Carvedilol titration in patients with congestive heart failure receiving inotropic therapy

Reinforcement of pimobendan with guideline-directed medical therapy may reduce the rehospitalization rates in patients with heart failure: retrospective cohort study

BACKGROUND

Pimobendan reportedly improves the subjective symptoms of heart failure. However, evidence of improved prognosis is lacking. This study aimed to determine whether reinforcing guideline-directed medical therapy (GDMT) improved rehospitalization rates for worsening heart failure in patients administered pimobendan.

METHODS

A total of 175 patients with heart failure who were urgently admitted to our hospital for worsening heart failure and who received pimobendan between January 2015 and February 2022 were included. Of the 175 patients, 44 were excluded because of in-hospital death at the time of pimobendan induction. The remaining 131 patients were divided into two groups, the reduced ejection fraction (rEF) (n = 93) and non-rEF (n = 38) groups, and further divided into the GDMT-reinforced and non-reinforced groups.

RESULTS

In patients with rEF, the rate of rehospitalization for heart failure was significantly lower in the GDMT-reinforced group than in the non-reinforced group (log-rank test, P = .04). However, the same trend was not observed in the non-rEF group.

CONCLUSIONS

Reinforcing GDMT may reduce the heart failure rehospitalization rate in patients with pimobendan administration and rEF. However, multicenter collaborative research is needed.

TRIAL REGISTRATION

IRB Approval by the Nippon Medical School Hospital Ethics Committee B-2021-433 (April 10, 2023).

Beta-blocker management in patients admitted for acute heart failure and reduced ejection fraction: a review and expert consensus opinion

The role of the beta-adrenergic signaling pathway in heart failure (HF) is pivotal. Early blockade of this pathway with beta-blocker (BB) therapy is recommended as the first-line medication for patients with HF and reduced ejection fraction (HFrEF). Conversely, in patients with severe acute HF (AHF), including those with resolved cardiogenic shock (CS), BB initiation can be hazardous. There are very few data on the management of BB in these situations. The present expert consensus aims to review all published data on the use of BB in patients with severe decompensated AHF, with or without hemodynamic compromise, and proposes an expert-recommended practical algorithm for the prescription and monitoring of BB therapy in critical settings.

Palliative Inotropes in Advanced Heart Failure: Comparing Outcomes Between Milrinone and Dobutamine

BACKGROUND

We sought to describe and compare outcomes among advanced patients with heart failure (not candidates for orthotopic heart transplant/left ventricular assist device) on long-term milrinone or dobutamine, which are not well-studied in the contemporary era.

METHODS AND RESULTS

We included adults with refractory stage D heart failure who were not candidates for orthotopic heart transplant or left ventricular assist device and discharged on palliative dobutamine or milrinone. The primary outcome was 1-year survival. A 6-month predictor of survival analysis was conducted. A total of 248 patients (133 on milrinone, 115 on dobutamine) were included. There were no differences in baseline comorbidities between milrinone and dobutamine cohorts, except for the prevalence of chronic kidney disease, which was higher in the dobutamine group. On discharge, the proportion of patients on beta-blockers and mineralocorticoid antagonists was higher in milrinone group. Overall, the 1-year mortality rate was 70%. The dobutamine cohort had a significantly higher 1-year mortality rate (84% vs 58%, P <0.001). The type of inotrope did not predict survival at 6 months when adjusted for discharge medications and comorbidities. Beta-blockers and angiotensin-converting enzyme/angiotensin receptor blocker/angiotensin receptor neprilysin inhibitor continued at discharge predicted survival at 6 months.

CONCLUSIONS

The 1-year mortality from palliative inotropes remains high. Compared with dobutamine, use of milrinone was associated with improved survival owing to better optimization of guideline-directed medical therapy, primarily beta-blocker therapy.

Beta-blockers and Ambulatory Inotropic Therapy

BACKGROUND

Continuous infusion of ambulatory inotropic therapy (AIT) is increasingly used in patients with end-stage heart failure (HF). There is a paucity of data concerning the concomitant use of beta-blockers (BB) in these patients.

METHODS

We retrospectively reviewed all patients discharged from our institution on AIT. The cohort was stratified into 2 groups based on BB use. The 2 groups were compared for differences in hospitalizations due to HF, ventricular arrhythmias and ICD therapies (shock or antitachycardia pacing).

