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

Heart Failure and All-Cause Hospitalizations in Patients With Heart Failure: A Meta-Analysis

Importance

Heart failure (HF) hospitalization is a common end point in HF trials; however, how HF hospitalization is associated with all-cause hospitalization in terms of proportionality, correlation of treatment effects, and concomitant reporting has not been studied.

Objective

To determine the ratio of HF to all-cause hospitalizations, whether reported treatment effects on HF hospitalization are associated with treatment effects on all-cause hospitalization, and how often all-cause hospitalization is reported alongside HF hospitalization.

Data Sources

PubMed was searched from inception to September 2, 2024, for randomized clinical trials (RCTs) of HF treatments using MeSH (medical subject heading) terms and keywords associated with heart failure, ventricular failure, ventricular dysfunction, and cardiac failure, as well as the names of specific journals.

Study Selection

RCTs of HF treatments and reporting on HF hospitalization published in 1 of 3 leading medical journals (New England Journal of Medicine, The Lancet, or JAMA).

Data Extraction and Synthesis

The PRISMA guidelines were followed. Data extraction was performed by 2 reviewers, and disagreements were resolved by consensus. Trial baseline characteristics and outcome data on HF and all-cause hospitalizations were extracted. The ratio of HF to all-cause hospitalizations was calculated. The association of HF hospitalization effects with all-cause hospitalization effects was evaluated using hierarchical bayesian models with weak priors. The posterior distribution was used to calculate the HF hospitalization treatment effects that would need to be observed before a high probability (97.5%) of a reduction in all-cause hospitalization could be achieved. The proportion of trials reporting all-cause hospitalization was calculated.

Main Outcomes and Measures

HF and all-cause hospitalizations.

Results

Of 113 trials enrolling 261 068 patients (median proportion of female participants, 25.4% [IQR, 21.3%-34.2%]; median age, 66.2 [IQR, 62.8-70.0] years), 60 (53.1%) reported on all-cause hospitalization. The weighted median ratio of HF to all-cause hospitalizations was 45.9% (IQR, 30.7%-51.7%). This ratio was higher in trials with greater proportions of New York Heart Association class III or IV HF, with lower left ventricular ejection fractions, investigating nonpharmaceutical interventions, and that restricted recruitment to patients with HF and reduced ejection fraction. Reported effects on HF and all-cause hospitalizations were well-correlated (R2 = 90.1%; 95% credible interval, 62.3%-99.8%). In a large trial, the intervention would have to decrease the odds of HF hospitalization by 16% to ensure any reduction, 36% to ensure a 10% reduction, and 56% to ensure a 20% reduction in the odds of all-cause hospitalization with 97.5% probability.

Conclusions and Relevance

In this meta-analysis of HF trials, all-cause hospitalization was underreported despite a large burden of non-HF hospitalizations. Large reductions in HF hospitalization must be observed before clinically relevant reductions in all-cause hospitalization can be inferred.

The role of the methoxy group in approved drugs

The methoxy substituent is prevalent in natural products and, consequently, is present in many natural product-derived drugs. It has also been installed in modern drug molecules with no remnant of natural product features because medicinal chemists have been taking advantage of the benefits that this small functional group can bestow on ligand-target binding, physicochemical properties, and ADME parameters. Herein, over 230 methoxy-containing small-molecule drugs, as well as several fluoromethoxy-containing drugs, are presented from the vantage point of the methoxy group. Biochemical mechanisms of action, medicinal chemistry SAR studies, and numerous X-ray cocrystal structures are analyzed to identify the precise role of the methoxy group for many of the drugs and drug classes. Although the methoxy substituent can be considered as the hybridization of a hydroxy and a methyl group, the combination of these functionalities often results in unique effects that can amount to more than the sum of the individual parts.

