Comparison of high-dose and medium-dose propranolol in the relief of exercise-induced myocardial ischemia.

The effects of medium-dose (160 mg/day) and high-dose (480 mg/day) oral propranolol were compared in 22 patients who had typical angina pectoris and objective evidence of myocardial ischemia during exercise. Left ventricular (LV) ejection fraction (EF) and wall motion score (WMS) (an index of regional LV dysfunction) were assessed by radionuclide angiography both at rest and during exercise to the pretreatment maximum work load. Functional class improved in 11 of the 22 patients during medium-dose propranolol therapy. Medium-dose propranolol reduced mean resting heart rate from 71 to 55 beats/min, exercise heart rate from 122 to 93 beats/min, and exercise systolic blood pressure from 183 to 162 mm Hg (p less than 0.001 for each). The incidences of exercise-induced chest pain and S-T segment depression were reduced from 19 to 9 patients (p less than 0.001), and from 20 to 10 patients (p = 0.002), respectively. Medium-dose propranolol had no effect on mean EF or WMS at rest, but improved function in ischemic regions during exercise; WMS decreased (p = 0.001), and mean exercise EF increased from 0.51 to 0.56 (p = 0.025). Compared with the medium dose, high-dose propranolol improved functional class in 3 additional patients, and further reduced mean resting heart rate (from 55 to 52 beats/min, p = 0.001) and mean exercise heart rate (from 93 to 86 beats/min, p = 0.001). Exercise-induced chest pain and S-T segment depression were abolished in a further 7 and 6 patients, respectively. Exercise EF and WMS improved further in several patients, but the changes were not statistically significant for the group (p = 0.095 and 0.082, respectively). Thus, in patients with coronary artery disease and exercise-induced ischemia, propranolol reduced heart rate and blood pressure and the incidence of exercise-induced chest pain, electrocardiographic changes, and ischemic LV dysfunction. Although most of these effects were seen with medium-dose propranolol, higher doses provided additional relief of chest pain and S-T segment depression, and further improved global and regional LV function in several patients.

Duke Scholars

Author Kenneth Gregory Morris Medicine, Cardiology