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)

Oral digoxin effects on exercise performance, K+ regulation and skeletal muscle Na+ ,K+ -ATPase in healthy humans

Abstract

We investigated whether digoxin lowered muscle Na⁺,K⁺‐ATPase (NKA), impaired muscle performance and exacerbated exercise K⁺ disturbances. Ten healthy adults ingested digoxin (0.25 mg; DIG) or placebo (CON) for 14 days and performed quadriceps strength and fatiguability, finger flexion (FF, 105%_{peak‐workrate}, 3 × 1 min, fourth bout to fatigue) and leg cycling (LC, 10 min at 33% VO2peak and 67% VO2peak, 90% VO2peak to fatigue) trials using a double‐blind, crossover, randomised, counter‐balanced design. Arterial (a) and antecubital venous (v) blood was sampled (FF, LC) and muscle biopsied (LC, rest, 67% VO2peak, fatigue, 3 h after exercise). In DIG, in resting muscle, [³H]‐ouabain binding site content (OB‐F_ab) was unchanged; however, bound‐digoxin removal with Digibind revealed total ouabain binding (OB+F_ab) increased (8.2%, P = 0.047), indicating 7.6% NKA–digoxin occupancy. Quadriceps muscle strength declined in DIG (−4.3%, P = 0.010) but fatiguability was unchanged. During LC, in DIG (main effects), time to fatigue and [K⁺]_a were unchanged, whilst [K⁺]_v was lower (P = 0.042) and [K⁺]_a‐v greater (P = 0.004) than in CON; with exercise (main effects), muscle OB‐F_ab was increased at 67% VO2peak (per wet‐weight, P = 0.005; per protein P = 0.001) and at fatigue (per protein, P = 0.003), whilst [K⁺]_a, [K⁺]_v and [K⁺]_a‐v were each increased at fatigue (P = 0.001). During FF, in DIG (main effects), time to fatigue, [K⁺]_a, [K⁺]_v and [K⁺]_a‐v were unchanged; with exercise (main effects), plasma [K⁺]_a, [K⁺]_v, [K⁺]_a‐v and muscle K⁺ efflux were all increased at fatigue (P = 0.001). Thus, muscle strength declined, but functional muscle NKA content was preserved during DIG, despite elevated plasma digoxin and muscle NKA–digoxin occupancy, with K⁺ disturbances and fatiguability unchanged.

Key points

The Na⁺,K⁺‐ATPase (NKA) is vital in regulating skeletal muscle extracellular potassium concentration ([K⁺]), excitability and plasma [K⁺] and thereby also in modulating fatigue during intense contractions.

NKA is inhibited by digoxin, which in cardiac patients lowers muscle functional NKA content ([³H]‐ouabain binding) and exacerbates K⁺ disturbances during exercise.

In healthy adults, we found that digoxin at clinical levels surprisingly did not reduce functional muscle NKA content, whilst digoxin removal by Digibind antibody revealed an ∼8% increased muscle total NKA content.

Accordingly, digoxin did not exacerbate arterial plasma [K⁺] disturbances or worsen fatigue during intense exercise, although quadriceps muscle strength was reduced.

Thus, digoxin treatment in healthy participants elevated serum digoxin, but muscle functional NKA content was preserved, whilst K⁺ disturbances and fatigue with intense exercise were unchanged. This resilience to digoxin NKA inhibition is consistent with the importance of NKA in preserving K⁺ regulation and muscle function.

Progress in heart failure management in the Netherlands and beyond: long-term commitment to deliver high-quality research and patient care

Heart failure (HF) remains a major global problem. In the Netherlands, 1.5–2.0% of the total population is diagnosed with HF. Over 30,000 HF patients are admitted annually in the Netherlands, and this number is expected to further increase given the ageing population and the chronic nature of HF. Despite ongoing efforts to reduce the burden of HF, morbidity and mortality rates of this disease remain high. However, several new treatment modalities have become available or are expected to become available in the coming years. This review will provide an overview of HF research conducted in the Netherlands (often in an international setting) that may have clinical consequences for diagnosis, treatment and prevention of HF, and will also evaluate outcomes of larger clinical trials that have been conducted in the Netherlands.

Left Ventricular Assist Improves Autonomic Imbalance in Patients with Persistent Myocardial Dysfunction

Background

Left ventricular assist devices (LVAD) are an effective therapeutic option for end-stage heart failure (HF). Reduced heart rate variability (HRV) as a result of autonomic derangement is evident in chronic heart failure and several studies have established the independent prognostic value of HRV in chronic heart failure.

Objective

In the present study we investigated whether autonomic function is restored in patients after LVAD implantation with persistent, severely depressed left ventricular function.