Design, Synthesis, and In Vivo Evaluation of Isosteviol Derivatives as New SIRT3 Activators with Highly Potent Cardioprotective Effects

Cardiovascular diseases (CVDs) persist as the predominant cause of mortality, urging the exploration of innovative pharmaceuticals. Mitochondrial dysfunction stands as a pivotal contributor to CVDs development. Sirtuin 3 (SIRT3), a prominent mitochondrial deacetylase known for its crucial role in protecting mitochondria against damage and dysfunction, has emerged as a promising therapeutic target for CVDs treatment. Utilizing isosteviol, a natural ent-beyerene diterpenoid, 24 derivatives were synthesized and evaluated in vivo using a zebrafish model, establishing a deduced structure-activity relationship. Among these, derivative 5v exhibited significant efficacy in doxorubicin-induced cardiomyopathy in zebrafish and murine models. Subsequent investigations revealed that 5v selectively elevated SIRT3 expression, leading to the upregulation of SOD2 and OPA1 expression, effectively preventing mitochondrial dysfunction, mitigating oxidative stress, and preserving cardiomyocyte viability. As a novel structural class of SIRT3 activators with robust therapeutic effects, 5v emerges as a promising candidate for further drug development.

Possible nonimmunological toxicological mechanisms of vesnarinone-associated agranulocytosis in HL-60 cells: role of reduced glutathione as cytotoxic defense

This study was conducted as part of an investigation into the cause of vesnarinone-associated agranulocytosis. When HL-60 cells were exposed to vesnarinone for 48 hr, little cytotoxicity was observed, although reduced glutathione (GSH) content decreased in a concentration-dependent manner. Significant cytotoxicity and reactive oxygen species (ROS) production were observed when intracellular GSH content was reduced by treatment with L-buthionine-(S, R)-sulphoximine. The involvement of myeloperoxidase (MPO) metabolism was suggested, as when HL-60 cells were exposed to a reaction mixture of vesnarinone-MPO/H2O2/Cl-, cytotoxicity was also observed. In contrast, the presence of GSH (1 mM) protected against these cytotoxic effects. Liquid chromatography-mass spectrometry analysis of the MPO/H2O2/Cl- reaction mixture revealed that vesnarinone was converted into two metabolites, (4-(3,4-dimethoxybenzoyl)piperazine [Metabolite 1: M1] and 1-chloro-4-(3,4-dimethoxybenzoyl)piperazine [Metabolite 2: M2]). M2 was identified as the N-chloramine form, a reactive metabolite of M1. Interestingly, M2 was converted to M1, which was accompanied by the conversion of GSH to oxidized GSH (GSSG). Furthermore, when HL-60 cells were exposed to synthetic M1 and M2 for 24 hr, M2 caused dose-dependent cytotoxicity, whereas M1 did not. Cells were protected from M2-derived cytotoxicity by the presence of GSH. In conclusion, we present the first demonstration of the cytotoxic effects and ROS production resulting from the MPO/H2O2/Cl- metabolic reaction of vesnarinone and newly identified the causative metabolite, M2, as the N-chloramine metabolite of M1, which induces cytotoxicity in HL-60 cells. Moreover, a protective role of GSH against the cytotoxicity was revealed. These findings suggest a possible nonimmunological cause of vesnarinone agranulocytosis.

Protective effect of cilostazol and verapamil against thioacetamide-induced hepatotoxicity in rats may involve Nrf2/GSK-3β/NF-κB signaling pathway

BACKGROUND

Verapamil (VER) and cilostazol (Cilo) are mostly used as cardiovascular drugs; they have beneficial effects on different organs toxicities.

AIM

we investigated whether the Nuclear factor erythroid 2-related factor 2 (Nrf2), Glycogen synthase kinase-3β (GSK-3β), and Nuclear factor-kappa B (NF-κB) pathway involved in the protective role of these drugs against Thioacetamide (TAA) induced hepatotoxicity.

METHOD

male rats were randomized divided into five groups, each group (n = 10): control, TAA, VER+TAA, Cilo+TAA, and VER+Cilo+TAA groups. Hepatotoxicity induced in rats by TAA injection once on the 7th day of the experiment.

