Cardiac findings during uncomplicated acute influenza in ambulatory adults

Fulminant myocarditis associated with novel H1N1 influenza A

Myocarditis secondary to H1N1 influenza has been described in children, but only very rarely in adults. We describe a 36-year-old man with no significant medical history who presented with flu-like symptoms of 3-week duration. When he sought medical attention, he was already manifesting heart failure secondary to fulminant myocarditis, along with multiorgan failure. Despite aggressive management, including circulatory support with a catheter-based mechanical cardiac assist device (Impella 2.5 Cardiac Assist Device, Abiomed, Danvers, MA) as a bridge to cardiac transplant, and aggressive antiviral and antibacterial therapy, the patient died of cardiac arrest. An H1N1 polymerase chain reaction postmortem assay produced positive results, and a diagnosis of fulminant viral myocarditis and multiorgan system failure was established.

H1N1 influenza A virus induced atrioventricular block

We report a case of an 18-year-old female who presented with respiratory failure secondary to H1N1 infection, and who subsequently developed high-degree atrioventricular (AV) block. The conduction abnormalities persisted over 2 weeks following complete resolution of respiratory symptoms. A permanent pacemaker was implanted for safety and subsequent pacemaker follow-up suggested reversibility of the conduction abnormality. This case highlights the potential impact of the H1N1 influenza virus on the cardiac conduction system.

Successful management of fulminant influenza A subtype H1N1 myocarditis

The outbreak and spread of the new influenza A subtype H1N1 reached pandemic levels during 2009, with greater numbers of cases reported daily and numerous complications described. The present report concerns an atypical manifestation of the disease in a previously healthy middle-aged patient who presented with severe, refractory cardiogenic shock 4 days after being diagnosed as having influenza A. The patient was considered for emergency heart transplant. Successful treatment involved the use of a left ventricular assist device, extracorporeal membrane oxygenation, intravenous immunoglobulin and peramivir as therapeutics and bridging therapies for transplant. This case is a report of H1N1 fulminant myocarditis and illustrates the usefulness of a multidisciplinary approach in the care of these patients.

Right and left heart failure in severe H1N1 influenza A infection

Influenza infection can affect cardiac function. The recent pandemic of H1N1 influenza A provided an opportunity to study echocardiographic findings in critically ill infected patients. We hypothesised that critically ill patients with H1N1 infection would have a higher incidence of right and left heart failure than is seen in unselected populations of patients with septic shock and/or acute respiratory distress syndrome (ARDS). We retrospectively studied all patients admitted to four intensive care units at three hospitals in Salt Lake County, UT, USA, with laboratory-confirmed H1N1 infection in whom a clinical echocardiogram was available. 23 out of 48 patients had qualifying echocardiograms. Right ventricular (RV) dilatation (50-80%) and at least moderate systolic impairment (23%) were common, higher than the range described in general populations with ARDS. Left ventricular systolic dysfunction was present in 17% of patients. No single echocardiographic parameter was associated with 28-day mortality or ventilator-free days to 28 days. Critically ill patients with H1N1 infection frequently exhibit right heart dilatation and failure. RV basal dilatation was extremely common. These patients have less left heart failure than expected on the basis of prior descriptions of influenza myopericarditis or of general populations of septic patients.

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.

Complications of seasonal and pandemic influenza

Influenza is a seasonal viral infection associated with significant morbidity and mortality. In 2009, a novel H1N1 influenza A virus emerged and has been classified as a pandemic. In contrast to seasonal influenza, severe disease from pandemic H1N1 seems concentrated in older children and young adults, with almost no cases reported in patients older than 60 yrs. Although patients with underlying cardiopulmonary disease remain at risk, most complications have occurred among previously healthy individuals, with obesity and respiratory disease as the strongest risk factors. Pulmonary complications are common. Primary influenza pneumonia occurs most commonly in adults and may progress rapidly to acute lung injury requiring mechanical ventilation. Secondary bacterial infection is more common in children. Staphylococcus aureus, including methicillin-resistant strains, is an important cause of secondary bacterial pneumonia with a high mortality rate. Treatment of pneumonia should include empirical coverage for this pathogen. Neuromuscular and cardiac complications are unusual but may occur.

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.

