A comparison of oral milrinone, digoxin, and their combination in the treatment of patients with chronic heart failure

Cell death in the failing heart: role of an unnatural growth response to overload

Hypertrophy of the overloaded heart, characterized by an increased number of sarcomeres, provides an adaptive, short-term response. However, when cardiac overload is long-standing, the hypertrophic response appears to cause shortened myocyte survival. The mechanisms responsible for the deleterious effects of chronic myocardial hypertrophy may include a maladaptive growth response of the mature heart. Because terminally differentiated adult cardiac myocytes have little or no capacity to divide, stimuli that promote growth in the overloaded adult heart cannot lead to normal cell division. Instead, overload initiates an unnatural growth response that appears to shorten cardiac myocyte survival, possibly because the same growth factors that mediate the hypertrophic response of the adult heart can also induce programmed cell death (apoptosis). The converting enzyme inhibitors and nitrates, which have growth-inhibitory as well as vasodilator effects, may improve prognosis in heart failure by inhibiting the production of transcription factors. These transcription factors stimulate both the unnatural growth response to overload and stimuli that lead to apoptosis. Since both beta-adrenergic agonists and cytokines, such as tumor necrosis factor-alpha, can stimulate production of similar transcription factors, evidence suggests that beta blockers and vesnarinone improve the prognosis in patients with heart failure possibly because of their ability to inhibit maladaptive growth.

Economic outcomes of withdrawal of digoxin therapy in adult patients with stable congestive heart failure

OBJECTIVES

This study sought to analyze the health and economic outcomes of withdrawal of digoxin therapy among U.S. adult patients with stable congestive heart failure.

BACKGROUND

New information regarding the outcomes of digoxin withdrawal has been provided by the Prospective Randomized Study of Ventricular Failure and Efficacy of Digoxin (PROVED) and Randomized Assessment of Digoxin and Inhibitors of Angiotensin-Converting Enzyme (RADIANCE) trials. We interpreted and extrapolated the results of these trials to describe implications on a national level.

METHODS

We used a decision-analytic model to estimate the outcomes of two alternative strategies to 1) continue and 2) withdraw digoxin in patients with congestive heart failure with normal sinus rhythm, New York Heart Association functional class II or III and left ventricular ejection fraction < or = 35%. Epidemiologic assumptions were derived from published reports and expert opinion. Assumptions regarding the effectiveness of digoxin therapy were derived from the RADIANCE and PROVED digoxin withdrawal trials. Hospital and Medicare data were used for economic assumptions. Calculated outcomes included treatment failures, cases of digoxin toxicity and health care costs.

RESULTS

The continuation of digoxin therapy in these patients with congestive heart failure nationally would avoid an estimated 185,000 clinic visits, 27,000 emergency visits and 137,000 hospital admissions for congestive heart failure. After accounting for an estimated 12,500 cases of digoxin toxicity, the net annual savings would be $406 million, with a 90% range of uncertainty of $106 to $822 million. One-way sensitivity analysis indicated that digoxin therapy is cost-saving when the assumed annual incidence of digoxin toxicity is < or = 33%.

CONCLUSIONS

The continuation of digoxin therapy in patients with stable congestive heart failure should be strongly considered, because this strategy is likely to lead to both lower costs and greater health benefits on the basis of available information.

Hemodynamic effects of the novel selective cAMP-phosphodiesterase III inhibitor R 80122 in anesthetized patients with moderate left ventricular dysfunction before coronary artery bypass grafting

OBJECTIVE(S)

To investigate the hemodynamic effects and safety of R 80122, a novel selective phosphodiesterase (PDE) III inhibitor, and its solvent hydroxypropyl-beta-cyclodextrin.

DESIGN

Prospective, randomized study.

SETTING

Operating theater of a university hospital in the Netherlands.

PARTICIPANTS

Twelve patients with impaired left ventricular function scheduled for coronary artery bypass grafting after induction of anesthesia were included.

INTERVENTIONS

R 80122 (n = 6) or its solvent (n = 6) was administered using the same infusion regimen. A bolus of 0.1 mL/kg (= 0.1 mg/kg R 80122) was infused over 10 minutes followed by a maintenance infusion of 5 microliters/kg/min (5 micrograms/kg/min R 80122) over 20 minutes.

MEASUREMENTS AND MAIN RESULTS

Compared with the solvent, patients receiving R 80122 did not show any significant changes in heart rate, arterial blood pressure, or pulmonary artery pressures. However, R 80122 produced a marked increase (P < 0.05) in cardiac output (thermodilution) and echocardiographically obtained percentage area reduction. No arrhythmias or ischemic episodes occurred during the infusion period. The plasma half-life of R 80122 was 10.6 +/- 1.9 minutes.

CONCLUSIONS

R 80122 appears to be a potent positive inotropic agent in these patients. Its use is not associated with marked vasodilation, it is devoid of positive chronotropic effects, and it can be administered safely in patients with impaired left ventricular function.

