Effects of propranolol, atenolol, and chlordesmethyldiazepam on response to mental stress in patients with recent myocardial infarction.

Stress testing was carried out by two stressors, mental arithmetic and Sacks-Levy's test in randomized sequence, in 64 male patients with a mean age of 51 +/- 7 years in NYHA Classes I or II within 3 months after acute myocardial infarction. The stress profile was obtained after drug withdrawal by continuous recording of electrocardiogram, frontal electromyogram, and peripheral skin temperature and conductance. Blood pressure was measured each minute by cuff. The patients were subdivided into 4 groups of 16 each and were studied in an identical fashion after a 48-h oral treatment with propranolol 120 mg daily, atenolol 100 mg daily, chlordesmethyldiazepam 2 mg daily, or placebo. During stress, signs of myocardial ischemia or pump failure were not observed; minor arrhythmias were recorded. Cardiovascular activation was observed with significant increments (p less than 0.001) in heart rate, systolic and diastolic blood pressures in all 4 groups for both stressors with a slightly greater effect of mental arithmetic; Sacks' test was more effective on the frontal electromyograph response. Following beta blockade the stress profile of heart rate was significantly lower and flattened. The stress profile of blood pressure was also lower, but the reduction in the increment during stress was not significant. No differences were observed in the effects of the two beta blockers; no significant changes were evident in the stress profile of the noncardiovascular psychophysiologic indexes. Stress profiles were not altered by the benzodiazepine. In conclusion beta-blocker agents seem to be more useful than anxiolytic drugs in preventing cardiovascular activation induced by mental stress in patients with recent myocardial infarction.