RESULTS

Between 2010 and 2017, 349 patients were discharged on AIT (95% on milrinone); 74% were males with a mean age of 61 ± 14 years. BB were used in 195 (56%) patients, whereas 154 (44%) did not receive these medications. Patients in the BB group had longer duration of AIT support compared to those in the non-BB group (141 [1-2114] vs 68 [1-690] days). After adjusting for differences in baseline characteristics and indication for AIT, patients in the BB group had significantly lower rates of hospitalizations due to HF (hazard ratio [HR] 0.61 (0.43-0.86); P = 0.005), ventricular arrhythmias (HR 0.34 [0.15-0.74]; P = 0.007) and ICD therapies (HR 0.24 [0.07-0.79]; P = 0.02).

CONCLUSION

In patients with end-stage HF on AIT, the use of BB with inotropes was associated with fewer hospitalizations due to HF and fewer ventricular arrhythmias.

Long-term milrinone therapy as a bridge to heart transplantation: Safety, efficacy, and predictors of failure

BACKGROUND

Studies of long-term inotrope use in advanced HF have previously provided limited and conflicting results. This study aimed to evaluate the safety and efficacy of long-term milrinone use and identify predictors of failure to bridge to orthotropic heart transplant (OHT) in a cohort of end-stage heart failure (HF) patients listed for heart transplantation and receiving inotrope therapy.

METHODS

The study included 150 adults listed for OHT at a single center from 2001 to 2017 who received milrinone therapy for ≥30 days. Multivariate Cox proportional hazards models were used to identify factors associated with "failure" (left ventricular assist device, intra-aortic balloon pump, status downgrade due to instability, death) vs. "success" (OHT, recovery) during bridging to OHT.

RESULTS

"Failure" occurred in 33 (22%) patients. Factors independently associated with failure included male sex (HR = 7.6; p = 0.004), no implantable cardioverter-defibrillator (HR = 3.8; p = 0.009), and lack of guideline-directed medical therapy (GDMT) with a beta-blocker (HR = 7.8; p = 0.002) or angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (HR = 6.3; p < 0.001). Patients who received fewer guideline-directed medications had a higher cumulative probability of failure. Adverse events included central line-associated bloodstream infection (2.55 per 1000 line-days) and arrhythmia (1.59 per 1000 treatment-days).

CONCLUSIONS

Our findings suggest that long-term milrinone therapy in selected patients is associated with a high rate of successful bridging to OHT and a low rate of adverse events. Patients intolerant of GDMT are more likely to fail to bridge to OHT without mechanical support. Sex differences in outcomes associated with milrinone therapy should be explored.

Comparing the effects of milrinone and olprinone in patients with congestive heart failure

Phosphodiesterase-3 (PDE3) inhibitors are widely used among patients with congestive heart failure (CHF). However, no studies have compared the cardiovascular outcomes between different PDE3 inhibitors in CHF management. In this report, we retrospectively compared the clinical benefits of two PDE3 inhibitors, milrinone and olprinone, to determine which better controls the progression of CHF. A total of 288 hospitalized patients who received PDE3 inhibitors [(milrinone; n = 77 and olprinone; n = 211, respectively)] for CHF were retrospectively enrolled. The primary endpoint was defined as having a major adverse cardiovascular and cerebrovascular event (MACCE) or cardiac death by day 60. Kaplan-Meier curves and multivariate Cox proportional models were used to compare the outcomes for patients treated with milrinone and olprinone. We found no significant differences in the baseline characteristics between the two groups. In patients treated with milrinone, a greater incidence of a MACCE or cardiac death was observed (log rank; P = 0.005 and P = 0.01, respectively). Milrinone-treated patients with ischemic heart disease and chronic kidney disease (CKD) at stage ≥ 4 presented with greater incidence of MACCE (log rank; P < 0.001 and P = 0.006, respectively). Similarly, these patients were significantly more likely to succumb to cardiac death (log rank; P < 0.001 and P = 0.02). Multivariate Cox proportional hazard models demonstrated that milrinone treatment was an independent predictor of MACCE [hazard ratio (HR) 3.17; 95% CI 1.64-6.10] and cardiac death (HR 2.64; 95% CI 1.42-4.91). Oral administration of a β-blocker at discharge occurred more often in the olprinone-treated patients than in the milrinone-treated patients (63% vs. 29%, P = 0.004). We compared the outcomes of milrinone and olprinone treatment in patients with CHF. Those treated with milrinone were more likely to succumb to a MACCE or cardiac death within 60 days of treatment, which was especially true for patients with ischemic heart disease or CKD.

