Comparison of dobutamine versus milrinone therapy in hospitalized patients awaiting cardiac transplantation: a prospective, randomized trial

Pharmacotherapy for acute heart failure syndromes

PURPOSE

Drug therapies for patients with acute heart failure syndromes (AHFS) are reviewed, including clinical practice guideline recommendations for the treatment of hospitalized patients with heart failure (HF).

SUMMARY

AHFS may be defined as new-onset, gradual, or rapidly worsening HF signs and symptoms that require urgent therapy. Clinical practice guidelines from the American College of Cardiology Foundation-American Heart Association, Heart Failure Society of America, and European Society of Cardiology offer recommendations for the management of AHFS, addressing the role of diuretics, vasodilators, and inotropes. The guidelines emphasize the utility of vasodilators for patients with signs and symptoms of pulmonary congestion, including pulmonary edema or severe hypertension or both, who have not responded to diuretics. The early initiation of vasoactive medications, including diuretics and vasodilators, has been linked to improved outcomes in some reports. Conversely, the use of inotropes is de-emphasized, particularly as part of the routine management of these patients. Newer agents, including vasopressin antagonists, have also been approved recently but are not addressed by the clinical practice guidelines. The guidelines address the importance of initiating and optimizing evidence-based oral medications for long-term use, including angiotensin-converting-enzyme (ACE) inhibitors, angiotensin-receptor blockers, β-blockers, and aldosterone antagonists, during the patient's hospital stay in an effort to address long-term outcomes.

CONCLUSION

Drug therapy of AHFS may include diuretics, vasodilators, morphine, ACE inhibitors, digoxin, inotropes, and vasopressin antagonists. Clinical practice guidelines for patients with AHFS provide a useful mechanism to incorporate available evidence and standards of practice into patient care.

Comparison of the effects of dobutamine and milrinone on hemodynamic parameters and oxygen supply in patients undergoing cardiac surgery with low cardiac output after anesthetic induction

BACKGROUND AND OBJECTIVES

Several classes of inotropic drugs with different hemodynamic effects are used in the treatment of low cardiac output in patients with diastolic dysfunction undergoing cardiac surgery. The objective of the present study was to compare the effects of dobutamine and milrinone on hemodynamic parameters and oxygen supply in this population of patients.

METHODS

After approval by the Ethics Committee of the institution and signing of the informed consent, 20 patients undergoing cardiac surgery with cardiac index < 2 L*min(-1)*m(2) after anesthetic induction and placement of a pulmonary artery catheter were randomly divided to receive dobutamine 5 microg*kg(-1). min(-1) (n = 10), or milrinone 0.5 microg*kg(-1)*min(-1) (n = 10). Hemodynamic parameters were measured after anesthetic induction and after 30 and 60 minutes, and arterial and venous blood gases were measured at baseline and 60 minutes. Non-paired Student t test or two-way ANOVA for repeated measurements was used to compare the data.

RESULTS

Dobutamine and milrinone promoted significant increases in cardiac index (56% and 47%) and oxygen supply (53% and 45%), and reduction in systemic (33% and 36%) and pulmonary (34% and 19%) vascular resistance, respectively. However, statistically significant differences were not observed between both drugs.

CONCLUSIONS

Both inotropic drugs were similarly effective in restoring tissue blood flow and oxygen supply to adequate levels in patients with low cardiac output undergoing cardiac surgery.

The use of continuous milrinone therapy as bridge to transplant is safe in patients with short waiting times

OBJECTIVE

The limited availability of donor organs creates a need for more effective management of heart disease when bridging a patient to cardiac transplant. Inotropic therapy is becoming more commonly used long term to maintain baseline function. The effectiveness and complications associated with their use have not been fully evaluated, and indications for mechanical versus medical therapy as a bridge have not been delineated.

METHODS AND RESULTS

The purpose of this study is to evaluate the safety and efficacy of milrinone as a bridge to transplant. This was a retrospective study of 60 patients listed for a cardiac transplant and committed to home intravenous milrinone therapy. A subgroup of patients who eventually progressed to the use of a ventricular assist device were analyzed. Complications and survivals were analyzed for each group. Forty-six patients (76%) were successfully bridged to transplant with milrinone alone, and 14 patients' (24%) conditions deteriorated and required a left ventricular assist device (LVAD); 1-year survivals were 83% and 71%, respectively. The mean waiting time was 59.5 days (9-257 days) for patients receiving milrinone who did not require an LVAD and 112 days (24-270 days) for those whose conditions deteriorated to require an LVAD.

