Systolic functional response of normal older and younger adult left ventricles to beta-blockade during exercise

Abstract

There is controversy over the effects of beta-blockade on the left ventricular systolic response of the heart of the elderly to stress. In this study we compared the effects of acute beta-blockade in normal older and younger adult left ventricles during exercise. The study population consisted of 17 healthy elderly people, 67 +/- 3 years old, while 18 young normal subjects, 31 +/- 4 years old, served as controls. A symptom-limited exercise treadmill test was performed before and 15 minutes after intravenous administration of 0.12 mg propranolol/kg. M-mode echocardiographic studies were performed before and immediately after each test. Intravenous propranolol at rest decreased heart rate by 14 +/- 7 beats/min in the elderly and by 7.5 +/- 8 beats/min in the young (p = 0.02), decreased the double product by 2500 +/- 1200 mmHg/min and 1830 +/- 970 mmHg/min (p = 0.05), respectively; changed the left ventricular end-systolic dimension by +0.21 +/- 0.36 cm and +0.03 +/- 0.24 cm (p = 0.09), respectively; and changed the end-diastolic dimension by +0.22 +/- 0.46 cm in the elderly and by -0.02 +/- 0.32 cm in the young (p = 0.08). The change in fractional shortening was -1.22 +/- 4.17% in the elderly and -0.78 +/- 4.05% in the young (p > 0.05), and the decrease in the systolic blood pressure/end-systolic dimension ratio was 5.9 +/- 7 mmHg/cm and 4.3 +/- 3.8 mmHg/cm, respectively (p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)