolution optical projection tomography and histology. 68% of LPS-exposed mice developed vulnerable plaques, characterised by intraplaque haemorrhage and thrombus, versus 12% of saline-exposed mice (p=0.0004). Plaque instability was detectable as early as 8 h post-intratracheal LPS instillation, but not with intraperitoneal instillation. Depletion of circulating neutrophils attenuated plaque rupture.

We have established a novel plaque rupture model related to lung injury induced by intratracheal exposure to LPS. In this model, neutrophils play an important role in both lung inflammation and plaque rupture. This model could be useful for screening therapeutic targets to prevent acute vascular events related to lung inflammation.

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.

Cardiac diseases complicating community-acquired pneumonia

PURPOSE OF REVIEW

The aim is to evaluate basic mechanisms, prevalence, risk factors, outcomes, and potential treatments of cardiovascular events (CVEs) in patients with community-acquired pneumonia (CAP).

RECENT FINDINGS

In this review, we present a new model to evaluate the pathophysiology of cardiac disease in patients with pneumonia based on plaque-related events, such as acute myocardial infarction, versus plaque-unrelated events, such as arrhythmias and heart failure. CAP increases the risk for both plaque-related and plaque-unrelated events with an absolute rate of CVE across different cohorts that varies broadly from 10 to 30%. These complications may happen among both ambulatory patients and inpatients, either on admission or during hospitalization, and/or after discharge. CVEs represent a major cause for increased mortality in CAP patients, contributing to more than 30% of deaths at long-term follow-up.

SUMMARY

From a clinical perspective, especially during the first 24 h after hospitalization, CAP patients should be tested for the probability to have or develop during hospitalization a cardiac event. From a research point of view, there is an urgent need to prospectively evaluate cardioprotective interventions.

Lower mortality rate in elderly patients with community-onset pneumonia on treatment with aspirin

BACKGROUND

Pneumonia is complicated by high rate of mortality and cardiovascular events (CVEs). The potential benefit of aspirin, which lowers platelet aggregation by inhibition of thromboxane A2 production, is still unclear. The aim of the study was to assess the impact of aspirin on mortality in patients with pneumonia.

METHODS AND RESULTS

Consecutive patients admitted to the University-Hospital Policlinico Umberto I (Rome, Italy) with community-onset pneumonia were recruited and prospectively followed up until discharge or death. The primary end point was the occurrence of death up to 30 days after admission; the secondary end point was the intrahospital incidence of nonfatal myocardial infarction and ischemic stroke. One thousand and five patients (age, 74.7±15.1 years) were included in the study: 390 were receiving aspirin (100 mg/day) at the time of hospitalization, whereas 615 patients were aspirin free. During the follow-up, 16.2% of patients died; among these, 19 (4.9%) were aspirin users and 144 (23.4%; P<0.001) were aspirin nonusers. Overall, nonfatal CVEs occurred in 7% of patients, 8.3% in nonaspirin users, and 4.9% in aspirin users (odds ratio, 1.77; 95% confidence interval, 1.03 to 3.04; P=0.040). The Cox regression analysis showed that pneumonia severity index (PSI), severe sepsis, pleural effusion, and PaO(2)/FiO(2) ratio <300 negatively influenced survival, whereas aspirin therapy was associated with improved survival. Compared to patients receiving aspirin, the propensity score adjusted analysis confirmed that patients not taking aspirin had a hazard ratio of 2.07 (1.08 to 3.98; P=0.029) for total mortality.

CONCLUSIONS

This study shows that chronic aspirin use is associated with lower mortality rate within 30 days after hospital admission in a large cohort of patients with pneumonia.

Increased Expressions of Integrin Subunit β1, β2 and β3 in Patients with Acute Infection

OBJECTIVE

Our previous studies have shown that integrin subunits β1, β2 and β3 were the core proteins of venous thrombi and potential useful biomarker of venous thromboembolism (VTE). Patients with acute infection have a high risk of VTE. In this study we explored that is there any relevance between core proteins and acute infection.

METHODS

A total of 230 patients (112 females) with clinically proven acute infection in the emergency unit were recruited into this study, meanwhile 230 patients without acute infection matched in sex and age were recruited as control group. Flow cytometry was done to measure the expressions of blood integrin β1, β2, β3 and cellular immunity (CD3, CD4, CD8, CD4/CD8, CD16CD56 and CD19). The association degree between increased core proteins and acute infection was analyzed by calculating the relative risk (RR).

