Reversible cardiac dysfunction associated with pandemic 2009 influenza A(H1N1)

Associations Between Severe Influenza-Complicated Thromboembolism Events, Intensive Care Unit Stays and Mortality, and Associated Risk Factors: A Retrospective Cohort Study

The association between influenza infection and thromboembolism (TE) events, including cardiovascular events, cerebrovascular events, pulmonary embolism, and deep vein thrombosis, is supported by compelling evidence. However, there is a disparity in the risk factors that impact the outcomes of severe influenza-complicated TE in intensive care unit (ICU) patients. The objective of this study was to evaluate the outcomes of severe influenza-complicated TE in ICU patients and identify any associated risk factors.

METHODS

A retrospective cohort study was conducted, recruiting consecutive patients with TE events admitted to the ICU between December 2015 through December 2018 at our institution in Taiwan. The study included a group of 108 patients with severe influenza and a control group of 192 patients with severe community-acquired pneumonia. Associations between complicated TE, length of ICU stay, and 90-day mortality were evaluated using logistic regression analysis, and risk factors were identified using univariate and multivariate generalized linear regression analyses.

RESULTS

TE event prevalence was significantly higher in ICU patients with severe influenza than in ICU patients with severe CAP (21.3% vs. 5.7%, respectively; p < 0.05). Patients with severe influenza who developed TE experienced a significant increase in the ratio of mechanical ventilation use, length of mechanical ventilation use, ICU stay, and 90-day mortality when compared to patients without TE (all p < 0.05). The comparison of severe CAP patients with and without TE revealed no significant differences (p > 0.05). The development of thromboembolic events in patients with severe influenza or severe noninfluenza CAP is linked to influenza infection and hypertension (p < 0.05). Furthermore, complicated TE and the severity of the APACHE II score are risk factors for 90-day mortality in ICU patients with severe influenza (p < 0.05).

CONCLUSIONS

Patients with severe influenza and complicated TE are more likely to have an extended ICU stay and 90-day mortality than patients with severe CAP. The risk is significantly higher for patients with a higher APACHE II score. The results of this study may aid in defining better strategies for early recognition and prevention of severe influenza-complicated TE.

The association between pre-exposure to glucocorticoids and other immunosuppressant drugs with severe COVID-19 outcomes

OBJECTIVES

Whether preinfection use of immunosuppressant drugs is associated with COVID-19 severity remains unclear. The study was aimed to determine the association between preinfection use of immunosuppressant drugs with COVID-19 outcomes within 1 month after COVID-19 diagnosis.

METHODS

This cohort study included individuals aged ≥18 years with underlying conditions associated with an immunocompromised state and diagnosed with COVID-19 between February 2020 and January 2021 at Karolinska University Hospital, Stockholm. Exposure to immunosuppressant drugs was defined based on dose and duration of drugs (glucocorticoids and drugs included in L01 or L04 chapter of Anatomical Therapeutic Chemical classification) before COVID-19 diagnosis. Outcomes included hospital admission, ICU admission, mechanical ventilation, mortality, renal failure, stroke, pulmonary embolism, and cardiac event. ORs were calculated using logistic regression and baseline covariate adjustment for confounding with inverse probability of treatment weights.

RESULTS

Of 1067 included individuals, 444 were pre-exposed to immunosuppressive treatments before COVID-19 diagnosis (72 high-dose glucocorticoids, 255 L01 drugs (antineoplastics), 198 L04 (other immunosuppressants) and 78 to multiple drugs). There was no association between pre-exposure and hospital admission (OR 0.83, 95% CI 0.64 to 1.09) because of COVID-19. Pre-exposure to L01 or L04 drugs were not associated with hospital admission (adjusted ORs (aORs): 1.23, 0.86 to 1.76 and 1.31, 0.77 to 2.21) or other outcomes. High-dose glucocorticoids (≥20 mg/day prednisolone equivalent) were associated with hospital admission (aOR 2.50, 1.26 to 4.96), cardiac events (aOR 1.93, 1.08 to 3.46), pulmonary embolism (aOR 2.78, 1.08 to 7.15), and mortality (aOR 3.48, 1.77 to 6.86) due to COVID-19.

DISCUSSION

Antineoplastic and other immunosuppressants drugs were not associated with COVID-19 severity whereas high-dose glucocorticoids were associated. Further studies should evaluate the effect of pre-exposure of different dose of glucocorticoids on COVID-19 prognosis.

Inpatient cardiovascular outcomes in patients with cancer affected by viral influenza infection

Background

Influenza disproportionately affects individuals with underlying comorbidities. Long-term follow-up studies have shown that patients with cancer with influenza have higher mortality. However, very little is known about the in-hospital mortality and cardiovascular outcomes of influenza infection in cancer hospitalisations.

Methods

We compared the in-hospital mortality and cardiovascular outcomes in patients with cancer with and without influenza by screening the National Inpatient Sample from 2015 to 2017. A total of 9 443 421 hospitalisations with any cancer were identified, out of which 14 634 had influenza while 9 252 007 did not. A two-level hierarchical multivariate logistic regression analysis adjusted for age, sex, race, hospital type and relevant comorbidities was performed.

Results

The group with cancer and influenza had higher in-hospital mortality (OR 1.08; 95% CI 1.003 to 1.16; p=0.04), acute coronary syndromes (OR 1.74; 95% CI 1.57 to 1.93; p<0.0001), atrial fibrillation (OR 1.24; 95% CI 1.18 to 1.29; p<0.0001) and acute heart failure (OR 1.41; 95% CI 1.32 to 1.51; p<0.0001).

Conclusion

Patients with cancer affected by influenza have higher in-hospital mortality and a higher prevalence of acute coronary syndrome, atrial fibrillation and acute heart failure.

Cardiac Complications in Patients Hospitalised With COVID-19 in Australia

OBJECTIVES

Describe the incidence of cardiac complications in patients admitted to hospital with COVID-19 in Australia.

DESIGN

Observational cohort study.

SETTING

Twenty-one (21) Australian hospitals.

PARTICIPANTS

Consecutive patients aged ≥18 years admitted to hospital with laboratory confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

MAIN OUTCOME MEASURES

Incidence of cardiac complications.

