Short- and long-term dobutamine treatment in chronic ischemic heart failure

The effectiveness and relative effectiveness of intravenous inotropic drugs acting through the adrenergic pathway in patients with heart failure-a meta-regression analysis

AIMS

To review systematically the use of intravenous (IV) inotropic agents acting through the adrenergic signalling pathway, compared with placebo or an active agent, in patients with heart failure.

METHODS

Studies investigating the use of intravenous inotropes in patients with heart failure published between 1966 and 2000 were identified using MEDLINE, the Cochrane register and Embase databases. Reference lists from relevant papers and reviews were hand searched for further papers. In total, 21 trials, that included 632 patients receiving IV inotropic drugs, placebo or non-treatment control, were identified. Drugs of the following classes were included, the beta-agonists; dobutamine, high-dose (>2.5 microg/kg/min) dopamine, dopexamine and the phosphodiesterase (PDE) inhibitors; amrinone, milrinone, enoximone and toborinone. Sixteen trials (474 patients) contributed data from acute invasive haemodynamic studies of symptomatically severe heart failure. Five trials (158 patients) were based on intermittent inotropic therapy in an outpatient context.

RESULTS

With few exceptions, trials of intravenous inotropic agents were small and often failed to report clinically important outcomes. Compared to placebo, intravenous inotropic agents acting through the adrenergic system tended to increase mortality (odds ratio 1.50 (95% CI=0.51 to 3.92) but this did not reach significance and insufficient data were available to determine whether symptoms improved. There appeared to be little difference in the effect of beta-agonists compared to PDE inhibitors on patient outcomes but this could be attributed to the paucity of data.

CONCLUSIONS

Intravenous inotropic agents acting through the adrenergic pathway are often used in patients with worsening heart failure to achieve arbitrary haemodynamic targets. Our analyses show that there is very little evidence that such treatment improves symptoms or patient outcomes and may not be safe. This highlights the need for further well designed randomised clinical trials.

Continuous intravenous dobutamine is associated with an increased risk of death in patients with advanced heart failure: insights from the Flolan International Randomized Survival Trial (FIRST)

OBJECTIVE

To evaluate clinical characteristics and outcomes of patients with advanced heart failure receiving intravenous continuous dobutamine in the FIRST Trial (Flolan International Randomized Survival Trial).

METHODS

Four hundred seventy-one patients with class IIIb to IV heart failure who were enrolled in the FIRST trial were included. Eighty patients treated with dobutamine at FIRST randomization were compared with 391 patients not treated with dobutamine at randomization. The occurrence of worsening heart failure, need for vasoactive medications, resuscitated cardiac arrest, myocardial infarction, and total mortality were compared between the 2 groups.

RESULTS

The dobutamine group had a higher occurrence of first event (85.3% vs 64. 5%; P =.0006) and a higher mortality rate (70.5% vs 37.1%; P =.0001) compared with the no dobutamine group. Intravenous continuous dobutamine was an independent risk factor for death after adjusting for baseline differences.

CONCLUSIONS

Dobutamine use at the time of randomization was associated with a higher 6-month mortality rate. This effect persisted after adjustment for baseline differences. This analysis challenges the concept that continuous intravenous dobutamine is beneficial to advanced heart failure patients with respect to survival.

The hemodynamic effects of dobutamine infusion in the chronically instrumented newborn piglet

OBJECTIVE

To determine the systemic, pulmonary, mesenteric, and renal hemodynamic effects of short and prolonged infusions of dobutamine.

DESIGN

Prospective randomized unblinded study.

SETTING

University research laboratory.

SUBJECTS

Thirteen newborn (1-3 days old) piglets.

INTERVENTIONS

Piglets were instrumented and studied 48 hrs later. Fifteen-minute infusions of dobutamine at 5, 10, 20 and 50 microg/ kg x min were randomly given with 15-min rests between the doses. After a 1-hr hiatus, a dose of 10 microg/kg x min was continuously administered for 2 hrs.

MEASUREMENTS AND MAIN RESULTS

Systemic and pulmonary arterial pressures, cardiac index (thermodilution), and superior mesenteric and renal artery flows were measured. Vascular resistance values were calculated.

MAIN RESULTS

Fifteen-minute infusions: Dobutamine dose-dependently increased cardiac index with tachycardia but not stroke volume (from 187 +/- 43 to 238 +/- 51 mL/kg x min at baseline and 50 microg/ kg x min, respectively, p < .05; values expressed as mean +/- SD). Systemic, but not pulmonary, vascular resistance decreased, resulting in a significant decrease in systemic to pulmonary arterial pressure ratio (from 3.8 +/- 0.8 at baseline to 3.2 +/- 1.0 at 50 microg/ kg x min). Superior mesenteric and renal flows were not affected. Two-hour infusion at 10 microg/kg x min: Cardiac index progressively increased from 173 +/- 34 to 240 +/- 58 mL/kg x min at baseline and 120 mins, respectively, (p < .05). The initial tachycardia was transient, and stroke volume was significantly increased at 60 mins and thereafter. Although systemic and pulmonary vascular resistance values fell simultaneously, systemic to pulmonary arterial pressure ratio decreased significantly to 3.4 +/- 0.9 at 120 mins from 3.9 +/- 0.7 at baseline. Superior mesenteric and renal artery flows increased significantly with vasodilation after 60 mins.

CONCLUSIONS

Short infusions of dobutamine dose-dependently increase cardiac output due to tachycardia, without significant effect on mesenteric and renal blood flows. Prolonged infusion of dobutamine at 10 microg/kg x min progressively increases cardiac output and stroke volume with transient tachycardia, and increases mesenteric and renal blood flows. Caution is required in the treatment of critically ill neonates with dobutamine, which could also reduce systemic to pulmonary arterial pressure ratio.

Outpatient dobutamine therapy: the rhyme and the riddle

Advances in critical care medicine have increased survival for victims of myocardial infarction and other acute cardiac events so that increasingly patients are receiving long-term, labor-intensive, and costly medical care. Innovations in drug delivery systems and skyrocketing health care costs have fostered the growth of home health care which has blossomed into a $2.8 billion industry. There is evidence that outpatient dobutamine therapy produces definite physical and possibly psychological improvements of variable degree and duration. Hemodynamic improvements are generally associated with improvement in functional class, and the financial savings are recognizably substantial. However, three major problems confront therapies with beta-adrenergic agonists: tendency for tolerance, ventricular arrhythmias, and increased myocardial oxygen consumption. There is a dire need for establishment of exclusionary patient criteria and for risk stratification, as well as for development of a portable radionuclide nonimaging monitor. Given the current fund of knowledge, outpatient dobutamine therapy should be undertaken cautiously after meticulous patient selection reflecting an awareness of the tremendous complexities and inherent risks. The therapeutic implications are dependent on the nature of the underlying cardiomyopathy and the fact that beta-adrenergic receptor desensitization is unlikely to be overcome by progressive dosage increases. Therapy is initiated with the understanding that treatment will remain blindly empirical and conjectural in the absence of a continuous physiologic monitor and an expanded comprehension of the molecular pathophysiology of the failing ventricle.