Bioenergetics in the pathogenesis, progression and treatment of cardiovascular disorders

The aim of this manuscript is to review perturbations in bioenergetics that are redundant denominators in the diversity of factors mediating the pathogenesis and progression of coronary heart disease (CHD), congestive heart failure (CHF), hypertension and arrhythmias. This paper likewise assesses the pharmacodynamics of widely prescribed drugs that enhance cellular respiration, maintain positive inotropic, chronotropic, dromotropic cardiac effects, sustain myocardial biosynthesis, reverse the morbidity of heart disease, and assure low levels of toxicity commensurate with the agent's biocompatability. Conversely, it is essential to delineate the modality of xenobiotic drugs that inhibit energy transformations, enhance the pathogenesis of CHD, worsen survival in CHF, provoke arrhythmogenic effects, and induce serious side-effects. Documented evidence, derived from biochemical, physiological and pharmacological data sources, consistently links inhibited mitochondrial decarboxylation to aberrations in cholesterol metabolism, biosynthesis, and calcium balance. Underutilized citrates evolved from inhibited decarboxylation are degraded to acetyl CoA. The acetate is the source of steroid synthesis; its carbon atoms form the molecular basis for all endogenous cholesterol. Myocardial anoxia, a consequence of the atheromatous plaque, inhibits ATP production, impairs biosynthesis, induces negative cardiac inotropic and chronotropic effects, and enhances the pathogenesis of CHF. Inhibited decarboxylation is likewise a factor in the mobilization of in situ cardiac Ca2+, resulting in arrhythmias provoked by the cation's deficiency. The restoration of calcium homeostasis decreases peripheral vasotension, reducing hypertension. Parameters drawn from endocrinopathies and the new physiological dimension of microgravity are developed to illustrate the detrimental effect of inhibited bioenergetics on cardiac pathomorphism and cardiovascular dysfunction. In conclusion, anabolic agents, adjunctive to a productive life-style, can provide the rational basis for the prevention and treatment of cardiac diseases. Failure to understand mechanisms generating cardiovascular morbidity eventuates in ineffective and empirical treatment.

Effect of long-term digoxin therapy on autonomic function in patients with chronic heart failure

OBJECTIVES

This study was conducted to determine the effect of long-term digoxin therapy on autonomic function in patients with mild to moderate chronic heart failure.

BACKGROUND

Chronic heart failure is characterized by increased sympathetic activity and decreased parasympathetic activity. Intravenous digitalis has been found to reduce sympathetic activity immediately in these patients, but whether short-term neurohormonal effects are sustained during long-term oral therapy has not been assessed.

METHODS

We determined sympathetic activity in 26 patients with heart failure by measuring plasma norepinephrine levels and parasympathetic activity from variables of heart period variability derived from 24-h ambulatory electrocardiographic Holter recordings obtained before and after 4 to 8 weeks of digoxin therapy.

RESULTS

After digoxin therapy, plasma norepinephrine decreased significantly from a mean +/- SEM of 552 +/- 80 to 390 +/- 37 ng/ml. In addition, the RR interval increased significantly from 719 +/- 19 to 771 +/- 20 ms. High frequency power increased from 84 +/- 24 to 212 +/- 72 ms2, and the root mean square of successive differences in RR interval increased from 20.3 +/- 1.8 to 27.0 +/- 3.4 ms, indicating a substantial increase in parasympathetic activity. Low frequency power, an index of baroreflex activity, was also significantly increased (239 +/- 80 to 483 +/- 144 ms2) by digoxin therapy.

CONCLUSIONS

These results indicate 1) that long-term therapy with digoxin acts to ameliorate the autonomic dysfunction of patients with heart failure, and 2) that the short-term neurohormonal effects of digoxin are sustained during prolonged treatment with the drug.

Pharmacotherapy of congestive heart failure. Currently used and experimental drugs

A survey is given of the currently used therapeutics in the treatment of chronic congestive heart failure. Symptomatic treatment is usually performed along the following lines: rest, sodium and fluid restriction to unload the decompensating heart, loop diuretics, angiotensin-converting enzyme inhibitors or other vasodilators; inotropic agents to improve the heart's mechanical performance; attempts to counteract the neuro-endocrine compensatory mechanisms, that is the activated sympathetic nervous and renin-angiotensin-aldosterone systems, as well as the rise in vasopressine levels. New insights have been obtained in the effects of cardiac glycosides, which are probably rather based on counteracting the elevated sympathetic neuronal activity than on their weak and uncertain inotropic action. Angiotensin-converting enzyme inhibitors are probably more effective than classical vasodilators owing to their additional interaction with the neuro-endocrine compensatory mechanisms. Ibopamine, a prodrug of epinine, appears to be rather a vasodilator and antagonist of the neuro-endocrine compensatory mechanisms than an inotropic agent. The most important clinical trials addressing the efficacy and adverse reactions to the various aforementioned therapeutics are discussed. New, experimental approaches in the drug treatment of chronic congestive heart failure include beta-blockers, calcium antagonists, vasopressin antagonists and inhibitors of atrial natriuretic peptide degradation.

Is there a role for positive inotropic agents in congestive heart failure: focus on mortality

Congestive heart failure (CHF) is a common clinical syndrome that may result from a variety of etiologies. Impaired contractility can lead to pump failure and a number of hemodynamic and neurohormonal alterations. Vasodilator therapy improves symptoms and survival in patients with CHF due to systolic dysfunction. Inotropic therapy, on the other hand, has not been shown to improve survival and may even worsen survival. This article reviews the mechanism of action and clinical trials of inotropic therapy in patients with CHF.