RESULTS

TAA-induced hepatotoxicity indicated by a significant elevated in serum markers (Alanine aminotransferases (ALT), Aspartate aminotransferases (AST), and bilirubin), oxidative stress markers (Malondialdehyde (MDA), and Nitric oxide (NO)), and protein levels markers (NF-κB, and S100 calcium-binding protein A4 (S100A4)). Also, TAA decreased Nrf2, and increased GSK-3β genes expression. Histopathological alterations in the liver also appeared as a response to TAA injection. On the other hand VER and/or Cilo significantly prevented TAA-induced hepatotoxicity in rats through significantly decreased in ALT, AST, bilirubin, MDA, NO, NF-κB, and S100A4 protein levels. Also, they increased Nrf2 and decreased GSK-3β genes expression which caused improvement in the histopathological changes of the liver.

CONCLUSION

the addition of verapamil to cilostazol potentiated the hepatoprotective activity, and inhibited the progression of hepatotoxicity caused by TAA through the Nrf2/GSK-3β/NF-κBpathway and their activity on oxidative stress, inflammation, and NF-κB protein expression.

Impact of digoxin utilization on clinical outcomes following left ventricular assist device implantation

INTRODUCTION

We aimed to assess the impact of digoxin use following left ventricular assist device (LVAD) implantation on clinical outcomes.

METHODS

Patients implanted with continuous flow LVADs at a single academic medical center and survived to initial hospital discharge were included in the analysis (n = 346). Clinical events were captured at a maximum of 2 years of follow up. Digoxin use was defined as 30-day continuous use post-LVAD. Negative binomial regression and Kaplan-Meier method were used to assess the association between digoxin use and clinical outcomes.

RESULTS

Mean age of the cohort was 56 years (±13) and 23% (79/346) were female sex. Digoxin was used in 144 patients (41.6%) for a median of 268 days (IQR 154, 616). Digoxin use was associated with a significant reduction in cumulative incidence of gastrointestinal bleeding (GIB) (15% vs 26%, p = 0.004). After adjusting for age, hypertension, post-operative hemoglobin, RDW, potassium, and GFR, and use of angiotensin receptor/neprilysin inhibitor, there remained a significant 47% reduction in GIB incidence in patients treated with digoxin. There was no significant difference in cumulative incidence in right ventricular failure (RVF) between the two groups. There was no difference in overall 2-year survival between groups.

CONCLUSIONS

Digoxin use was associated with reduction in GIB events, but not in RVF or mortality. Further studies are needed to confirm these findings and to investigate optimal timing and patient population.

Early Termination of Clinical Trials for Futility - Considerations for a Data and Safety Monitoring Board

Early Termination of Clinical Trials for FutilityClinical trials may be stopped for futility if there is little or no chance of demonstrating the hoped-for effect. Reasons include evidence of no treatment effect, substantial missing data that would unacceptably undermine trial conclusions, or event rates too low to support meaningful comparisons. This review examines issues faced by DSMBs in such settings.

Endpoints in Heart Failure Drug Development

Heart failure (HF) is a major health problem worldwide. The development of effective drug and/or device therapy is crucial to mitigate the significant morbidity, mortality and healthcare costs associated with HF. The choice of endpoint in clinical trials has important practical and clinical implications. Outcomes of interest including mortality and HF hospitalisations provide robust evidence for regulatory approval granted there is sufficiency of safety data. At the same time, it is important to recognise that HF patients experience significant impairments in functional capacity and quality of life, underscoring the need to incorporate parameters of symptoms and patient-reported outcomes in clinical trials. In this review, the authors summarise the evolution and definition of cardiovascular endpoints used in clinical trials, discuss approaches to study design to allow the incorporation of mortality, morbidity and functional endpoints and, finally, examine the current challenges and suggest steps for the development of cardiovascular endpoints that are effective, meaningful and meet the needs of all relevant stakeholders, including patients, physicians regulators and sponsors.