Novel role of phosphodiesterase inhibitors in the management of end-stage heart failure

In advanced heart failure (HF), chronic inotropic therapy with intravenous milrinone, a phosphodiesterase III inhibitor, is used as a bridge to advanced management that includes transplantation, ventricular assist device implantation, or palliation. This is especially true when repeated attempts to wean off inotropic support result in symptomatic hypotension, worsened symptoms, and/or progressive organ dysfunction. Unfortunately, patients in this clinical predicament are considered hemodynamically labile and may escape the benefits of guideline-directed HF therapy. In this scenario, chronic milrinone infusion may be beneficial as a bridge to introduction of evidence based HF therapy. However, this strategy is not well studied, and in general, chronic inotropic infusion is discouraged due to potential cardiotoxicity that accelerates disease progression and proarrhythmic effects that increase sudden death. Alternatively, chronic inotropic support with milrinone infusion is a unique opportunity in advanced HF. This review discusses evidence that long-term intravenous milrinone support may allow introduction of beta blocker (BB) therapy. When used together, milrinone does not attenuate the clinical benefits of BB therapy while BB mitigates cardiotoxic effects of milrinone. In addition, BB therapy decreases the risk of adverse arrhythmias associated with milrinone. We propose that advanced HF patients who are intolerant to BB therapy may benefit from a trial of intravenous milrinone as a bridge to BB initiation. The discussed clinical scenarios demonstrate that concomitant treatment with milrinone infusion and BB therapy does not adversely impact standard HF therapy and may improve left ventricular function and morbidity associated with advanced HF.

Infections, Arrhythmias, and Hospitalizations on Home Intravenous Inotropic Therapy

Inotropes improve symptoms in advanced heart failure (HF) but were associated with higher mortality in clinical trials. Recurrent hospitalizations, arrhythmias, and infections contribute to morbidity and mortality, but the risks of these complications with modern HF therapies are not well known. We collected arrhythmia, infection, and hospitalization data on 197 patients discharged from our institution from January 2007 to March 2013 on intravenous inotropes. Patients were followed until they died, received a transplant or left ventricular assist device, were weaned off inotropes, or remained on inotropes at the end of the study. All patients had stage D HF. At baseline, 30% had a history of ventricular tachycardia, 7.1% had a history of cardiac arrest, and 39% had a history of atrial fibrillation. During follow-up, 33 patients (17%) had one or more implantable cardioverter-defibrillator shocks. Of patients who had shocks, 27 patients (82%) had appropriate shocks for ventricular tachycardia/ventricular fibrillation, 3 patients (9%) had inappropriate shocks, and 3 patients (9%) had both appropriate and inappropriate shocks. The risk of implantable cardioverter-defibrillator shock was not related to dose of inotrope (p = 0.605). Fifty-seven patients (29%) had one or more infections during follow-up. Bacteremia was the most common type of infection. Implanted electrophysiology devices did not confer an increased risk of infection. One hundred twelve patients (57%) had one or more hospitalizations during follow-up. Common causes of hospitalizations were worsening HF symptoms (41%), infections (20%), and arrhythmias (12%). In conclusion, arrhythmias, infections, and rehospitalizations are important complications of inotropic therapy.

Weaning from inotropic support and concomitant beta-blocker therapy in severely ill heart failure patients: take the time in order to improve prognosis

AIMS

Beta-blockers improve the prognosis in heart failure (HF), but their introduction may seem impossible in patients dependent on inotropic support. However, many of these patients can be titrated on beta-blockers, but there is little evidence of successful clinical strategies.