Functional and antiischemic effects of luteolin-7-glucoside in isolated rabbit hearts

1. The functional effects of the flavonoid luteolin-7-glucoside (LUT) were investigated in Langendorff-rabbit hearts perfused at constant pressure. Repetitive myocardial ischemia was induced by coronary artery ligature and quantified from NADH-fluorescence photography. 2. LUT significantly enhanced left ventricular pressure and the global and relative coronary flow (= global coronary flow/pressure-rate product). 3. LUT significantly diminished epicardial NADH-fluorescence area and intensity. 4. LUT is an inodilator possessing cardioprotective properties. These might be related to an improvement of myocardial perfusion and/or to free radical scavenging properties.

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.

Optimising heart failure pharmacotherapy: the ideal combination

Good management of all patients with heart failure is complex. Fortunately most patients fall into only one or two categories, making management less daunting. Most patients with heart failure need treatment with loop diuretics and ACE inhibitors and for many these drugs, possibly combined with antithrombotic measures, are all that is needed for optimal treatment, but optimal treatment can only follow adequate diagnosis. This needs a partnership between the specialist and the family doctor, with ease of access to non-invasive investigations such as echocardiography.

Optimizing the treatment of heart failure

The introduction of new drugs, and a re-evaluation of older drugs, have radically changed the pharmacological management of heart failure. Angiotensin converting enzyme (ACE) inhibitors, digitalis, diuretics and the combination of nitrates and hydralazine are now used. The first Cooperative North Scandinavian Enalapril Survival Study (CONSENSUS I) and the second Vasodilator therapy in Heart Failure Trial (V-HeFT II) have demonstrated that patients with severe or advanced heart failure should be treated with ACE inhibitors, digitalis and diuretics (other vasodilators can be used if ACE inhibitors are contraindicated) to improve symptoms and duration of life. The Studies Of Left Ventricular Dysfunction (SOLVD) and the Munich Heart Failure trial have shown that patients with mild heart failure should be treated with ACE inhibitors. However, data from several large clinical registries suggest that only 40% of patients with heart failure are being given ACE inhibitors perhaps through fear of serious renal damage or hypotension; these fears are unfounded. Patients with anterior myocardial infarcts and reduced left ventricular function also benefit from ACE inhibitors. The fourth International Study of Infarct Survival (ISIS 4) and results from the Gruppo Italiano per Io Studio della Sopravvivenza nell'Infarto miocardico 3 (GISSI 3) have indicated that patients with acute myocardial infarction benefit from early ACE inhibitor therapy and that survival is increased. Heart failure treatment can be optimized by establishing a disease etiology and stressing the need to restrict dietary sodium. ACE inhibitors should be used for depressed left systolic ventricular function, including patients in New York Heart Association class I heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk stratification after myocardial infarction: role of electrical instability, ischemia, and left ventricular function

The problem of risk stratification after myocardial infarction is reviewed. There are three major complications: new ischemic events, congestive heart failure, and malignant arrhythmias and sudden death, related to the presence of residual ischemia, left ventricular dysfunction, and electrical instability. The bidirectional interactions among these three factors is analyzed. The risk is in the middle of a triangle, the three angles of which are the above-mentioned factors. All the "satellite" factors that appear from all three angles are presented. Furthermore, the most important parameters and techniques employed to detect risk, multifactorial approach of risk stratification, and changes of risk stratification in the thrombolytic era are briefly reviewed.

Incidence of hospitalization for digitalis toxicity among elderly Americans

OBJECTIVE

To document the prevalence of digitalis use and the incidence of hospitalization caused by digitalis toxicity.

DESIGN

Observational cohort followed for 6 years.

SETTING

Urban community.

PARTICIPANTS

Persons were eligible if they were (1) enrolled in the Yale Health and Aging Project and (2) using digitalis when interviewed in 1982 or 1985. The Project comprises a sample of noninstitutionalized persons aged 65 years and over living in New Haven, Connecticut.

METHODS

Between 1982 and 1988 when a Project participant was hospitalized in New Haven, a researcher reviewed the medical record and coded up to 16 International Classification of Diseases-Class 9 (ICD-9) diagnoses. To identify hospitalizations caused by digitalis, we reexamined records with ICD-9 codes suggesting toxicity. We confirmed the admission illness was an adverse drug reaction with a decision algorithm.

RESULTS

The prevalence of digitalis use was 13% in 1982 and 12% in 1985. The incidence of hospitalization caused by definite or probable toxicity was 4.2% (95% confidence interval = 0.3% to 8.1%) over 6 years. Manifestations of toxicity were malaise or gastrointestinal symptoms (two patients) and heart block plus malaise or gastrointestinal symptoms (six patients). Use of quinidine was associated (P < .05) with toxicity.

CONCLUSION

Knowledge about the incidence of severe, morbid toxicity may help clinicians estimate and compare the risks and benefits of digitalis and alternate therapies.

Hemodynamic effects of the novel cardiotonic drug simendan: echocardiographic assessment in healthy volunteers

Simendan is a novel cardiotonic drug with mixed properties, including calcium sensitization. Simendan was given intravenously to eight healthy volunteers in doses from 0.1 to 10.0 mg to define its safety and dose-response effects. Its effects on myocardial function were recorded by echocardiography with simultaneous measurement of heart rate (HR) and blood pressure (BP). A linear dose response was observed in all echocardiographic indices. Fractional shortening increased from a basal value of 29.5% to 32.4% (p < 0.05), 34.7% (p < 0.001), and 39.4% (p < 0.001) 10 minutes after doses of 1.0, 2.0, and 5.0 mg of simendan, respectively. The mean velocity of maximal circumferential fiber shortening increased from the baseline of 2.22 lengths/sec to 2.7 lengths/sec after the 2.0 mg dose (p < 0.05) and to 3.31 lengths/sec after the 5.0 mg dose (p < 0.001). Mean BP decreased slightly and mean HR increased only by 5.2 beats/min after the 5.0 mg dose. Because of the potent effect seen on hemodynamic indices and due to two vasovagal reactions, 10 mg was given to two subjects only. These results revealed that simendan has hemodynamic effects that can be explained by positive inotropy as well as vasodilatation, in agreement with preclinical findings. Further studies with patients disabled by heart failure are warranted.

