title: Analysis of troponin I levels after spontaneous implantable cardioverter defibrillator shocks.
abstract: BACKGROUND
  Serum cardiac troponin I (cTnI) is a sensitive and specific marker for myocardial injury. Myocardial ischemia and/or injury can be a trigger for ventricular arrhythmias. The aim of this study was to assess the frequency and significance of elevated serum cTnI levels after spontaneous implantable cardioverter defibrillator (ICD) shocks.
  
  
  RESULTS
  Serial cTnI measurements and ECGs were performed in 35 patients with transvenous ICDs who were admitted after spontaneous ICD shocks. Elevated cTnI levels were found in 18 patients (51%). Acute coronary syndrome was diagnosed in 5 (22%) of 23 patients with known coronary artery disease. After excluding the patients with acute coronary syndrome, elevated cTnI levels were present in 13 (43%) of 30 patients: 18% of patients with < or =3 shocks and 58% of patients with >3 shocks. Patients with elevated cTnI levels received a higher number of shocks (16+/-18 vs 5+/-7; P < 0.05) and had higher total delivered energies (475+/-538 J vs 128+/-184 J; P < 0.05) compared with patients with normal cTnI. Patients with acute coronary syndrome had higher peak cTnI levels (18+/-16 ng/mL) compared with patients with elevated cTnI without acute coronary syndrome (3.8+/-4.3 ng/mL; P < 0.01).
  
  
  CONCLUSIONS
  Serum cTnI rises occur in the majority of patients after multiple (>3) spontaneous ICD discharges but are due to acute coronary syndrome only 14% of the time (22% of the time in patients with known coronary artery disease).
authors.affiliation: Cardiac Arrhythmia Research Institute and Cardiovascular Section, The University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA.
authors.forename: Can
authors.initials: C
authors.lastname: Hasdemir
authors.forename: Nayyar
authors.initials: N
authors.lastname: Shah
authors.forename: Arun P
authors.initials: AP
authors.lastname: Rao
authors.forename: Helbert
authors.initials: H
authors.lastname: Acosta
authors.forename: Kagari
authors.initials: K
authors.lastname: Matsudaira
authors.forename: Barbara R
authors.initials: BR
authors.lastname: Neas
authors.forename: Dwight W
authors.initials: DW
authors.lastname: Reynolds
authors.forename: Sunny
authors.initials: S
authors.lastname: Po
authors.forename: Ralph
authors.initials: R
authors.lastname: Lazzara
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Beckman
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000097:blood* / Q000628:therapy; D003402:Creatine Kinase / Q000097:blood; D052279:Creatine Kinase, MB Form; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009206:Myocardium / Q000378:metabolism*; D012189:Retrospective Studies; D019210:Troponin I / Q000097:blood*
chemical_list: D007527:Isoenzymes; D019210:Troponin I; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form