Transient cardiac injury during H7N9 infection

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.

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.

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.

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