Postinfarct heart failure: role of diuretic therapy

There can be no doubt that ACE inhibitors prolong survival in patients with a low ejection fraction. There is no evidence whether or not diuretics have the same effect. The pathophysiology of asymptomatic patients with poor left ventricular function differs from that of patients with the clinical syndrome of heart failure, and different treatments may well be needed. Diuretics still have a crucial role in the relief of symptoms.

Digoxin is effective, but is it safe?

In the last 15 years several double-blind, placebo-controlled clinical trials have unequivocally shown that digitalis decreases symptoms of cardiac failure, results in a reduction in the need for hospitalization for treatment of congestive heart failure, and improves cardiac function. The major unresolved question concerning digitalis use is its safety. There are experimental data and clinical evidence that digitalis use may be associated with an increased mortality, particularly in the first year or two after an acute myocardial infarction. This increased mortality appears to be present even after adjustment for predictor covariants. This conclusion depends on the ability of statistical methods to account for differences in comorbidity. Since the question of digitalis safety remains after myocardial infarction, the physician should carefully examine the indications for administration of digitalis. More than the usual surveillance is required during chronic digitalis administration.

Medical advances in the treatment of congestive heart failure

The increased incidence and prevalence of congestive heart failure place a high priority on novel treatment strategies. Left ventricular ejection fraction remains the single most valuable measurement providing both diagnostic and prognostic insights. The most systematic approach to heart failure involves an objective assessment of functional disability, to include exercise tests such as a 6-minute walk under standardized conditions. Left ventricular dysfunction incites a host of neurohumoral compensations that are of fundamental importance in the heart failure syndrome expression. Both vasoconstrictor and vasodilator neurohormones are stimulated and provide new therapeutic opportunities. The therapeutic approach to heart failure begins with a strong emphasis on prevention, patient education, and self-participation in therapy with respect to both its monitoring and adjustment. Diuretics remain a mainstay of therapy but, in the face of severe heart failure, may become ineffectual, requiring constant infusion of loop-active diuretics, combination diuretics, or diuretics in association with concomitant low-dose dopamine infusion. Vasodilator therapy has been an important advance: combination hydralazine and nitrate therapy was initially shown to be efficacious in improving survival, and more recently, angiotensin-converting enzyme (ACE) inhibitors, in the form of enalapril, have shown incremental benefit on survival over this combination. Interestingly, there is now evidence from both SOLVD and SAVE to demonstrate an unexpected and, as yet, unexplained reduction in the frequency of both unstable angina and myocardial infarction. Although, on balance, the weight of evidence concerning the long-term efficacy of inotropic agents has been disappointing, especially as it relates to their unfavorable effects on survival, recent information on vesnarinone, an agent with a complex and diversified mechanism of action, suggests that with appropriate doses, improved symptoms and survival are possible. A substantial amount of new information from randomized placebo-controlled trials attests to the symptomatic relief, hemodynamic improvement, and gain in exercise performance achieved by digoxin. A long-term survival study is ongoing to assess its effects on mortality. beta-Blockers, especially metoprolol, appear beneficial in some patients with heart failure, possibly related to their reduction in sympathetic nervous activity and restoration of beta-receptor population, with resultant improved contractile performance, enhanced myocardial relaxation, and overall increase in cardiac efficiency. Based on available evidence, the best contemporary approach to treatment involves the use of ACE inhibitors coupled with diuretic therapy, either continuous or intermittent, to relieve central or peripheral congestion. The addition of digoxin or a hydralazine nitrate combination is a logical next step, with commencement of low-dose beta-blocker a reasonable option.(ABSTRACT TRUNCATED AT 400 WORDS)

Double-blind placebo-controlled study of ibopamine and digoxin in patients with mild to moderate heart failure: results of the Dutch Ibopamine Multicenter Trial (DIMT)

OBJECTIVES

This study was conducted to determine the efficacy and safety of long-term treatment with the orally active dopamine agonist ibopamine in patients with mild to moderate chronic congestive heart failure and to compare the results with those of treatment with digoxin and placebo.

BACKGROUND

Ibopamine and digoxin are drugs that exert hemodynamic and neurohumoral effects. Because there is accumulating evidence that progression of disease in chronic heart failure is related not only to hemodynamic but also to neurohumoral factors, both drugs might be expected to have a favorable long-term effect.

METHODS

We studied 161 patients with mild to moderate chronic heart failure (80% in New York Heart Association functional class II and 20% in class III), who were treated with ibopamine (n = 53), digoxin (n = 55) or placebo (n = 53) for 6 months. Background therapy consisted of furosemide (0 to 80 mg); all other drugs for heart failure were excluded. Clinical assessments were made at baseline and after 1, 3 and 6 months.

