title: Rate and patient features associated with recurrence of acute myocarditis.
abstract: BACKGROUND
  Rate and patient features associated with recurrence after acute myocarditis are largely unknown.
  
  
  RESULTS
  First recurrence of acute myocarditis was studied in 1662 patients aged 16-70 years using a registry data of 29 hospitals in Finland (median follow-up 4.5 years). Matched intoxication patients served as controls. Incidence rate of first time hospitalization due to acute myocarditis was 5.52 (CI 5.26-5.79) per 100,000 person-years during 2001-2008. During the first 30 days 5.5% (CI 3.5-4.4%) of patients were re-admitted to hospital with acute myocarditis (p<0.0001 vs. controls). After 30 days, recurrence rate was 7.0% (CI 5.7-8.6%; p<0.0001 vs. controls). Acute myocarditis recurred after 365 days in 4.7% (CI 3.2-6.7%) of patients (p<0.0001 vs. controls). During the whole follow-up, recurrence rate was 10.3% (CI 8.8-12.1%; p<0.0001 vs. controls) with median recurrence time of 34.5 days. Prolonged (>7 days) initial admission was associated with recurrences during (HR 2.9; CI 1.6-5.2) and after first month (HR 1.8; CI 1.2-3.2), and overall (HR 2.0; CI 1.3-3.2). Ventricular arrhythmia at initial occurrence was associated with recurrence after 30 days (HR 8.6; CI 2.5-30.1), after 1 year (HR 22.6; CI 2.5-201.4) and overall (HR 6.7; CI 2.3-6.7). Other features associated with recurrence were younger age (>365 days), inflammatory bowel disease (during first month), and chronic pulmonary disease (≥ 30 days).
  
  
  CONCLUSIONS
  Acute myocarditis reoccurs in a significant proportion of patients. Prolonged initial admission, ventricular arrhythmias, younger age, inflammatory bowel disease and chronic pulmonary disease are associated with recurrences at different phases after acute myocarditis.
authors.affiliation: Heart Center, Turku University Hospital, Turku, Finland; PET Center, University of Turku, Turku, Finland; Medicine, University of Turku, Turku, Finland. Electronic address: ville.kyto@utu.fi.
authors.forename: Ville
authors.initials: V
authors.lastname: Kytö
authors.affiliation: Clinical Neurosciences, Neurology, Turku University Hospital, Turku, Finland; Neurology, University of Turku, Turku, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Sipilä
authors.affiliation: Clinical Research Center, Turku University Hospital, Turku, Finland; Public Health, University of Turku, Turku, Finland.
authors.forename: Päivi
authors.initials: P
authors.lastname: Rautava
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000453:epidemiology*; D053840:Brugada Syndrome; D000075224:Cardiac Conduction System Disease; D015897:Comorbidity; D005260:Female; D005387:Finland / Q000453:epidemiology; D006329:Heart Conduction System / Q000002:abnormalities*; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology; D007902:Length of Stay / Q000706:statistics & numerical data*; D008171:Lung Diseases / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009205:Myocarditis / Q000453:epidemiology*; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: Epidemiology; Myocardial disease; Myocarditis; Recurrence