Failure of intravenous metoprolol to limit acute myocardial infarct size in a nonreperfused porcine model.
The usefulness of intravenous beta-adrenergic receptor blockade in limiting infarct size when neither reperfusion nor collateral flow occurs is unknown. The effect of intravenous metoprolol on limiting myocardial infarct size was therefore examined in a nonreperfused porcine model. Closed-chest techniques were used to occlude the left anterior descending coronary artery, after which animals were randomized at 20 minutes to receive intravenous metoprolol, 0.75 mg/kg, or placebo. Infarct size examined at 5 hours with Evans blue and triphenyltetrazolium staining techniques was expressed as a percentage of total ventricular myocardium at ischemic risk. This percentage was not significantly different between the groups (84% +/- 5% with metoprolol vs 90% +/- 4% with placebo; p = 0.4). Myocardial infarct size was not significantly decreased at 5 hours by early administration of intravenous metoprolol when the infarct artery remained occluded and collateral flow was minimal.
Kern
K B
KB
Department of Medicine, University of Arizona College of Medicine, Tucson.
Hilwig
R W
RW
Warner
A
A
Basnight
M
M
Ewy
G A
GA
D000818:Animals; D003331:Coronary Vessels / Q000503:physiopathology; D004562:Electrocardiography; D006439:Hemodynamics / Q000502:physiology; D007262:Infusions, Intravenous; D008790:Metoprolol / Q000008:administration & dosage / Q000627:therapeutic use*; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology; D013552:Swine; D013997:Time Factors; D017211:Treatment Failure
D008790:Metoprolol