METHODS AND RESULTS

We analysed the records of inotropy-dependent patients referred for assessment for heart transplantation. Thirty-six patients (45%) could not be weaned (NW) and underwent left ventricular assist device (LVAD) implantation or transplantation, or died. However, 44 (55%) were successfully weaned (SW). Neither the aetiology (ischaemic vs. non-ischaemic) nor cardiac indexes were different in the SW as compared with the NW group (2.27±0.5 vs. 2.15±0.6 L/min/m2). The NW patients had lower LVEF (15±5% vs. 19±5%, P=0.001), higher right atrial pressure (12±6 vs. 8±6 mmHg, P=0.02), and more severe mitral regurgitation (P<0.001) than the SW patients. At discharge, 35 of 44 SW patients were receiving beta-blockers. In 29 of them, a beta-blocker could only be initiated or continued during concomitant support with i.v. enoximone for a duration of 14.1±7.2 days. Patients discharged on a beta-blocker had an LVAD/transplantation-free cumulative survival of 71% during a follow-up of 2074±201 days (confidence interval 1679–2470).

CONCLUSION

It takes time to put severely ill HF patients on beta-blockers and it may require bridging with inotropes which are independent of beta-adrenergic receptors. Whether such a strategy may result in a better clinical outcome warrants further research.

Clinical Characteristics and Outcomes of Intravenous Inotropic Therapy in Advanced Heart Failure

BACKGROUND

Inotrope use in heart failure treatment was associated with improved symptoms, but worse survival in clinical trials. However, these studies predated use of modern heart failure therapies. This study evaluates contemporary outcomes on long-term inotropes.

METHODS AND RESULTS

We collected baseline and postinotrope data on 197 patients discharged on inotropes between January 2007 and March 2013. Baseline characteristics, hemodynamic and clinical changes on inotropes, and survival were evaluated. Patients initiated on inotropes had refractory heart failure, with median baseline New York Heart Association class IV, cardiac index of 1.7 L/min per m(2), pulmonary capillary wedge pressure of 25.6 mm Hg, and left ventricular ejection fraction of 18.7%. Inotropes were used in patients listed for transplant or scheduled for left ventricular assist device (LVAD; 60 patients), in patients being evaluated for LVAD/transplant (20 patients), for stabilization pending cardiac resynchronization therapy/percutaneous coronary intervention (4 patients), in patients who were offered LVAD but chose inotropes (15 patients), and for palliation (98 patients). Milrinone was used in 84.8% and dobutamine in 15.2%. At the end of the study, 68 patients had died, 24 were weaned off inotropes, 23 were transplanted, 32 received LVADs, and 50 remained on inotropes. Patients who received inotropes for palliation or those who preferred inotropes over LVAD had median survival of 9.0 months (interquartile range, 3.1-37.1 months), actuarial 1-year survival of 47.6%, and 2-year survival of 38.4%. Of 60 patients who were placed on inotropes as a bridge to transplant/LVAD, 55 were successfully maintained on inotropes until transplant/LVAD.

CONCLUSIONS

Survival on inotropes for patients who are not candidates for transplant/LVAD is modestly better than previously reported, but remains poor. Inotropes are effective as a bridge to transplant/LVAD.

Effects of cilostazol in the heart

Cilostazol is a selective phosphodiesterase 3 (PDE3) inhibitor approved by the Food and Drug Administration for treatment of intermittent claudication. It has also been used in bradyarrhythmic patients to increase heart rates. Recently, cilostazol has been shown to prevent ventricular fibrillation in patients with Brugada syndrome. Cilostazol is hypothesized to suppress transient outward potassium (Ito) current and increase inward calcium current, thus, maintaining the dome (phase 2) of action potential, decreasing transmural dispersion of repolarization and preventing ventricular fibrillation. Although many PDE3 inhibitors have been shown to increase cardiac arrhythmia in heart failure, cilostazol has presented effects that are different from other PDE3 inhibitors, especially adenosine uptake inhibition. Owing to this effect, cilostazol could be an effective cardioprotective drug, with its beneficial effects in preventing arrhythmia. In this review, the cardiac electrophysiological effects of cilostazol are presented and its possible cardioprotective effects, particularly in preventing ventricular fibrillation, are discussed, with emphasis on the need to further verify its clinical benefits.

Use of Combination Therapy with a β-Blocker and Milrinone in Patients with Advanced Heart Failure

Objective:

To review the literature evaluating the clinical effects of combination therapy with a β-blocker and milrinone in patients with severe heart failure (HF).

