Beneficial effects of early initiation of vasoactive agents in patients with acute decompensated heart failure

Early diagnosis and treatment of acute decompensated heart failure (ADHF) results in improved clinical outcomes, reduced resource utilization, improved quality of life, and lower treatment costs. Currently, heart failure results in nearly 1 million hospitalizations annually in the United States, and 50% of hospitalized patients are readmitted within 6 months of initial discharge. The costs associated with resource utilization are substantial. Despite the personal and societal burden of this condition, until recently, very little progress had been made in optimizing treatment of ADHF. Nesiritide, a human recombinant B-type natriuretic peptide, is a safe, effective vasodilator that can be easily used early in the emergency department to improve outcomes in ADHF.

Milrinone Facilitates Resuscitation From Cardiac Arrest and Attenuates Postresuscitation Myocardial Dysfunction

Background— Left ventricular (LV) dysfunction with a low cardiac index after successful CPR contributes to early death attributable to multiorgan failure, and an effective treatment has not been identified. The purpose of this study was to investigate the use of milrinone, a selective phosphodiesterase III inhibitor, as treatment for LV dysfunction after resuscitation.

Methods and Results— Ventricular fibrillation (VF) was induced electrically in 32 swine. After 5 minutes of VF, CPR was initiated and animals were randomized to receive either saline (control group, n=16) as a bolus and infusion or milrinone 50 μg/kg as a bolus and then 0.5 μg/kg per min for 60 minutes (treatment group, n=16). After 2 minutes of CPR (total VF time, 7 minutes), countershocks were given. Coronary perfusion pressures during CPR were similar for the groups (24±2 versus 21±4 mm Hg). All animals were defibrillated; 6 of 16 control animals developed refractory postcountershock pulseless electrical activity compared with 0 of 16 treated animals ( P =0.018). At 30 minutes after restoration of spontaneous circulation, stroke volume (16±3 versus 26±7 mL, P <0.01) and LV dp/dt (793±197 versus 1108±316 mm Hg/s, P <0.02) were higher in the treatment group. Similar differences were observed 60 minutes after restoration of spontaneous circulation. Significant differences in heart rates between groups were not observed, and peripheral vascular resistance was significantly greater in the control group 30 and 60 minutes after resuscitation.

Conclusions— Milrinone facilitates resuscitation from prolonged VF and attenuates LV dysfunction after resuscitation without worsening major determinants of myocardial oxygen demand.

Case studies in heart failure

This article presents four case studies of patients with heart failure and the rationale for optimal treatment in each case.

Prophylactic milrinone during OPCAB of posterior vessels: implication in angina patients taking β-blockers

OBJECTIVE

To determine whether a phosphodiesterase type 3 inhibitor can improve hemodynamics during off-pump coronary artery bypass grafting (OPCAB) of posterior vessels in patients on beta(1)-adrenoreceptor blockers.

METHODS

Thirty patients scheduled for OPCAB of the obtuse marginal artery (OM), and taking atenolol 100 mg a day were randomized in a double-blind manner to receive either milrinone or placebo. Hemodynamic data were obtained after induction, before pericardial incision, during left anterior descending artery grafting, during OM grafting, and after removal of the stabilizer. During the OM grafting, dopamine was infused when the cardiac index (CI) decreased below 2.0 L/min/m(2), and phenylephrine was infused to maintain the arterial pressure with a CI above 2.0 L/min/m(2).

RESULTS

During OM anastomosis, there were significant differences in CI (milrinone [M] = +7.7%, control [C] = -13.7%, p=0.01), SVI (M=-21.5%, C=-35.8%, p=0.03), SvO(2) (M=-2.6%, C=-8.9%, p=0.02), and SVR (M=-28.1%, C=+1.1%, p=0.01) between the two groups, in terms of percentage change from baseline value. Dopamine was required more frequently and at a higher dose in the control group (M=13%, 5.0 microg/kg/min; C=67%, 10.1 microg/kg/min, p<0.05). Phenylephrine was infused in 33% of the patients in the milrinone group compared to 13% in the control group (p>0.05).

