Digoxin Withdrawal Worsens Clinical Status in Stable Patients With Heart Failure Receiving Optimal Contemporaneous Therapy—A Randomized Controlled Trial

Consequences of Discontinuing Long-Term Drug Treatment in Patients With Heart Failure and Reduced Ejection Fraction

There is uncertainty regarding the clinical effects of discontinuation of drugs for heart failure after long-term use. The withdrawal of long-term treatment can follow 1 of 4 distinct patterns: 1) loss of on-treatment effect with no observed changes following discontinuation (eg, prazosin); 2) attenuation or loss of on-treatment effect with rebound clinical worsening following discontinuation (eg, nitroprusside); 3) persistence of deleterious on-treatment effect followed by clinical worsening after discontinuation (eg, milrinone and flosequinan); and 4) persistence of favorable on-treatment effect followed by clinical worsening after discontinuation (eg, digoxin and sodium-glucose cotransporter 2 inhibitors). Persuasive evidence for persistence of efficacy has been demonstrated for the use of digoxin, diuretic agents, sodium-glucose cotransporter 2 inhibitors, and (to a limited extent) for angiotensin-converting enzyme inhibitors. Available evidence for worsening of clinical status following the withdrawal of neurohormonal antagonists largely consists of observational studies. However, their findings are difficult to interpret because of considerable confounding related to the fact that drugs were withdrawn for clinical reasons, which represented a more important contributor to the poor outcome of these patients than the withdrawal of an effective drug. Nevertheless, the totality of available evidence points to a meaningful clinical deterioration within a few weeks following the withdrawal for most drugs that have been evaluated for the treatment of heart failure. These findings suggests that that our current emphasis on the implementation of foundational drugs needs to include an equally important emphasis to avoid even short-term gaps in treatment.

The effect of down-titration and discontinuation of heart failure pharmacotherapy in older people: A systematic review and meta-analysis

The aim of this study was to investigate whether interventions to discontinue or down-titrate heart failure (HF) pharmacotherapy are feasible and associated with risks in older people. A systematic review and meta-analysis were conducted according to PRISMA 2020 guidelines. Electronic databases were searched from inception to 8 March 2023. Randomized controlled trials (RCTs) and observational studies included people with HF, aged ≥50 years and who discontinued or down-titrated HF pharmacotherapy. Outcomes were feasibility (whether discontinuation or down-titration of HF pharmacotherapy was sustained at follow-up) and associated risks (mortality, hospitalization, adverse drug withdrawal effects [ADWE]). Random-effects meta-analysis was performed when heterogeneity was not substantial (Higgins I2 < 70%). Sub-analysis by frailty status was conducted. Six RCTs (536 participants) and 27 observational studies (810 499 participants) across six therapeutic classes were included, for 3-260 weeks follow-up. RCTs were conducted in patients presenting with stable chronic HF. Down-titrating a renin-angiotensin system inhibitor (RASI) in patients with chronic kidney disease was 76% more likely than continuation (risk ratio [RR] 1.76, 95% confidence interval [CI] 1.14-2.73), with no difference in mortality (RR 0.64, 95% CI 0.30-1.64). Discontinuation of beta-blockers were feasible compared to continuation in preserved ejection fraction (RR 1.00, 95% CI 0.68-1.47). Participants were 25% more likely to re-initiate discontinued diuretics (RR 0.75, 95% CI 0.66-0.86). Digoxin discontinuation was associated with 5.5-fold risk of hospitalization compared to continuation. Worsening HF was the most common ADWE. One observational study measured frailty but did not report outcomes by frailty status. The appropriateness and associated risks of down-titrating or discontinuing HF pharmacotherapy in people aged ≥75 years is uncertain. Evaluation of outcomes by frailty status necessitates investigation.

Sensational site: the sodium pump ouabain-binding site and its ligands

Cardiotonic steroids (CTS), used by certain insects, toads, and rats for protection from predators, became, thanks to Withering's trailblazing 1785 monograph, the mainstay of heart failure (HF) therapy. In the 1950s and 1960s, we learned that the CTS receptor was part of the sodium pump (NKA) and that the Na+/Ca2+ exchanger was critical for the acute cardiotonic effect of digoxin- and ouabain-related CTS. This "settled" view was upended by seven revolutionary observations. First, subnanomolar ouabain sometimes stimulates NKA while higher concentrations are invariably inhibitory. Second, endogenous ouabain (EO) was discovered in the human circulation. Third, in the DIG clinical trial, digoxin only marginally improved outcomes in patients with HF. Fourth, cloning of NKA in 1985 revealed multiple NKA α and β subunit isoforms that, in the rodent, differ in their sensitivities to CTS. Fifth, the NKA is a cation pump and a hormone receptor/signal transducer. EO binding to NKA activates, in a ligand- and cell-specific manner, several protein kinase and Ca2+-dependent signaling cascades that have widespread physiological effects and can contribute to hypertension and HF pathogenesis. Sixth, all CTS are not equivalent, e.g., ouabain induces hypertension in rodents while digoxin is antihypertensinogenic ("biased signaling"). Seventh, most common rodent hypertension models require a highly ouabain-sensitive α2 NKA and the elevated blood pressure is alleviated by EO immunoneutralization. These numerous phenomena are enabled by NKA's intricate structure. We have just begun to understand the endocrine role of the endogenous ligands and the broad impact of the ouabain-binding site on physiology and pathophysiology.