Increase in PKCα Activity during Heart Failure Despite the Stimulation of PKCα Braking Mechanism

Rationale: Heart failure (HF) is marked by dampened cardiac contractility. A mild therapeutic target that improves contractile function without desensitizing the β-adrenergic system during HF may improve cardiac contractility and potentially survival. Inhibiting protein kinase C α (PKCα) activity may fit the criteria of a therapeutic target with milder systemic effects that still boosts contractility in HF patients. PKCα activity has been observed to increase during HF. This increase in PKCα activity is perplexing because it is also accompanied by up-regulation of a molecular braking mechanism. Objective: I aim to explore how PKCα activity can be increased and maintained during HF despite the presence of a molecular braking mechanism. Methods and Results: Using a computational approach, I show that the local diacylglycerol (DAG) signaling is regulated through a two-compartment signaling system in cardiomyocytes. These results imply that after massive myocardial infarction (MI), local homeostasis of DAG signaling is disrupted. The loss of this balance leads to prolonged activation of PKCα, a key molecular target linked to LV remodeling and dysfunctional filling and ejection in the mammalian heart. This study also proposes an explanation for how DAG homeostasis is regulated during normal systolic and diastolic cardiac function. Conclusions: I developed a novel two-compartment computational model for regulating DAG homeostasis during Ang II-induced heart failure. This model provides a promising tool with which to study mechanisms of DAG signaling regulation during heart failure. The model can also aid in identification of novel therapeutic targets with the aim of improving the quality of life for heart failure patients.

Why has positive inotropy failed in chronic heart failure? Lessons from prior inotrope trials

Current pharmacological therapies for heart failure with reduced ejection fraction are largely either repurposed anti‐hypertensives that blunt overactivation of the neurohormonal system or diuretics that decrease congestion. However, they do not address the symptoms of heart failure that result from reductions in cardiac output and reserve. Over the last few decades, numerous attempts have been made to develop and test positive cardiac inotropes that improve cardiac haemodynamics. However, definitive clinical trials have failed to show a survival benefit. As a result, no positive inotrope is currently approved for long‐term use in heart failure. The focus of this state‐of‐the‐art review is to revisit prior clinical trials and to understand the causes for their findings. Using the learnings from those experiences, we propose a framework for future trials of such agents that maximizes their potential for success. This includes enriching the trials with patients who are most likely to derive benefit, using biomarkers and imaging in trial design and execution, evaluating efficacy based on a wider range of intermediate phenotypes, and collecting detailed data on functional status and quality of life. With a rapidly growing population of patients with advanced heart failure, the epidemiologic insignificance of heart transplantation as a therapeutic intervention, and both the cost and morbidity associated with ventricular assist devices, there is an enormous potential for positive inotropic therapies to impact the outcomes that matter most to patients.

Home-based rehabilitation for heart failure with reduced ejection fraction: mixed methods process evaluation of the REACH-HF multicentre randomised controlled trial

OBJECTIVE

To identify and explore change processes explaining the effects of the Rehabilitation Enablement in Chronic Heart Failure (REACH-HF) intervention taking account of reach, amount of intervention received, delivery fidelity and patient and caregiver perspectives.

DESIGN

Mixed methods process evaluation parallel to a randomised controlled trial using data from the intervention group (REACH-HF plus usual care).

SETTING

Four centres in the UK (Birmingham, Cornwall, Gwent and York).

PARTICIPANTS

People with heart failure with reduced ejection fraction (HFrEF) and their caregivers.

METHODS

The REACH-HF intervention consisted of a self-help manual for patients with HFrEF and caregivers facilitated over 12 weeks by trained healthcare professionals. The process evaluation used multimodal mixed methods analysis. Data consisted of audio recorded intervention sessions; demographic data; intervention fidelity scores for intervention group participants (107 patients and 53 caregivers); qualitative interviews at 4 and 12 months with a sample of 19 patients and 17 caregivers.

OUTCOME MEASURES

Quantitative data: intervention fidelity and number, frequency and duration of intervention sessions received. Qualitative data: experiences and perspectives of intervention participants and caregivers.