Data Sources:

Literature was accessed through MEDLINE (1950–June 2009), PubMed (1966–June 2009), and International Pharmaceutical Abstracts (1970–June 2009), with combinations of the following terms: positive inotrope, milrinone, dobutamine, and β-receptor blocker. In addition, reference citations from publications identified were reviewed.

Study Selection and Data Extraction:

All articles that examined the effect of combination therapy with a β-blocker and milrinone on clinical endpoints in patients with advanced HF were assessed.

Data Synthesis:

A search of the literature revealed 4 studies examining the clinical effects of combination therapy with a β-blocker and milrinone. Three of these studies were retrospective reviews, while one was a post hoc subgroup analysis from the OPTIME-CHF study. Concomitant therapy with milrinone and a β-blocker was well tolerated, with no significant increase in adverse events or deterioration in clinical status in any study. Tolerability rates for combination therapy ranged from 88% to 92%. In 2 of the studies, roughly 50% of the patients in the combination arm were able to be weaned off milrinone. One study suggested a mortality reduction in favor of combination therapy over milrinone alone, while another study suggested no difference in mortality with combination therapy versus milrinone monotherapy. One study suggested a potential increase in mortality when β-blocker therapy was withdrawn in patients who were started on milrinone. None of the studies demonstrated any significant differences in hospitalization rates. All of the studies were limited by their retrospective nature and small sample size.

Conclusions:

Data are insufficient to make firm conclusions on the clinical benefit of combination therapy with a β-blocker and milrinone in patients with advanced HF, although it appears that this regimen is well tolerated and may allow weaning of inotropic support.

Quality-adjusted life year weights among elderly patients with heart failure

BACKGROUND

When assessing health-related quality of life (HRQoL) in elderly patients with heart failure (HF), the process of obtaining quality-adjusted life year (QALY) weights is generally complicated and time-consuming.

AIM

To evaluate whether information regarding HRQoL and QALY weights can be derived directly from the established and widely used New York Heart Association (NYHA) functional classification system.

METHODS

NYHA functional status was assessed independently both by the individual patients and by the examining cardiologist in 323 elderly patients with symptoms of HF recruited from primary care. HRQoL was evaluated using the SF-36 questionnaire and a time trade-off (TTO) scenario. The TTO technique generates direct QALY weights.

RESULTS

Both the TTO technique and SF-36 values demonstrated a statistically significant correlation with NYHA functional status. The TTO values also correlated with all SF-36 dimensions. Increasing impairment was associated with statistically significant drops in both SF-36 values and TTO-based QALY weights. For patients in NYHA classes I-IV the QALY weights were 0.77, 0.68, 0.61, and 0.50, respectively. Thus in elderly patients, symptoms of HF have a major impact on perceived quality of life.

CONCLUSION

The results of the present study show that QALY weights, an important instrument in the health economic evaluation of treatment strategies, can be derived directly from NYHA classification in elderly HF patients.

Pediatric heart failure therapy with beta-adrenoceptor antagonists

Management of chronic heart failure in pediatrics has been altered by the adult literature showing improvements in mortality and hospitalization rates with the use of beta-adrenoceptor antagonists (beta-blockers) for routine therapy of all classes of ischemic and non-ischemic heart failure. Many pediatric heart failure specialists have incorporated these agents into their routine management of pediatric heart failure related to dilated cardiomyopathy or ventricular dysfunction in association with congenital heart disease. Retrospective and small prospective case series have shown encouraging improvements in cardiac function and symptoms, but interpretation has been complicated by the high rate of spontaneous recovery in pediatric patients. A recently completed pediatric double-blind, randomized, placebo-controlled clinical trial showed no difference between placebo and two doses of carvedilol over a 6-month period of follow-up, with significant improvement of all three groups over the course of evaluation. Experience with adults has suggested that only certain beta-blockers, including carvedilol, bisoprolol, nebivolol, and metoprolol succinate, should be used in the treatment of heart failure and that patients with high-grade heart failure may derive the most benefit. Other studies surmise that early or prophylactic use of these medications may alter the risk of disease progression in some high-risk subsets, such as patients receiving anthracyclines or those with muscular dystrophy. This article reviews these topics using experience as well as data from all the recent pediatric studies on the use of beta-blockers to treat congestive heart failure, especially when related to systolic ventricular dysfunction.

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.

