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.