RESULTS

Of the 161 patients, 128 (80%) completed the study. Compared with placebo, digoxin but not ibopamine significantly increased exercise time after 6 months (p = 0.008 by intention to treat analysis). Ibopamine was only effective in patients with relatively preserved left ventricular function, as it significantly increased exercise time in this subgroup (for patients with a left ventricular ejection fraction > 0.30; p = 0.018 vs. placebo). No patient receiving digoxin withdrew from the study because of progression of heart failure, compared with six patients receiving ibopamine and two receiving placebo. At 6 months, plasma norepinephrine was decreased with digoxin and ibopamine therapy (-106 and -13 pg/ml, respectively) but increased with placebo administration (+62 pg/ml) (both p < 0.05 vs. placebo). Plasma aldosterone was unaffected, but renin was decreased by both agents after 6 months (p < 0.05 vs. placebo). Total mortality and ambulatory arrhythmias were not significantly affected by the two drugs.

CONCLUSIONS

Ibopamine and digoxin both inhibit neurohumoral activation in patients with mild to moderate chronic heart failure. However, the clinical effects of these drugs are different and appear to be related to the degree of left ventricular dysfunction.

The impact of age on risk of adverse drug reactions to digoxin. For The Gruppo Italiano di Farmacovigilanza nell' Anziano

To assess the association of age and other potential risk factors with digoxin toxicity, adverse drug reactions to digoxin (ADRDIG) were studied in all patients (n = 1338) on digoxin therapy consecutively admitted to 41 clinical wards throughout Italy during 4 months in 1988. At the time of admission, 28 patients (2.1%) had evidence of ADRDIG. In multivariate logistic regression analysis, significant associations with ADRDIG were found for age > or = 80 years compared to age 65-79 years (OR = 2.75, 95% CI = 1.17-6.45), daily digoxin dosage of > or = 0.25 mg (OR = 2.51, 95% CI = 1.16-5.47), serum creatinine > or = 120 mumol/L (OR = 3.75, 95% CI = 1.69-8.32), and for treatment with amiodarone, propafenone, quinidine or verapamil (OR = 2.60, 95% CI = 1.07-6.30). Those aged < 65 years had a similar risk of digoxin toxicity as those aged 65-79 years (OR = 1.07, 95% CI = 0.28-4.12). Adverse drug reactions to digoxin were found in 1 in 50 patients hospitalized on digoxin therapy. Patients aged 65-79 years were not at increased risk for digoxin toxicity compared to younger patients, while advanced age (> or = 80 years) was an independent risk factor for this outcome.

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

We describe the results of two placebo-controlled trials (MIL-1077 and MIL-1078) designed to evaluate the clinical efficacy of oral milrinone administered together with converting enzyme inhibitors to patients with congestive heart failure. Although these trials were terminated prematurely, they provide the only controlled data regarding the effect of oral milrinone on exercise capacity in patients receiving converting enzyme inhibitors. Of the 254 patients randomized, 140 completed one of the trials or reached an end point and are the basis of this report. In both trials, there was a clear trend for an increase in exercise capacity in the milrinone-treated patients (+26 +/- 8% vs. +5 +/- 7% in MIL-1077 and +11 +/- 5% vs. +2 +/- 4% in MIL-1078). Symptoms of congestive heart failure were decreased in one trial but not the other. Quality of life, as assessed by a questionnaire, was not effected in either trial. There was an increased incidence of adverse events in milrinone-treated patients. Adverse events related primarily to hypotension and vasodilation led to discontinuation of drug in 18 milrinone-treated patients vs. 1 placebo-treated patient. Milrinone had little or no proarrhythmic effect and cardiovascular deaths were distributed equally between the milrinone and placebo groups. These data suggest that when used in combination with a converting enzyme inhibitor, oral milrinone improves exercise capacity but is associated with a high incidence of adverse events that appear to be related to excessive vasodilation.

Effect on exercise performance of enalapril therapy initiated early after myocardial infarction. Nordic Enalapril exercise Trial

OBJECTIVES

The Nordic Enalapril Exercise Trial was a multicenter subtrial of the Cooperative New Scandinavian Enalapril Survival Study (CONSENSUS II) designed to evaluate the effect on maximal exercise performance of a 6-month period of enalapril treatment initiated early after myocardial infarction.

BACKGROUND

When begun early after myocardial infarction, converting enzyme inhibition therapy has been shown to attenuate infarct expansion and reduce left ventricular volume. Therapy has been associated with improved exercise performance.

METHODS

Three hundred twenty-seven men (mean age 63.3 +/- 10.9 years) with documented acute myocardial infarction were randomized to treatment with enalapril or placebo on a double-blind basis. Intravenous enalaprilat or placebo therapy was initiated within 24 h after the onset of symptoms. Oral therapy was continued at a target dose of 20 mg/day. Patients exercised maximally at 1 month and 6 months after infarction to symptom-limited end points on a cycle ergometer with a 20 W/min incremental protocol.

RESULTS

The treatment and control groups were comparable in patient age, concurrent therapy and type and site of infarction. At 1 month, for all patients, mean total work performed was 34.9 +/- 20.9 kJ in the enalapril group (n = 169) versus 28.5 +/- 20.6 kJ in the placebo group (n = 158) (difference = 18.4%, p < 0.01). This between-group difference in favor of enalapril was greatest in patients > 70 years old (difference = 41.4%, p < 0.01, n = 105) and those with clinical evidence of heart failure (difference = 33.0%, p < 0.01, n = 122). At 6 months for all patients, mean total work performed was 35.4 +/- 23.8 kJ in the enalapril group versus 34.0 +/- 23.9 kJ in the placebo group (difference = 4.1%, NS).