RESULTS

Intervention session attendance with facilitators was high. Fidelity scores were indicative of adequate quality of REACH-HF intervention delivery, although indicating scope for improvement in several areas. Intervention effectiveness was contingent on matching the intervention implementation to the concerns, beliefs and goals of participants. Behaviour change was sustained when shared meaning was established. Respondents' comorbidities, socio-economic circumstances and existing networks of support also affected changes in health-related quality of life.

CONCLUSIONS

By combining longitudinal mixed methods data, the essential ingredients of complex interventions can be better identified, interrogated and tested. This can maximise the clinical application of research findings and enhance the capacity of multidisciplinary and multisite teams to implement the intervention.

TRIAL REGISTRATION NUMBER

ISRCTN25032672; Pre-results.

Risk of Heart Failure Hospitalization Associated With Cilostazol in Diabetes: A Nationwide Case-Crossover Study

Background and Objective: It has been suggested to avoid cilostazol, the first-line therapy for peripheral arterial disease, in patients with congestive heart failure (HF). The objective of this study was to evaluate the risk of hospitalization for heart failure (HHF) associated with cilostazol use in the patients of diabetes mellitus. Methods: This case-crossover study retrieved records on diabetic patients > 20 years of age who were hospitalized for heart failure during the period of 2009-2011 from the Taiwan National Health Insurance Database. The "current" period was defined as 1-30 days prior to HHF whereas the 91-120 days prior to HHF served as the "reference" period. The exposure status just preceding the event is compared with exposure of the same person in one or more referent remote to the event. Adjusted odds ratios (OR) were used to estimate time-varying discordant exposure by the ratio of the number exposed to cilostazol only during the case period to the number exposed to cilostazol only during the control period. Results: A total of 47,506 diabetic patients were included in the analysis (average age: 72.7 ± 12.4, percentage of males: 48%). A total of 399 patients (0.84%) received cilostazol only in the current period, and 252 (0.53%) received cilostazol only in the reference period. After adjustment for other medications, a significant association was found between cilostazol and HHF (OR: 1.35, 95% CI: 1.14-1.59). After further adjustment for time-varying co-morbidities the ORs remained essentially the same. Sensitivity analyses using different definitions of control period (ranging from 31-60, 61-90, to 121-150 days before index date) yielded adjusted ORs of 1.43 (95% CI: 1.14-1.79), 1.31 (95% CI: 1.09-1.57) and 1.23 (95% CI: 1.06-1.44), respectively suggesting the robustness of our study findings. Conclusion: Use of cilostazol may be positively related to the risk of HHF. Further studies are warranted to explore the underlying mechanisms and to confirm the association.

Nutritional screening based on the controlling nutritional status (CONUT) score at the time of admission is useful for long-term prognostic prediction in patients with heart failure requiring hospitalization

The objective of the study was to clarify whether controlling nutritional status (CONUT) is useful for predicting the long-term prognosis of patients hospitalized with heart failure (HF). A total of 482 (57.5%) HF patients from the Ibaraki Cardiovascular Assessment Study-HF (N = 838) were enrolled (298 men, 71.7 ± 13.6 years). At admission, blood samples were collected and nutritional status assessed using CONUT. CONUT scores were defined as follows: 0-1, normal; 2-4, light; 5-8, moderate; and 9-12, severe undernutrition. Accordingly, 352 (73%) patients had light-to-severe nutritional disturbances. In the follow-up period [median 541.5 (range 354-786) days], 109 deaths were observed. A Kaplan-Meier analysis revealed that all-cause deaths occurred more frequently in HF patients with nutritional disturbances [n = 93 (26.4%)] than in those with normal nutrition [n = 16 (12.3%); log-rank p < 0.001]. The Cox proportional hazard analyses revealed that a per point increase in the CONUT score was associated with an increased risk of all-cause death (hazard ratio 1.142; 95% confidence interval, 1.044-1.249) after controlling simultaneously for age, sex, previous history of HF hospitalization, log brain natriuretic peptide, and use of therapeutic agents at admission (tolvaptan and aldosterone antagonists). This study suggests that nutritional screening using CONUT scores is helpful in predicting the long-term prognosis of patients hospitalized with HF in a multicenter registry setting.

