Effects of intravenous milrinone followed by titration of high-dose oral vasodilator therapy on clinical outcome and rehospitalization rates in patients with severe heart failure

Effects of milrinone on serum IL-6, TNF-α, Cys-C and cardiac functions of patients with chronic heart failure

Effects of milrinone on serum interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cystatin C (Cys-C) and cardiac functions of patients with chronic heart failure were analyzed to investigate the value of milrinone in chronic heart failure. A total of 70 patients diagnosed with chronic heart failure were selected and randomly divided into treatment group (n=35) and control group (n=35). All patients were treated with conventional anti-heart failure therapy, and patients in the treatment group received milrinone on the basis of conventional therapy. The general data of patients, such as age, sex and course of chronic heart failure, were collected; the levels of serum IL-6, TNF-α and Cys-C before and after treatment were compared between the groups, and the cardiac function indexes were also compared, including cardiac output (CO), stroke volume (SV), left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVDd), left ventricular end-systolic diameter (LVSd) and brain natriuretic peptide (BNP) level. Besides, the curative effects and adverse reactions in the two groups were recorded. The results revealed that serum IL-6, TNF-α and Cys-C levels had no significant difference between the two groups before treatment; however, the curative effect in the treatment group was significantly superior to that in control group (p<0.05); after treatment, CO, SV and LVEF in both groups were obviously increased, but LVDd, LVSd and BNP levels were obviously decreased; the curative effect in the treatment group was significantly superior to that in control group (p<0.05); heart rate in both groups was obviously decreased after treatment (p<0.05); the total effective rate in the treatment group was significantly higher than that in control group after treatment (p<0.05). In conclusion, based on the conventional anti-heart failure therapy, the application of milrinone can reduce the serum IL-6, TNF-α and Cys-C levels and improve the cardiac functions of patients effectively.

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.

Inotropes do not increase mortality in advanced heart failure

Inotrope use is one of the most controversial topics in the management of heart failure. While the heart failure community utilizes them and recognizes the state of inotrope dependency, retrospective analyses and registry data have overwhelmingly suggested high mortality, which is logically to be expected given the advanced disease states of those requiring their use. Currently, there is a relative paucity of randomized control trials due to the ethical dilemma of creating control groups by withholding inotropes from patients who require them. Nonetheless, results of such trials have been mixed. Many were also performed with agents no longer in use, on patients without an indication for inotropes, or at a time before automatic cardio-defibrillators were recommended for primary prevention. Thus, their results may not be generalizable to current clinical practice. In this review, we discuss current indications for inotrope use, specifically dobutamine and milrinone, depicting their mechanisms of action, delineating their patterns of use in clinical practice, defining the state of inotrope dependency, and ultimately examining the literature to ascertain whether evidence is sufficient to support the current view that these agents increase mortality in patients with heart failure. Our conclusion is that the evidence is insufficient to link inotropes and increased mortality in low output heart failure.

Elevation of Plasma Milrinone Concentrations in Stage D Heart Failure Associated With Renal Dysfunction

Purpose:

To determine steady state milrinone concentrations in patients with stage D heart failure (HF) with and without renal dysfunction

Methods:

We retrospectively identified patients with stage D HF at a single medical center on continuous milrinone infusion at the time of plasma collection for entry into a research registry database. Milrinone was prescribed and titrated to improve hemodynamic and clinical status by a cardiologist. Plasma samples were obtained at steady state milrinone concentrations. Patients were stratified by creatinine clearance (CrCl) into 4 groups: group 1 (CrCl >60 mL/min), group 2 (CrCl 60-30 mL/min), group 3 (CrCl <30 mL/min), and group 4 (intermittent hemodialysis). Retrospective chart review was performed to quantify the postmilrinone hemodynamic changes by cardiac catheterization and electrophysiologic changes by implantable cardiac defibrillator (ICD) interrogation.

Results:

A total of 29 patients were identified: group 1 (n = 14), group 2 (n = 10), group 3 (n = 3), and group 4 (n = 2). The mean infusion rate (0.391 ± 0.08 µg/kg/min) did not differ between groups ( P = 0.14). The mean milrinone concentration was 451± 243 ng/mL in group 1, 591 ± 293 ng/mL in group 2, 1575 ± 962 ng/mL in group 3, and 6252 ± 4409 ng/mL in group 4 ( P<0.05 compared to groups 1). There was no difference in postmilrinone hemodynamic improvements between the groups ( P=0.41). The ICD interrogation revealed limited comparisons, but 6 of the 8 postmilrinone ventricular tachycardia episodes requiring defibrillation occurred in group 4 patients.