CONCLUSIONS

Prophylactic milrinone improves CI, SVI and SvO(2) reducing the need for high doses of dopamine during OM anastomosis in patients taking atenolol. Therefore, it can be used as an alternative to dopamine improving hemodynamics and organ perfusion during OPCAB of posterior vessels in patients on beta(1)-blockers.

Anesthetic Management for Implantation of the Jarvik 2000??? Left Ventricular Assist System

The Jarvik 2000 Heart(TM) is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a single, rotating, vaned impeller. Anesthetic and perioperative considerations of the Jarvik 2000 Heart(TM) differ from those of conventional assist devices. The Jarvik 2000 is implanted within the left ventricle through a left thoracotomy, which is aided by left lung isolation. A brief period of cardiopulmonary bypass and induced ventricular fibrillation facilitate implantation. Transesophageal echocardiography is essential to assure proper intraventricular positioning of the device and aortic outflow, confirmed by observation of aortic valve opening in the presence of adequate left ventricular volume. Because continuous flow devices function best in the presence of lower systemic and pulmonary vascular resistance, milrinone was preferentially used as an inotropic drug. In the first group of 10 patients to receive the Jarvik 2000, the pump provided a cardiac output of up to 8 L/min, depending on preload, afterload, and pump speed. There were no early perioperative deaths. The average support duration was 81.2 days; the range was 13-214 days. Seven of the 10 patients survived to transplantation. Survivors underwent complete physical rehabilitation during pump support.

IMPLICATIONS

The Jarvik 2000 is a left ventricular assist device that produces continuous nonpulsatile axial flow by means of a rotating, vaned impeller. Because the anesthetic considerations differ from those of conventional left ventricular assist devices, we report the perioperative management of the first 10 patients who participated in a bridge-to-transplantation feasibility study of the Jarvik 2000.

Critical care in cardiovascular medicine

The field of cardiac intensive care is rapidly evolving with nearly simultaneous advances in surgical techniques and adjunctive therapies, respiratory care, intensive care technology and monitoring, pharmacologic research and development, and computing and electronics. The focus of care has now shifted toward reducing morbidity and improving "quality of life" while the survival of infants and children with congenital heart defects, including those with univentricular hearts has dramatically improved during the last three decades. Despite these advances, there remains a predictable fall in cardiac output after cardiopulmonary bypass. This article focuses on early identification and aggressive treatment of the low cardiac output syndrome peculiar to these patients. The authors also briefly review the recent advances in the treatment of pulmonary hypertension, mechanical support, and neurologic surveillance after cardiac surgery.

Usefulness of anemia as a predictor of death and rehospitalization in patients with decompensated heart failure

We investigated the prevalence of anemia and its relation to clinical events in patients with decompensated heart failure enrolled in the OPTIME-CHF study. Our data demonstrate that anemia is common in patients hospitalized with decompensated heart failure and is associated with a greater number of co-morbid conditions. Lower baseline hemoglobin is associated with risk of short-term adverse clinical outcomes in this population, even after controlling for other baseline differences.

Effect of nesiritide versus milrinone in the treatment of acute decompensated heart failure

The use of nesiritide in the improvement of patient hemodynamics, decreased length of stay (LOS), and rehospitalization is discussed. Nesiritide is a useful agent for the treatment of the acutely decompensated heart failure patient. Previous trials suggest that the use of nesiritide results in improved outcomes as compared with other agents. To date, there are no data comparing nesiritide to milrinone in the treatment of the acutely decompensated heart failure patient. Fifty-five patients admitted to the heart failure service were identified retrospectively; 29 received nesiritide and 26 received milrinone. Baseline characteristics, hemodynamic data, and LOS data were collected. Primary outcomes were the overall LOS, intensive care LOS, and readmission within 30 days of discharge. Other outcomes included duration of vasoactive agents used, overall diuresis, and total cost of therapy. Baseline hemodynamic data were similar between groups. Patients in the milrinone group had an overall LOS of 8.2 days compared to 7 days in the nesiritide group (p = NS). LOS in the intensive care unit was 5.9 days in the milrinone group compared with 3.9 days in the nesiritide group (p = 0.007). Readmission at 30 days was 28% in the milrinone group compared with 16% in the nesiritide group (p = NS). Infusion time was shorter in the nesiritide group, 50 versus 117 hours (p = 0.001). Cost of therapy (cost of bed, supplies, and drug) was $398 less per patient receiving nesiritide. The use of nesiritide led to improvement in patient hemodynamics and resulted in a trend toward decreases in LOS and rehospitalization. Total cost of therapy was lower in the nesiritide group as compared to those patients treated with milrinone.