RESULTS

Six-hundred-and-forty-four (644) hospitalised patients (62.5±20.1 yo, 51.1% male) with COVID-19 were enrolled in the study. Overall in-hospital mortality was 14.3%. Twenty (20) (3.6%) patients developed new atrial fibrillation or flutter during admission and 9 (1.6%) patients were diagnosed with new heart failure or cardiomyopathy. Three (3) (0.5%) patients developed high grade atrioventricular (AV) block. Two (2) (0.3%) patients were clinically diagnosed with pericarditis or myopericarditis. Among the 295 (45.8%) patients with at least one troponin measurement, 99 (33.6%) had a peak troponin above the upper limit of normal (ULN). In-hospital mortality was higher in patients with raised troponin (32.3% vs 6.1%, p<0.001). New onset atrial fibrillation or flutter (6.4% vs 1.0%, p=0.001) and troponin elevation above the ULN (50.3% vs 16.4%, p<0.001) were more common in patients 65 years and older. There was no significant difference in the rate of cardiac complications between males and females.

CONCLUSIONS

Among patients with COVID-19 requiring hospitalisation in Australia, troponin elevation was common but clinical cardiac sequelae were uncommon. The incidence of atrial arrhythmias and troponin elevation was greatest in patients 65 years and older.

Influenza Myocarditis: A Literature Review

Viral myocarditis is not uncommon but the role of the influenza virus in causing myocarditis is less studied. It is difficult to diagnose influenza myocarditis. Due to bacterial and viral co-infection during influenza outbreaks, it becomes more difficult to distinguish influenza myocarditis from other causes. Our article provides current information on influenza myocarditis. We did a literature search using appropriate terms and reviewed articles published by November 2020. Our study highlights the incidence of influenza myocarditis and the need to become aware of this condition, especially during epidemics and pandemics. Our study highlights that although influenza myocarditis is a rare condition, it can be fatal. There should be increased awareness about the condition. By the early diagnosis and treatment of influenza myocarditis, we can prevent fatal complications.

Association of influenza infection and vaccination with cardiac biomarkers and left ventricular ejection fraction in patients with acute myocardial infarction

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We examined the association of influenza infection and vaccination with cardiac biomarkers and LVEF .

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Mean and median CK-MB levels were significantly higher among unvaccinated cases .

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Large size infarcts were more frequent in influenza positive cases and less frequent in vaccinated cases.

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Influenza vaccine may have a protective effect against large infarcts .

Aims

The aim of this study was to examine the association of influenza infection and vaccination with extent of cardiac damage during acute myocardial infarctions (AMIs) as measured by serum biomarkers and left ventricular ejection function (LVEF) in patients.

Methods

Post-hoc analysis was performed on data from a prospective case-control study of influenza and AMI, conducted in a tertiary care hospital in Sydney, Australia. We included 275 cases of AMI, aged ≥ 40 years admitted to the cardiology during the study period.

Results

Mean and median CK-MB levels were significantly higher among unvaccinated group compared to vaccinated group (p value < 0.05). Troponin levels were also higher among unvaccinated group compared to vaccinated group; although not statistically significant. Troponin and CKMB values were not statistically different among influenza positive cases and influenza negative cases. Large size infarcts were less frequent among vaccinated cases compared to unvaccinated cases (25% vs 35.5%) and were more frequent among influenza positive cases compared to influenza negative cases (35.3% vs 31.5%), however differences were not statistically significant. LVEF was lower among vaccinated cases compared to unvaccinated cases (62.5% vs. 52.8%) and influenza positive cases compared to influenza negative cases (58.8% vs 55.4), however differences were not significant.

Conclusion

Lower CKMB levels among vaccinated groups showed that influenza vaccine may have a protective effect against large infarcts, therefore influenza vaccination should be recommended for high risk groups. The study suggests an association of larger infarcts with influenza infection, but larger studies are required to confirm this.

Severe influenza: overview in critically ill patients

PURPOSE OF REVIEW

Overview of influenza infection, focusing on outcome and complications in critically ill patients. We also discuss relevant elements in immunopathogenesis and their role as predictors of severity.

RECENT FINDINGS

Pandemic influenza A (H1N1) virus circulates seasonally and remains the predominant subtype among intensive care patients. Mortality in acute respiratory failure (ARF) is around 20%, independent of influenza subtypes. During severe infection, the imbalance between pro-inflammatory and anti-inflammatory molecules, such as Th1 and Th17 cytokines, is associated with complicated infections and mortality. Primary viral pneumonia presents in more than 70% of ICU influenza patients and more than 50% develop acute respiratory distress syndrome. Bacterial secondary infection occurs in 20% of severe cases and Streptococcus pneumoniae and Staphylococcus aureus remain the prevalent pathogens. Myocarditis and late-onset cardiovascular complications are associated with mortality. Antiviral therapy within 48 h after onset, avoidance of corticosteroids and rescue therapies for ARF or myocarditis, such as extracorporeal membrane oxygenation, improve survival.

SUMMARY

The present review summarizes current knowledge on pathogenesis and clinical manifestations of severe influenza. Immunological dysfunction during viral infection correlates with severity and mortality among ICU patients. A theranostics strategy should be implemented to improve outcomes.

The hidden burden of influenza: A review of the extra-pulmonary complications of influenza infection

Severe influenza infection represents a leading cause of global morbidity and mortality. Although influenza is primarily considered a viral infection that results in pathology limited to the respiratory system, clinical reports suggest that influenza infection is frequently associated with a number of clinical syndromes that involve organ systems outside the respiratory tract. A comprehensive MEDLINE literature review of articles pertaining to extra‐pulmonary complications of influenza infection, using organ‐specific search terms, yielded 218 articles including case reports, epidemiologic investigations, and autopsy studies that were reviewed to determine the clinical involvement of other organs. The most frequently described clinical entities were viral myocarditis and viral encephalitis. Recognition of these extra‐pulmonary complications is critical to determining the true burden of influenza infection and initiating organ‐specific supportive care.

Viral-bacterial coinfection affects the presentation and alters the prognosis of severe community-acquired pneumonia

BACKGROUND

Multiplex polymerase chain reaction (mPCR) enables recovery of viruses from airways of patients with community-acquired pneumonia (CAP), although their clinical impact remains uncertain.