CONCLUSIONS

This trial found that chronic converting enzyme inhibition initiated early after myocardial infarction was associated with significantly greater exercise capacity in men tested at 1 month. This difference was independent of type or site of infarction, patient age or the presence of clinical heart failure. The difference between the treatment and control groups was not significant at 6 months because of improvement in the placebo group. Further research is needed to elucidate the potential mechanisms involved, profile those patients most likely to profit from early therapy and establish the optimal timing and duration for intervention.

Digoxin in heart failure: implications of recent trials

Although supported by 2 centuries of anecdotal clinical evidence, the safety and efficacy of the cardiac glycosides for the treatment of congestive heart failure due to systolic ventricular dysfunction had never been rigorously examined by prospective clinical trials until the past decade. A reevaluation of the appropriate role of these drugs in modern cardiovascular pharmacology was prompted by the introduction in the 1970s of new classes of drugs for the treatment of congestive heart failure and supraventricular arrhythmias. Concurrently, several reports appeared, questioning the routine prescription of digoxin for the treatment of heart failure, particularly in patients in sinus rhythm. The majority of clinical trials published since 1980, most of which examined patients with New York Heart Association class II and III congestive heart failure, indicate that digoxin with or without concomitant administration of a vasodilator lessens symptoms and reduces the morbidity associated with congestive heart failure, particularly in patients with more advanced symptoms and ventricular dysfunction. The data on efficacy are less clear in support of the routine prescription of digoxin in the treatment of mild (class I and II) congestive heart failure. Although most recent trials attest to the relative safety and efficacy of digoxin in patients with congestive heart failure whose serum levels are maintained between 1 and 2 ng/ml, there is no conclusive evidence as yet that cardiac glycosides improve survival, as has been documented for vasodilators and, in particular, angiotensin-converting enzyme inhibitors. The National Institutes of Health-sponsored Digitalis Investigators Group (DIG) trial now underway should provide an answer to this question within the next few years.

Classification of positive inotropic agents

Although there is increasing recognition that all inotropic agents are not alike, they continue to be viewed in the generic sense because of the lack of a classification system. Analogous to the classification system proposed for the antiarrhythmic agents over 20 years ago, a classification system is proposed that categorizes inotropic agents according to their mechanisms of action. Agents are classified as those that augment contractility by increasing intracellular levels of cyclic adenosine monophosphate (class I); affect ion channels or pumps (class II); modulate intracellular calcium regulation (class III), and augment contractility through multiple pathways (class IV). This classification system does not suggest that some classes of inotropic agents might be more effective than others nor does it imply that potential beneficial effects are shared by all members of each class of drugs. However, it provides a framework for better understanding of the potential benefits and limitations of the traditional inotropic agents as well as the increasing number of new investigational drugs.

Randomized study assessing the effect of digoxin withdrawal in patients with mild to moderate chronic congestive heart failure: results of the PROVED trial. PROVED Investigative Group

OBJECTIVES

The purpose of this study was to determine whether digoxin is effective in patients with chronic, stable mild to moderate heart failure.

BACKGROUND

Digoxin has been a traditional therapy in heart failure, but methodologic limitations in earlier studies have prevented definitive conclusions regarding its efficacy.

METHODS

Withdrawal of digoxin (placebo group, n = 46) or its continuation (digoxin group, n = 42) was performed in a prospective, randomized, double-blind, placebo-controlled multicenter trial of patients with chronic, stable mild to moderate heart failure secondary to left ventricular systolic dysfunction who had normal sinus rhythm and were receiving long-term treatment with diuretic drugs and digoxin.

RESULTS

Patients withdrawn from digoxin therapy showed worsened maximal exercise capacity (median change in exercise time -96 s) compared with that of patients who continued to receive digoxin (change in exercise time +4.5 s) (p = 0.003). Patients withdrawn from digoxin therapy showed an increased incidence of treatment failures (p = 0.039) (39%, digoxin withdrawal group vs. 19%, digoxin maintenance group) and a decreased time to treatment failure (p = 0.037). In addition, patients who continued to receive digoxin had a lower body weight (p = 0.044) and heart rate (p = 0.003) and a higher left ventricular ejection fraction (p = 0.016).

CONCLUSIONS

These data provide strong evidence of the clinical efficacy of digoxin in patients with normal sinus rhythm and mild to moderate chronic heart failure secondary to systolic dysfunction who are treated with diuretics.

What to try while congestive heart failure patients are still ambulatory

As understanding of the mechanisms of congestive heart failure (CHF) has improved, it has become apparent that the previously applied stepped-care approach (ie, diuretic, digitalis, then vasodilator) is no longer valid. There is compelling evidence that use of vasodilators increases survival in CHF, and angiotensin-converting enzyme (ACE) inhibitors are the vasodilators of choice. Use of an ACE inhibitor in patients with New York Heart Association classes II, III, and IV CHF improves survival over that achieved with use of placebo or direct-acting vasodilators. In patients with asymptomatic left ventricular dysfunction after myocardial infarction, long-term administration of captopril improved survival and reduced morbidity and mortality from major cardiovascular events. Using an ACE inhibitor as preventive therapy in post-myocardial infarction patients without overt CHF but with evidence of muscle dysfunction (ie, left ventricular ejection fraction 40% or less) should be considered. The role of a newer vasodilator (eg, amlodipine besylate [Norvasc]) as an adjunct to therapy remains to be defined. If current theories on the pathophysiology of CHF are correct, continued interest in beta blockers is justified, especially in newer agents that have actual vasodilatory action in addition to their other beneficial properties.

