Hemodynamic, antiischemic, and neurohumoral effects of tedisamil and atenolol in patients with coronary artery disease.

ABSTRACT

Clinical drawbacks of beta-blocker treatment in stable angina have motivated researchers to provide alternative heart-rate-lowering agents, such as tedisamil, which additionally exerts antiischemic and antiarrhythmic effects by blockade of cellular repolarizing K+ currents. Forty-eight patients with stable angina pectoris were investigated (doubleblind, randomized, parallel grouped) comparing the hemodynamic, antiischemic, metabolic and neurohumoral effects of tedisamil 100 mg b.i.d. and atenolol 50 mg b.i.d. after a single dose and over 6 days of treatment. Tedisamil and atenolol produced a decrease in heart rate both at rest [day 1-13.6 versus - 15.4 bpm; day 6 - 14.8 versus - 22.2 bpm, resp.; p > 0.05] and exercise [day 1 - 9.1 versus - 18.3 bpm; p = 0.001; day 6 - 12.0 versus - 24.8 bpm, resp.; p = 0.001], while anginal threshold increased. Cardiac output decreased with tedisamil and atenolol at rest [day 1 -1.01 versus -1.19 l/min; p > 0.05; day 6 - 0.86 versus - 1.10 l/min, resp.; p > 0.05] and exercise [day 1 - 0.82 versus - 1.28 l/min; p > 0.05; day 6 - 0.65 versus - 2.68 l/min, resp.; p = 0.03], while stroke volume remained unchanged. Right atrial pressure changed during exercise only it decreased with tedisamil (-1.7 mmHg) and increased with atenolol (+ 3.7 mmHg) (p < .001). Mean pulmonary capillary wedge pressures decreased both at rest (- 0.5 mmHg) and exercise (- 6.9 mmHg) in the tedisamil group but tended to increase with atenolol on day 6 of treatment [rest + 1.7; exercise + 3.7 mmHg) (p = 0.03). Arterial pressure decreased under atenolol treatment only. Exercise-induced plasma norepinephrine levels were reduced by tedisamil (- 93 pg/ml) but elevated by atenolol (+ 172 pg/ml) (p = 0.001). As compared to atenolol, tedisamil produced a prolongation of QTc interval [+ 31 versus 8 ms] at initial values of 0.408 +/- 0.018 s with PQ and QRS remaining unaltered. In patients with stable angina, tedisamil (100 mg b.i.d.) as compared to atenolol (50 mg b.i.d.) generated similar hemodynamic, neurohumoral and antiischemic effects. The antiischemic efficacy of tedisamil, as measured by ST segment depression and angina threshold, was comparable to that of atenolol.