METHODS

Among consecutive adult patients who had undergone a mPCR within 72 hours following their admission to one intensive care unit (ICU), we retrospectively included those with a final diagnosis of CAP. Four etiology groups were clustered: bacterial, viral, mixed (viral-bacterial) and no etiology. A composite criterion of complicated course (hospital death or mechanical ventilation > 7 days) was used. A subgroup analysis compared patients with bacterial and viral-bacterial CAP matched on the bacterial pathogens.

RESULTS

Among 174 patients (132 men [76 %], age 63 [53-75] years, SAPSII 38 [27;55], median PSI score 106 [78;130]), bacterial, viral, mixed and no etiology groups gathered 46 (26 %), 53 (31 %), 45 (26 %) and 30 (17 %) patients, respectively. Virus-infected patients displayed a high creatine kinase serum level, a low platelet count, and a trend toward more frequent alveolar-interstitial infiltrates. A complicated course was more frequent in the mixed group (31/45, 69 %), as compared to bacterial (18/46, 39 %), viral (15/53, 28 %) and no etiology (12/30, 40 %) groups (p < 0.01). In multivariate analysis, the mixed (viral-bacterial) infection was independently associated with complicated course (reference: bacterial pneumonia; OR, 3.58; CI 95 %, 1.16-11; p = 0.03). The subgroup analysis of bacteria-matched patients confirmed these findings.

CONCLUSIONS

Viral-bacterial coinfection during severe CAP in adults is associated with an impaired presentation and a complicated course.

Influenza Induced Cardiomyopathy: An Unusual Cause of Hypoxemia

Influenza has considerable burden on public health funds. The complications of influenza can be devastating. We present a case of a 42-year-old woman with history of asthma who presented to the emergency room in winter with shortness of breath and general malaise and was found to be in hypoxemic respiratory failure. She was diagnosed with influenza and workup revealed severely depressed systolic cardiac function (ejection fraction of 25%). She was treated with oseltamivir and diuresis and regained cardiac function within a week. We review the pathophysiology and management of influenza induced cardiomyopathy.

Ultrasonic evaluation of the heart

PURPOSE OF REVIEW

To discuss the role of echocardiography for the hemodynamic evaluation of critically ill patients.

RECENT FINDINGS

In addition to its crucial role in evaluating heart abnormalities as in the classical cardiological approach, echocardiography is now frequently used by intensivists for noninvasive hemodynamic evaluation of the critically ill patient. Using echocardiography, it is possible to measure cardiac output, intravascular pressures and volumes, systolic and diastolic function of both ventricles, and preload responsiveness. This not only allows characterization of the precise nature of hemodynamic alterations in patients with circulatory and respiratory failure, but also provides guidance for hemodynamic optimization and optimization of ventilatory settings. There are now many data showing how echocardiography can be useful in detecting otherwise unrecognized myocardial depression in sepsis and right ventricular dysfunction in mechanically ventilated patients. The main limitation of echocardiography for hemodynamic monitoring is its intermittent nature. Hence, echocardiography is often combined with other monitoring devices, allowing continuous measurement of flow and triggering new echocardiographic evaluations.

SUMMARY

Echocardiography has now become an important tool for hemodynamic evaluation of the critically ill patient. Echocardiography should be performed in most patients with circulatory and respiratory failure.

Transient cardiac injury during H7N9 infection

BACKGROUND

Recent reports have characterized virological and clinical features of the novel reassortant avian-origin influenza A (H7N9) virus. However, cardiovascular involvement during H7N9 infection is still unclear. In this study, we evaluate cardiac injury among H7N9-infected patients.

MATERIALS AND METHODS

A total of 40 patients who were laboratory-confirmed with H7N9 infection were retrospectively included and grouped by Acute Physiology and Chronic Health Evaluation II (APACHE II) score into four subgroups I(0-10), II(11-20), III(21-30) and IV(31-71). Cardiovascular complications and markers of cardiac injury including creatinine kinase (CK), CK iso-enzyme (CK-MB), cardiac troponin I (cTNI) and brain natriuretic peptide (BNP) were assessed. Electrocardiogram (ECG) and echocardiography (ECHO) were also performed.

RESULTS

Half of patients manifested with cardiovascular complications, with hypotension (47.5%) and heart failure (40.0%) the most prevalent. CK, CK-MB and cTNI showed marked increase with H7N9 virus infection but significantly decreased after H7N9 viral tests turned negative. More than half of patients presented with an abnormal ECG, but most of them are benign changes. ECHO examination showed different degree of impairment of cardiac function. Pulmonary artery systolic pressure was increased in all groups. Cardiac damage was more evident in patients with higher APACHE II score.

CONCLUSIONS

H7N9 virus exerts a transient impairment on the cardiovascular system. Patients with a higher APACHE II score are more susceptible to cardiac damage.

Management of fulminant myocarditis: a diagnosis in search of its etiology but with therapeutic options

Fulminant myocarditis is a clinical syndrome with signs of acute heart failure, cardiogenic shock, or life-threating rhythm disturbances in the context of suspected myocarditis. It is not an etiological diagnosis, but may have different underlying causes and pathogenetic processes - viral, bacterial, toxic, and autoreactive. Clinical management of the disease entity at the acute stage involves hemodynamic monitoring in an intensive care unit or similar setting. Rapid routine work-up is mandatory with serial EKGs, echocardiography, cardiac MRI, heart catheterization with endomyocardial biopsy for histology, immunohistology, and molecular analysis for the underlying infection and pathogenesis. Heart failure therapy is warranted in all cases according to current guidelines. For fulminant autoreactive myocarditis, immunosuppressive treatment is beneficial; for viral myocarditis, IVIg can resolve the inflammation, reduce the viral load, and even eradicate the microbial agent. ECMO, IABP, ventricular assist devices, LifeVest, or ICD implantation can bridge to recovery or to heart transplantation.

Impact of H1N1 on socially disadvantaged populations: summary of a systematic review

BACKGROUND

Previous reviews found that the H1N1 pandemic was associated with a large proportion of hospitalizations, severe illness, workplace absenteeism, and high costs. However, the burden among socially disadvantaged groups of the population is unclear. This is a summary of a previously published systematic review commissioned by the World Health Organization on the burden of H1N1 pandemic (influenza A/Mexico/2009 (H1N1)) among socially disadvantaged populations.