The development of positive inotropic agents for chronic heart failure: how have we gone astray?

Because cardiac contractility is impaired in chronic heart failure, many pharmacologic agents have been developed to increase the contractile state of the failing heart. These drugs produce impressive hemodynamic effects, but long-term therapy has failed to produce clinical benefits and has increased mortality in treated patients. This experience has led many physicians to suggest that positive inotropic therapy be abandoned as a therapeutic approach for heart failure. However, recent studies suggest that the efficacy and safety of many (if not all) positive inotropic drugs can be greatly enhanced by reducing the dose of these drugs. The importance of dose is dramatically illustrated by the results of trials with vesnarinone, which decreases mortality when used in low doses but increases mortality when administered in doses only twice as large. Although low doses of positive inotropic drugs may be clinically superior to high doses, it is not clear that these low doses exert significant inotropic effects. All positive inotropic drugs exert actions on the circulation in addition to stimulating the heart, and these ancillary properties may be particularly important at low doses of these drugs. Low doses of milrinone and pimobendan may act primarily to dilate peripheral blood vessels; low doses of digitalis may exert only neurohormonal effects, and low doses of vesnarinone may act as an antiarrhythmic agent. If the noninotropic actions of low doses account for the therapeutic benefits of these drugs, then the positive inotropic effects seen at high doses may be primarily responsible for their adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy and acceptability of perindopril in mild to moderate chronic congestive heart failure

The aim of this 3-month double-blind, placebo-controlled, multicenter trial was to evaluate the clinical efficacy and safety of perindopril, a new long-acting angiotensin-converting enzyme inhibitor in the second-line treatment of mild to moderate chronic congestive heart failure. After a run-in period of at least 14 days, 125 patients with grade II or III New York Heart Association chronic congestive heart failure on baseline diuretic therapy were randomized to perindopril, 2 mg (n = 61), or placebo (n = 64), once daily. Assessment was at 2-week intervals for the first month and then monthly for the 2 following months. After 2 weeks, active treatment was increased to perindopril, 4 mg once daily, if systolic blood pressure was 100 mm Hg or greater. Apart from sex, the two groups were homogeneous before treatment. As shown by the end-point analysis, the increase in exercise time was greater with perindopril than with placebo for both the ergometric bicycle (+111 +/- 21 versus +16 +/- 20 seconds; p = 0.002) and the treadmill (+171 +/- 39 versus +36 +/- 42 seconds; p = 0.024). Compared with placebo, this increase in exercise tolerance with perindopril was accompanied by an improvement in New York Heart Association functional class (p = 0.009), overall heart failure severity score (p < 0.001), and cardiothoracic ratio (p = 0.05). Of the 12 withdrawals from the study, seven were attributed to adverse events, two in the perindopril group and five, including one death, in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Can further benefit be achieved by adding flosequinan to patients with congestive heart failure who remain symptomatic on diuretic, digoxin, and an angiotensin converting enzyme inhibitor? Results of the flosequinan-ACE inhibitor trial (FACET)

BACKGROUND

Angiotensin converting enzyme inhibitors, diuretics, and digoxin are each effective in treating congestive heart failure, but many patients remain symptom-limited on all three medications. This trial was designed to determine whether the addition of oral flosequinan, a new direct-acting arterial and venous vasodilator with possible dose-dependent positive inotropic effects, improves exercise tolerance and quality of life in such patients.

METHODS AND RESULTS

In a randomized, double-blind multicenter trial, 322 patients with predominantly New York Heart Association class II or III congestive heart failure and left ventricular ejection fractions of 35% or less, who were stabilized on a diuretic, angiotensin converting enzyme inhibitor, and digoxin, were treated with 100 mg flosequinan once daily, 75 mg flosequinan twice daily, or matching placebo. Efficacy was evaluated with serial measurements of treadmill exercise time, responses to the Minnesota Living With Heart Failure Questionnaire (LWHF), and clinical assessments during a baseline phase and a 16-week treatment period. After 16 weeks, 100 mg flosequinan once daily produced a significant increment in median exercise time (64 seconds at 16 weeks) compared with placebo (5 seconds), whereas the higher-dose flosequinan group did not show a statistically significant increase. Flosequinan (100 mg once daily) also improved the overall LWHF score significantly compared with placebo; both active therapies decreased the physical component, but 75 mg flosequinan twice daily was associated with a trend toward worsening of the emotional component. Most clinical assessments tended to improve on active therapy.

CONCLUSIONS

These results indicate that additional symptomatic benefit can be attained by adding flosequinan to a therapeutic regimen already including a converting enzyme inhibitor. Because in the future most patients will fall into this category, flosequinan is a potential adjunctive agent in the management of severe congestive heart failure. However, because recent evidence indicates that the flosequinan dose studied in the present trial has an adverse effect on survival, the benefit-to-risk ratio must be assessed in individual patients.

The management of heart failure: a matter of definition?

