Despite 200 years of use, the ability of
digitalis glycosides to improve exercise capacity in patients with
congestive heart failure remains controversial, partly because of imprecise end points and suboptimal study design. Therefore, this question was examined in 10 ambulatory patients (8 men and 2 women) aged 46 to 70 years (mean 57.8) in sinus rhythm with mild to moderate chronic stable
congestive heart failure due to
coronary artery disease and systolic
left ventricular dysfunction (ejection fraction 32 +/- 12). All underwent maximal treadmill exercise with respiratory gas analysis and upright cycle ergometry with gated
radionuclide angiography after 4 weeks of
digoxin or placebo
therapy, administered in a randomized double-blind crossover protocol. Neither treadmill exercise duration (7.7 +/- 2.3 versus 7.3 +/- 2.7 min) nor peak oxygen consumption (18.7 +/- 3.7 versus 18.4 +/- 5.4 ml/kg per min) differed between
digoxin and placebo regimens. However, the change in peak oxygen consumption induced by
digoxin was inversely related to the peak oxygen consumption during placebo
therapy (r = -0.64, p less than 0.05). At maximal treadmill effort, heart rate (138 +/- 16 versus 141 +/- 21 beats/min),
oxygen pulse (10.3 +/- 2.1 versus 9.9 +/- 2.2 ml/beat), ventilation (40.3 +/- 10.6 versus 42.0 +/- 10.8 liters/min) and ventilatory equivalent (29.4 +/- 4.8 versus 31.5 +/- 6.8) did not differ between
digoxin and placebo treatment, although systolic blood pressure was higher during
digoxin therapy (163.0 +/- 23.1 versus 153.2 +/- 25.3 mm Hg, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)