EFFECT OF PROPRANOLOL ON AEROBIC-HEMODYNAMIC SUPPORT OF PHYSICAL ACTIVITY IN PATIENTS WITH EFFORT ANGINA, POSITIVE ANTIANGINAL ACTION AND THE ABSENCE OF CLINICAL EFFECT AFTER PROPRANOLOL-BASED TREATMENT

Abstract

Aim. To analyze the changes in the aerobic-hemodynamic parameters during physical exercise in patients with effort angina administered with reference non-selective beta-blocker propranolol (Obsidan) with positive antianginal action and the absence of clinical effect after the drug intake.Material and Methods. A total of 58 patients (mean age of 54.2 [48.5; 59.5] years) with effort angina of functional class II–IV were examined with spiro-veloergometry tests before and after administration of propranolol (Obsidan: manufactured by Isis Pharma GmbH, Germany) at a dose of 40 mg. At threshold physical activity the following parameters were assessed: oxygen consumption (VO2 ), specific oxygen consumption, cardiac index (CI), rate pressure product (RPP); total peripheral vascular resistance (TPVR), arteriovenous oxygen difference (a-vDО2 ) and mechanical work of the heart (HW).Results. The efficacy of single-dose obsidian was observed in 58.6% of patients with angina (group 1); in this, tolerance to physical exercise increased from 50.0 [25.0; 75.0] W to 75.0 [50.0; 100.0] W. In the rest of patients (group 2), no antianginal effect was registered. At the first stage (at initial threshold physical activity level), administration of propranolol was characterized by saving pattern of heart function: statistically significant decrease in the heart rate, mean arterial pressure, CI and HW. This naturally resulted in reduction of myocardial oxygen demand (decrease in RPP from 163.0 [134.5; 218.5] U to 102.0 [90.0; 142.5] U; p<0.001) and predetermined the drug anti-ischemic action. At the second stage (maximum physical effort), an increase in the physical activity, caused by increase in VO2 from 738.0 [604.5; 1148.0] mL/min to 972.0 [774.5; 1458.0] mL/min, occurred due to higher oxygen extraction from peripheral blood (a-vDО2 increase; p<0.002). In group 2, despite the absence of an increase in tolerance to physical exercise, administration of propranolol was characterized by low RPP threshold i.e. the physical effort similar to the initial level was performed at a lower cardiac energy consumption.Conclusion. Therefore, anti-ischemic effect of Obsidan was due to a decrease in theenergy expenditure of the cardiac function along with a limitation in the hemodynamic productivity efficiently compensated by an increase in the oxygen extraction from circulating blood during physical activity.