The term heart failure has become a label for more than one clinical entity. For many years heart failure has been used to denote patients with various heart diseases who have begun to suffer from fluid retention, pulmonary venous hypertension, or systemic venous hypertension, either alone or in combination. More recently, the term heart failure has been applied to the combination of effort intolerance and reduced left ventricular contractility due to ischemic heart disease or other myocardial disease. Comparison of the results of epidemiological studies and therapeutic trials is complicated by variation in the composition of the patient populations selected for study. Drug treatment of heart failure remains fairly empirical. Distinction should be made between immediate or prognostic benefits related to the etiological diagnosis, and benefits related specifically to prevention and relief of, for example, fluid retention, rhythm disturbances, or ventricular hypertrophy. The response of individual patients to several forms of drug treatment, including digoxin, ACE inhibitors, and beta-blockade, is unpredictable. Prospective identification of patients liable to respond well to these drugs is not yet possible, but would greatly assist the choice of treatment. At present, trial of therapy is required in each patient to establish benefit and to avoid long-term treatment of nonresponders.

Effects of vesnarinone on morbidity and mortality in patients with heart failure. Vesnarinone Study Group

BACKGROUND

Inotropic therapy, other than with digitalis glycosides, has had limited success in patients with chronic congestive heart failure. We investigated whether vesnarinone, a new positive inotropic agent, reduces morbidity and mortality and improves the quality of life of patients with symptomatic heart failure.

METHODS

Patients receiving concomitant therapy with digoxin (87 percent) and an angiotensin-converting-enzyme inhibitor (90 percent) who had ejection fractions of 30 percent or less were randomly assigned to receive double-blinded therapy with 60 mg of vesnarinone per day, 120 mg of vesnarinone per day, or placebo. Afer 253 patients had been enrolled, randomization to the 120-mg vesnarinone group had to be stopped because of a significant increase in early mortality in this group. Thereafter, patients were randomly assigned only to 60 mg of vesnarinone per day (a total of 239 patients) or placebo (a total of 238 patients).

RESULTS

Significantly fewer patients in the group receiving 60 mg of vesnarinone than in the group receiving placebo (26 vs. 50 patients; P = 0.003) died or had worsening heart failure during the six-month study period. The reduction in risk was 50 percent (95 percent confidence interval, 20 to 69 percent). Similarly, there was a 62 percent reduction (95 percent confidence interval, 28 to 80 percent) in the risk of dying from any cause among the patients receiving vesnarinone. Furthermore, quality of life improved to a greater extent in the vesnarinone group than in the placebo group over 12 weeks (P = 0.008). The principal side effect associated with vesnarinone was reversible neutropenia, which occurred in 2.5 percent of the patients.

CONCLUSIONS

Six months of therapy with 60 mg of vesnarinone per day resulted in lower morbidity and mortality and improved the quality of life of patients with congestive heart failure. However, a higher dose of vesnarinone (120 mg per day) increased mortality, suggesting that this drug has a narrow therapeutic range; the long-term effects of vesnarinone are unknown.

Acute circulatory support

Numerous drugs can increase cardiac output, thereby improving tissue oxygen delivery, but often they do this at the expense of increasing myocardial oxygen demand. This may be critical when cardiac function is substantially impaired or ischaemia is the precipitating cause. Using polypharmacy to substantially improve cardiovascular status requires detailed knowledge of the pharmacodynamics and interactions of the available agents so that they may be tailored to the individual patient. In some settings combinations of inotropes and vasodilators may be desirable to minimise cardiac workload. In other instances vasopressors may be necessary to urgently restore a minimum perfusion pressure. This paper reviews the use of this group of drugs as well as the mechanical assist devices that may be used when drugs fail.

Withdrawal of digoxin from patients with chronic heart failure treated with angiotensin-converting-enzyme inhibitors. RADIANCE Study

BACKGROUND

Although digoxin is effective in the treatment of patients with chronic heart failure who are receiving diuretic agents, it is not clear whether the drug has a role when patients are receiving angiotensin-converting-enzyme inhibitors, as is often the case in current practice.

METHODS

We studied 178 patients with New York Heart Association class II or III heart failure and left ventricular ejection fractions of 35 percent or less in normal sinus rhythm who were clinically stable while receiving digoxin, diuretics, and an angiotensin-converting-enzyme inhibitor (captopril or enalapril). The patients were randomly assigned in a double-blind fashion either to continue receiving digoxin (85 patients) or to be switched to placebo (93 patients) for 12 weeks. Otherwise, their medical therapy for heart failure was not changed.

RESULTS

Worsening heart failure necessitating withdrawal from the study developed in 23 patients switched to placebo, but in only 4 patients who continued to receive digoxin (P < 0.001). The relative risk of worsening heart failure in the placebo group as compared with the digoxin group was 5.9 (95 percent confidence interval, 2.1 to 17.2). All measures of functional capacity deteriorated in the patients receiving placebo as compared with those continuing to receive digoxin (P = 0.033 for maximal exercise tolerance, P = 0.01 for submaximal exercise endurance, and P = 0.019 for New York Heart Association class). In addition, the patients switched from digoxin to placebo had lower quality-of-life scores (P = 0.04), decreased ejection fractions (P = 0.001), and increases in heart rate (P = 0.001) and body weight (P < 0.001).

CONCLUSIONS

These findings indicate that the withdrawal of digoxin carries considerable risks for patients with chronic heart failure and impaired systolic function who have remained clinically stable while receiving digoxin and angiotensin-converting-enzyme inhibitors.