Efficacy of phosphodiesterase inhibition with milrinone in combination with converting enzyme inhibitors in patients with heart failure. The Milrinone Multicenter Trials Investigators

Anesthetic management of the patient undergoing heart transplantation

Cardiac transplantation is the treatment of choice for patients with end-stage heart failure. Over the years, significant advances in patient selection, donor optimization and selection, and optimization of immunosuppression strategies have markedly improved outcomes. In this review, we highlight patient selection, donor management and procurement, heart transplantation procedure, and intraoperative and postoperative management of heart transplants.

Incidence of Acute Renal Failure Associated with Milrinone

Background:

Milrinone is a phosphodiesterase type III inhibitor with positive inotropic and vasodilatory effects used in patients with severe congestive heart failure (CHF).

Objectives:

To determine the incidence rate of acute renal failure (ARF) associated with milrinone therapy.

Methods:

Medical records of 116 patients with cardiomyopathy/severe CHF who received milrinone were reviewed from January 1993 to January 1996. Twenty-nine patients were excluded, resulting in 87 patients, 4 of whom received milrinone twice.

Results:

During a 3-year period, 11 of 91 milrinone therapies became complicated with ARF (incidence 12%). The patients' age (mean ± SD) was 52.3 ± 13.6 years, baseline serum creatinine (SCr) was 1.6 ± 1.0 mg/dL, milrinone dose was 0.47 ± 0.16 μg/kg/min, and mean duration of therapy was 6.5 ± 10.6 days. Fourteen treatments were <24 hours, 2 (14%) of which were complicated with ARF; of the remaining 77 treatments (≥24 h), 9 (11.7%) were complicated with ARF. Their peak SCr was 3.2 ± 1.5 mg/dL and time to peak SCr was 4.9 ± 2.8 days. There was no significant difference in the incidence of ARF in patients who received therapy for <24 hours versus ≥24 hours; in the prevalence rate of diabetes mellitus, hypertension, coronary artery disease; or in baseline SCr, milrinone dose, and duration of therapy between patients who did and did not develop ARF.

Conclusions:

We found a 12% incidence of ARF in patients receiving milrinone therapy for severe CHF, which in the absence of an appropriate control group could be the aggregate effects of milrinone therapy and severe CHF.

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.

Temporary biventricular pacing postcardiopulmonary bypass in patients with reduced ejection fraction

BACKGROUND AND AIM

Patients with low ejection fraction (EF) undergoing myocardial revascularization frequently require ventricular pacing following cardiopulmonary bypass (CPB). While the benefits of chronic biventricular (BiV) pacing in patients with low EF are well established, there are little data on acute effects during heart surgery. This study analyzed the response of BiV versus single ventricle lead pacing on hemodynamics and left ventricular (LV) function immediately following CPB.

METHODS

Ten patients with decreased LV EF (mean = 35 +/- 6%) underwent open-heart surgery with CPB. Temporary pacing electrodes were placed on the right atrium, apex of the right ventricle, and lateral wall of the LV after separation from CPB. The hemodynamic effects of three atrio-ventricular (right, left, and BiV) pacing modes were studied for four minutes each. The pacing sequence was randomly allocated with a resting period of three minutes between each mode. Hemodynamic and echocardiographic data of LV function were collected. Statistical analysis was performed with analysis of variance.

RESULTS

BiV pacing increased cardiac output by 4%, 13%, and 44% over right ventricular pacing, LV pacing, and pre-bypass values, respectively. The fractional area of change increased significantly with BiV pacing compared to right ventricular and LV pacing (36%, 35% to 44%, p < 0.01). An increased propagation velocity of 49 cm/s compared to 38 cm/s and 40 cm/s for right ventricular and LV pacing, respectively, suggested an improvement in diastolic function.

CONCLUSION

In patients with low EF, BiV pacing immediately after CPB significantly improves LV systolic function and cardiac output, and suggests significantly improved diastolic function.

