Effects of enoximone in patients with heart failure uncontrolled by captopril and diuretics

Abstract

Ten patients with severe heart failure, symptomatic despite treatment with diuretics and captopril, completed a study of the effect of adding enoximone to their normal treatment. Enoximone or matching placebo was given for 4 weeks in randomized double-blind order following a single-blind placebo run-in period. Exercise capability was measured with two different treadmill protocols, a corridor walk test and by step-counting with body-worn pedometers. Cardiac output and limb blood flow were assessed non-invasively by measuring respiratory gases and by venous occlusion plethysmography. Measurements were made at rest and in response to treadmill exercise. The mean exercise tolerance measured using the modified Bruce treadmill protocol was increased from the placebo value (498 ± 91 seconds) after both 2 weeks (573 ± 94 seconds, P = 0.051) and 4 weeks of enoximone (572 ± 100 seconds, P = 0.057). Enoximone increased exercise duration in fixed workload tests from the placebo value (252 ± 75 seconds) after 2 weeks' treatment (431 ± 98 seconds, P = 0.011) and after 4 weeks (381 ± 85 seconds, P = 0.01). The percentage improvement with the fixed workload test was greater than with the modified Bruce protocol at week 2 ( P = 0.03) and at week 4 ( P = 0.051). Enoximone increased the speed of walking 100 m at self-selected slow, normal and fast paces. It had little effect on customary activity of the patients. Enoximone increased cardiac output measured at rest and during submaximal exercise ( P = 0.001). It also improved blood flow to the calf muscle at rest and after exercise ( P = 0.01). Enoximone has a beneficial effect in chronic heart failure symptomatic despite treatment with diuretics and captopril. The magnitude of its effect, however, depends upon the technique used to assess it.