RESULTS

The expression of integrin β1, β2 and β3 was markedly increased in patients with acute infection (P=0.000, 0.000 and 0.015, respectively). The relative risk ratio (RR) of increased integrin β1, β2 and β3 in acute infection patients was 1.424 (95%CI: 1.156-1.755, P=0.001), 1.535 (95%CI: 1.263-1.865, P=0.000) and 1.20 (95%CI: 0.947-1.521, P=0.148), respectively. Combined integrin β1, β2 and β3 analysis showed that the relative risk ratio (RR) of increased in patients with acute infection was 2.962 (95%CI: 1.621-5.410, P=0.001), and this relative risk (RR) rise to 3.176 (95%CI: 1.730-5.829, P=0.000) in patients with respiratory tract infection (RTI).

CONCLUSION

As the core proteins of venous thrombi, integrinβ1, β2 and β3 were markedly increased expression in patients with acute infection, which maybe explain the increased risk of VTE in acute infection patients. A weakened immune system could be the basic condition of VTE occurrence.

Risk of cardiovascular events in survivors of severe sepsis

RATIONALE

The risk of cardiovascular events after severe sepsis is not known, and these events may explain increased long-term mortality in survivors of severe sepsis.

OBJECTIVES

To determine whether survivors of severe sepsis hospitalization have high long-term risk of cardiovascular events. We examined whether higher risk is due to severe sepsis hospitalization or poor prehospitalization health status, and if the higher risk is also observed in patients hospitalized for infectious and noninfectious reasons, and in other critically ill patients.

METHODS

Unmatched and matched-cohort analyses of Medicare beneficiaries. For unmatched analysis, we compared patients with severe sepsis admitted to the intensive care unit (ICU) and survived hospitalization (n = 4,179) to unmatched population control subjects (n = 819,283). For matched analysis, we propensity-score-matched each patient with severe sepsis to four control subjects (population, hospitalized, non-severe sepsis ICU control subjects, and infection hospitalization). Primary outcome was 1-year incidence rate of hospitalization for cardiovascular events.

MEASUREMENTS AND MAIN RESULTS

Cardiovascular events were common among patients discharged alive after severe sepsis hospitalization (29.5%; 498.2 events/1,000 person-years). Survivors of severe sepsis had a 13-fold higher risk of cardiovascular events compared with unmatched control subjects (498.2 vs. 36 events/1,000 person-years; P < 0.0001), and a 1.9-fold higher risk compared with matched-population control subjects (P < 0.0001). Survivors of severe sepsis had 1.1-fold higher risk compared with matched hospitalized patients and infection hospitalizations (P = 0.002 and 0.001) and similar risk compared with matched-ICU control subjects.

CONCLUSIONS

Survivors of severe sepsis have high risk of cardiovascular events. The higher risk is mainly due to poor prehospitalization health status, and is also seen in a broader population of acutely ill patients.

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.

Pneumonia: an arrhythmogenic disease?

BACKGROUND

Recent studies suggest that there is an increase in cardiovascular disease after pneumonia; however, there is little information on cardiac arrhythmias after pneumonia. The aims of this study were to assess the incidence of, and examine risk factors for, cardiac arrhythmias after hospitalization for pneumonia.

METHODS

We conducted a national cohort study using Department of Veterans Affairs administrative data including patients aged ≥65 years hospitalized with pneumonia in fiscal years 2002-2007, receiving antibiotics within 48 hours of admission, having no prior diagnosis of a cardiac arrhythmia, and having at least 1 year of Veterans Affairs care. We included only the first pneumonia-related hospitalization, and follow-up was for the 90 days after admission. Cardiac arrhythmias included atrial fibrillation, ventricular tachycardia/fibrillation, cardiac arrest, and symptomatic bradycardia. We used a multilevel regression model, adjusting for hospital of admission, to examine risk factors for cardiac arrhythmias.

RESULTS

We identified 32,689 patients who met the inclusion criteria. Of these, 3919 (12%) had a new diagnosis of cardiac arrhythmia within 90 days of admission. Variables significantly associated with increased risk of cardiac arrhythmia included increasing age, history of congestive heart failure, and a need for mechanical ventilation or vasopressors. Beta-blocker use was associated with a decreased incidence of events.

CONCLUSION

An important number of patients have new cardiac arrhythmia during and after hospitalization for pneumonia. Additional research is needed to determine whether use of cardioprotective medications will improve outcomes for patients hospitalized with pneumonia. At-risk patients hospitalized with pneumonia should be monitored for cardiac arrhythmias during the hospitalization.