Quality of life and long-term mortality in patients with advanced chronic heart failure treated with intermittent low-dose intravenous inotropes in an outpatient setting

AIMS

There are limited data on the effect of low-dose, intermittent inotropic therapy in an outpatient setting on the quality of life (QOL) in patients with advanced refractory heart failure (HF) symptoms. We aimed to analyse the effect of this treatment modality on QOL and subsequent survival.

METHODS AND RESULTS

The study population comprised 287 consecutive patients with advanced refractory HF symptoms who were treated with low-dose, intravenous intermittent inotropic therapy in the HF Day Care Service at Sheba Medical Centre between September 2000 and September 2012. All patients completed a baseline Minnesota Living with Heart Failure Questionnaire (MLWHFQ), and 137 (48%) completed a 1 year follow-up questionnaire. MLWHFQ scores' means ranged from 0 (better QOL) to 5 (worse QOL). Mean age was 68 ± 12, 86% were men, 77% had ischaemic cardiomyopathy, and the mean left ventricle ejection fraction (LVEF) was 26% ± 13. The mean baseline MLWHFQ score was 3.1 (±1), while the mean at 1 year of treatment was of 2.7 (±1.1), indicating an overall improvement in QOL associated with intermittent low-dose inotrope therapy (p < 0.01). Multivariate analysis showed that younger age, non-ischaemic cardiomyopathy, and worse renal function were independently associated with improvement in QOL at 1 year. Improvement in QOL was not associated with a significant survival benefit during subsequent follow-up.

CONCLUSIONS

In patients with advanced refractory HF symptoms, treatment with low-dose, intermittent intravenous inotropes in an outpatient setting is associated with significant improvement in QOL. However, improvement in QOL in this population does not appear to affect subsequent long-term survival.

Futility approaches to interim monitoring by data monitoring committees

Clinical trials involving participants with high risk of serious events or being exposed to a new intervention with potential serious risk are typically monitored during the course of the trial. Often, this monitoring activity is conducted by an independent group of experts, often referred to as a Data Monitoring Committee (DMC). The DMC responsibility includes monitoring for early evidence of a harmful effect or convincing evidence of a benefit. If the data are consistent and overwhelming, the DMC may recommend that a trial be terminated early. Trials may also be terminated early if the initial goal of demonstrating a benefit cannot in all likelihood be attained, or is futile. These are complicated issues and should be sorted out in the protocol and the DMC charter prior to the start of the trial before data begin to accumulate. Several statistical methods have been developed to assist a DMC in determining when a negative or harmful trend is substantial enough to render the trial continuation futile. These will be briefly summarized. However useful these methods might be, they alone are not adequate to make the decision and the DMC must take into account other issues to make a judgment.

Statistical Methods for Cardiovascular Researchers

RATIONALE

Biostatistics continues to play an essential role in contemporary cardiovascular investigations, but successful implementation of biostatistical methods can be complex.

OBJECTIVE

To present the rationale behind statistical applications and to review useful tools for cardiology research.

METHODS AND RESULTS

Prospective declaration of the research question, clear methodology, and study execution that adheres to the protocol together and serve as the critical foundation of a research endeavor. Both parametric and distribution-free measures of central tendency and dispersion are presented. T testing, ANOVA, and regression analyses are reviewed. Survival analysis, logistic regression, and interim monitoring are also discussed. Finally, common weaknesses in statistical analyses are considered.

CONCLUSIONS

Biostatistics can be productively applied to cardiovascular research if investigators (1) develop and rely on a well-written protocol and analysis plan, (2) consult with a biostatistician when necessary, and (3) write results clearly, differentiating confirmatory from exploratory findings.