Tips and tricks on outpatient initiation and uptitration of beta-blockade in heart failure

beta-blockade has a therapeutic role across the continuum of patients with heart failure (HF), with a demonstrated mortality benefit in stage II and III HF. Concerns regarding initiation and uptitration linger as patients with resting bradycardia, pulmonary, or vascular disease are often unnecessarily excluded from receiving therapy. We will review the risk data on beta-blockade and offer therapeutic strategies to help overcome residual barriers to the initiation and uptitration of this important therapy in patients with HF.

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.

Beta-blocker use in decompensated heart failure

Despite the current advances in treatment, acute decompensated heart failure accounts for more than 1 million hospital admissions annually. Many of the patients hospitalized are already receiving long-term treatment with beta-blockers. For patients who receive full dose beta-blocker therapy and suffer acute decompensated heart failure, clinicians face two key questions: what to do, if anything, with the dosage of beta-blocker and what is the best way to integrate inotropic and beta-blocker therapies for patients who require inotropes. This article discusses these issues and reviews the available literature. Because these topics have received little systematic evaluation, we also present our clinical approaches to these problems.

Cardiovascular effects of a phosphodiesterase III inhibitor in the presence of carvedilol in dogs

The aim of this study was to determine whether dobutamine, dopamine, or milrinone (a phosphodiesterase [PDE] III inhibitor) would support cardiac function that had been attenuated by administration of the beta-blocker, carvedilol (0.2, 0.4, or 0.8 mg/kg). Hemodynamic and cardiac parameters including the heart rate (HR), left-ventricular fractional shortening (FS), and arterial pressure were measured in six healthy dogs without cardiac disease. Carvedilol did not affect FS or arterial pressure, but decreased the HR significantly. The positive inotropic and chronotropic responses to dobutamine and dopamine were attenuated by carvedilol, whereas arterial pressure was unaffected. Milrinone did not affect the HR and decreased arterial pressure, whereas FS was significantly greater both in the control and carvedilol-treated groups. Although milrinone affect the negative chronotropic effects of carvedilol, milrinone increased FS and prevented the decrease in arterial pressure. These results suggest that inhibition of PDE III preserves cardiac contractility and hemodynamic function in the presence of carvedilol.

Inhibitors of cyclic nucleotide phosphodiesterase 3 and 5 as therapeutic agents in heart failure

Cyclic nucleotide phosphodiesterases (PDE) 3 and 5 regulate cAMP and cGMP signalling in cardiac and smooth muscle myocytes. Important advances in the understanding of the roles of these enzymes have recently been made. PDE3 inhibitors have inotropic and vasodilatory properties, and although they acutely improve haemodynamics in patients with heart failure, they do not improve long-term morbidity and mortality. Although combination therapy with beta-adrenergic receptor antagonists or selective inhibition of specific PDE3 isoforms might result in a more favourable long-term outcome, more clinical data are needed to test this proposition. The role of PDE5 inhibitors in the treatment of cardiac disease is evolving. PDE5 inhibitors cause pulmonary and systemic vasodilation. How these drugs will compare with other vasodilators in terms of long-term outcomes in patients with heart failure is unknown. Recent studies also suggest that PDE5 inhibitors may have antihypertropic effects, exerted through increased myocardial cGMP signalling, that could be of additional benefit in patients with heart failure.

BNP-guided therapy not better than expert's clinical assessment for beta-blocker titration in patients with heart failure

B-type natriuretic peptide (BNP) is a cardiac neurohormone used as a noninvasive tool for diagnosing and monitoring heart failure. Beta blockers have beneficial effects in patients with heart failure as well as a direct effect on BNP plasma levels. The aim of this study is to compare the efficacy of a BNP-guided approach vs. standard care on beta-blocker titration in heart failure patients. Forty-one patients with heart failure were randomized into a clinical trial. Bisoprolol was started, and the dose was regularly up-titrated. BNP was measured monthly. The clinical group had beta-blocker dosage increased according to standard care, whereas the BNP group had beta-blocker dosage up-titrated according to plasma BNP levels plus standard care. The primary outcome was mean beta-blocker dose achieved after 3 months. BNP levels, left ventricular ejection fraction, clinical score, quality of life, and hospitalization were collected in all patients. BNP-guided up-titration of beta blocker in ambulatory patients with heart failure did not result in higher doses of beta blocker at the end of 3 months+/-SD (5.9+/-4.3 mg vs. 4.4+/-3.4 mg, p=0.22). Left ventricular ejection fraction was significantly improved in both groups by 7.3% (95% confidence interval, 4.1%-10.4%; p<0.0001). A trend toward better quality of life was seen in the BNP group.

