title: Myocardial protection with prophylactic oral metoprolol during coronary artery bypass grafting surgery: evaluation by troponin I.
abstract: BACKGROUND
  Biochemical markers of myocardial injury are frequently altered after cardiac surgery. So far there is no evidence whether oral beta-blockers may reduce myocardial injury after coronary artery bypass grafting.
  
  
  OBJECTIVE
  To determine if oral administration of prophylactic metoprolol reduces the release of cardiac troponin I in isolated coronary artery bypass grafting, not complicated by new Q waves.
  
  
  METHODS
  A prospective randomized study, including 68 patients, divided in 2 groups: Group A (n=33, control) and B (n=35, beta-blockers). In group B, metoprolol tartrate was administered 200 mg/day. The myocardial injury was assessed by troponin I with 1 hour and 12 hours after coronary artery bypass grafting.
  
  
  RESULTS
  No significant difference between groups regarding pre-surgical, surgical, complication in intensive care (15% versus 14%, P=0.92) and the total number of hospital events (21% versus 14%, P=0.45) was observed. The median value of troponin I with 12 hours in the study population was 3.3 ng/ml and was lower in group B than in group A (2.5 ng/ml versus 3.7 ng/ml, P<0,05). In the multivariate analysis, the variables that have shown to be independent predictors of troponin I release after 12 hours were: no beta-blockers administration and number of vessels treated.
  
  
  CONCLUSIONS
  The results of this study in uncomplicated coronary artery bypass grafting, comparing the postoperative release of troponin I at 12 hours between the control group and who used oral prophylactic metoprolol for at least 72 hours, allow to conclude that there was less myocardial injury in the betablocker group, giving some degree of myocardial protection.
authors.forename: João Manoel
authors.initials: JM
authors.lastname: Rossi Neto
authors.forename: Carlos
authors.initials: C
authors.lastname: Gun
authors.forename: Rui Fernando
authors.initials: RF
authors.lastname: Ramos
authors.forename: Antonio Flavio Sanchez de
authors.initials: AF
authors.lastname: Almeida
authors.forename: Mario
authors.initials: M
authors.lastname: Issa
authors.forename: Vivian Lener
authors.initials: VL
authors.lastname: Amato
authors.forename: Jarbas J
authors.initials: JJ
authors.lastname: Dinkhuysen
authors.forename: Leopoldo Soares
authors.initials: LS
authors.lastname: Piegas
mesh_terms: D000284:Administration, Oral; D058671:Adrenergic beta-1 Receptor Antagonists / Q000008:administration & dosage*; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002316:Cardiotonic Agents / Q000008:administration & dosage*; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006321:Heart / Q000187:drug effects*; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage*; D008875:Middle Aged; D011184:Postoperative Period; D011379:Prognosis; D011446:Prospective Studies; D012016:Reference Values; D013997:Time Factors; D016896:Treatment Outcome; D019210:Troponin I / Q000097:blood*
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D015415:Biomarkers; D002316:Cardiotonic Agents; D019210:Troponin I; D008790:Metoprolol