title: The prevalence of myocarditis and skeletal muscle injury during acute viral infection in adults: measurement of cardiac troponins I and T in 152 patients with acute influenza infection.
abstract: BACKGROUND
  Current literature suggests that myocarditis is a common event during influenza infection, occurring with a prevalence rate of up to 10%, but these studies have relied on relatively nonspecific techniques of varying sensitivities for the detection of myocyte injury. Using measurement of cardiac troponins I and T, this study sought to determine the prevalence of myocarditis in a large unselected cohort of patients with serologically confirmed acute influenza infection.
  
  
  METHODS
  A total of 152 subjects were recruited from 60 primary care and university health centers. Serial creatine kinase (CK), CK-MB, and cardiac troponin I and T measurements were taken on days 1, 6, and 21 following presentation.
  
  
  RESULTS
  Creatine kinase levels were elevated (mean +/- SD levels, 830 +/- 1531 U/L; range, 181-7280 U/L) during the collection period in 18 patients (12%). Twelve (67%) of these had elevated CK levels on day 1 of presentation. Overall CK-MB levels were higher than 25 U/L in 3 patients with elevated CK readings but in no patient was the CK-MB fraction greater than 6%. Cardiac troponin I and T levels were not raised in any of the patients.
  
  
  CONCLUSIONS
  Using more sensitive and specific markers of myocardial injury, we demonstrate that the prevalence of myocarditis during acute influenza infection is substantially lower than previously thought, whereas skeletal muscle injury is relatively common. Although we were unable to conclude that no myocardial inflammation was present, it seems likely that this complication is rare.
authors.affiliation: Cardiology Department, Northwick Park Hospital, Watford Road, Harrow, Middlesex HA1 3UJ, England. kimickc@yahoo.co.uk
authors.forename: Kim
authors.initials: K
authors.lastname: Greaves
authors.forename: John S
authors.initials: JS
authors.lastname: Oxford
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Price
authors.forename: Geraldine H
authors.initials: GH
authors.lastname: Clarke
authors.forename: Tom
authors.initials: T
authors.lastname: Crake
mesh_terms: D000328:Adult; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000097:blood / Q000150:complications*; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D018482:Muscle, Skeletal / Q000473:pathology*; D009205:Myocarditis / Q000097:blood / Q000209:etiology*; D016032:Randomized Controlled Trials as Topic; D019209:Troponin C / Q000097:blood*; D019210:Troponin I / Q000097:blood*
chemical_list: D019209:Troponin C; D019210:Troponin I; D003402:Creatine Kinase