METHODS

MEDLINE and EMBASE were searched to identify studies reporting hospitalization, severe illness, and mortality attributable to the 2009 H1N1 pandemic among socially disadvantaged populations, including ethnic minorities and low-income or lower-middle-income economy countries (LIC/LMIC). SAS and Review Manager were used to conduct random effects meta-analysis.

RESULTS

Forty-eight cohort studies and 14 companion reports including 44 777 patients were included after screening 787 citations and 164 full-text articles. Twelve of the included studies provided data on LIC/LMIC, including one study from Guatemala, two from Morocco, one from Pakistan, and eight from India, plus four companion reports. The rest provided data on ethnic minorities living in high-income economy countries (HIC). Significantly more hospitalizations were observed among ethnic minorities versus nonethnic minorities in two North American studies [1313 patients, odds ratio (OR) 2·26 (95% confidence interval: 1·53-3·32)]. Among hospitalized patients in HIC, statistically significant differences in intensive care unit admissions (n = 8 studies, 15 352 patients, OR 0·84 [0·69-1·02]) and deaths (n = 6 studies, 14 757 patients, OR 0·85 [95% CI: 0·73-1·01]) were not observed.

CONCLUSION

We found significantly more hospitalizations among ethnic minorities versus nonethnic minorities in North America, yet no differences in intensive care unit admissions or deaths among H1N1-infected hospitalized patients were observed in North America and Australia. Our results suggest a similar burden of H1N1 between ethnic minorities and nonethnic minorities living in HIC.

A fatal case of acute myocardial infarction following the improvement of influenza A(H1N1)pdm2009-related acute myocarditis

A 52-year-old Indian man was hospitalized due to dyspnea and a high fever caused by influenza A(H1N1)pdm2009. Elevated cardiac enzymes, a chest X-ray showing bilateral infiltrative shadows, cardiomegaly and pleural effusion and echocardiography indicating diffuse hypokinesis of the left ventricle suggested cardiac failure due to acute myocarditis. Owing to the administration of combined modality therapy, including steroids and intravenous γ-globulin, the patient's clinical symptoms of influenza completely resolved. However, he suddenly complained of epigastric pain due to acute myocardial infarction and died. This report is an educational case, the results of which suggest that greater attention should be paid to the potential for myocardial infarction even after an influenza virus infection is found to improve.

Atypical clinic presentation of pandemic influenza A successfully rescued by extracorporeal membrane oxygenation - Our experience and review of the literature

The novel pandemic influenza A (H1N1) caused an epidemic of critical illness, and some patients developed severe acute respiratory distress syndrome (ARDS) or severe cardiopulmonary failure despite the use of conventional management. Extracorporeal membrane oxygenation (ECMO) support may successfully rescue these severely ill patients. We demonstrate the causative role of H1N1 in refractory ARDS of a previously healthy 15-year-old man who presented to the intensive care unit with a hypoxic and persistent cardiogenic shock refractory to conventional management as the leading symptom of influenza A. Because of compromised cardiopulmonary function, venovenous ECMO was applied 24 h after admission. Despite that the patient was manifesting heart failure, we decided the placement of venovenous ECMO because we believed that the real problem was the uncontrollable hypoxia and hypercapnia. A normal left ventricular ejection fraction was documented on a 2D echocardiography on day 2. The patient, after 6 days of ECMO, recovered completely and was successfully weaned from the mechanical ventilator on the 9th day after admission. The patient was discharged from the hospital on the 15th day. This experience showed that ECMO can be lifesaving for severe H1N1 infection also in patients with atypical clinical presentation of influenza.

Atrial septostomy in cardiogenic shock related to H1N1 infection

The circulatory assistance, mainly the extra-corporeal membrane oxygenation (ECMO) restores hemodynamics and serves to limit the myocardial work, in order to avoid left ventricular dilation, high end-diastolic pressures, increased wall stress, subendocardial ischemia and consequently worsening pulmonary congestion and edema. In patients with large myocardial damage, sometimes an additional unloading of the left ventricle is warranted. We report a case of percutaneous blade and balloon atrial septostomy (BAS) as an add-on to the circulatory assistance to unload the left heart in a cardiogenic shock related to H1N1 infection.

Influenza-like illness in acute myocardial infarction patients during the winter wave of the influenza A H1N1 pandemic in London: a case-control study

OBJECTIVE

To investigate recent respiratory and influenza-like illnesses (ILIs) in acute myocardial infarction patients compared with patients hospitalised for acute non-vascular surgical conditions during the second wave of the 2009 influenza A H1N1 pandemic.

DESIGN

Case-control study.

SETTING

Coronary care unit, acute cardiology and acute surgical admission wards in a major teaching hospital in London, UK.

PARTICIPANTS

134 participants (70 cases and 64 controls) aged ≥40 years hospitalised for acute myocardial infarction and acute surgical conditions between 21 September 2009 and 28 February 2010, frequency-matched for gender, 5-year age-band and admission week. PRIMARY EXPOSURE: ILI (defined as feeling feverish with either a cough or sore throat) within the last month. SECONDARY EXPOSURES: Acute respiratory illness within the last month not meeting ILI criteria; nasopharyngeal and throat swab positive for influenza virus.

RESULTS

29 of 134 (21.6%) participants reported respiratory illness within the last month, of whom 13 (9.7%) had illnesses meeting ILI criteria. The most frequently reported category for timing of respiratory symptom onset was 8-14 days before admission (31% of illnesses). Cases were more likely than controls to report ILI-adjusted OR 3.17 (95% CI 0.61 to 16.47)-as well as other key respiratory symptoms, and were less likely to have received influenza vaccination-adjusted OR 0.46 (95% CI 0.19 to 1.12)-although the differences were not statistically significant. No swabs were positive for influenza virus.

CONCLUSIONS

Point estimates suggested that recent ILI was more common in patients hospitalised with acute myocardial infarction than with acute surgical conditions during the second wave of the influenza A H1N1 pandemic, and influenza vaccination was associated with cardioprotection, although the findings were not statistically significant. The study was underpowered, partly because the age groups typically affected by acute myocardial infarction had low rates of infection with the pandemic influenza strain compared with seasonal influenza.