Methods

Ambulatory Holter ECG recordings were collected in heart failure patients with an LVAD (n=8) und age-matched heart failure patients without an LVAD (n=7) both on optimal medical therapy. Cardiac dimensions and function were assessed by echocardiography or angiography.

Results

Analysis for heart rate variability revealed reduced SDNN (67±4ms), SDANN (56±4ms) and triangular index (18±1) in heart failure patients on optimal medical therapy. However patients with LVAD demonstrated a restoration in heart rate variability with normal SDNN (108±9ms), SDANN (103±8ms) and triangular index (29±2). Compared to patients without LVAD this difference was statistically significant (p<0.01).

Conclusions

In end-stage heart failure patients autonomic imbalance indicated by severely reduced heart rate variability is restored after LVAD implantation with unloading of the failing heart.

Contemporary Controversies in Digoxin Use in Systolic Heart Failure

Digoxin remains one of the oldest therapies for heart failure; however, its safety and efficacy have been controversial since its initial use. Questions that remain include the clinical efficacy of digoxin when added to contemporary medical therapy, when and if it should be added, and how to minimize adverse effects. In this review, we will summarize recent data on the use of digoxin in systolic heart failure and address some of the controversies regarding the role of digoxin in the modern era of heart failure treatment.

The Room Where It Happens: A Skeptic's Analysis of the New Heart Failure Guidelines

New heart failure guidelines have been issued during the past several months, both in the United States and in Europe, in response to recent advances in and the approval of new drugs for the treatment of heart failure. Although guidelines documents are often viewed as authoritative and purely evidence-based, there are replete with meaningful (and inexplicable) inconsistencies, which derive from a review of the same body of scientific data by different groups. This satirical review highlights several examples of the entertaining foolishness of recent guideline documents in the good-natured hope that physicians will understand what the guidelines are, and more importantly, what they are not. Specifically, this paper describes the emergence of a new nonexistent disease; the strange battle between 2 bradycardic drugs (digoxin and ivabradine); the confusion that reigns over the positioning and dosing of inhibitors of the renin-angiotensin system; and the special recommendations that have been issued for certain special populations. As Otto von Bismarck remarked, guideline deliberations are like sausages; it is better not to see them being made. Yet, even after they are ready for public view, we should be cautious. Practitioners who rely on them for clinical decision-making engage in an unnecessary form of self-deception; those who read them literally and adhere to them strictly do not practice evidence-based medicine; and those who delve into them in a search for the truth are destined to be disappointed.

Digoxin in Heart Failure with a Reduced Ejection Fraction: A Risk Factor or a Risk Marker?

Digoxin is one of the oldest compounds used in cardiovascular medicine. Nevertheless, its mechanism of action and most importantly its clinical utility have been the subject of an endless dispute. Positive inotropic and neurohormonal modulation properties are attributed to digoxin, and it was the mainstay of heart failure therapeutics for decades. However, since the institution of β-blockers and aldosterone antagonists as part of modern heart failure medical therapy, digoxin prescription rates have been in free fall. The fact that digoxin is still listed as a valid therapeutic option in both American and European heart failure guidelines has not altered clinicians' attitude towards the drug. Since the publication of original Digitalis Investigation Group trial data, a series of reports based predominately on observational studies and post hoc analyses have raised concerns about the clinical efficacy and long-term safety of digoxin. In the present review, we will attempt a critical appraisal of the available clinical evidence regarding the efficacy and safety of digoxin in heart failure patients with a reduced ejection fraction. The methodological issues, strengths, and limitations of individual studies will be highlighted.

Safety and efficacy of digoxin: systematic review and meta-analysis of observational and controlled trial data

OBJECTIVE

To clarify the impact of digoxin on death and clinical outcomes across all observational and randomised controlled trials, accounting for study designs and methods.

DATA SOURCES AND STUDY SELECTION

Comprehensive literature search of Medline, Embase, the Cochrane Library, reference lists, and ongoing studies according to a prospectively registered design (

PROSPERO

CRD42014010783), including all studies published from 1960 to July 2014 that examined treatment with digoxin compared with control (placebo or no treatment).

DATA EXTRACTION AND SYNTHESIS

Unadjusted and adjusted data pooled according to study design, analysis method, and risk of bias.

MAIN OUTCOME MEASURES

Primary outcome (all cause mortality) and secondary outcomes (including admission to hospital) were meta-analysed with random effects modelling.