Assessment of quality of life in severe heart failure

Improvement of health-related quality of life (HRQL) is increasingly recognized as a priority in the management of heart failure (HF). In this review, we highlight the dramatic improvement in HRQL often observed in patients with severe HF and give particular emphasis to the nonpharmacologic therapy of cardiac resynchronization therapy, left ventricular assist devices, and cardiac rehabilitation. We juxtapose this to the less consistent improvement in HRQL seen with interventions aimed at treatment of acute HF syndromes. Conflicting data wherein HRQL improves in parallel to a detrimental or neutral effect on cardiovascular morbidity and mortality are also presented. We conclude with future directions and make the case for HF-specific instruments intended for the assessment of HRQL in hospitalized patients, longitudinal studies in which HRQL is followed over time, and continued attention to the preferences of those with severe and acute HF.

Phosphodiesterase III inhibitors for heart failure

BACKGROUND

In the treatment of chronic heart failure, vasodilating agents, ACE inhibitors and beta-blockers have shown an increase of life expectancy. Another strategy is to increase the inotropic state of the myocardium : phosphodiesterase inhibitors (PDIs) act by increasing intra-cellular cyclic AMP, thereby increasing the concentration of intracellular calcium, and lead to a positive inotropic effect.

OBJECTIVES

This overview on summarised data aims to review the data from all randomised controlled trials of PDIs III versus placebo in symptomatic patients with chronic heart failure. The primary endpoint is total mortality. Secondary endpoints are considered such as cause-specific mortality, worsening of heart failure (requiring intervention), myocardial infarction, arrhythmias and vertigos. We also examine whether the therapeutic effect is consistent in the subgroups based on the use of concomitant vasodilators, the severity of heart failure, and the type of PDI derivative and/or molecule. This overview updates our previous meta-analysis published in 1994.

SEARCH STRATEGY

Randomised trials of PDIs versus placebo in heart failure were searched using MEDLINE (1966 to 2004 January), EMBASE (1980 to 2003 December), Cochrane CENTRAL trials (The Cochrane Library Issue 1, 2004) and McMaster CVD trials registries, and through an exhaustive handsearching of international abstracting publications (abstracts published in the last 22 years in the "European Heart Journal", the "Journal of the American College of Cardiology" and "Circulation").

SELECTION CRITERIA

All randomised controlled trials of PDIs versus placebo with a follow-up duration of more than three months.

DATA COLLECTION AND ANALYSIS

21 trials (8408 patients) were eligible for inclusion in the review. 4 specific PDI derivatives and 8 molecules of PDIs have been considered.

MAIN RESULTS

As compared with placebo, treatment with PDIs was found to be associated with a significant 17% increased mortality rate (The relative risk was 1.17 (95% confidence interval 1.06 to 1.30; p<0.001). In addition, PDIs significantly increase cardiac death, sudden death, arrhythmias and vertigos. Considering mortality from all causes, the deleterious effect of PDIs appears homogeneous whatever the concomitant use (or non-use) of vasodilating agents, the severity of heart failure, the derivative or the molecule of PDI used.

AUTHORS' CONCLUSIONS

Our results confirm that PDIs are responsible for an increase in mortality rate compared with placebo in patients suffering from chronic heart failure. Currently available results do not support the hypothesis that the increased mortality rate is due to additional vasodilator treatment. Consequently, the chronic use of PDIs should be avoided in heart failure patients.

Acute renal failure secondary to milrinone in a patient with cardiac amyloidosis

Milrinone is a phosphodiesterase type III inhibitor with positive inotropic and vasodilatory effects. A common side effect of milrinone is hypotension from the peripheral vasodilation. Although mild elevations in serum creatinine have been described previously in the setting of milrinone-induced hypotension, acute oligoanuric renal failure requiring renal replacement therapy has not yet been described. This case report is the first to document such a result and to report the successful use of peritoneal dialysis in this setting. Previous case reports documented vasopressin as an effective alternative to catecholamines in the treatment of milrinone-induced hypotension. This report documents the use of four vasopressor agents (including vasopressin) in this patient, with only vasopressin resulting in improvement in systemic vascular resistance and blood pressure. Vasopressin may be the most effective vasopressor agent in the treatment of milrinone-induced hypotension.