CONCLUSIONS

This study suggests that chronic intravenous milrinone provides an adequate strategy as a bridge to transplant if the waiting time is short (<100 days), whereas an elective ventricular assist device implantation may be a safer strategy for patients expected to wait longer. These data provide the basis for a prospective evaluation of inotrope versus LVAD as a bridge to transplantation.

Comparison of the initial hospitalization costs between the patients treated with dobutamine and the patients treated with amrinone for acute decompensated heart failure in a Japanese institute

OBJECTIVES

Phosphodiesterase (PDE) III inhibitor therapy is effective for treatment of acute decompensated heart failure (ADHF). Nevertheless, this drug is expensive than conventional inotropic agent dobutamine. We compared total medication costs of the patients treated with PDE III inhibitor amrinone therapy to that of the patients treated with conventional dobutamine therapy during initial hospitalization.

METHODS

We analyzed 160 consecutive patients with ADHF admitted to our hospital. Shock, dehydration, severe infection, multiple organ failure, and mild heart failure (New York Heart Association class IIs) were not eligible for the study. Ninety-seven patients were divided into two groups: 1) DOB group treated with dobutamine therapy; and 2) AMR group treated with amrinone therapy. Total medication costs and cost for hospital room charge were calculated based on their usage during the initial hospitalization for each patient. Group comparison was done between the DOB and AMR groups.

RESULTS

Length of stay was longer in the DOB group than in the AMR group. Mean calculated cost of intravenous drugs was higher in the DOB group (173,186 +/- 239,147 yen) than in the AMR group (63,145 +/- 47,223 yen, P < 0.05). Total medication costs were higher in the DOB group than in the AMR group. Cost for hospital room charge was higher in the DOB group than in the AMR group.

CONCLUSIONS

In the treatment of ADHF, appropriate therapy even with expensive drugs makes total medication costs less expensive comparing with conventional therapy with cheaper drugs during initial hospitalization.

Tolerability of beta-blockers in outpatients with refractory heart failure who were receiving continuous milrinone

STUDY OBJECTIVE

To investigate the dosing, tolerability, and outcomes associated with the use of concomitant beta-blockers and inotropic therapy in patients with refractory heart failure during the first 6 months of their therapy.

DESIGN

Retrospective review.

SETTING

University-based, tertiary care heart failure and transplant center.

PATIENTS

Sixteen inotrope-dependent outpatients with end-stage refractory heart failure who were receiving continuous intravenous milrinone. Of these patients, 12 also received an oral beta-blocker; the remaining four patients who did not receive beta-blockers served as the comparator group.

MEASUREMENTS AND MAIN RESULTS

For each patient, the initial and final study drug doses of continuous intravenous milrinone and oral beta-blocker treatment, when applicable, were recorded over the 6-month period. Mean heart rate, blood pressure, ejection fraction, and oxygen consumption were measured, and 95% confidence intervals were calculated. Serum sodium and creatinine concentrations, as well as the creatinine clearance, were measured. In the 12 patients who received concomitant milrinone and beta-blockers, the mean baseline ejection fraction was approximately 18%, and they received milrinone for 18.6 weeks. Seven patients received carvedilol for 16.1 weeks, and five received metoprolol tartrate for 17.6 weeks. Dosages of the beta-blockers were titrated. Final daily doses were carvedilol 42.8 mg (95% confidence interval 20.3-65.4) and metoprolol 42.5 mg (95% confidence interval 28.0-57.2). Patients continued to receive other standard oral drug therapy for heart failure. One patient discontinued metoprolol and one discontinued carvedilol because of hypotension and/or worsening heart failure. Cardiac adverse events in the concomitant milrinone plus beta-blocker group were heart failure requiring hospitalization in 10 patients and ventricular arrhythmias in one.

CONCLUSION

Inotrope-dependent patients with refractory end-stage heart failure tolerated continuous intravenous milrinone plus beta-blockers in addition to diuretics and vasodilators for the 6-month observation period. Beta-blocker dosages were titrated, and three patients achieved the target beta-blocker dosage established for stage A-C heart failure. Additional studies are needed to determine the optimal selection and dosing of drug combinations in this population.