RESULTS

52 studies were systematically reviewed, comprising 621,845 patients. Digoxin users were 2.4 years older than control (weighted difference 95% confidence interval 1.3 to 3.6), with lower ejection fraction (33% v 42%), more diabetes, and greater use of diuretics and anti-arrhythmic drugs. Meta-analysis included 75 study analyses, with a combined total of 4,006,210 patient years of follow-up. Compared with control, the pooled risk ratio for death with digoxin was 1.76 in unadjusted analyses (1.57 to 1.97), 1.61 in adjusted analyses (1.31 to 1.97), 1.18 in propensity matched studies (1.09 to 1.26), and 0.99 in randomised controlled trials (0.93 to 1.05). Meta-regression confirmed that baseline differences between treatment groups had a significant impact on mortality associated with digoxin, including markers of heart failure severity such as use of diuretics (P=0.004). Studies with better methods and lower risk of bias were more likely to report a neutral association of digoxin with mortality (P<0.001). Across all study types, digoxin led to a small but significant reduction in all cause hospital admission (risk ratio 0.92, 0.89 to 0.95; P<0.001; n=29,525).

CONCLUSIONS

Digoxin is associated with a neutral effect on mortality in randomised trials and a lower rate of admissions to hospital across all study types. Regardless of statistical analysis, prescription biases limit the value of observational data.

Is there a role for digitalis in chronic heart failure?--First update

This Living FRISBEE (Living FRIendly Summary of the Body of Evidence using Epistemonikos) is an update of the summary published in April 2015, based on a new systematic review published in May 2015. The main clinical guidelines recommend the use of digitalis for chronic heart failure when moderate to severe symptoms persist after standard therapy, even though there is controversy about its efficacy and security. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified four systematic reviews including 13 randomized trials. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded the use of digitalis for chronic heart failure probably leads to little or no decrease in mortality, but they might reduce hospitalizations and clinical deterioration. However, the certainty of the evidence is low.

The use of biomarkers in human pharmacology (Phase I) studies

The development of a new medicine is a risky and costly undertaking that requires careful planning. This planning is largely applied to the operational aspects of the development and less so to the scientific objectives and methodology. The drugs that will be developed in the future will increasingly affect pathophysiological pathways that have been largely unexplored. Such drug prototypes cannot be immediately introduced in large clinical trials. The effects of the drug on normal physiology, pathophysiology, and eventually the desired clinical effects will need to be evaluated in a structured approach, based on the definition of drug development as providing answers to important questions by appropriate clinical studies. This review describes the selection process for biomarkers that are fit-for-purpose for the stage of drug development in which they are used. This structured and practical approach is widely applicable and particularly useful for the early stages of innovative drug development.

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.

Digitalis for treatment of heart failure in patients in sinus rhythm

BACKGROUND

Digitalis glycosides have been in clinical use for the treatment of heart failure (HF) for longer than 200 years. In recent years, several trials have been conducted to address concerns about their efficacy and toxicity.

OBJECTIVES

To examine the effectiveness of digitalis glycosides in treating HF in patients with normal sinus rhythm. To examine the effects of digitalis in patients taking diuretics and angiotensin-converting enzyme inhibitors; in patients with varying severity and duration of disease; in patients with prior exposure to digitalis versus no prior exposure; and in patients with "HF due to systolic dysfunction" versus "HF with preserved ejection fraction."

SEARCH METHODS

Searches on the following databases were updated in May 2013: The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and Dissertation Abstracts. Annual meeting abstracts of the American Heart Association, the American College of Cardiology, and the European Society of Cardiology were searched from 1996 to March 2013. In addition, reference lists provided by the pharmaceutical industry (GlaxoSmithKline and Covis Pharma) were searched.

SELECTION CRITERIA

Included were randomized placebo-controlled trials of 20 or more adult participants of either sex with symptomatic HF who were studied for seven weeks or longer. Excluded were trials in which the prevalence of atrial fibrillation was 2% or greater, or in which any arrhythmia that might compromise cardiac function or any potentially reversible cause of HF such as acute ischemic heart disease or myocarditis was present.

DATA COLLECTION AND ANALYSIS

Articles selected from the searches described above were evaluated in a joint effort of the review authors. The staff of the Cochrane Heart Group ran searches on the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE.

MAIN RESULTS

No new studies were identified in the updated searches. Thirteen studies (7896 participants) are included, and major endpoints of mortality, hospitalization, and clinical status, based respectively on 8, 4, and 12 of these selected studies, were recorded and analyzed. The data show no evidence of a difference in mortality between treatment and control groups, whereas digitalis therapy is associated with lower rates of both hospitalization and clinical deterioration. The largest study, in which most participants were taking angiotensin-converting enzyme inhibitors, showed a significant rise in "other cardiac" deaths, possibly due to arrhythmias. However collectively, these findings were based on studies done before beta-blockers, as well as angiotensin receptor blockers and aldosterone antagonists, became widely used to treat HF.