Effects of preemptive therapy with milrinone or amrinone on perioperative platelet function and haemostasis in patients undergoing coronary bypass grafting

Preemptive therapy with a phosphodiesterase III inhibitor preserves cardiac function and oxygen transport after cardiac surgery, and its safety on platelet function and haemostasis must be verified. We examined the effects of preemptively administered milrinone or amrinone on platelet function and haemostasis. In 45 cardiac surgery patients, we randomly administered milrinone 50 microg/kg plus 0.5 microg/kg/min for 10 hours, amrinone 1.5 mg/kg plus 10 microg/kg/min infusion for 10 hours, or placebo at release of aortic cross-clamp. Whole blood platelet aggregation, haematological values, and postoperative chest drainage were examined. Three patients in the placebo, 1 patient in the amrinone, and 2 patients in the milrinone groups received allogenic blood transfusion (654 +/- 365 ml) intraoperatively, but no patient postoperatively. The mean platelet counts 3 days postoperative in the milrinone and amrinone groups did not significantly differ from the placebo group (10.9 +/- 3.3 and 12.1 +/- 3.8, vs. 12.1 +/- 3.4x10(4) per cubic millimeter, respectively), and chest-tube drainage in the first 24 hours did not significantly differ (450 +/- 156 and 391 +/- 184, vs. 448 +/- 140 ml, respectively). Although there were changes in platelet aggregation consequent to surgery there was no significant differences in platelet aggregation or other haematological values among the three groups. Preemptive therapy of milrinone or amrinone does not deteriorate perioperative platelet function and haemostasis beyond surgical interventions.

[The use of milrinone in a patient with mitral regurgitation and severe pulmonary hypertension: a case report]

A 65-year-old female with mitral regurgitation was scheduled for the mitral valve surgery. However, because of the severe pulmonary hypertension, the patient needed evaluation on the reversibility of pulmonary hypertension and the safety of the surgical procedure. Milrinone, a phosphodiesterase inhibitor with vasodilating and positive inotropic properties, known to lower pulmonary vascular resistance was administered to the patient. Milrinone showed a prompt decrease of pulmonary artery pressure and an increase of cardiac output, and the cardiac surgery was performed uneventfully. It is considered that milrinone is useful in lowering pulmonary vascular resistance and assessing the reversibility of pulmonary hypertension in patients with severe pulmonary hypertension undergoing cardiac surgery.

Milrinone improves lung compliance in patients receiving mechanical ventilation for cardiogenic pulmonary edema

BACKGROUND

Cardiogenic pulmonary edema is a frequent cause of respiratory failure. We investigated whether milrinone improved lung compliance.

METHODS

We selected 10 patients with respiratory failure due to severe cardiogenic pulmonary edema to receive mechanical ventilation. Patients were administered a bolus injection of milrinone (50 microg kg-1) over 10 min, followed by continuous intravenous infusion (0.5 microg kg-1 min-1). Lung compliance, blood gas values, hemodynamic parameters, and sample plasma milrinone levels were assessed over 120 min after the onset of the continuous infusion of milrinone.

