title: Effect of beta-blockade on low heart rate-related ischemia during mental stress.
abstract: To explore the effect of beta-adrenergic blockade on low heart rate-related (mental stress) ischemia, 19 patients with coronary artery disease were randomized into a double-blind crossover trial of metoprolol, 100 mg twice daily, and underwent serial mental stress/bicycle exercise studies. Mental stress-induced wall motion abnormalities occurred at a lower heart rate than exercise-induced wall motion abnormalities during placebo administration (81 +/- 16 vs. 123 +/- 20 beats/min, p less than 0.05). Metoprolol reduced the mean magnitude of exercise-induced wall motion abnormalities (2.8 +/- 2.0 vs. 1.6 +/- 2.4, p = 0.003); improvement was related to the magnitude of hemodynamic beta-blockade effect. Metoprolol did not significantly reduce the mean magnitude of mental stress-induced wall motion abnormalities (3.0 +/- 2.2 vs. 2.6 +/- 2.2), although individual responses predominantly either improved (50%) or worsened (29%). Unlike exercise, the magnitude of hemodynamic beta-blockade did not predict mental stress response and metoprolol did not block mental stress-induced blood pressure elevations. Patients with abolition of exercise-induced ischemia were more likely to have reduction of mental stress-induced ischemia. Patients whose ischemia worsened with metoprolol during mental stress had more easily inducible ischemia, as assessed by exercise-induced placebo wall motion abnormality, chest pain and prior myocardial infarction. Beta-blockade was associated with a lowering of ischemia-related hemodynamic thresholds compared with placebo. These results suggest that beta-blockade has a variable effect on low heart rate-related ischemia that may be due to a lack of effect on mental stress-induced blood pressure elevation in patients with easily induced ischemia or to effects on coronary vasomotor tone, or both.
authors.affiliation: Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048.
authors.forename: C N
authors.initials: CN
authors.lastname: Bairey
authors.forename: D S
authors.initials: DS
authors.lastname: Krantz
authors.forename: V
authors.initials: V
authors.lastname: DeQuattro
authors.forename: D S
authors.initials: DS
authors.lastname: Berman
authors.forename: A
authors.initials: A
authors.lastname: Rozanski
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000368:Aged; D003327:Coronary Disease / Q000209:etiology* / Q000503:physiopathology; D004056:Differential Threshold; D015444:Exercise; D005260:Female; D006185:Habituation, Psychophysiologic; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D008875:Middle Aged; D013315:Stress, Psychological / Q000150:complications*
chemical_list: D000319:Adrenergic beta-Antagonists; D008790:Metoprolol