Conclusion:

Patients with stage D HF having severe renal dysfunction have elevated milrinone concentrations. Future studies of milrinone concentrations are warranted to investigate the potential risk of life-threatening arrhythmias and potential dosing regimens in renal dysfunction.

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.

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.

Outpatient continuous inotrope infusion as an adjunct to heart failure therapy in Duchenne muscular dystrophy

We report the use of continuous intravenous inotrope infusion as a palliative management strategy for the treatment of symptomatic, refractory, end stage cardiac dysfunction in patients with Duchenne muscular dystrophy. Milrinone and/or dobutamine administered by continuous intravenous infusion provided symptomatic and objective cardiovascular improvement up to 30 months in 3 individuals with Duchenne muscular dystrophy and severe dilated cardiomyopathy. Continuous inotrope infusion should be considered a practical treatment strategy for end stage cardiac dysfunction in Duchenne muscular dystrophy patients when cardiac transplantation is not a viable option.

Home continuous positive inotropic infusion as a bridge to cardiac transplantation in patients with end-stage heart failure

BACKGROUND

The clinical use of positive inotropic therapy at home in patients awaiting cardiac transplantation has not been reported since United Network for Organ Sharing (UNOS) regulations were changed to allow home infusions in Status 1B patients.

METHODS

We observed 21 consecutive patients with UNOS 1B status during positive inotropic therapy at home. We used hemodynamic monitoring at the initiation of therapy to optimize dosing. We selected for home therapy patients with stable clinical status and improved functional capacity during inotropic treatment. Implantable cardioverter defibrillators were placed in all but 1 patient before discharge.

RESULTS

Initial positive inotropic therapy included dobutamine in 12 patients (mean dose, 4.5 mcg/kg/min; range, 2.5-7.5 mcg/kg/min), milrinone in 8 patients (mean dose, 0.44 mcg/kg/min; range, 0.375-0.55 mcg/kg/min), and dopamine at a dose of 3 mcg/kg/min in 1 patient. Patients had improved functional capacity (New York Heart Association Class 3.7 +/- 0.1 to 2.4 +/- 0.2, p < 0.01), improved renal function (serum creatinine, 1.5 +/- 0.1 to 1.3 +/- 0.1, p < 0.01), improved resting hemodynamics, and decreased number of hospitalizations during positive inotropic infusion therapy when compared with pre-treatment baseline. Implantable cardioverter defibrillator discharges were infrequent (0.19 per 100 patient days of follow-up). Actuarial survival to transplantation at 6 and 12 months was 84%.

CONCLUSIONS

Continuous positive inotropic therapy at home was safe and was associated with decreased health care costs in selected patients awaiting cardiac transplantation.

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.

Hemodynamic effects of a new inotropic compound, PST-2744, in dogs with chronic ischemic heart failure

Inotropic agents for acute decompensated heart failure are associated with a lack of efficacy or increased mortality. New compounds are needed to support patients with acute exacerbations of heart failure. This study examined the hemodynamic effects of a new inotropic agent (PST-2744) in dogs with chronic ischemic heart failure. Eight mongrel dogs at low risk for postmyocardial infarction (MI) sudden death entered the protocol. Dogs were studied after ischemic left ventricular dysfunction was induced by repeated injections of latex microspheres into the circumflex artery until the ejection fraction reached 35%. Hemodynamic parameters were measured at baseline and peak drug effect (PST-2744 5 microg.kg-1.min-1). In 5 animals, PST-2744 effects were compared with dobutamine. Heart rates, PR intervals and QT intervals were unchanged following PST-2744 administration. PST-2744 increased contractility (+dP/dt) by 56% from 1881 +/- 282 mm Hg/s to 2939 +/- 734 mm Hg/s (P < 0.01). The inotropic effect of PST-2744 was equal to that produced by 5-microg.kg-1.min-1 dobutamine (56% increase in +dP/dt), but peak heart rates were significantly higher with dobutamine (129 +/- 24 bpm PST-2744 versus 160 +/- 6 bpm 5-microg.kg-1.min-1 dobutamine, P < 0.002). No arrhythmias or conduction delays were seen with either compound. PST-2744 is an effective inotropic agent without positive chronotropic effect in subjects with stable moderate left ventricular dysfunction.