Heart failure therapy at the turn of the century

Major changes in the treatment of heart failure have occurred in the last fifty years that have had a dramatic effect on its morbidity and mortality. Over two hundred years have passed since the demonstration of the benefit of digitalis in heart failure to the development of potent loop diuretics. The observation that vasodilators could improve both cardiac function and mortality led to the investigation of the Angiotensin Converting Enzyme Inhibitors (ACEI). Although these agents had significant vasodilator properties, their major benefit appears to be related to their ability to effect remodeling of the failing left ventricle. The most recent randomized clinical trials demonstrate that Beta Adrenergic Blocking agents can provide an incremental effect on both mortality and morbidity when added to therapy with ACEI. Although these agents have improved the outlook for the heart failure patient, they have had very little effect on the improvement of left ventricular function. Future research must be directed at methods to deal with this issue by either changing the contractile properties of the cardiomyocyte by pharmacologic or electrical therapy or by transplanting functional cells that can increase the number of functioning contractile units.

Low-dose enoximone improves exercise capacity in chronic heart failure. Enoximone Study Group

OBJECTIVES

This study was designed to evaluate the effects of low-dose enoximone on exercise capacity.

BACKGROUND

At higher doses the phosphodiesterase inhibitor, enoximone, has been shown to increase exercise capacity and decrease symptoms in heart failure patients but also to increase mortality. The effects of lower doses of enoximone on exercise capacity and adverse events have not been evaluated.

METHODS

This is a prospective, double-blind, placebo-controlled, multicenter trial (nine U.S. centers) conducted in 105 patients with New York Heart Association class II to III, ischemic or nonischemic chronic heart failure (CHF). Patients were randomized to placebo or enoximone at 25 or 50 mg orally three times a day. Treadmill maximal exercise testing was done at baseline and after 4, 8 and 12 weeks of treatment, using a modified Naughton protocol. Patients were also evaluated for changes in quality of life and for increased arrhythmias by Holter monitoring.

RESULTS

By the protocol-specified method of statistical analysis (the last observation carried-forward method), enoximone at 50 mg three times a day improved exercise capacity by 117 s at 12 weeks (p = 0.003). Enoximone at 25 mg three times a day also improved exercise capacity at 12 weeks by 115 s (p = 0.013). No increases in ventricular arrhythmias were noted. There were four deaths in the placebo group and 2 and 0 deaths in the enoximone 25 mg three times a day and enoximone 50 mg three times a day groups, respectively. Effects on degree of dyspnea and patient and physician assessments of clinical status favored the enoximone groups.

CONCLUSIONS

Twelve weeks of treatment with low-dose enoximone improves exercise capacity in patients with CHF, without increasing adverse events.

Crosstalk of the heart and periphery: skeletal and cardiac muscle as therapeutic targets in heart failure

Heart failure syndrome is initiated as the body's metabolic needs temporarily exceed the pumping capacity of the heart. In most cases, this phenomenon tends to occur during physical exercise. Although not always subjectively recognized, limited exercise capacity remains the clinical hallmark of congestive heart failure. It can be measured objectively as reduced skeletal muscle performance and maximal whole-body oxygen uptake, which are not necessarily explained by central haemodynamic abnormalities. In fact, the initial cardiac condition sets forth a series of peripheral adaptations that are potentially life-saving during acute decompensation but become disadvantageous and symptom-generating in stable heart failure. Inodilator drugs were theoretically ideal to revert the adverse haemodynamic crosstalk between the heart and periphery. However, these drugs failed to improve prognosis in congestive heart failure, whereas drugs that did so showed typically unimpressive haemodynamic effects. Exercise therapy has recently emerged as a safe and effective way to enhance physical performance and subjective well-being in congestive heart failure. A dual therapeutic approach is suggested, consisting of exercise training to improve the periphery and the use of cardioprotective drugs to limit cardiac cellular damage from neurohormonal activation.

Inotropic agents in the treatment of heart failure: despair or hope?

Depression of myocardial contractility plays an important role in the development of heart failure; therefore, intensive interest and passion have been generated to develop cardiotonic agents to improve the contractile function of the failing heart. Inotropic agents that increase cyclic AMP, either by increasing its synthesis or reducing its degradation, exert dramatic short-term hemodynamic benefits, but these acute effects cannot be extrapolated into long-term improvement of the clinical outcome in patients with advanced heart failure. Administration of these agents to an energy-starved failing heart would be expected to increase myocardial energy use and could accelerate disease progression. The role of digitalis in the management of heart failure has been controversial, but ironically the drug has now been proved to favorably affect the neurohormonal disorders and its reevaluation is now being intensively investigated. More recently, attention has been focused on other inotropic agents that have a complex and diversified mechanism. Recent clinical studies have demonstrated that they are potentially useful in the long-term treatment of heart failure patients. These agents have some phosphodiesterase-inhibitory action but also possess additional effects, including acting as cytokine inhibitors, immunomodulators, or calcium sensitizers. However, their therapeutic ratio is narrow and further studies are warranted to establish their optimal doses and their eventual status in the treatment of heart failure.

