Effect of metoprolol on "non-specific" ST-segment and T-wave changes

Metoprolol, a cardio-selective beta-adrenergic blocking agent, was studied in 25 patients to assess its effect on "non-specific" ST-segment and T-wave changes both at rest and during exercise. In two thirds of the patients with ST-T-abnormalities at rest, the changes disappeared completely after beta-blockade but reappeared during exercise in some of them. Only in 9 patients were the changes eliminated also during exercise implying that they were "functional", i.e., caused by increased sympathetic discharge. In those patients, where the ST-T-abnormalities were not affected at all by the beta-blockade, they were probably due to organic heart disease, whereas when they were reduced but not completely abolished, increased sympathetic tone as well as organic heart disease might be the cause. It is inferred that the diagnostic information is increased by studying the effect of beta-blockade not only at rest but also during exercise. Metoprolol seems to be well suited for the evaluation of "non-specific" ST-T-abnormalities, especially when non-selective beta-blockers should be avoided, e.g. in obstructive lung disease.