AUTHORS' CONCLUSIONS

The literature indicates that digitalis may have a useful role in the treatment of patients with HF who are in normal sinus rhythm. New trials are needed to elucidate the importance of the dosage of digitalis and its usefulness in the era of beta-blockers and other agents shown to be effective in treating HF.

The use of digoxin in patients with worsening chronic heart failure: reconsidering an old drug to reduce hospital admissions

Digoxin is the oldest cardiac drug still in contemporary use, yet its role in the management of patients with heart failure (HF) remains controversial. A purified cardiac glycoside derived from the foxglove plant, digoxin increases ejection fraction, augments cardiac output, and reduces pulmonary capillary wedge pressure without causing deleterious increases in heart rate or decreases in blood pressure. Moreover, it is also a neurohormonal modulator at low doses. In the pivotal DIG (Digitalis Investigation Group) trial, digoxin therapy was shown to reduce all-cause and HF-specific hospitalizations but had no effect on survival. With the discovery of neurohormonal blockers capable of reducing mortality in HF with reduced ejection fraction, the results of the DIG trial were viewed as neutral, and the use of digoxin declined precipitously. Although modern drug and device-based therapies have dramatically improved the survival of ambulatory patients with HF, outcomes for patients with worsening chronic HF, defined as deteriorating signs and symptoms on standard therapy often leading to unscheduled clinic or emergency department visits or hospitalization, have largely remained unchanged over the past 2 decades. The available data suggest that a therapeutic trial of digoxin may be appropriate in patients with worsening chronic heart failure who remain symptomatic.

Digoxin use and lower 30-day all-cause readmission for Medicare beneficiaries hospitalized for heart failure

BACKGROUND

Heart failure is the leading cause for hospital readmission, the reduction of which is a priority under the Affordable Care Act. Digoxin reduces 30-day all-cause hospital admission in chronic systolic heart failure. Whether digoxin is effective in reducing readmission after hospitalization for acute decompensation remains unknown.

METHODS

Of the 5153 Medicare beneficiaries hospitalized for acute heart failure and not receiving digoxin, 1054 (20%) received new discharge prescriptions for digoxin. Propensity scores for digoxin use, estimated for each of the 5153 patients, were used to assemble a matched cohort of 1842 (921 pairs) patients (mean age, 76 years; 56% women; 25% African American) receiving and not receiving digoxin, who were balanced on 55 baseline characteristics.

RESULTS

Thirty-day all-cause readmission occurred in 17% and 22% of matched patients receiving and not receiving digoxin, respectively (hazard ratio [HR] for digoxin, 0.77; 95% confidence interval [CI], 0.63-0.95). This beneficial association was observed only in those with ejection fraction <45% (HR 0.63; 95% CI, 0.47-0.83), but not in those with ejection fraction ≥ 45% (HR 0.91; 95% CI, 0.60-1.37; P for interaction, .145), a difference that persisted throughout the first 12 months postdischarge (P for interaction, .019). HRs (95% CIs) for 12-month heart failure readmission and all-cause mortality were 0.72 (0.61-0.86) and 0.83 (0.70-0.98), respectively.

CONCLUSIONS

In Medicare beneficiaries with systolic heart failure, a discharge prescription of digoxin was associated with lower 30-day all-cause hospital readmission, which was maintained at 12 months, and was not at the expense of higher mortality. Future randomized controlled trials are needed to confirm these findings.

Standard nonspecific therapies in the management of pulmonary arterial hypertension

Recent advances in pulmonary arterial hypertension (PAH) research have created a new era of PAH-specific therapies. Although these therapeutics have revolutionized PAH therapy, their innovation was predated by supportive but nonspecific medical therapies adapted from their use in more common cardiopulmonary diseases. These therapies include oxygen therapy, diuretics, digoxin, anticoagulation, and high-dose calcium channel blockers. Expert opinion continues to support the use of adjunct therapies based on current pathologic understandings of PAH combined with some evidence extrapolated from small studies. This article discusses why these therapies continue to play an important role in the treatment of patients with PAH.

Synthesis, biological evaluation, and pharmacokinetic study of novel liguzinediol prodrugs

Liguzinediol (LZDO) ester prodrugs 3-5 were synthesized and evaluated in vitro and in vivo for their potential use in prolonging the half-life of the parent drug LZDO (1a) in vivo. Prodrugs 3-5 were found to display a potent positive inotropic effect on the myocardium, without the risk of arrhythmia. Prodrugs 3-5 rapidly underwent enzymatic hydrolysis to release the parent compound LZDO in 1-3 h in rat liver microsomes and rat plasma. The half-life of the parent compound was prolonged after intragastric administration of prodrug 3, which was found to be a superior prodrug candidate for increasing myocardial contractility.

