Tolerability of extended duration intravenous milrinone in patients hospitalized for advanced heart failure and the usefulness of uptitration of oral angiotensin-converting enzyme inhibitors

Intensive symptom control of opioid-refractory dyspnea in congestive heart failure: Role of milrinone in the palliative care unit

OBJECTIVE

We describe an exemplary case of congestive heart failure (CHF) symptoms controlled with milrinone. We also analyze the benefits and risks of milrinone administration in an unmonitored setting.

METHOD

We describe the case of a patient with refractory leukemia and end-stage CHF who developed severe dyspnea after discontinuation of milrinone. At that point, despite starting opioids, she had been severely dyspneic and anxious, requiring admission to the palliative care unit (PCU) for symptom control. After negotiation with hospital administrators, milrinone was administered in an unmonitored setting such as the PCU. A multidisciplinary team approach was also provided.

RESULTS

Milrinone produced a dramatic improvement in the patient's symptom scores and performance status. The patient was eventually discharged to home hospice on a milrinone infusion with excellent symptom control.

SIGNIFICANCE OF RESULTS

This case suggests that milrinone may be of benefit for short-term inpatient administration for dyspnea management, even in unmonitored settings and consequently during hospice in do-not-resuscitate (DNR) patients. This strategy may reduce costs and readmissions to the hospital related to end-stage CHF.

From acute decompensated to chronic heart failure

An acute decompensation of heart failure resulting in hospital admission represents a critical juncture in the natural history of the disease, as evidenced by poor mortality and readmission outcomes after hospital discharge. For this reason, a number of new short-term vasoactive therapies have been or are being tested in clinical trials. Furthermore, in response to unacceptable readmission rates, there has been intense interest in improving the transition from hospital discharge to the outpatient arena. Between these 2 areas of focus exists an often overlooked internal transition from acute vasoactive therapies to oral chronic heart failure medications. This transition from acute presentation to the rest of the hospital stay forms the basis of this review.

Milrinone in Advanced Heart Failure

Advanced chronic heart failure (ACHF) patients often require inotropes before transplantation or ventricular assist device implantation. Milrinone, an inotrope and vasodilator, may accumulate in cardiorenal syndrome with serious adverse effects. We investigated the potential for therapeutic drug monitoring of milrinone levels using High Performance Liquid Chromatography Mass Spectrometry (HPLC-MS). 22 ACHF patients (15 males, 49±9 years) received milrinone 50 µg/kg intravenously (i.v.) during heart catheterization. Milrinone levels were 216±71 ng/ml (within the reported therapeutic range: 100-300 ng/ml), followed by improvements in cardiac index, pulmonary artery and wedge pressures (p < 0.005). 18 ACHF patients (17 males, 50±12 years, 13 had renal dysfunction) received continuous i.v. milrinone (5-26 days) at 0.1-0.2 µg/kg/min, titrated according to plasma milrinone levels. No adverse events occurred. Therapeutic levels were achieved with doses of 0.2±0.06 µg/Kg/min, below those recommended in Summary of Product Characteristics. Milrinone therapy can be noninvasively monitored by HPLC-MS, while avoiding toxicity in ACHF.

Positive inotropes in heart failure: a review article

Increasing myocardial contractility has long been considered a big help for patients with systolic heart failure, conferring an augmented haemodynamic profile in terms of higher cardiac output, lower cardiac filling pressure and better organ perfusion. Though concerns have been raised over the safety issues regarding the clinical trials of different inotropes in hearts with systolic dysfunction, they still stand as a main therapeutic strategy in many centres dealing with such patients. They must be used as short in duration, low in dose and stopped as early as possible. Evidence-based guidelines have provided clinicians with valuable data for better applying inotropes in heart failure patients. In this paper, the authors address clinical trials with different agents used for increasing cardiac contractility in heart failure patients. Furthermore, the authors focus on recent guidelines on making the most out of inotropes in heart failure patients.

Dobutamine as bridge to angiotensin-converting enzyme inhibitor-nitrate therapy in endstage heart failure

BACKGROUND

Intravenous inotropic intervention in congestive heart failure is generally associated with a poor prognosis and is largely used as a "bridge" to mechanical support or heart transplantation.

HYPOTHESIS

We hypothesized that the inotropic support afforded by dobutamine may serve as a bridge to the introduction and intensification of angiotensin-converting enzyme (ACE) inhibitor-nitrate therapy.

METHODS

We studied the efficacy of transitioning inotrope-dependent patients in endstage heart failure from intravenous dobutamine to high-dose ACE inhibitor-nitrates, with 1-year follow-up. Forty-nine sequential dobutamine-dependent patients with left ventricular ejection fraction (LVEF) 17+/-17% were treated with increasing lisinopril (1.9+/-1.5 to 46+/-28 mg/day) and isosorbide dinitrate (7+/-6 to 229+/-161 mg/day). Outpatient dobutamine was continued or repeat infusions pursued, as indicated, and dobutamine was tapered when feasible.

RESULTS

During the following year, 14 of 49 patients required repeat dobutamine, with home treatment with dobutamine for 6.3+/-3.7 months (n = 5). At 1 year, New York Heart Association (NYHA) classification improved from 3.6+/-0.5 to 1.9+/-1.0, p < 0.0001; yearly hospitalizations fell from 2.7+/-2.3 to 1.2+/-3.0, p = 0.02; and LVEF rose from 17+/-7% to 24+/-11%, p < 0.0001. At 1 year, 14 patients who remained dobutamine dependent had significantly more severe symptoms than dobutamine-independent patients (n = 35). Transplant or death occurred in 7 of 14 patients with follow-up dobutamine, and in 5 of 35 patients free of subsequent dobutamine, p = 0.03. Patients with poor outcome (transplant n = 10, death n = 12) continued to be more limited (NYHA 2.7+/-0.9 vs. 1.7+/-0.9, p = 0.0002), with more follow-up hospitalizations (3.6+/-5.4 vs. 0.6+/-0.8, p = 0.0004), and no improvement in LVEF (17+/-8vs. 28+/-11%, p = 0.003).

