title: Early angiotensin converting enzyme inhibitor therapy enhances the benefits of late coronary artery reperfusion on infarct expansion.
abstract: BACKGROUND
  Individually, both late reperfusion and early angiotensin converting enzyme (ACE) inhibitor treatment prevent infarct expansion after acute myocardial infarction.
  
  
  OBJECTIVE
  To examine the effect and mechanism of early post-myocardial infarction ACE inhibitor treatment, when used in combination with late coronary artery reperfusion, on infarct expansion.
  
  
  METHODS
  Sprague-Dawley rats underwent 8 h of coronary occlusion followed by permanent reperfusion. The treatment group received enalapril, started 1 h after coronary occlusion and continued for 13 days. A control group received placebo. Two weeks after acute myocardial infarction, hemodynamic, morphometric and histologic analyses were performed.
  
  
  RESULTS
  Hemodynamic parameters were similar in both groups (P = NS). Infarct size was similar in the ACE inhibitor and placebo treatment groups (44 +/- 4% compared with 39 +/- 4%, P = NS). Septal thickness was also similar in the two groups (2.8 +/- 0.3 mm compared with 2.7 +/- 0.3 mm, P = NS). The ACE inhibitor-treated group had thicker infarcts than those in the placebo-treated group (0.93 +/- 0.07 mm compared with 0.76 +/- 0.04 mm, P < 0.05) and these infarcts were less expanded (expansion index 1.17 +/- 0.12 compared with 1.57 +/- 0.12, P < 0.05). ACE inhibitor treatment was associated with hypertrophy of viable myocytes within the scar compared with placebo treatment (cell diameter 11.1 +/- 0.5 microns compared with 8.9 +/- 0.4 microns, P < 0.01).
  
  
  CONCLUSIONS
  Early post-myocardial infarction ACE inhibitor treatment enhances the benefits of late coronary reperfusion on infarct expansion. The benefits may be related to hypertrophy of still-viable myocytes within the infarcted zone.
authors.affiliation: Department of Medicine, Bronx-Lebanon Hospital Center, Bronx, NY 10457, USA. alhaddad@pol.net
authors.forename: I A
authors.initials: IA
authors.lastname: Alhaddad
authors.forename: P
authors.initials: P
authors.lastname: Sahgal
authors.forename: R
authors.initials: R
authors.lastname: Mir
authors.forename: E J
authors.initials: EJ
authors.lastname: Brown
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D004195:Disease Models, Animal; D004656:Enalapril / Q000494:pharmacology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D009203:Myocardial Infarction / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy*; D015425:Myocardial Reperfusion / Q000379:methods*; D009206:Myocardium / Q000473:pathology; D009336:Necrosis; D011336:Probability; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D004656:Enalapril