More than half of the patients with acute Puumala hantavirus infection have abnormal cardiac findings

This study was conducted to determine the frequency, severity and outcome of cardiac findings in patients with acute Puumala hantavirus-induced nephropathia epidemica (NE). 70 consecutive, hospital-treated patients with serologically confirmed NE were prospectively examined using serial electrocardiograms (ECG), plasma troponin I, tumour necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and echocardiography (ECHO). Examinations were repeated after 3 and 12 months. ECG changes were observed in 57% of patients. Plasma troponin I levels remained normal in all. In six patients, ECHO showed left ventricular contraction abnormalities, and 1 patient had mild pericardial effusion. There were no differences in clinical or standard laboratory findings or in plasma TNF-alpha and IL-6 concentrations between patients with and without ECG or ECHO changes. During the follow-up, all acute-phase changes in ECG and ECHO reverted to normal, which probably reflects their benign nature. We conclude that abnormal cardiac findings are surprisingly common during NE.

Cardiovascular manifestations associated with influenza virus infection

Influenza accounts for 3 to 5 million cases of severe illness and up to 300,000 deaths annually. Cardiovascular involvement in acute influenza infection can occur through direct effects of the virus on the myocardium or through exacerbation of existing cardiovascular disease. Epidemiological studies have demonstrated an association between influenza epidemics and cardiovascular mortality and a decrease in cardiovascular mortality in high risk patients has been demonstrated following vaccination with influenza vaccine. Influenza is a recognised cause of myocarditis which can lead to significant impairment of cardiac function and mortality. With recent concerns regarding another potential global pandemic of influenza the huge potential for cardiovascular morbidity and mortality is discussed.

Complications of viral influenza

Viral influenza is a seasonal infection associated with significant morbidity and mortality. In the United States more than 35,000 deaths and 200,000 hospitalizations due to influenza occur annually, and the number is increasing. Children aged less than 1 year and adults aged more than 65 years, pregnant woman, and people of any age with comorbid illnesses are at highest risk. Annual vaccination is the cornerstone of prevention, but some older patients may derive less benefit from immunization than otherwise fit individuals. If started promptly, antiviral medications may reduce complications of acute influenza, but increasing resistance to amantadine and perhaps neuraminidase inhibitors underscores the need for novel prevention and treatment strategies. Pulmonary complications of influenza are most common and include primary influenza and secondary bacterial infection. Either may cause pneumonia, and each has a unique clinical presentation and pathologic basis. Staphylococcus aureus, including methicillin-resistant strains, is an important cause of secondary bacterial pneumonia with high mortality. During influenza season, treatment of pneumonia should include empiric coverage for this pathogen. Neuromuscular and cardiac complications are unusual but may manifest in persons of any age.

Efficacy and Tolerability of the Oral Neuraminidase Inhibitor Peramivir in Experimental Human Influenza: Randomized, Controlled Trials for Prophylaxis and Treatment

Objective

Oseltamivir is the only oral neuraminidase inhibitor currently available; we determined the tolerability and antiviral efficacy of oral peramivir for treatment and prophylaxis of experimental human influenza A and B.

Participants

288 susceptible, healthy volunteers (ages 18–45) were inoculated intranasally with A/Texas/36/ 91/H1N1 or B/Yamagata/16/88 virus in four randomized, double-blind, placebo-controlled trials. Interventions: For treatment dosing was initiated at 24 h after inoculation with peramivir doses ranging from 100–800 mg/day for 5 days. For prophylaxis dosing was initiated 24 h before inoculation and continued for 4 days with peramivir doses ranging from 50–800 mg/day.

Outcomes

The primary outcome measure for treatment was quantitative viral detection defined by the area under the curve (AUC) for nasal wash viral titres. For prophylaxis the primary outcome measure was the incidence of virus recovery.

Results

In influenza A treatment, peramivir 400 mg q24h and 200mg q12h, but not lower doses, resulted in significant reductions in viral titre AUC. In influenza B treatment, both 400 and 800/400 mg once daily dose groups reduced AUC values. In influenza A prophylaxis, the percentage of individuals with nasal viral shedding did not differ significantly in the placebo (58%), 50 mg (61%), 200 mg (37%) and 400 mg (31%) dose groups. In influenza B prophylaxis, shedding frequencies were similar in placebo (55%), 200 mg (41%), 400 mg (35%) and 800 mg (47%) dose groups. The drug was well tolerated in all four studies, with nausea and headache being the most common side effects. No drug-resistant variants were detected.

Conclusion

Early treatment with peramivir was associated with significant antiviral effects in experimentally induced influenza in humans. Prophylaxis did not significantly reduce viral shedding. The relatively low blood peramivir concentrations observed may explain the lack of more robust antiviral effects, and parenteral dosing should be studied.