RESULTS

Ten min following milrinone infusion, dynamic compliance (Cdyn) and static compliance (Cst) increased from 37 +/- 12 to 42 +/- 12 ml cmH2O-1 and from 40 +/- 13 to 45 +/- 12 ml cmH2O-1, respectively (P < 0.01). Plasma milrinone levels reached a therapeutic level for vasodilator and positive inotropic effect at 10 min after milrinone infusion. A significant decrease in mean pulmonary artery pressure and pulmonary artery wedge pressure occurred simultaneously with an increase in respiratory system compliance. However, an increase in cardiac index was observed later than these changes. There were significant correlations between the mean pulmonary artery pressure and Cdyn (r = -0.39, P < 0.01) and Cst (r = -0.38, P < 0.01).

CONCLUSIONS

Milrinone-induced improvement in lung compliance along with an improvement of hemodynamics was found together with an inverse relationship between compliance and mean pulmonary artery pressure.

Milrinone

MANY NEONATES WHO UNDERGO SURGICAL REPAIR FOR congenital heart defects are at high risk for developing low cardiac output syndrome following surgery.1A variety of causes contributes to diminished cardiac output. Four major factors are (1) age less than one month, (2) weight less than 2.5 kg, (3) preoperative condition, and (4) complexity of the heart defect.2

Morbidity and mortality of UNOS status 1B cardiac transplant candidates at home

BACKGROUND

On January 20, 1999, UNOS listing regulations changed, allowing stable patients on inotropic support (Status IB) to be discharged home until cardiac transplant. The outcome, morbidity and cost savings of this new strategy has not been evaluated.

METHODS

From 1/20/99 through 1/1/01, 155 patients were classified as UNOS Status 1B at our institution; 64 patients were never discharged and 91 were discharged home. Criteria for discharge were hemodynamic stability on low-dose, single-agent parenteral inotropic infusion, defined as dobutamine at a dose <7.5 microg/kg/min or milrinone <0.5 microg/kg/min. Data on re-admissions were collected prospectively. The frequency of complex ventricular arrhythmias was evaluated in a sub-group discharged with external or internal cardiodefibrillators (n = 38).

RESULTS

Total Status I time to transplant for the 91 discharged patients was 139 +/- 91 days, with 87 +/- 67 days spent at home. Inpatient time to transplant was still high, with a mean of 51 +/- 45 days. The in-hospital time was comparable to that of the 64 patients who were never discharged (51 +/- 41 days). Fifty-nine percent of discharged patients were re-admitted, with 37% of patients requiring more than 1 admission. Sixty-six percent of admissions were for worsening heart failure (CHF), and 34% for infection or occlusion of the indwelling intravenous line. No significant arrhythmic events were recorded in the 38 patients who had internal or external cardiodefibrillators. Two patients died suddenly at home. One patient had declined to wear the external cardiodefibrillator. The other patient was not wearing the defibrillator at the time of the event, and in 634 hours of previous monitoring he had had no events.

CONCLUSIONS

In UNOS Status 1B patients awaiting cardiac transplant on home inotropic therapy, mortality remains low but the re-admission rate was high. There appeared to be a low incidence of complex ventricular arrhythmias.

Heart failure etiology and response to milrinone in decompensated heart failure: results from the OPTIME-CHF study

OBJECTIVES

The goal of this study was to assess the interaction between heart failure (HF) etiology and response to milrinone in decompensated HF.

BACKGROUND

Etiology has prognostic and therapeutic implications in HF, but its relationship to response to inotropic therapy is unknown.

METHODS

The Outcomes of a Prospective Trial of Intravenous Milrinone for Exacerbations of Chronic Heart Failure (OPTIME-CHF) study randomized 949 patients with systolic dysfunction and decompensated HF to receive 48 to 72 h of intravenous milrinone or placebo. The primary end point was days hospitalized from cardiovascular causes within 60 days. In a post-hoc analysis, we evaluated the interaction between response to milrinone and etiology of HF.

