Drug-induced conditioning in congestive heart failure.

Abstract

Continuous 72-h infusions of dobutamine reportedly effect sustained clinical improvement in patients with congestive heart failure. This study was designed to determine if shorter, more frequent infusions, delivered in an outpatient setting, elicit a similar response. Patients (26) with moderately severe congestive heart failure were randomized, 11 into a control group and 15 into a dobutamine treatment group. Baseline data were collected for 4 wk in each group. Thereafter, the dobutamine treatment group received 4-h infusions of dobutamine weekly for 24 wk. Systolic time intervals, echocardiography, cardiac index and treadmill exercise tolerance were used to follow the progress of the control and dobutamine treatment groups. The ratio of preejection period to left ventricular ejection time and the cardiac index did not change significantly in either group. The velocity of circumferential fiber shortening and the percent change in the minor axis of the left ventricle during systole improved modestly (P < 0.05) above baseline in the dobutamine group after 14 wk of treatment and above the corresponding control values (P < 0.05) after 22 wk. Exercise tolerance (duration) improved 25-51% (all P < 0.05) above baseline in the dobutamine group compared with 10-17% (all P < 0.05 vs. baseline) in the control group. Heart rate at maximal exercise did not change significantly from baseline for either group and did not differ significantly between the 2 groups. Functional classification improved in 12 of 15 dobutamine treatment patients and in only 2 of 11 control patients (P < 0.05). In these patients with congestive heart failure, weekly 4-h dobutamine infusions did not elicit a major change in resting left ventricular function; exercise performance and clinical status improved considerably.