Effect of beta 1 blockade with atenolol on progression of heart failure in patients pretreated with high-dose enalapril

BACKGROUND

The survival benefit of beta-blocker treatment in patients with heart failure has been established in recent trials. Yet, the impact of beta-blockers added on high dose angiotensin converting enzyme inhibitors has not been reported.

AIMS

To investigate the effect of atenolol, a hydrophilic, selective beta1-adrenergic antagonist, added on enalapril 40 mg/day in patients with advanced left ventricular dysfunction in a double-blind placebo-controlled trial.

METHODS

One hundred and nineteen patients with class II or III heart failure, left ventricular ejection fraction < or = 25% and treatment with 40 mg enalapril daily were given an initial challenge dose of atenolol 12. 5 mg. One hundred patients (54 with idiopathic, 28 with ischemic, 18 with other dilated cardiomyopathy) tolerated challenge and were randomized to atenolol (maintenance dose 89+/-11 mg/day, range 50-100 mg/day) or placebo. The primary endpoint was combined worsening heart failure or death within 2 years, the secondary endpoint was hospitalization for cardiac events.

RESULTS

After 395+/-266 days interim analysis revealed a significant difference between the atenolol and placebo group (log rank P<0.01) and the trial was concluded. Twenty-seven patients had developed worsening heart failure (8 in the atenolol group vs. 19 in the placebo group) and 13 patients had died (5 in the atenolol vs. 8 in the placebo group). Overall there were 23 hospitalizations for cardiac events (6 in the atenolol group vs. 21 in the placebo group, P=0.07); 17 hospitalizations were due to worsening heart failure (5 in the atenolol group, 12 in the placebo-group, P=0.05) and 10 due to arrhythmias (1 in the atenolol group vs. 9 in the placebo group, P<0.01)

CONCLUSIONS

The data suggest that in patients with advanced left ventricular dysfunction, beta-blockers can provide substantial benefits supplementary to that already achieved with high dose enalapril treatment.

Milrinone for long-term pharmacologic support of the status 1 heart transplant candidates

BACKGROUND

We determined the efficacy of long-term therapy with milrinone alone or in combination with inotropic agents in status 1 heart transplant candidates as a pharmacological support until heart transplantation.

METHODS

Hemodynamic and biochemical variables were recorded in 29 status 1 men with symptoms of severe congestive heart failure, who received continuous intravenous milrinone alone (group 1, n = 21) or in combination with inotropic agents (group 2, n = 8) while awaiting heart transplantation.

RESULTS

Symptomatic relief was noted in all patients of both groups without any preoperative deaths. One patient (4.8%) of group 1 died on the second day and 1 patient of group 2 died 16.4 months after transplantation. Although pulmonary capillary wedge pressure (group 1, p = 0.021; group 2, p = 0.0002), mean pulmonary artery pressure (group 1, p = 0.051; group 2, p = 0.004), and pulmonary vascular resistance (group 1, p = 0.0026; group 2, p = 0.056) were reduced by 1 hour after the onset of treatment and maintained unchanged until transplantation, the changes in mean pulmonary artery pressure in group 1 and pulmonary vascular resistance in group 2 were statistically insignificant except in the posttransplantation period.

CONCLUSIONS

Long-term therapy with milrinone in combination with inotropic agents is safe and effective when only milrinone infusion is inadequate for pharmacologic support in status 1 candidates.

Intravenous therapy for advanced heart failure

Because of the standard use of oral neurohumoral antagonists, the role of intravenous agents for advanced heart failure patients has changed profoundly. Their current use as medical therapy is restricted to two indications: first, as short-term infusion (hours to days) in advanced heart failure patients who decompensate into a symptomatic New York Heart Association class IV condition and who are admitted for rapid hemodynamic support with intravenous vasodilators or inotropes; in these patients after hemodynamic and clinical stabilization, optimization of conventional heart failure therapy has to be reconsidered; second, as long-term application in heart transplantation candidates who are in a similar desperate condition although already receiving maximal oral heart failure therapy.

Tailored therapy using dobutamine and nitroglycerin in advanced heart failure

In 29 patients with advanced heart failure, therapy tailored to hemodynamic goals was attempted using an initial infusion of dobutamine and nitroglycerin (the latter in those with pulmonary hypertension) followed by escalating doses of oral vasodilators. In the 23 patients who were weaned from inodilator therapy, significant improvements in hemodynamic parameters and a low 90-day hospital readmission rate were documented.