RESULTS

The primary end point was 13.0 days for ischemic patients and 11.7 days for nonischemic patients (p = 0.2). Sixty-day mortality was 11.6% for the ischemic group and 7.5% for the nonischemic group (p = 0.03). After adjustment for baseline differences, there was a significant interaction between etiology and the effect of milrinone. Milrinone-treated patients with ischemic etiology tended to have worse outcomes than those treated with placebo in terms of the primary end point (13.6 days for milrinone vs. 12.4 days for placebo, p = 0.055 for interaction) and the composite of death or rehospitalization (42% vs. 36% for placebo, p = 0.01 for interaction). In contrast, outcomes in nonischemic patients treated with milrinone tended to be improved in terms of the primary end point (10.9 vs. 12.6 days placebo) and the composite of death or rehospitalization (28% vs. 35% placebo).

CONCLUSIONS

Milrinone may have a bidirectional effect based on etiology in decompensated HF. Milrinone may be deleterious in ischemic HF, but neutral to beneficial in nonischemic cardiomyopathy.

Role of nonglycosidic inotropic agents: indications, ethics, and limitations

Nonglycosidic inotropic agents have been used for the short-term management of low output states and hypotension complicating acute myocardial infarction for several years. Without adequate reperfusion of the ischemic myocardium, inotropic agents are seldom effective in producing sustained hemodynamic responses. Furthermore, the potential exists for enhancement of ischemia and extension of myocardial necrosis. Thus, inotropic and vasopressors therapy should be regarded as temporary supportive treatment in patients with acute coronary syndrome and should be discontinued as soon as feasible. Parenteral sympathomimetic agents, usually dobutamine, and phosphodiesterase inhibitors, usually milrinone, are used for the management of exacerbations of chronic systolic heart failure. Although hemodynamics, and occasionally clinical status, improve, such therapy is associated with increased mortality and can potentially hasten a patient's demise. Nonparenteral sympathomimetics, such as ibopamine, phosphodiesterase-III inhibitors, such as milrinone and enoximone, calcium-sensitizing agents, such as pimobendan, and other novel inotropic agents, such as vesnarinone, all increase mortality of patients with chronic heart failure. Furthermore, newer noninotropic agents, such as B-natriuretic peptide, have been introduced for treatment of decompensated heart failure. New nonpharmacologic devices, such as biventricular pacing, are available for the treatment of advanced heart failure. Thus, indications for the use of presently available nonglycosidic inotropic agents are limited and should be considered only for short-term therapy or when no other treatment is available.

Efficacy and safety of milrinone in preventing low cardiac output syndrome in infants and children after corrective surgery for congenital heart disease

BACKGROUND

Low cardiac output syndrome (LCOS), affecting up to 25% of neonates and young children after cardiac surgery, contributes to postoperative morbidity and mortality. This study evaluated the efficacy and safety of prophylactic milrinone in pediatric patients at high risk for developing LCOS.

METHODS AND RESULTS

The study was a double-blind, placebo-controlled trial with 3 parallel groups (low dose, 25- microg/kg bolus over 60 minutes followed by a 0.25- microg/kg per min infusion for 35 hours; high dose, 75- microg/kg bolus followed by a 0.75- microg/kg per min infusion for 35 hours; or placebo). The composite end point of death or the development of LCOS was evaluated at 36 hours and up to 30 days after randomization. Among 238 treated patients, 25.9%, 17.5%, and 11.7% in the placebo, low-dose milrinone, and high-dose milrinone groups, respectively, developed LCOS in the first 36 hours after surgery. High-dose milrinone significantly reduced the risk the development of LCOS compared with placebo, with a relative risk reduction of 55% (P=0.023) in 238 treated patients and 64% (P=0.007) in 227 patients without major protocol violations. There were 2 deaths, both after infusion of study drug. The use of high-dose milrinone reduced the risk of the LCOS through the final visit by 48% (P=0.049).

CONCLUSIONS

The use of high-dose milrinone after pediatric congenital heart surgery reduces the risk of LCOS.

