Effect of intravenous metoprolol or intravenous metoprolol plus glucagon on dobutamine-induced myocardial ischemia.
OBJECTIVE
To determine the effect of metoprolol on dobutamine stress testing with technetium-99m sestamibi single-photon emission computed tomography imaging and ST-segment monitoring, and to assess the impact of intravenous glucagon on metoprolol's effects.


METHODS
Randomized, double-blind, placebo-controlled trial.


METHODS
Community hospital.


METHODS
Twenty-two patients with known reversible perfusion defects.


METHODS
Patients underwent dobutamine stress tests per standard protocol. Before dobutamine was begun, no therapy was given during the first visit, and patients were randomized on subsequent visits to receive metoprolol or metoprolol plus glucagon 1 mg. Metoprolol was dosed to achieve a resting predobutamine heart rate below 65 beats/minute or a total intravenous dose of 20 mg.


RESULTS
Metoprolol reduced maximum heart rate 31%, summed stress scores 29%, and summed difference scores 43% versus control. Metoprolol plus glucagon also reduced the maximum heart rate 29% versus control. Summed stress and summed difference scores were not significantly reduced, although they were 18% and 30% lower, respectively, than control. No significant differences were found in any parameter between metoprolol and metoprolol-glucagon.


CONCLUSIONS
During dobutamine stress testing, metoprolol attenuates or eliminates evidence of myocardial ischemia. Glucagon 1 mg, although somewhat effective, does not correct this effect to the extent that it can be administered clinically.
Murthy
D R
DR
Division of Cardiology, Hartford Hospital, Connecticut, USA.
White
C M
CM
Katten
D
D
Ahlberg
A W
AW
Salloum
A
A
Heller
G V
GV
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000704:Analysis of Variance; D004280:Dobutamine / Q000494:pharmacology*; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D005080:Exercise Test / Q000187:drug effects*; D005260:Female; D005934:Glucagon / Q000008:administration & dosage / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000188:drug therapy*; D011500:Protein Synthesis Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D015899:Tomography, Emission-Computed, Single-Photon
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011500:Protein Synthesis Inhibitors; D004280:Dobutamine; D005934:Glucagon; D008790:Metoprolol