Medical Therapy in Peripheral Artery Disease and Critical Limb Ischemia

OPINION STATEMENT

Peripheral artery disease (PAD) comprises atherosclerosis of the aorta and lower extremities. Many patients with PAD are asymptomatic, while others present with intermittent claudication (IC) or critical limb ischemia (CLI). Defined as rest pain or tissue loss that persists for >2 weeks, CLI represents the most severe clinical manifestation of PAD and is associated with an increased risk of limb loss and death. Patients with PAD, including those with CLI, are underdiagnosed and undertreated. In addition to smoking cessation, medical therapy with an antiplatelet agent and statin is recommended for all patients with PAD. Regular exercise has been shown to improve walking distance and quality of life in patients with symptomatic PAD and should be incorporated into each patient's treatment plan. In patients who have CLI and in those with persistent lifestyle-limiting claudication despite optimal medical therapy and an exercise program, revascularization is indicated for limb salvage and symptom relief, respectively. Consensus guidelines currently support an endovascular first approach to revascularization in the majority of cases. Surgical procedures provide an alternative to endovascular therapy in select cases.

Pharmacophore generation and atom based 3D-QSAR of quinoline derivatives as selective phosphodiesterase 4B inhibitors

Reported PDE4B inhibitors were used to design QSAR based pharmacophore model. Using developed pharmacophore model, virtual screening was performed followed by cross-docking to identify novel PDE4B specific inhibitors.

What can we do about exploratory analyses in clinical trials?

The research community has alternatively embraced then repudiated exploratory analyses since the inception of clinical trials in the middle of the twentieth century. After a series of important but ultimately unreproducible findings, these non-prospectively declared evaluations were relegated to hypothesis generating. Since the majority of evaluations conducted in clinical trials with their rich data sets are exploratory, the absence of their persuasive power adds to the inefficiency of clinical trial analyses in an atmosphere of fiscal frugality. However, the principle argument against exploratory analyses is not based in statistical theory, but pragmatism and observation. The absence of any theoretical treatment of exploratory analyses postpones the day when their statistical weaknesses might be repaired. Here, we introduce examination of the characteristics of exploratory analyses from a probabilistic and statistical framework. Setting the obvious logistical concerns aside (i.e., the absence of planning produces poor precision), exploratory analyses do not appear to suffer from estimation theory weaknesses. The problem appears to be a difficulty in what is actually reported as the p-value. The use of Bayes Theorem provides p-values that are more in line with confirmatory analyses. This development may inaugurate a body of work that would lead to the readmission of exploratory analyses to a position of persuasive power in clinical trials.

Phosphodiesterase-3 inhibitor (cilostazol) attenuates oxidative stress-induced mitochondrial dysfunction in the heart

Background

Cilostazol is a type 3 phosphodiesterase inhibitor which has been previously demonstrated to prevent the occurrence of tachyarrhythmia and improve defibrillation efficacy. However, the mechanism for this beneficial effect is still unclear. Since cardiac mitochondria have been shown to play a crucial role in fatal cardiac arrhythmias and that oxidative stress is one of the main contributors to arrhythmia generation, we tested the effects of cilostazol on cardiac mitochondria under severe oxidative stress.

Methods

Mitochondria were isolated from rat hearts and treated with H₂O₂ to induce oxidative stress. Cilostazol, at various concentrations, was used to study its protective effects. Pharmacological interventions, including a mitochondrial permeability transition pore (mPTP) blocker, cyclosporine A (CsA), and an inner membrane anion channel (IMAC) blocker, 4′-chlorodiazepam (CDP), were used to investigate the mechanistic role of cilostazol on cardiac mitochondria. Cardiac mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential change and mitochondrial swelling were determined as indicators of cardiac mitochondrial function.

Results

Cilostazol preserved cardiac mitochondrial function when exposed to oxidative stress by preventing mitochondrial depolarization, mitochondrial swelling, and decreasing ROS production.

Conclusions

Our findings suggest that cardioprotective effects of cilostazol reported previously could be due to its prevention of cardiac mitochondrial dysfunction caused by severe oxidative stress.

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.

Clinical trials in cardiology: pinnacle or inflection point?