New therapeutic choices in the management of acute congestive heart failure

Patients with acute congestive heart failure generally present with profound fluid retention states and dyspnea due to pulmonary edema. If the condition is not aggressively and appropriately treated, irreversible cardiac decompensation may ensue, leading to cardiogenic shock, multiorgan failure, and death. Intravenous inotropic, vasopressor, and vasodilator therapies have proved effective in initial stabilization of acute heart failure decompensation, but these agents, particularly the traditionally used ones, are generally limited by side effects that can be egregious and include substantive ventricular arrhythmias. Dobutamine has largely replaced agents with rather profound toxicity, such as isoproterenol and epinephrine. The phosphodiesterase-inhibiting agent milrinone, having both vasodilator and inotropic properties, can produce tachycardia and significant ventricular arrhythmias, but has proven quite useful for seriously ill patients. Clinical trials of levosimendan have found a positive inotropic response when the drug is given parenterally; vasodilating properties are also evident. Clinical trials are under way to evaluate the potential benefits of endothelin receptor antagonists when given intravenously. Intravenous administration of nesiritide, a recombinant human B-type natriuretic peptide, has been shown to produce favorable hemodynamic effects, including balanced vasodilation associated with a rapid improvement in clinical symptoms.

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

BACKGROUND

The use of dobutamine or milrinone for inotropic support in patients with heart failure awaiting cardiac transplantation is largely arbitrary and based on institutional preference. The costs and effectiveness of these drugs have yet to be compared in a prospective, randomized study.

METHODS

We compared clinical outcomes and costs associated with the use of dobutamine or milrinone in 36 hospitalized patients awaiting cardiac transplantation. Patients were randomly assigned to receive either dobutamine or milrinone at the time of initial hospitalization and were followed until death, transplantation, or placement of mechanical cardiac support (intra-aortic balloon pump or left ventricular assist device).

RESULTS

Seventeen patients were randomly assigned to receive dobutamine (mean dose 4.1 +/- 1.4 microg/kg/min) and 19 patients received milrinone (mean dose 0.39 +/- 1.0 microg/kg/min). Therapy lasted 50 +/- 46 days for those in the dobutamine group and 63 +/- 45 days in the milrinone group. We did not detect differences between the 2 groups in right heart hemodynamics, death, need for additional vasodilator/inotropic therapy, or need for mechanical cardiac support before transplantation. Ventricular arrhythmias requiring increased antiarrhythmic therapy occurred frequently in both groups. Total acquisition cost of milrinone was significantly higher than that of dobutamine (16,270 dollars +/- 1334 vs 380 dollars +/- 533 P <.00001).

CONCLUSIONS

Both dobutamine and milrinone can be used successfully as pharmacologic therapy for a bridge to heart transplantation. Despite similar clinical outcomes, treatment with milrinone incurs greater cost.

Clinical outcomes in patients on beta-blocker therapy admitted with worsening chronic heart failure

Beta blockers have been shown to reduce morbidity and mortality in patients with heart failure without evidence of overt congestion. No data are available describing outcomes of patients admitted with exacerbated chronic heart failure who are receiving beta blockade at the time of admission. The purpose of this analysis was to evaluate clinical outcomes in patients from the Outcomes of the Prospective Trial of Intravenous Milrinone for Exacerbations of Chronic Heart Failure (OPTIME-CHF) study who were prescribed beta blockers on admission compared with patients who were not prescribed beta blockers at admission. In all, 212 patients were treated with beta blockers at admission and 737 patients were not. Baseline characteristics were similar between groups, except that patients prescribed beta blockers on admission had slightly higher ejection fractions, fewer New York Heart Association class IV symptoms, and lower heart rates. There was no difference in clinical events between patients who were treated with beta blockers at the time of admission and those who were not. Exploratory analyses suggested that patients whose beta-blocker therapy was discontinued had a higher risk of adverse outcomes, particularly in the subset of patients randomized to milrinone. The data from this nonrandom comparison suggest that continuation of pre-existing beta-blocker therapy is not associated with an increased risk of adverse clinical events in patients admitted with worsening heart failure. These results also suggest that caution should be taken when withdrawing beta blockade in this population.