title: Cardiac complications associated with the influenza viruses A subtype H7N9 or pandemic H1N1 in critically ill patients under intensive care.
abstract: OBJECTIVE
  The clinical presentations and disease courses of patients hospitalized with either influenza A virus subtype H7N9 (H7N9) or 2009 pandemic H1N1 influenza virus were compared in a recent report, but associated cardiac complications remain unclear. The present retrospective study investigated whether cardiac complications in critically ill patients with H7N9 infections differed from those infected with the pandemic H1N1 influenza virus strain.
  
  
  METHODS
  Suspect cases were confirmed by reverse transcription polymerase chain reaction assays with specific confirmation of the pandemic H1N1 strain at the Centers for Disease Control and Prevention. Comparisons were conducted at the individual-level data of critically ill patients hospitalized with H7N9 (n=24) or pandemic H1N1 influenza virus (n=22) infections in Suzhou, China. Changes in cardiac biochemical markers, echocardiography, and electrocardiography during hospitalization in the intensive care unit were considered signs of cardiac complications.
  
  
  RESULTS
  The following findings were more common among the H7N9 group relative to the pandemic H1N1 influenza virus group: greater tricuspid regurgitation pressure gradient, sinus tachycardia (heartbeat≥130bpm), ST segment depression, right ventricular dysfunction, and elevated cardiac biochemical markers. Pericardial effusion was more often found among pandemic H1N1 influenza virus patients than in the H7N9 group. In both groups, most of the cardiac complications were detected from day 6 to 14 after the onset of influenza symptoms. Those who developed cardiac complications were especially vulnerable during the first four days after initiation of mechanical ventilation. Cardiac complications were reversible in the vast majority of discharged H7N9 patients.
  
  
  CONCLUSIONS
  Critically ill hospitalized H7N9 patients experienced a higher rate of cardiac complications than did patients with 2009 pandemic H1N1 influenza virus infections, with the exception of pericardial effusion. This study may help in the prevention, identification, and treatment of influenza-induced cardiac complications in both pandemic H1N1 influenza virus and H7N9 infections.
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Wang
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Xu
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Xinjing
authors.initials: X
authors.lastname: Yang
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Daguo
authors.initials: D
authors.lastname: Zhao
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Shenglan
authors.initials: S
authors.lastname: Liu
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Sun
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China.
authors.forename: Jian-An
authors.initials: JA
authors.lastname: Huang
authors.affiliation: The First Affiliated Hospital of Soochow University, Department of Medicine, Respiratory, Emergency and Critical Care Medicine, Suzhou, China. Electronic address: ggqq1018@hotmail.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Guo
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D016638:Critical Illness; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006331:Heart Diseases / Q000401:mortality / Q000821:virology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D064766:Influenza A Virus, H7N9 Subtype; D007251:Influenza, Human / Q000150:complications* / Q000401:mortality; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010343:Patient Admission; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D015415:Biomarkers
keywords: Cardiac complications; H1N1; H7N9