Right ventricular failure complicating heart failure: pathophysiology, significance, and management strategies

Right heart failure most commonly results from the complication of left heart failure (systolic or nonsystolic dysfunction) or pulmonary hypertension. Over the past decade, greater attention has been paid to the role of right ventricular failure in the morbidity and mortality associated with cardiomyopathy and pulmonary hypertension. The right ventricle is distinct from the left ventricle not only in its spatial localization, but also in its response to increased afterload and signaling mechanisms. This article discusses the role of right ventricular failure in the setting of heart failure as well as the clinical diagnosis and management of right ventricular failure.

Cardiovascular pharmacotherapy update for the intensive care unit

Pharmacologic agents including vasodilators, inotropes, and vasopressors are frequently used in the critical care setting for management of the unstable cardiac patient. These medications are used to elicit varying effects on vascular resistance, myocardial contractility, and heart rate to help achieve desired hemodynamic and clinical endpoints. Therefore, it is important for the critical care nurse to have a practical understanding and working knowledge of cardiovascular pharmacotherapy in the intensive care unit setting. This article reviews the pharmacology and clinical utility of commonly used intravenous "vasoactive" medications encountered in the intensive care unit. We also highlight innovations in pharmacotherapy for this patient population, and provide practical considerations for the most appropriate and safe use of these medications.

Myocardial phosphodiesterases and regulation of cardiac contractility in health and cardiac disease

Phosphodiesterase (PDE) inhibitors are potent cardiotonic agents used for parenteral inotropic support in heart failure. Contractile effects of these agents are mediated through cAMP-protein kinase A-induced stimulation of I (Ca2+) which ultimately results in increased Ca(2+)-induced sarcoplasmic reticulum Ca(2+) release. A number of additional effects such as increases in sarcoplasmic reticulum Ca(2+) stores, stimulation of reverse mode Na(+)-Ca(2+) exchange, direct or cAMP-mediated effects on sarcoplasmic reticulum ryanodine receptor, stimulation of the voltage-sensitive sarcoplasmic reticulum Ca(2+) release mechanism, as well as A(1) adenosine receptor blockade could contribute to positive inotropic responses to PDE inhibitors. Moreover, some PDE inhibitors exhibit Ca(2+) sensitizer properties as they could increase the affinity of troponin C Ca(2+)-binding sites as well as reduce Ca(2+) threshold for thin myofilament sliding and facilitate cross-bridge cycling. Inotropic responses to PDE inhibitors are significantly reduced in cardiac disease, an effect largely attributed to downregulation of cAMP-mediated signalling due to sustained sympathetic activation. Four PDE isoenzymes (PDE1, PDE2, PDE3 and PDE4) are present in myocardial tissue of various mammalian species, of which PDE3 and PDE4 are particularly involved in regulation of cardiac myocyte contraction. PDE cAMP-hydrolysing activity is preserved in compensated cardiac hypertrophy but significantly reduced in animal models of heart failure. However, clinical studies have not revealed any changes in distribution profile as well as kinetic and regulatory properties of myocardial PDEs in failing human hearts. A reduction of PDE inhibitors-induced contractile responses in heart failure has therefore been ascribed to reduced cAMP synthesis due to uncoupling of adenylyl cyclase from beta-adrenoreceptor. In cardiac myocytes, PDEs are targeted to distinct subcellular compartments by scaffolding proteins such as myomegalin, mAKAP and beta-arrestins. Over subcellular microdomains, cAMP hydrolysis by PDE3 and PDE4 allows to control the activity of local pools of protein kinase A and therefore the extent of protein kinase A-mediated phosphorylation of cellular proteins.

Chronic inotropic therapy in end-stage heart failure

BACKGROUND

Interventions in advanced heart failure that provide symptom relief and decrease hospital readmission are important. Chronic intravenous inotropic therapy represents a pharmacologic approach that has been advocated for palliative treatment. However, little is known about associated mortality and cost. Therefore, we sought to describe the impact of chronic infusions on resource use and survival.

METHODS

Data were reviewed for a 17-state Medicare region from 1995 to 2002. We obtained hospital and outpatient expenditures accrued up to 180 days before and after the initiation of chronic infusions. Health care use was defined by dollars reimbursed for drug and hospitalizations per beneficiary. Average accumulated cost curves were generated for dollars reimbursed for drug and for hospitalizations by days at risk.

