[Evaluation by exercise test of effects of a single oral dose of atenolol in patients with stable angina (author's transl)].
Academic Article
Overview
abstract
Thirty patients with stable angina have been undergone a multistage treadmill test, after a single oral dose of 100 mg of Atenolol, a beta 1 . selective blocking agent, in comparison to a previous test carried out after an identical looking placebo tablet. After placebo all the patients showed ischemic ST segment response (ST depression greater than 1 mm), 25 of them interrupting the test because of anginal pain (20 patients), or of ST depression greater than 3 mm (3 patients), or of ventricular ectopics (one patient), or of fatigue (one patient). After Atenolol 10 patients completed the planned test, 7 of them without ischemic changes of ST. 27 patients (90%) showed increased working capacity with significant reduction of heart-rate (FC), systolic blood pressure (PAS) and their product and of ST depression, either before and during and at the end of exercise. The recovery time of ischemic ECG change has been significantly reduced. The observed increased working capacity is attributed to the reduced myocardial O2 consumption expressed from the reduction of the product FC x PAS. Nevertheless at the end of exercise test after beta-blocking drug this product didn't reach the threshold value at which the test was interrupted in the first test after placebo. The authors discuss the possible cause of this effect of beta-blocking drugs, which could be attributed to a reduction of coronary blood flow and/or to an increased myocardial tension because of increased end diastolic ventricular volume. However the Authors outline that the per cent increases of FC, PAS, and FC x PAS have not been reduced by the Atenolol, unlike their absolute values, at the threshold of angina: the ischemic reveals itself at same levels of per cent increase of the factors of O2 myocardial consumption, the later reaching of threshold values depending on the lower starting values. The advantages of Atenolol as regards the other beta-blocking drugs (better acceptability, stability and duration of action) are outlined too.