Left ventricular myocardial performance in patients with dengue hemorrhagic fever and thrombocytopenia as assessed by two-dimensional speckle tracking echocardiography

OBJECTIVES

We obtained longitudinal, radial and circumferential strains in patients with dengue hemorrhagic fever (DhF) and thrombocytopenia using two-dimensional (2D) speckle tracking echocardiography to analyze left ventricular (LV) myocardial performance.

METHODS

In this prospective study, 2D echocardiographic images of the left ventricle in the four-, three- and two-chamber views and parasternal short-axis views at the basal, mid and apical levels were obtained in 40 subjects: 20 patients (23 ± 8 years, 12 male) with DhF and thrombocytopenia and 20 healthy controls (23 ± 5 years, 11 male). Of the 20 patients, imaging was performed again in 19 at discharge after a hospital stay of 8 ± 1 days. Longitudinal, circumferential and radial strains were quantified and compared in an 18-segment model using a novel speckle tracking system.

RESULTS

Left ventricular global ejection fraction was reduced in patients with DhF at presentation as compared with controls (51.25 ± 0.96% vs. 59.32 ± 1.26%; p = 0.032). Peak longitudinal strain in patients with DhF was significantly attenuated in the subendocardial region compared with normal controls (p < 0.001). A significant increase in circumferential strain for patients with DhF was evident only in the subepicardial region (p = 0.009). Patients with DhF showed significantly higher radial strain than controls (p < 0.001). On multivariate analysis, subendocardial longitudinal strain independently predicted the duration of hospital stay in patients with DhF.

CONCLUSION

Assessment of speckle tracking echocardiography-derived LV mechanics helps in understanding myocardial mechanics in patients with DhF and thrombocytopenia. Identification of reduced LV longitudinal strain helps in understanding the mechanism of reduced LV myocardial performance seen in patients with DhF.

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.

A case series of reversible acute cardiomyopathy associated with H1N1 influenza infection

Cardiomyopathy refers to nonspecific myocardial dysfunction that may be due to a variety of causes. Viral illnesses have long been known to cause cardiomyopathy, and the list of viral causes is extensive. Influenza infection is a rare cause of myocarditis. Recent reports, however, indicate that influenza A (H1N1) can cause acute myocarditis and cardiomyopathy in adults and fulminant myocarditis in children as seen during the 2009 global outbreak of the H1N1 influenza virus. The following presents a case series of adult patients with acute reversible cardiomyopathy associated with influenza A (H1N1) infection (see Table 1 for patient characteristics).

Myocarditis Associated with Influenza A H1N1pdm2009

Acute myocarditis is a well-known complication of influenza infection. The frequency of myocardial involvement in influenza infection varies widely, with the clinical severity ranging from asymptomatic to fulminant varieties. The worst cases can result in death due to impaired cardiac function, although such fulminant myocarditis associated with influenza infection is rare, as shown by previous papers. Following the 2009 influenza pandemic, we reported on the clinical features of a cohort of 15 patients in Japan with H1N1pdm2009 myocarditis. In our subsequent survey of the literature for case reports or series of patients with myocarditis associated with H1N1pdm2009, we identified 58 detailed cases. We discuss here the high prevalence of fulminant myocarditis (36/58, 62%) among patients reported to have myocarditis associated with H1N1pdm2009. Mechanical circulatory support was required in 17 of the patients with fulminant myocarditis, 13 of whom recovered. We stress the need for increased awareness of influenza-associated myocarditis; such knowledge will facilitate earlier diagnosis and treatment of this fatal complication during future influenza pandemics.

A case of fatal fulminant myocarditis presenting as an acute ST-segment elevation myocardial infarction and persistent ventricular tachyarrhythmia associated with influenza A (H1N1) virus in a previously healthy pregnant woman

Several studies have reported influenza A (H1N1) virus as a cause of fulminant myocarditis. We report the first fatal case of fulminant myocarditis presenting as an acute ST-segment elevation myocardial infarction and ventricular tachyarrhythmia associated with influenza A (H1N1) in a previously healthy pregnant woman. A 38-year-old Asian woman, gravida 3, para 1-0-1-1, presented with flu-like symptoms. Initially, she developed wide-complex tachycardia requiring several defibrillations and was later intubated. Electrocardiogram showed ST-segment elevation. Coronary angiogram was negative and a pulmonary angiogram ruled out pulmonary embolism. Fetal compromise was noted on the monitor, and the patient underwent an emergent cesarean section. She subsequently expired. Autopsy confirmed severe myocarditis. Further testing confirmed influenza A (H1N1) virus. This case of a rare, yet lethal, complication of H1N1 infection underscores the importance of increased awareness among health care professionals to provide pregnant women with vaccination and prompt treatment.

Impact of H1N1 on socially disadvantaged populations: systematic review

BACKGROUND

The burden of H1N1 among socially disadvantaged populations is unclear. We aimed to synthesize hospitalization, severe illness, and mortality data associated with pandemic A/H1N1/2009 among socially disadvantaged populations.

METHODS/PRINCIPAL FINDINGS

Studies were identified through searching MEDLINE, EMBASE, scanning reference lists, and contacting experts. Studies reporting hospitalization, severe illness, and mortality attributable to laboratory-confirmed 2009 H1N1 pandemic among socially disadvantaged populations (e.g., ethnic minorities, low-income or lower-middle-income economy countries [LIC/LMIC]) were included. Two independent reviewers conducted screening, data abstraction, and quality appraisal (Newcastle Ottawa Scale). Random effects meta-analysis was conducted using SAS and Review Manager.

CONCLUSIONS/SIGNIFICANCE

Sixty-two studies including 44,777 patients were included after screening 787 citations and 164 full-text articles. The prevalence of hospitalization for H1N1 ranged from 17-87% in high-income economy countries (HIC) and 11-45% in LIC/LMIC. Of those hospitalized, the prevalence of intensive care unit (ICU) admission and mortality was 6-76% and 1-25% in HIC; and 30% and 8-15%, in LIC/LMIC, respectively. There were significantly more hospitalizations among ethnic minorities versus non-ethnic minorities in two studies conducted in North America (1,313 patients, OR 2.26 [95% CI: 1.53-3.32]). There were no differences in ICU admissions (n = 8 studies, 15,352 patients, OR 0.84 [0.69-1.02]) or deaths (n = 6 studies, 14,757 patients, OR 0.85 [95% CI: 0.73-1.01]) among hospitalized patients in HIC. Sub-group analysis indicated that the meta-analysis results were not likely affected by confounding. Overall, the prevalence of hospitalization, severe illness, and mortality due to H1N1 was high for ethnic minorities in HIC and individuals from LIC/LMIC. However, our results suggest that there were little differences in the proportion of hospitalization, severe illness, and mortality between ethnic minorities and non-ethnic minorities living in HIC.

