Background: In March 2009, the novel 2009 influenza A (H1N1) was first reported in the southwest of Mexico, and rapidly spread worldwide. We investigated the clinical features of cardiovascular involvement of patients infected with the 2009 influenza A (H1N1) virus in China.
Methods: This retrospective study recruited one hundred and seventy-two patients with 2009 influenza A (H1N1) of different severity (non-severe, severe, critically severe) and 21 patients who were influenza A (H1N1)-negative but who had an influenza-like illness. Blood was obtained for measurement of the concentration of creatine kinase (CK), creatine kinase-MB (CK-MB) and high sensitivity C-reactive protein (hs-CRP) in plasma. Chest radiography was also undertaken to calculate the cardiothoracic ratio (CTR).
Results: influenza A (H1N1) caused more illness in middle-aged people. The patients in the non-severe group were younger than in the severe group (P < 0.05) and the non-influenza A (H1N1) group (P < 0.01). The level of CK, CK-MB, hs-CRP and the CTR was higher in the critically severe group than in the other three groups (P < 0.001, P < 0.05, P < 0.01, P < 0.01, respectively).
Conclusions: Myocardial injury was quite serious in severe infection by the influenza A (H1N1) virus, particularly in critically severe patients. Patients with 2009 influenza A (H1N1) had injury and dilation of the heart, which may be a potential cause of death.