Lack of evidence of increased mortality among patients with atrial fibrillation taking digoxin: findings from post hoc propensity-matched analysis of the AFFIRM trial

AIMS

Digoxin is recommended for long-term rate control in paroxysmal, persistent, and permanent atrial fibrillation (AF). While some analyses suggest an association of digoxin with a higher mortality in AF, the intrinsic nature of this association has not been examined in propensity-matched cohorts, which is the objective of the current study.

METHODS AND RESULTS

In Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM), 4060 patients with paroxysmal and persistent AF were randomized to rate (n = 2027) vs. rhythm (n = 2033) control strategies. Of these, 1377 received digoxin as initial therapy and 1329 received no digoxin at baseline. Propensity scores for digoxin use were estimated for each of these 2706 patients and used to assemble a cohort of 878 pairs of patients receiving and not receiving digoxin, who were balanced on 59 baseline characteristics. Matched patients had a mean age of 70 years, 40% were women, and 11% non-white. During the 3.4 years of the mean follow-up, all-cause mortality occurred in 14 and 13% of matched patients receiving and not receiving digoxin, respectively [hazard ratio (HR) associated with digoxin use: 1.06; 95% confidence interval (CI): 0.83-1.37; P = 0.640]. Among matched patients, digoxin had no association with all-cause hospitalization (HR: 0.96; 95% CI: 0.85-1.09; P = 0.510) or incident non-fatal cardiac arrhythmias (HR: 0.90; 95% CI: 0.37-2.23; P = 0.827). Digoxin had no multivariable-adjusted or propensity score-adjusted associations with these outcomes in the pre-match cohort.

CONCLUSIONS

In patients with paroxysmal and persistent AF, we found no evidence of increased mortality or hospitalization in those taking digoxin as baseline initial therapy.

Mortality and morbidity of heart failure treated with digoxin. A propensity-matched study

BACKGROUND

The role of digoxin in the prognosis of patients with heart failure (HF) remains unclear.

AIMS

To evaluate the relationship of commencing treatment with digoxin (CTDig) with the mortality and the morbidity of patients with HF.

METHODS

Prospective study over 8 years on 4467 patients with HF. Main outcomes were all-cause and cardiovascular mortality, hospitalisations and visits. We analyse the independent relationship of CTDig, with the mortality and the morbidity, stratifying patients for cardiovascular comorbidity, after propensity score-matching for potential confounders (1421 patients who CTDig vs. another 1421 patients non-exposed to digoxin).

RESULTS

During a median follow up of 46.1 months, 1872 patients (65.9%) died, and 2203 (77.5%) were hospitalised. CTDig was associated with a lower all-cause mortality (HR = 0.90 [95% CI, 0.84-0.97]), and cardiovascular mortality (HR = 0.87 [0.81-0.96]), hospitalisation (HR = 0.91 [0.86-0.97]), 30-day readmission for HF (HR = 0.88 [0.79-0.95]), and visits (HR = 0.94 [0.90-0.98]) (p < 0.001 in all cases), after adjustment for the propensity to take digoxin, other medications, and other potential confounders. These effects of digoxin were independent of gender, or type of HF (systolic or non-systolic).

CONCLUSION

The data suggest that therapy with digoxin is associated with an improved mortality and morbidity of HF, including women and patients with non-systolic HF.

Characterization of the mechanisms of the increase in PPARδ expression induced by digoxin in the heart using the H9c2 cell line

BACKGROUND AND PURPOSE

Digoxin has been used as an inotropic agent in heart failure for a long time. Troponin I (TnI) phosphorylation is related to cardiac contractility, and the genes are regulated by peroxisome proliferator-activated receptors (PPARs). Our previous studies indicated that cardiac abnormality related to the depressed expression of PPARδ in the hearts of STZ rats is reversed by digoxin. However, the cellular mechanisms for this effect of digoxin have not been elucidated. The aim of the present study was to investigate possible mechanisms for this effect of digoxin using the H9c2 cell line cultured in high glucose (HG) conditions.

METHODS

The effects of digoxin on PPARδ expression, intracellular calcium and TnI phosphorylation were investigated in cultured H9c2 cells, maintained in a HG medium, by using Western blot analysis.

RESULTS

Digoxin increased PPARδ expression in H9c2 cells subjected to HG conditions, and increase the intracellular calcium concentration. This effect of digoxin was blocked by BAPTA-AM at concentrations sufficient to chelate calcium ions. In addition, the calcineurin inhibitor cyclosporine A and KN93, an inhibitor of calcium/calmodulin-dependent protein kinase, inhibited this action. Digoxin also increased TnI phosphorylation and this was inhibited when PPARδ was silenced by the addition of RNAi to the cells. Similar changes were observed on the contraction of H9c2 cells.