Postinfection A77-1726 treatment improves cardiopulmonary function in H1N1 influenza-infected mice

Acute respiratory disease is associated with significant morbidity and mortality in influenza. Because antiviral drugs are only effective early in infection, new agents are needed to treat nonvaccinated patients presenting with late-stage disease, particularly those who develop acute respiratory distress syndrome. We found previously that the de novo pyrimidine synthesis inhibitor A77-1726 reversed the influenza-induced impairment of alveolar fluid clearance. Patients with acute respiratory distress syndrome and intact alveolar fluid clearance demonstrate lower mortality than those with compromised fluid clearance. We therefore investigated the effects of treatment with nebulized A77-1726 (67.5 mg/kg) on indices of cardiopulmonary function relevant to the diagnosis of acute respiratory distress syndrome. BALB/cAnNCr mice (8-12 wk old) were inoculated intranasally with 10,000 plaque-forming units/mouse influenza A/WSN/33 (H1N1). Pulse oximetry was performed daily. Alveolar fluid clearance, lung water, and lung mechanics were measured at 2 and 6 days after inoculation in live, ventilated mice by BSA instillation, magnetic resonance imaging, and forced-oscillation techniques, respectively. A77-1726 treatment at 1 day after inoculation delayed mortality. Treatment on Days 1 or 5 reduced viral replication on Day 6, and improved alveolar fluid clearance, peripheral oxygenation, and cardiac function. Nebulized A77-1726 also reversed influenza-induced increases in lung water content and volume, improved pulmonary mechanics, reduced bronchoalveolar lavage fluid ATP and neutrophil content, and increased IL-6 concentrations. The ability of A77-1726 to improve cardiopulmonary function in influenza-infected mice and to reduce the severity of ongoing acute respiratory distress syndrome late in infection suggests that pyrimidine synthesis inhibitors are promising therapeutic candidates for the management of severe influenza.

Chest radiological findings of influenza A H1N1 pneumonia

OBJECTIVE

The objective of this study was to review chest radiographs (CXR) and chest computer tomography (CT) findings in patients with influenza A H1N1 virus pneumonia.

MATERIALS AND METHODS

Of ninety-eight patients with influenza A H1N1 infections seen in the General Hospitals of Villa Scassi, Genoa, and Sestri Levante from September 2009 to December 2009, twenty-eight developed pneumonia. The initial CXR were evaluated for radiological patterns: (ground-glass, consolidation, nodules, reticulation), distribution, and extent of the disease. Chest CT scans were reviewed for the same findings. A new radiographic score (CXR score) was used to evaluate the severity of the illness.

RESULTS

The predominant radiological findings on chest CT in the patients at presentation were unilateral or bilateral multifocal ground glass opacities (84.5% of the patients). Consolidation areas had a peribronchovascular and subpleural predominance and were found mainly in the middle and upper zones of the lung. Reticular opacities were found in about 20% of the cases. The most outstanding CXR and chest CT features of the disease were basal and axial alveolar consolidation and ground-glass opacities. The severity of disease as determinate by need for mechanical ventilation was greater in patients with a greater number of lobes involved and a higher CXR score.

CONCLUSION

Bilateral ground-glass opacities and areas of consolidation were the predominant radiological findings of influenza A (H1N1) virus pneumonia. Multifocal bilateral opacities and CXR score are strictly correlated with the severity of the illness.

Two years after pandemic influenza A/2009/H1N1: what have we learned?

The world had been anticipating another influenza pandemic since the last one in 1968. The pandemic influenza A H1N1 2009 virus (A/2009/H1N1) finally arrived, causing the first pandemic influenza of the new millennium, which has affected over 214 countries and caused over 18,449 deaths. Because of the persistent threat from the A/H5N1 virus since 1997 and the outbreak of the severe acute respiratory syndrome (SARS) coronavirus in 2003, medical and scientific communities have been more prepared in mindset and infrastructure. This preparedness has allowed for rapid and effective research on the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the disease, with impacts on its control. A PubMed search using the keywords "pandemic influenza virus H1N1 2009" yielded over 2,500 publications, which markedly exceeded the number published on previous pandemics. Only representative works with relevance to clinical microbiology and infectious diseases are reviewed in this article. A significant increase in the understanding of this virus and the disease within such a short amount of time has allowed for the timely development of diagnostic tests, treatments, and preventive measures. These findings could prove useful for future randomized controlled clinical trials and the epidemiological control of future pandemics.

[Recommendations of the Infectious Diseases Work Group (GTEI) of the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC) and the Infections in Critically Ill Patients Study Group (GEIPC) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) for the diagnosis and treatment of influenza A/H1N1 in seriously ill adults admitted to the Intensive Care Unit]