Long-term evaluation of treatment for chronic heart failure: a 1 year comparative trial of flosequinan and captopril

Two hundred and nine patients with moderate to severe chronic heart failure, all of whom remained symptomatic despite at least 80 mg of frusemide daily, were randomized to 12 months treatment with flosequinan or captopril. The patients were stratified into two groups, a treadmill group and a corridor walk test group, depending upon their exercise capability. Sixty-five out of 102 patients randomized to flosequinan and 43 out of 107 randomized to captopril (p < 0.001) did not complete the study. There was no difference between the groups in mortality: 19 patients died while taking flosequinan and 15 while taking captopril. Both drugs had similar effects on treadmill exercise tolerance; the mean increase at week 52 was 117 seconds in the flosequinan group and 156 seconds (p = 0.57) for the captopril group. For those patients stratified to the corridor walk test only, there was also very little difference in the improvement at 52 weeks; the mean increase for patients randomized to flosequinan was 61 meters and captopril was 75 meters (p = 0.65). However, when the walk tests from all patients are examined, captopril produced a significant improvement compared with flosequinan at week 52 (p = 0.015). Flosequinan has similar long-term efficacy to captopril but is associated with a higher incidence of adverse events.

Reassessment of digoxin and other low-dose positive inotropes in the treatment of chronic heart failure

Digoxin and other low doses of drugs that have inotropic properties may have an important role to play in the therapy of patients with chronic heart failure. There is convincing evidence that digoxin is effective in relieving the signs and symptoms of heart failure due to systolic dysfunction. While earlier results with some of the other agents have been disappointing, recent data suggest that a reevaluation of these agents is necessary. There is now compelling evidence that lower doses of these agents may be clinically useful without necessarily having any significant hemodynamic effects. The recent experience with vesnarinone is especially promising in showing that therapy with these agents may improve survival in addition to improving clinical status. It is becoming recognized that hemodynamic activity should not necessarily be a prerequisite for clinical utility for those agents. The neuroendocrine and electrophysiologic effects of many of these agents, including digitalis, remain incompletely characterized and may play an important role in their therapeutic benefit. It appears that certain drugs that have inotropic properties may be effective only when their inotropic effects are not readily demonstrated. Further research into the appropriate mechanisms of action and proper dosing of these drugs may lead to a renewed interest in the use of positive inotropes for chronic heart failure.

Treatment of severe heart failure: quantity or quality of life? A trial of enoximone. Enoximone Investigators

OBJECTIVES

To determine the effects of enoximone on mortality and quality of life in patients with severe end stage heart failure.

DESIGN

A randomised, double blind, placebo controlled trial of the addition of enoximone to conventional treatment. Planned minimum follow up of one year.

SETTING

District general hospitals and cardiological referral centres in the United Kingdom.

PATIENTS

Planned 200 patients with severe, symptomatic heart failure despite treatment with diuretics and where appropriate and tolerated angiotensin converting enzyme inhibitors and digoxin.

RESULTS

The study was ended early by the ethics committee after 151 patients had been recruited because of an excess mortality in the enoximone group: 27 deaths compared with 18 in the placebo group (P < 0.05). Quality of life measured with a disease specific questionnaire showed a clinically significant improvement at week 2 with a mean increase score of 0.48 in the enoximone treated patients compared with 0.14 in those receiving placebo (P = 0.0086). With the Nottingham health profile questionnaire the physical mobility score was improved after three months in the enoximone group, median 21.3 compared with 41.8 in the placebo group (P = 0.008).

CONCLUSIONS

In patients with severe heart failure who remain incapacitated despite conventional treatment enoximone reduced survival but had a beneficial effect on the quality of life. Drugs that improve symptoms in severe end stage heart failure should not be discarded lightly.