CONCLUSION

The results suggest that digoxin appears, through calcium-triggered signals, to reverse the reduced expression of PPARδ in H9c2 cells caused by HG treatment.

Role of mitochondrial dysfunction in cardiac glycoside toxicity

Cardiac glycosides, which inhibit the plasma membrane Na(+) pump, are one of the four categories of drug recommended for routine use to treat heart failure, yet their therapeutic window is limited by toxic effects. Elevated cytoplasmic Na(+) ([Na(+)](i)) compromises mitochondrial energetics and redox balance by blunting mitochondrial Ca(2+) ([Ca(2+)](m)) accumulation, and this impairment can be prevented by enhancing [Ca(2+)](m). Here, we investigate whether this effect underlies the toxicity and arrhythmogenic effects of cardiac glycosides and if these effects can be prevented by suppressing mitochondrial Ca(2+) efflux, via inhibition of the mitochondrial Na(+)/Ca(2+) exchanger (mNCE). In isolated cardiomyocytes, ouabain elevated [Na(+)](i) in a dose-dependent way, blunted [Ca(2+)](m) accumulation, decreased the NADH/NAD+redox potential, and increased reactive oxygen species (ROS). Concomitant treatment with the mNCE inhibitor CGP-37157 ameliorated these effects. CGP-37157 also attenuated ouabain-induced cellular Ca(2+) overload and prevented delayed afterdepolarizations (DADs). In isolated perfused hearts, ouabain's positive effects on contractility and respiration were markedly potentiated by CGP-37157, as were those mediated by β-adrenergic stimulation. Furthermore, CGP-37157 inhibited the arrhythmogenic effects of ouabain in both isolated perfused hearts and in vivo. The findings reveal the mechanism behind cardiac glycoside toxicity and show that improving mitochondrial Ca(2+) retention by mNCE inhibition can mitigate these effects, particularly with respect to the suppression of Ca(2+)-triggered arrhythmias, while enhancing positive inotropic actions. These results suggest a novel strategy for the treatment of heart failure.

Prognostic value of heart rate variability and ventricular arrhythmias during 13-year follow-up in patients with mild to moderate heart failure

BACKGROUND

In contrast to patients with moderate to severe chronic heart failure (CHF), data regarding long-term outcome in patients with mild CHF are scarce. We examined the place of Holter monitoring to study the prognostic value of ventricular arrhythmias and heart rate variability (HRV) in patients with mild to moderate CHF during long-term follow-up.

METHODS

We studied 90 patients with mild to moderate CHF and NYHA class II who had been enrolled in the Dutch Ibopamine Multicenter Trial. At baseline their mean age was 60.5 +/- 8.0 years, left ventricular ejection fraction (LVEF) was 0.29 +/- 0.09, and 85% were males. At the start of the study, patients were only using diuretics, while digoxin, and particularly ACE inhibitors and beta-blockers were initiated later. Univariate and multivariate proportional hazard analyses were performed.

RESULTS

At baseline 80% of patients were in NYHA class II, and 20% were in class III; their mean age was 60 years, mean LVEF was 0.29, and 85% were men. During a follow-up of 13 years, 47 patients (53%) died. Cardiovascular (CV) death occurred in 39 patients, of which 28 were sudden cardiac death (SCD). For both CV death and SCD, LVEF <30% and ventricular premature beats/h (>20) were independent risk markers. Of the HRV parameters, total power (>2,500 ms(2)) was an important risk marker for CV death, but not for SCD.

CONCLUSION

The present 13-year follow-up study in 90 patients with mild to moderate CHF showed that ventricular premature beats and HRV may have important value in predicting outcome.

Digoxin and reduction in mortality and hospitalization in geriatric heart failure: importance of low doses and low serum concentrations

BACKGROUND

Digoxin reduces hospitalizations due to heart failure (HF) and may also reduce mortality at low serum digoxin concentrations (SDC). Most HF patients are > or = 65 years, yet the effects of digoxin on outcomes in these patients have not been well studied.

METHODS

Of the 7788 ambulatory chronic HF patients in normal sinus rhythm in the Digitalis Investigation Group trial (1991-1995), 5548 (2890 were > or = 65 years) were alive at 1 month and were either receiving placebo or had data on SDC. Of these patients, 982 had low (0.5-0.9 ng/mL) and 705 had high (> or = 1 ng/mL) SDC.