The diagnosis of influenza A/H1N1 is mainly clinical, particularly during peak or seasonal flu outbreaks. A diagnostic test should be performed in all patients with fever and flu symptoms that require hospitalization. The respiratory sample (nasal or pharyngeal exudate or deeper sample in intubated patients) should be obtained as soon as possible, with the immediate start of empirical antiviral treatment. Molecular methods based on nucleic acid amplification techniques (RT-PCR) are the gold standard for the diagnosis of influenza A/H1N1. Immunochromatographic methods have low sensitivity; a negative result therefore does not rule out active infection. Classical culture is slow and has low sensitivity. Direct immunofluorescence offers a sensitivity of 90%, but requires a sample of high quality. Indirect methods for detecting antibodies are only of epidemiological interest. Patients with A/H1N1 flu may have relative leukopenia and elevated serum levels of LDH, CPK and CRP, but none of these variables are independently associated to the prognosis. However, plasma LDH> 1500 IU/L, and the presence of thrombocytopenia <150 x 10(9)/L, could define a patient population at risk of suffering serious complications. Antiviral administration (oseltamivir) should start early (<48 h from the onset of symptoms), with a dose of 75 mg every 12h, and with a duration of at least 7 days or until clinical improvement is observed. Early antiviral administration is associated to improved survival in critically ill patients. New antiviral drugs, especially those formulated for intravenous administration, may be the best choice in future epidemics. Patients with a high suspicion of influenza A/H1N1 infection must continue with antiviral treatment, regardless of the negative results of initial tests, unless an alternative diagnosis can be established or clinical criteria suggest a low probability of influenza. In patients with influenza A/H1N1 pneumonia, empirical antibiotic therapy should be provided due to the possibility of bacterial coinfection. A beta-lactam plus a macrolide should be administered as soon as possible. The microbiological findings and clinical or laboratory test variables may decide withdrawal or not of antibiotic treatment. Pneumococcal vaccination is recommended as a preventive measure in the population at risk of suffering severe complications. Although the use of moderate- or low-dose corticosteroids has been proposed for the treatment of influenza A/H1N1 pneumonia, the existing scientific evidence is not sufficient to recommend the use of corticosteroids in these patients. The treatment of acute respiratory distress syndrome in patients with influenza A/H1N1 must be based on the use of a protective ventilatory strategy (tidal volume <10 ml / kg and plateau pressure <35 mmHg) and positive end-expiratory pressure set to high patient lung mechanics, combined with the use of prone ventilation, muscle relaxation and recruitment maneuvers. Noninvasive mechanical ventilation cannot be considered a technique of choice in patients with acute respiratory distress syndrome, though it may be useful in experienced centers and in cases of respiratory failure associated with chronic obstructive pulmonary disease exacerbation or heart failure. Extracorporeal membrane oxygenation is a rescue technique in refractory acute respiratory distress syndrome due to influenza A/H1N1 infection. The scientific evidence is weak, however, and extracorporeal membrane oxygenation is not the technique of choice. Extracorporeal membrane oxygenation will be advisable if all other options have failed to improve oxygenation. The centralization of extracorporeal membrane oxygenation in referral hospitals is recommended. Clinical findings show 50-60% survival rates in patients treated with this technique. Cardiovascular complications of influenza A/H1N1 are common. Such problems may appear due to the deterioration of pre-existing cardiomyopathy, myocarditis, ischemic heart disease and right ventricular dysfunction. Early diagnosis and adequate monitoring allow the start of effective treatment, and in severe cases help decide the use of circulatory support systems. Influenza vaccination is recommended for all patients at risk. This indication in turn could be extended to all subjects over 6 months of age, unless contraindicated. Children should receive two doses (one per month). Immunocompromised patients and the population at risk should receive one dose and another dose annually. The frequency of adverse effects of the vaccine against A/H1N1 flu is similar to that of seasonal flu. Chemoprophylaxis must always be considered a supplement to vaccination, and is indicated in people at high risk of complications, as well in healthcare personnel who have been exposed.

Cardiac manifestations in patients with pandemic (H1N1) 2009 virus infection needing intensive care

PURPOSE

To characterize the cardiac manifestations in severe pandemic (H1N1) 2009 virus [P(H1N1)2009v] infection.

MATERIALS AND METHODS

Adult patients admitted to the intensive care unit were recruited. Patients with an elevated troponin I (>1.5 ng/mL) and those requiring vasoactive agents had an echocardiogram. Myocardial injury was defined as elevated troponin I. Patients with reduced ejection fraction lower than 50% were diagnosed as having left ventricular systolic dysfunction. Myocarditis was presumed when myocardial injury was associated with global myocardial dysfunction. Myocardial injury and dysfunction were correlated with mortality and expressed as odds ratio (OR) with 95% confidence intervals (CI).

RESULTS

Thirty-seven patients presented at 6.4 (SD 3.2) days of illness. Four patients had valvular heart disease and 1 preexisting ischemic heart disease. Seventeen (46%) patients had evidence of myocardial injury. Twenty of 28 patients in whom an echocardiogram was clinically indicated had left ventricular systolic dysfunction. Of these, 14 patients were diagnosed as having myocarditis, and most of them (12 patients) developed it early. Myocarditis was associated with longer duration of vasoactive agents (OR 1.46, 95% CI 1.06-2.02) and mortality. Patients with elevated troponin I had an increased risk of death (OR 8.7, 95% CI 1.5-60). A higher mortality was observed in patients with left ventricular systolic dysfunction (OR 9.6, 95% CI 1.7-58) compared with those in whom an echocardiogram was normal or not indicated.

CONCLUSION

In our cohort of severe P(H1N1)2009v infection, myocardial injury and dysfunction was frequent and associated with high mortality.

Clinical features, complications and mortality in critically ill patients with 2009 influenza A(H1N1) in Sfax,Tunisia

PURPOSE

Africa, as the rest of the world, was touched by the 2009 pandemic influenza A(H1N1). In the literature, a few publications covering this subject emerged from this continent. We prospectively describe baseline characteristics, treatment and outcomes of consecutive critically ill patients with confirmed 2009 influenza A(H1N1) in the intensive care unit (ICU) of Sfax hospital.

METHODS

From 29 November 2009 through 21 January 2010, 32 patients with confirmed 2009 influenza A(H1N1) were admitted to our ICU. We prospectively analysed data and outcomes of these patients and compared survivors and dead patients to identify any predictors of death.

RESULTS

Patients were young (mean, 36·1 [SD], 20·7 years) and 21 (65·6%) of whom had co-morbidities. During ICU care, 29 (90·6%) patients had respiratory failure; among these, 15 (46·9%) patients required invasive ventilation with a median duration of 9 (IQR 3-12) days. In our experience, respiratory dysfunction can remain isolated but may also be associated with other dysfunctions or complications, such as, septic shock, seizures, myasthenia gravis exacerbation, Guillan-Barre syndrome, acute renal failure, nosocomial infections and biological disturbances. The nine patients (28·1%) who died had greater initial severity of illness (SAPS II and sequential organ failure assessment (SOFA) scores) but also a higher SOFA score and increasing severity of organ dysfunction during their ICU evolution.

CONCLUSION

Critical illness from the 2009 influenza A(H1N1) in Sfax occurred in young individuals and was associated with severe acute respiratory and additional organ system failure. SAPS II and SOFA scores at ICU admission, and also during evolution, constitute a good predictor of death.