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.

Alterations in cAMP-mediated signaling and their role in the pathophysiology of dilated cardiomyopathy

Dilated cardiomyopathy is a disease characterized by enlargement of the chambers of the heart and a decrease in contractility of the heart muscle. The process involves several alterations in proteins involved in cyclic adenosine monophosphate (cAMP) generation that result in a decrease in intracellular cAMP content per unit of adrenergic stimulation in cardiac myocytes. A fundamental question is whether these changes constitute a pathologic mechanism that contributes to chamber enlargement and hypocontractility or a compensatory adaptation that protects the heart from the adverse effects of increased catecholamine stimulation. Clinical studies in humans suggest that the latter effect may be more important. Studies in animal models, however, make the picture more complex: changes in cAMP-mediated signaling can have different effects depending on the specific protein whose expression or function is altered and the setting in which the alteration occurs. It may be that dilated cardiomyopathy represents a collection of different diseases in which alterations in cAMP-mediated signaling have different roles in the pathophysiology of the disease, and, furthermore, that changes in the phosphorylation of individual substrates of cAMP-dependent protein kinase may be either beneficial or harmful. Identifying differences among patients with dilated cardiomyopathy with respect to the role of altered cAMP-mediated signaling in their pathology, and identifying the "good" and "bad" substrates of cAMP-dependent protein kinase, are important areas for further research.

Carvedilol: a review of its use in chronic heart failure

Carvedilol (Dilatrend) blocks beta(1)-, beta(2)- and alpha(1)-adrenoceptors, and has antioxidant and antiproliferative effects. Carvedilol improved left ventricular ejection fraction (LVEF) in patients with chronic heart failure (CHF) in numerous studies. Moreover, significantly greater increases from baseline in LVEF were seen with carvedilol than with metoprolol in a double-blind, randomised study and in a meta-analysis. Carvedilol also reversed or attenuated left ventricular remodelling in patients with CHF and in those with left ventricular dysfunction after acute myocardial infarction (MI). Combined analysis of studies in the US Carvedilol Heart Failure Trials Program (patients had varying severities of CHF; n = 1094) revealed that mortality was significantly lower in carvedilol than in placebo recipients. In addition, the risk of hospitalisation for any cardiovascular cause was significantly lower with carvedilol than with placebo. Mortality was significantly lower with carvedilol than with metoprolol in patients with mild to severe CHF in the Carvedilol Or Metoprolol European Trial (COMET) [n = 3029]. The Carvedilol Prospective Randomised Cumulative Survival (COPERNICUS) trial (n = 2289) demonstrated that compared with placebo, carvedilol was associated with significant reductions in all-cause mortality and the combined endpoint of death or hospitalisation for any reason in severe CHF. All-cause mortality was reduced in patients who received carvedilol in addition to conventional therapy compared with those who received placebo plus conventional therapy in the Carvedilol Post-Infarct Survival Control in LV Dysfunction (CAPRICORN) trial (enrolling 1959 patients with left ventricular dysfunction following acute MI). Carvedilol was generally well tolerated in patients with CHF. Adverse events associated with the alpha- and beta-blocking effects of the drug occurred more commonly with carvedilol than with placebo, whereas placebo recipients were more likely to experience worsening heart failure. In conclusion, carvedilol blocks beta(1)-, beta(2)- and alpha(1)-adrenoceptors and has a unique pharmacological profile. It is thought that additional properties of carvedilol (e.g. antioxidant and antiproliferative effects) contribute to its beneficial effects in CHF. Carvedilol improves ventricular function and reduces mortality and morbidity in patients with mild to severe CHF, and should be considered a standard treatment option in this setting. Administering carvedilol in addition to conventional therapy reduces mortality and attenuates myocardial remodelling in patients with left ventricular dysfunction following acute MI. Moreover, mortality was significantly lower with carvedilol than with metoprolol in patients with mild to severe CHF, suggesting that carvedilol may be the preferred beta-blocker.