RESULTS

Among patients > or = 65 years, compared with 38% placebo patients, 34% low SDC patients died during 39 months of median follow-up (adjusted hazard ratio [AHR] = 0.81; 95% confidence interval [CI] = 0.68-0.96; p =.017). All-cause hospitalizations occurred in 70% of placebo and 68% of low-SDC patients (AHR = 0.86; 95% CI = 0.76-0.98; p =.019). Reduction in hospitalizations for HF occurred in both low and high SDC groups. High SDC was not independently associated with all-cause hospitalization or all-cause mortality. Age, impaired renal function, and pulmonary congestion reduced the odds of low SDC. Low-dose digoxin (< or = 0.125 mg/d) was the strongest independent predictor of low SDC (adjusted odd ratio = 2.37; 95% CI = 1.65-3.39); p <.0001).

CONCLUSIONS

Digoxin at low SDC was associated with a reduction in mortality and hospitalization in chronic geriatric HF, and low-dose digoxin was the strongest predictor of low SDC.

A comparison of low versus high heart rate in patients with atrial fibrillation and advanced chronic heart failure: Effects on clinical profile, neurohormones and survival

BACKGROUND

Atrial fibrillation is common in chronic heart failure. Long-term restoration of sinus rhythm is generally unsuccessful. It may be speculated that higher heart rates are unfavorable, since this may lead to tachycardiomyopathy, but there are no data which have examined this.

METHODS AND RESULTS

Seventy-seven patients with atrial fibrillation and advanced chronic heart failure, age 70 +/- 7 years, left-ventricular ejection fraction 0.23 +/- 0.08, 61% with ischemic etiology were included. Patients were dichotomized according to the median heart rate (80 bpm) at inclusion (39 patients with "low" heart rate and 38 patients with "high" heart rate). At baseline, both patient groups were remarkably comparable. After a mean follow-up of 3.3 +/- 0.9 years, mortality was comparable (62% versus 55%, p = non-significant). An independent relation was found between lower heart rate and survival, in addition to absence of hypertension, digoxin use, and higher N-ANP, dopamine, and renin levels.

CONCLUSION

In the present analysis, patients with atrial fibrillation and advanced chronic heart failure with higher heart rates are comparable to those with lower heart rates. Not higher heart rates at baseline but, on the contrary, lower heart rates seem associated with a worse outcome.

Difference in long-term prognostic value of renal function between ischemic and non-ischemic mild heart failure

INTRODUCTION

Renal function is one of the strongest prognostic markers in patients with chronic heart failure, but it has been suggested that this might be due to (local, i.e. renal) vascular atherosclerosis. The aim of the present study is to evaluate the prognostic value of renal function in both ischemic and non-ischemic mild chronic heart failure.

METHODS

From 161 patients with early chronic heart failure and NYHA class II, who had been enrolled in a multicenter trial, ischemic chronic heart failure was present in 120 patients and non-ischemic chronic heart failure in 41 patients. Estimated glomerular filtration rate was calculated by the Cockcroft-Gault equation (GFRc).

RESULTS

Follow-up duration was 13 years (mean 11.7 years). Mean age was 60.5+/-8.0 years, 86% was male and mean left ventricular ejection fraction was 0.29+/-0.08. Baseline characteristics were not statistically different between the groups. Multivariate Cox regression analysis revealed that in non-ischemic chronic heart failure, renal function was an important predictor of all-cause mortality (Relative Risk; 1.65 (1.05-2.58); p=0.029). In contrast, in ischemic chronic heart failure, renal function was not related to all-cause mortality (Relative Risk; 1.07 (0.92-1.23); p=0.40).

CONCLUSION

In mild chronic heart failure, renal function is a prognostic risk marker for long-term mortality in non-ischemic chronic heart failure, but not in patients with coronary artery disease. These data suggest that renal vascular abnormalities are not primarily responsible for the prognostic value of renal function in patients with mild chronic heart failure.

Socioeconomic relevance of selected treatment strategies in patients with chronic heart failure

More than 2.8% of the population in the USA suffer from chronic heart failure, a condition that primarily afflicts people above the age of 60 years, and results in major expenses for social and health care of affected patients, their caregivers and families. The mainstay of treatment is drug therapy, complemented by comprehensive rehabilitation, invasive procedures, palliative treatment and monitoring. While sufficient health economic evidence exists on the cost-effectiveness of certain standard drugs, such as angiotensin converting enzyme inhibitors or beta-blockers, little or no information exists on the cost effectivty of diuretics or aldosterone antagonists. Recently, introduced treatment strategies such as ventricular assistance devices or telemonitoring have yet to be evaluated for their cost-effectiveness in terms of risk of hospitalization, life expectancy and quality of life. With respect to the aging population and the drastically increasing costs of healthcare for heart failure patients, the goal is a more conscious and cost-effective resource allocation. This can help reduce the incidence of over and under treatment, diminish side effects and consequently improve symptoms, quality of life and life expectancy in the affected population. Further clinical trials and health economic analyses are necessary to optimize recommendations for healthcare of patients with chronic heart failure.