Whither digitalis? What we can still learn from cardiotonic steroids about heart failure and hypertension

Cloning of the "Na⁺ pump" (Na⁺,K⁺-ATPase or NKA) and identification of a circulating ligand, endogenous ouabain (EO), a cardiotonic steroid (CTS), triggered seminal discoveries regarding EO and its NKA receptor in cardiovascular function and the pathophysiology of heart failure (HF) and hypertension. Cardiotonic digitalis preparations were a preferred treatment for HF for two centuries, but digoxin was only marginally effective in a large clinical trial (1997). This led to diminished digoxin use. Missing from the trial, however, was any consideration that endogenous CTS might influence digitalis' efficacy. Digoxin, at therapeutic concentrations, acutely inhibits NKA but, remarkably, antagonizes ouabain's action. Prolonged treatment with ouabain, but not digoxin, causes hypertension in rodents; in this model, digoxin lowers blood pressure (BP). Furthermore, NKA-bound ouabain and digoxin modulate different protein kinase signaling pathways and have disparate long-term cardiovascular effects. Reports of "brain ouabain" led to the elucidation of a new, slow neuromodulatory pathway in the brain; locally generated EO and the α2 NKA isoform help regulate sympathetic drive to the heart and vasculature. The roles of EO and α2 NKA have been studied by EO assay, ouabain-resistant mutation of α2 NKA, and immunoneutralization of EO with ouabain-binding Fab fragments. The NKA α2 CTS binding site and its endogenous ligand are required for BP elevation in many common hypertension models and full expression of cardiac remodeling and dysfunction following pressure overload or myocardial infarction. Understanding how endogenous CTS impact hypertension and HF pathophysiology and therapy should foster reconsideration of digoxin's therapeutic utility.

Effect of digitalis level on readmission and mortality rate among heart failure reduced ejection fraction patients

INTRODUCTION

Digitalis has been used for over 200 years to treat patients with heart failure, and evidence supports its use to improve clinical symptoms and quality of life, but not survival. The objective of this retrospective study was to evaluate the effects of digitalis on readmission and mortality in patients with heart failure with reduced ejection fraction (HFrEF) who were receiving current guideline recommended medical therapy.

METHODS

We reviewed medical record data from a retrospective cohort study of 1047 patients admitted to the hospital from 2005 to 2014 with decompensated HFrEF. 244 received digitalis, at some point during patient trajectory, and 803 never received digitalis. The primary outcomes of interest were the length of stay in hospital, readmission rates after discharge at 1, 6, 12, and 24 months and the overall mortality rate, at the same time points.

RESULTS

We studied the effects of digitalis after adjusting for age, sex, race, potentially confounding comorbidities, and prescription medications. Digitalis treatment is associated with decreases in EF in patients with HFrEF (OR = -2.83, P < 0.001) and was associated with an increased readmission rate for any reason after discharge from the hospital at 6, 12, and 24 months, 53%, 34%, and 35%, respectively. No statistically significant difference was found between patients who received digitalis and those who did not (referent group) for the length of hospital stay and overall mortality rate.

CONCLUSION

Digitalis use is associated with increased re-admission rates for any reason following discharge from the hospital at 6, 12, and 24 months.

A narrative review of the safety concerns of deprescribing in older adults and strategies to mitigate potential harms

INTRODUCTION

As with prescribing or continuing medications, deprescribing brings with it the potential for harm as well as benefit. Uncertainty and avoidance of harm has been reported as a barrier to deprescribing in practice and may contribute to continuation of inappropriate medications.

AREAS COVERED

This narrative review covers four main safety concerns/potential harms of deprescribing in older adults: adverse drug withdrawal events, return of medical condition(s), reversal of drug-drug interactions and damage to the doctor-patient relationship. These are discussed in relation to medications in general, with some examples of medication classes used to illustrate the potential safety concerns. The majority of these harms can be minimized or even prevented by using a patient-centered, structured deprescribing process with planning, tapering and close monitoring during, and after medication withdrawal.

EXPERT OPINION

More research is needed into the safety concerns of deprescribing, however, avenues exist during drug development and post-marketing surveillance to gain knowledge on this topic. Questions remain about when it is suitable to discontinue certain medications/medication classes and there is uncertainty about the harms and benefits of both medication continuation and discontinuation in complex older adults.

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.