CONCLUSIONS

Of the patients on dobutamine inotropic support, 70% were successfully transitioned to ACE inhibitor-nitrate therapy, with improved symptoms and LVEF, and with reduced hospitalizations and follow-up dobutamine or transplant. Thirty percent of patients with continued need for dobutamine had a significantly poorer 1-year clinical outcome.

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.

A prospective study of continuous intravenous milrinone therapy for status IB patients awaiting heart transplant at home

BACKGROUND

We performed a prospective study to determine the feasibility and safety of continuous intravenous milrinone therapy administered at home in patients listed as Status IB for heart transplant.

METHODS

Patients who were Status IB could participate if they met specific criteria including an optimal dose of milrinone < or =0.5 microg/kg/min, presence of an implantable cardioverter-defibrillator (ICD), and no other serious comorbidity. The primary end-point of the study was survival to transplant. Hospitalizations, quality of life and cost comparisons were assessed.

RESULTS

From May 1999 through October 2002, a total of 60 patients (51 men, 9 women), aged 55.5 +/- 8.4 years, entered the study. Before milrinone therapy, cardiac index was 1.98 +/- 0.66 liters/min/m2 and peak oxygen consumption was 11.4 +/- 2.6 ml/kg/min. Mean time in the study was 160.1 +/- 151.8 days. Fifty-three patients (88.3%) underwent heart transplant. There were only 2 deaths during the study. There were 89 hospital admissions in 46 patients over the 43-month follow-up period; 58 of these admissions were for heart failure. There were 6 episodes of ICD firing for ventricular tachycardia. Quality-of-life measures in a sub-group of patients significantly improved 1 month after discharge. Substantial estimated cost savings occurred.

CONCLUSIONS

Continuous intravenous milrinone therapy can be safely administered at home in selected patients with advanced heart failure who are listed for transplant. This strategy may be an acceptable alternative to prolonged hospitalization for patients dependent on continuous inotropic support. Re-hospitalization is to be expected. An implantable cardioverter-defibrillator should be present due to the incidence of ventricular tachycardia.

Acute decompensated heart failure: a contemporary approach to pharmacotherapeutic management

Hospital admissions for acute decompensated heart failure (ADHF) have increased precipitously during the past few decades and are projected to continue to increase in the future. To optimize patient outcomes and reduce the costs associated with this disorder, evidenced-based pharmacotherapy is essential. Continuous infusions of loop diuretic therapy rather than bolus dosing may enhance efficacy and reduce the extent of diuretic resistance. Nesiritide is a pharmacologically novel preload and afterload reducer but based on clinical trial evidence should be reserved for those unable to take or with resistance to intravenous nitrate therapy. Catecholamine- and phosphodiesterase-based inotropic therapies are efficacious, but the increased risk of arrhythmogenesis and the potential for negative survival effects limit their use. The experimental agent levosimendan is a positive inotropic agent but does not increase myocyte calcium concentrations as do catecholamines or phosphodiesterase inhibitors. Clinical trial evidence demonstrates a positive survival benefit for levosimendan versus dobutamine.

Evaluation of pulmonary hypertension in heart transplant candidates

Assessment of the pulmonary circulation and right ventricular function is a cornerstone in the evaluation of the patient as a potential heart transplant recipient. The importance of pulmonary hypertension is linked to outcomes in the posttransplant period. Preoperative pulmonary vascular resistance is an independent risk factor for early death after heart transplantation. Pulmonary hypertension can be classified as reversible, or irreversible if not rapidly responsive to pharmacologic maneuvers. However, in most patients, the major component is likely to reverse with vasodilators, because of the central role played by the endothelium in the control of pulmonary vascular tone. To discriminate between patients with reversible and irreversible pulmonary hypertension, provocative therapies are used, and baseline and the postprovocation hemodynamic parameters are measured. To date, there is no reliable hemodynamic threshold beyond which right ventricular failure is certain to occur, nor are there values below which right ventricular failure is always avoidable. Because of this uncertainty, it becomes clear that only through careful preoperative assessment can this life-threatening condition be recognized preoperatively and, hence, managed in the posttransplant recovery period.

Rationale for the short term use of intravenous milrinone under hemodynamic guidance in patients with severe systolic heart failure

Patients with severe systolic heart failure have a decrease in both number and function of cardiac beta receptors, which may result in a poor inotropic response to I.V. beta-adrenergic agonists such as dobutamine. The I.V. use of the phosphodiesterase inhibitor milrinone, which is a combined positive inotrope/vasodilator in this patient population, is a more rational choice, especially if heart failure is chronic. Many of these patients may also be referred for consideration for cardiac transplantation, for which the use of invasive hemodynamic monitoring is typically necessary to determine whether severe hemodynamic compromise and pulmonary hypertension are reversible with therapy. The use of hemodynamically guided I.V. vasodilator therapy has also been extensively described as a tool to optimize oral vasodilator therapy and predict prognosis in patients evaluated for cardiac transplantation. This review summarizes the important studies supporting the rationale for and benefits of using I.V. milrinone under hemodynamic guidance in this patient population. (c)2000 by CHF, Inc.