Digitalis for treatment of congestive heart failure in patients in sinus rhythm: a systematic review and meta-analysis

BACKGROUND

This review summarizes the current status of randomized trials of digitalis in treating patients with congestive heart failure who are in sinus rhythm. Methods and results Randomized double-blind placebo-controlled trials of 20 or more adult patients followed for 7 weeks or more were selected. We identified 13 trials that met the inclusion criteria, comprising a total of 7896 patients. Of this number, 7755 patients contributed to information on mortality, 7262 to information on hospitalization for worsening heart failure, and 1096 to information on clinical status. Patients treated with digitalis compared with placebo had an odds ratio and confidence intervals for mortality of 0.98 (0.89, 1.09), for hospitalization of 0.68 (0.61, 0.75), and for a lesser degree of deterioration in clinical status of 0.31 (0.21, 0.43).

CONCLUSIONS

The literature indicates that the drug has no effect on long-term mortality, but reduces the incidence of hospitalization, and has a positive effect on the clinical status of symptomatic patients. The drug has beneficial effects in patients who remain symptomatic despite being appropriately treated with diuretics and angiotensin-converting enzyme inhibitors. However the effects of coadministration with beta-blockers, spironolactone, and valsartan remain uncertain.

Anesthesiology: perioperative medicine or "when the anesthetic is a diuretic"

Two patients are reported, each with heart failure, who were treated with digoxin (case 1) and furosemide (case 2). Indications for medical treatment of patients with heart failure, the role of various drugs, and exercise therapy, are reviewed. At a time when the population of people over 65 years of age is increasing, it is important for physicians to recognize the symptoms of heart failure and to know the most up-to-date treatment for this disorder. These cases demonstrate the significance of the anesthesiologist as a perioperative physician.

Prognostic importance of renal function in patients with early heart failure and mild left ventricular dysfunction

We evaluated the prognostic value of renal function in an initially "untreated" population with mild heart failure and compared the prognosis of this population with a matched controlled population. During a follow-up of 13 years (mean 11.7), 90 patients (56%) died. Mortality was higher compared with a matched controlled population. Multivariate Cox regression analysis demonstrated that beside the well-established risk markers of left ventricular ejection fraction and heart rate, renal function (estimated glomerular filtration rate, hazard ratio 1.16/10 ml/min/1.73 m(2), p = 0.003) was the only additional independent predictor of cardiovascular mortality in patients with early heart failure.

Digitalis for treatment of congestive heart failure in patients in sinus rhythm

BACKGROUND

Digitalis glycosides have been in clinical use in the treatment of congestive heart failure (CHF) for more than 200 years. In recent years several trials have been conducted to address concerns about efficacy and toxicity. Although a systematic review of the literature was published in 1990, an update is required to include more current trials.

OBJECTIVES

To examine the effectiveness of digitalis glycosides in treating CHF in patients with normal sinus rhythm. To examine the effect of digitalis in patients taking diuretics, angiotensin converting enzyme inhibitors, and beta-blockers; patients with varying severity and duration of disease; patients with prior exposure to digitalis vs. no prior exposure; and patients with "CHF due to systolic dysfunction" vs. "CHF with preserved systolic function."

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) 2003 Issue 4, MEDLINE (1966 to December 2003) and EMBASE (1990 to December 2003) were searched. Dissertation Abstracts and annual meeting abstracts of the American Heart Association, American College of Cardiology, and European Society of Cardiology were also searched from 1996-2003. In addition, reference lists provided by the pharmaceutical industry (Glaxo Wellcome Inc.) were searched.

SELECTION CRITERIA

Included were randomized placebo-controlled trials of 20 or more adult patients of either sex with symptomatic CHF who were studied for seven weeks or more. Excluded were trials in which the prevalence of atrial fibrillation was 2% or greater, or in which any arrhythmia that might compromise cardiac function or any potentially reversible cause of CHF such as acute ischemic heart disease or myocarditis was present.

DATA COLLECTION AND ANALYSIS

Articles selected from the searches described above were evaluated as a joint effort of the coauthors. The staff of the Cochrane Heart Group ran searches on the Cochrane Central Register of Controlled Trials.

MAIN RESULTS

Thirteen articles meeting the defined criteria were identified, and major endpoints of mortality, hospitalization, and clinical status, based respectively upon 8, 4, and 12 of these selected studies, were recorded and analyzed. The data show that there is no evidence of a difference in mortality between treatment and control groups, whereas digitalis therapy is associated with a lower rate of hospitalization and of clinical deterioration.

REVIEWERS' CONCLUSIONS

The literature indicates that digitalis has a useful role in the treatment of patients with CHF who are in normal sinus rhythm.