2009 pandemic influenza A (H1N1) in pregnancy: a systematic review of the literature

To summarize the literature regarding 2009 H1N1 influenza A during pregnancy, we conducted a systematic literature review using a PubMed search and other strategies. Studies were included if they reported 2009 H1N1 influenza in pregnant women as original data. In all, 2153 abstracts were reviewed, and a total of 120 studies were included. Data were extracted regarding number of cases, additional risk factors for influenza-associated complications, treatment, and maternal and pregnancy outcomes. Authors were contacted to determine the extent of overlap when it was suspected. Pregnancy was associated with increased risk of hospital and intensive care unit admission and of death. Pregnant women who received delayed treatment with neuraminidase inhibitors or who had additional risk factors were more likely to develop severe disease. Preterm and emergency cesarean deliveries were frequently reported. These results reinforce the importance of early identification and treatment of suspected influenza in this high-risk population.

Influenza A(H1N1) infection and severe cardiac dysfunction in adults: A case series

BACKGROUND

While viral myocarditis and heart failure are recognized and feared complications of seasonal influenza A infection, only limited information is available for 2009 influenza A(H1N1)-induced heart failure.

METHODS AND MAIN FINDINGS

This case series summarizes the disease course of four patients with 2009 influenza A(H1N1) infection who were treated at our institution from November 2009 until September 2010. All patients presented with severe cardiac dysfunction (acute heart failure, cardiogenic shock or cardiac arrest due to ventricular fibrillation) as the leading symptom of influenza A(H1N1) infection. Two patients most likely had pre-existent cardiac pathologies, and three required catecholamine therapy to maintain hemodynamic function. Except for one patient who died before influenza A(H1N1) infection had been diagnosed, all patients received antiviral therapy with oseltamivir and supportive critical care. Acute respiratory distress syndrome due to influenza A(H1N1) infection developed in one patient. Heart function normalized in two of the three surviving patients but remained impaired in the other one at hospital discharge.

CONCLUSIONS

Influenza A(H1N1) infection may be associated with severe cardiac dysfunction which can even be the leading clinical symptom at presentation. During an influenza pandemic, a thorough history may reveal flu-like symptoms and should indicate testing for H1N1 infection also in critically ill patients with acute heart failure.

A national survey on myocarditis associated with the 2009 influenza A (H1N1) pandemic in Japan

BACKGROUND

An influenza pandemic occurred in 2009 and myocarditis associated with the 2009 influenza A (H1N1) pandemic was reported among hospitalized patients from August 2009.

METHODS AND RESULTS

The Japanese Circulation Society organized the Clinical Research Committee on Myocarditis Associated with Influenza Pandemic A (H1N1) 2009 and called for a case report on myocarditis for a national survey. The diagnosis of myocarditis was performed using the Guidelines for the Diagnosis and Treatment of Myocarditis (JCS 2009). Fifteen patients were reported to the committee. Fulminant myocarditis developed in 10 patients. Mechanical circulatory support (intra-aortic balloon pumping (IABP) and/or percutaneous cardiopulmonary support (PCPS)) was used on all 10 patients, 8 of whom were rescued. Abnormalities on echocardiography and elevated cardiac enzymes were seen in most of the patients. Myocarditis was found by endomyocardial biopsy in 6 patients. Three patients had complications with pneumonia.

CONCLUSIONS

In reality, myocarditis associated with pandemic influenza A (H1N1) seemed to be more common in hospitalized patients, compared with previous seasonal influenza virus outbreaks. To avoid misdiagnosis of acute myocarditis associated with influenza pandemic A (H1N1) 2009, it is essential to determine the characteristic symptoms, signs, and laboratory findings of acute myocarditis during influenza pandemics. Mechanical circulatory support (IABP and/or PCPS) was required to rescue patients with fulminant myocarditis.

Pathogenesis of pandemic H1N1 2009 influenza virus infection and the implication on management

The pandemic H1N1 2009 influenza virus has caused the first influenza pandemic of the 21st century, leading to disproportionate fatalities in the low-risk population despite the generally mild nature of the illness. Advances in science and technology have allowed very detailed study on the pathogenesis of this novel virus, and many have already been published in less than a year after the start of the pandemic. Information generated from cell lines, animal models, and clinical data analysis has provided us with greater understanding of the behavior of this virus and the associated host response. The new knowledge will allow us to formulate scientifically sound and evidence-based management plans.

Echocardiographic manifestations of pandemic 2009 (H1N1) influenza a virus infection

SUMMARY AIM: The prevalence of myocardial involvement in influenza infection ranges from 0% to 12% depending on the diagnostic criteria used to define myocarditis. Whether such an association holds for the novel influenza A strain, pandemic-2009-H1N1, remains unknown. The aim of this present study is to evaluate the cardiovascular manifestations of pandemic (H1N1) 2009 influenza A (pH1N1) by using standard echocardiography and tissue Doppler imaging (TDI).

METHODS

Twenty-eight young patients who had been hospitalized for at least 24 h due to an influenza-like illness and tested positive for pH1N1 by real-time polymerase chain reaction were included in the study. All patients underwent echocardiographic studies during the first 72 h of admission. Echocardiographic studies of thirty gender and age matched control subjects were performed and the results were compared.

RESULTS

Heart rate was significantly higher in patients infected with pH1N1 virus. Other clinical variables were similar between the two groups (p > 0.05). Echocardiographic variables were also similar except left ventricular end-systolic dimension, which was significantly increased in the patient group (P = 0.042). Left ventricular tissue Doppler assessment at mitral annulus showed that mean systolic velocities of pH1N1 infected patients and control group were statistically similar. However, early diastolic velocity was decreased and late diastolic velocity was increased in the patient group. Therefore early diastolic/late diastolic velocity ratio was significantly decreased in pH1N1 infected patients. Also, isovolumetric contraction time and isovolumetric relaxation time were prolonged and ejection time was significantly shortened in pH1N1 infected patients. As a result, global myocardial performance index was significantly higher in pH1N1 infected patients (p < 0.001). Right ventricular tissue Doppler assessment at tricuspid annulus showed similar results with the left ventricular measurements.

CONCLUSION

The results of the study suggest an association between hospitalized pH1N1 and subclinical cardiac dysfunction as measured by tissue Doppler echocardiography.