PDE3 inhibition in dilated cardiomyopathy: reasons to reconsider

BACKGROUND

PDE3 cyclic nucleotide phosphodiesterases have important roles in regulating cAMP- and cGMP-mediated signaling. Drugs that inhibit these enzymes raise cAMP and cGMP content in cardiac and vascular smooth muscle and increase the phosphorylation of proteins by cAMP- and cGMP-dependent protein kinases (PK-A and PK-G), thereby eliciting inotropic and vasodilatory responses.

METHODS

Although these actions are beneficial acutely in patients with dilated cardiomyopathy, long-term use of these agents was shown in several clinical trials to increase mortality. Several new clinical studies, however, suggest PDE3 inhibitors may be safe and effective when used in conjunction with beta-adrenergic receptor antagonists, whereas new studies at the cellular and molecular levels indicate that there are several isoforms of these enzymes in cardiac and vascular myocytes that are likely to regulate cAMP content in different intracellular compartments.

CONCLUSIONS

Both sets of observations suggest that PDE3 inhibition may be refined to allow more selective effects on phosphorylation of PK-A substrates, possibly allowing the beneficial effects of PDE3 inhibition to be separated from the adverse long-term consequences of their use.

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.

Inhibitors of cyclic nucleotide phosphodiesterase PDE3 as adjunct therapy for dilated cardiomyopathy

PDE3 cyclic nucleotide phosphodiesterases are important in cyclic AMP (cAMP) and possibly cyclic GMP-mediated signalling in cardiac and vascular smooth muscle myocytes. Drugs that inhibit these enzymes have inotropic and vasodilatory actions that have proven useful in the short-term treatment of contractile failure and pulmonary hypertension in dilated cardiomyopathy (both ischaemic and idiopathic). With long-term usage, however, these drugs appear to increase mortality in treated patients through an as yet undetermined mechanism that is in some way attributable to an increase in intracellular cAMP content in cardiac myocytes. Several recent clinical trials have raised the possibility that these drugs may be used to advantage in dilated cardiomyopathy when they are administered in combination with beta-adrenoceptor antagonists, which act to lower intracellular cAMP content. In this review, the relevant basic and clinical data are examined and the possible justification for the combination of two therapies with seemingly opposite effects on intracellular cAMP content is considered.

Beta-blocker therapy influences the hemodynamic response to inotropic agents in patients with heart failure: a randomized comparison of dobutamine and enoximone before and after chronic treatment with metoprolol or carvedilol

OBJECTIVE

We compared the hemodynamic effects of dobutamine and enoximone administration before and after long-term beta-blocker therapy with metoprolol or carvedilol in patients with chronic heart failure (HF).

BACKGROUND

Patients with HF on beta-blocker therapy may need hemodynamic support with inotropic agents, and the hemodynamic response may be influenced by both the inotropic agent and the beta-blocker used.

METHODS

The hemodynamic effects of dobutamine (5 to 20 microg/kg/min intravenously) and enoximone (0.5 to 2 mg/kg intravenously) were assessed by pulmonary artery catheterization in 29 patients with chronic HF before and after 9 to 12 months of treatment with metoprolol or carvedilol at standard target maintenance oral doses. Hemodynamic studies were performed after >/=12 h of wash-out from all cardiovascular medications, except the beta-blockers that were administered 3 h before the second study.

RESULTS

Compared with before beta-blocker therapy, metoprolol treatment decreased the magnitude of mean pulmonary artery pressure (PAP) and pulmonary wedge pressure (PWP) decline during dobutamine infusion and increased the cardiac index (CI) and stroke volume index (SVI) response to enoximone administration, without any effect on other hemodynamic parameters. Carvedilol treatment abolished the increase in heart rate, SVI, and CI and caused a rise, rather than a decline, in PAP, PWP, systemic vascular resistance, and pulmonary vascular resistance during dobutamine infusion. The hemodynamic response to enoximone, however, was maintained or enhanced in the presence of carvedilol.

CONCLUSIONS

In contrast with its effects on enoximone, carvedilol and, to a lesser extent, metoprolol treatment may significantly inhibit the favorable hemodynamic response to dobutamine. No such beta-blocker-related attenuation of hemodynamic effects occurs with enoximone.