RESULTS

The mean age of the cohort (n = 331) was 69.1 +/- 11.3 years. Mortality exceeded 40% at 6 months. Reductions in hospital days were observed at all time points. The amounts reimbursed at 30 and 60 days before and after initiation of inotrope favor drug therapy; however, at six months, the amounts reimbursed were greater due to the cost of milrinone.

CONCLUSIONS

Chronic intravenous inotrope use was associated with a high mortality. The cost for milrinone was significant, but there was a decrease in expenditures for subsequent hospitalizations. In the absence of appropriately designed clinical trials, the data suggest that the decision to use inotropes, the choice of inotrope, and the duration of treatment should reflect the impact on resource use.

Dobutamine versus milrinone after subarachnoid hemorrhage

OBJECTIVE

Neurogenic stunned myocardium is a well-recognized complication of subarachnoid hemorrhage. Dobutamine and milrinone are both used for neurogenic stunned myocardium, but there are few data comparing them after subarachnoid hemorrhage.

METHODS

We compared the physiological dose response of dobutamine and milrinone in patients with subarachnoid hemorrhage requiring a pulmonary artery catheter. We located 11 patients who received either inotrope. Physiological data were fitted to a mixed model accounting for drug, dose, and between-patient variation.

RESULTS

There were 11 patients who had 152 pulmonary artery catheter measurements. Two received both inotropes (but not within 4 h of each other), 2 only milrinone, and 7 only dobutamine. The groups had similar clinical and physiological characteristics. After adjustment for vasopressin, milrinone was significantly more potent in increasing cardiac output (P <0.0001) and stroke volume (P=0.03), while decreasing vascular resistance (P <0.0001) and systolic blood pressure (P=0.008), than dobutamine.

CONCLUSION

These data suggest that milrinone and dobutamine should be used in different clinical situations. Milrinone may be more effective in patients with severely depressed systolic function but who have at least normal vascular resistance and blood pressure and in whom raising cardiac output is the primary goal. Dobutamine may be superior when vascular resistance or blood pressure is low.

Reassessment of dobutamine, dopamine, and milrinone in the management of acute heart failure syndromes

The appropriate role of intravenous inodilator therapy (inotropic agents with vasodilator properties) in the management of acute heart failure syndromes (AHFS) has long been a subject of controversy, mainly because of the lack of prospective, placebo-controlled trials and a lack of alternative therapies. The use of intravenous inodilator infusions, however, remains common, but highly variable. As new options emerge for the treatment of AHFS, the available information should be reviewed to determine which approaches are supported by evidence, which are used empirically without evidence, and which should be considered inappropriate. For these purposes, we reviewed data available from randomized controlled trials on short-term, intermittent, and long-term use of intravenous inodilator agents (dobutamine, dopamine, and milrinone) in AHFS. Randomized controlled trials failed to show benefits with current medications and suggested that acute, intermittent, or continuous use of inodilator infusions may increase morbidity and mortality in patients with AHFS. Their use should be restricted to patients who are hypotensive as a result of low cardiac output despite a high left ventricular filling pressure.

Hemodynamic effects of levosimendan added to dobutamine in patients with decompensated advanced heart failure refractory to dobutamine alone

A 24-hour infusion of levosimendan was added to dobutamine in 18 patients (aged 63 +/- 9 years) hospitalized for management of decompensated New York Heart Association functional class IV heart failure refractory to a continuous 24-hour infusion of dobutamine (10 microg/kg/min) and furosemide (10 mg/hour); the primary study end point was a >or=40% increase in cardiac index and a >or=25% decrease in pulmonary capillary wedge pressure compared with pretreatment measurements. The primary end point was reached in one of the patients treated with dobutamine alone versus 7 patients (39%) treated with levosimendan and dobutamine combined (p = 0.008), whereas at 24 hours, the combined treatment was associated with a 0.76 +/- 0.78 L/min/m(2) (p = 0.001) mean increase in cardiac index and a 6.4 +/- 7.3 mm Hg (p = 0.002) mean decrease in pulmonary capillary wedge pressure compared with measurements obtained after 24 hours of dobutamine infusion alone. Symptoms were alleviated in all patients, and all but 3 were discharged from the hospital.