Incidence of cardiovascular events after hospital admission for pneumonia

OBJECTIVE

Several studies have suggested an increased risk of cardiovascular events, primarily acute myocardial infarction, around the time of hospital admission for pneumonia. Therefore, we examined cardiovascular events, including myocardial infarction, congestive heart failure, unstable angina, stroke, and serious cardiac arrhythmias, within 90 days after hospitalization for pneumonia.

METHODS

By using data from the administrative databases of the Department of Veterans Affairs, we examined a cohort of subjects hospitalized with pneumonia between October 2001 and September 2007. Subjects were at least 65 years of age. We examined the incidence of myocardial infarction, congestive heart failure, cardiac arrhythmias, unstable angina, and stroke by International Classification of Diseases, Ninth Revision codes, excluding those with a diagnosis before the admission for pneumonia.

RESULTS

The cohort comprised 50,119 subjects with a mean age of 77.5 years (standard deviation 6.7 years), 98% of whom were male. The 90-day incidence of cardiovascular events was 1.5% for myocardial infarction, 10.2% for congestive heart failure, 9.5% for arrhythmia, 0.8% for unstable angina, and 0.2% for stroke. The majority of events occurred during the hospitalization for pneumonia.

CONCLUSION

A clinically important number of subjects in this cohort had a cardiovascular event within 90 days of hospital admission, suggesting that such events may have an important role in post-pneumonia mortality. Additional research is needed to determine whether interventions may reduce the number of cardiovascular events after pneumonia.

Recent respiratory infection and risk of venous thromboembolism: case-control study through a general practice database

Background The association between respiratory infection and risk of heart attacks and strokes is well established. However, less evidence exists for an association between respiratory infection and venous thromboembolism (VTE). In this article, we describe the associations between respiratory infection and VTE.

Methods All cases aged ≥18 years of first-time diagnosis of deep-vein thrombosis (DVT) or pulmonary embolism (PE) were identified together with single-matched controls from a primary care general practice database. In addition to the matching characteristics, information was collected on other potentially important confounding factors.

Results There were 457/11 557 (4.0%) DVT cases with respiratory infection in the year before the index date (73 in the preceding month) compared with 262/11 557 (2.3%) controls (24 in the preceding month). There was an increased risk of DVT in the month following infection [adjusted odds ratio (OR) = 2.64, 95% confidence interval (95% CI) 1.62–4.29] which persisted up to a year. There were 180/5162 (3.5%) PE cases with respiratory infection in the year before the index date compared with 94/5162 (1.8%) controls excluding those in the preceding month to avoid the possible misdiagnosis of early PE. There was an increased risk of PE in the 3 months following infection (adjusted OR = 2.50, 95% CI 1.33–4.72) which may have persisted up to a year.

Conclusions There are strong associations between recent respiratory infection and VTE. There should be less distinction between venous and arterial events in decisions about preventing or aborting infections, especially in high-risk patients.

The association between Staphylococcus aureus bacteremia and acute myocardial infarction

We evaluated a possible association between S. aureus bacteremia (SAB) and the occurrence of myocardial infarction (MI) in 588 patients using the self-controlled case series method. SAB increased the risk for MI 35-fold in the 2 d after recognition of this infection (IRR = 35.3; CI 16.7-74.7).

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.

Acute bacterial pneumonia is associated with the occurrence of acute coronary syndromes

A link between acute infections and the development of acute coronary syndromes (ACS) has been proposed. We used retrospective cohort and self-controlled case series analyses to define the closeness of the association between acute bacterial pneumonia due to Streptococcus pneumoniae or Haemophilus influenzae and ACS. For the retrospective cohort analysis we included a control group of patients with admission diagnoses other than pneumonia or ACS. For the self-controlled case series analysis, we made within-person comparisons of the risk for ACS during the 15 days after admission for pneumonia with that of 365 days before and after that event. In 206 pneumonia patients (144 S. pneumoniae, 62 H. influenzae) we identified 22 (10.7%) cases of ACS, which compared to 6 (1.5%) among 395 controls resulted in an odds ratio (OR) of 7.8 (95% confidence interval [CI], 3.1-19.4). With multivariate logistic regression analysis, the OR for ACS in the pneumonia group remained elevated (OR, 8.5; 95% CI, 3.4-22.2). By the self-controlled case series method, the risk of ACS remarkably increased during the first 15 days after the diagnosis of pneumonia (incidence rate ratio, 47.6; 95% CI, 24.5-92.5). The characteristics and strength of these associations suggest a causal role for the acute infection in this relationship.