Controlled clinical trials conduct the research that completes the causal argument between a treatment and a disease's control. Yet, this pinnacle of clinical research is itself afflicted. Chronic problems with recruitment failure vitiate the potency of our research efforts. In addition, the collision of end-point multiplicity (the drive to measure multiple end points) with the requirement of statistical parsimony (ie, the need to reduce the number of interpretable end points to control the overall type I error) induces a core inefficiency in clinical trial productivity by reducing the number of endpoints findings that are generalizable to the population at large. Unless clinical trialists engage these problems with vigor and imagination, our pinnacle may be nothing more than an inflection point leading to decline.

Metabolic rates of ATP transfer through creatine kinase (CK Flux) predict clinical heart failure events and death

Morbidity and mortality from heart failure (HF) are high, and current risk stratification approaches for predicting HF progression are imperfect. Adenosine triphosphate (ATP) is required for normal cardiac contraction, and abnormalities in creatine kinase (CK) energy metabolism, the primary myocardial energy reserve reaction, have been observed in experimental and clinical HF. However, the prognostic value of abnormalities in ATP production rates through CK in human HF has not been investigated. Fifty-eight HF patients with nonischemic cardiomyopathy underwent ³¹P magnetic resonance spectroscopy (MRS) to quantify cardiac high-energy phosphates and the rate of ATP synthesis through CK (CK flux) and were prospectively followed for a median of 4.7 years. Multiple-event analysis (MEA) was performed for HF-related events including all-cause and cardiac death, HF hospitalization, cardiac transplantation, and ventricular-assist device placement. Among baseline demographic, clinical, and metabolic parameters, MEA identified four independent predictors of HF events: New York Heart Association (NYHA) class, left ventricular ejection fraction (LVEF), African-American race, and CK flux. Reduced myocardial CK flux was a significant predictor of HF outcomes, even after correction for NYHA class, LVEF, and race. For each increase in CK flux of 1 μmol g⁻¹ s⁻¹, risk of HF-related composite outcomes decreased by 32 to 39%. These findings suggest that reduced CK flux may be a potential HF treatment target. Newer imaging strategies, including noninvasive ³¹P MRS that detect altered ATP kinetics, could thus complement risk stratification in HF and add value in conditions involving other tissues with high energy demands, including skeletal muscle and brain.

Phosphodiesterase inhibitors, congestive heart failure, and sudden death: time for re-evaluation

A 42-year-old diabetic man was admitted with systolic heart failure and pulmonary hypertension being treated with sildenafil for the previous year. With an increase in creatinine, he experienced 3 episodes of ventricular tachycardia and ventricular fibrillation. Withdrawal of the phosphodiesterase (PDE) inhibitor resulted in no further episodes of dysrhythmias. The basic pharmacology of PDE inhibitors is presented and the use of PDE-3 inhibitors for the treatment of heart failure causing an increase in sudden death is also reviewed. There have been several cases of sudden death associated with sildenafil use and with its increasing use in patients with severe pulmonary hypertension and decompensated heart failure. The authors also reviewed the electrophysiologic effects of PDE-5 inhibitors associated with their use. The crossover between PDE-3 and PDE-5 inhibitors is also discussed and caution is urged when contemplating the use of PDE-5 inhibitors in patients with systolic heart failure and pulmonary hypertension.

Positive inotropes in heart failure: a review article

Increasing myocardial contractility has long been considered a big help for patients with systolic heart failure, conferring an augmented haemodynamic profile in terms of higher cardiac output, lower cardiac filling pressure and better organ perfusion. Though concerns have been raised over the safety issues regarding the clinical trials of different inotropes in hearts with systolic dysfunction, they still stand as a main therapeutic strategy in many centres dealing with such patients. They must be used as short in duration, low in dose and stopped as early as possible. Evidence-based guidelines have provided clinicians with valuable data for better applying inotropes in heart failure patients. In this paper, the authors address clinical trials with different agents used for increasing cardiac contractility in heart failure patients. Furthermore, the authors focus on recent guidelines on making the most out of inotropes in heart failure patients.

Phase II trials in heart failure: the role of cardiovascular imaging

The development of new therapies for heart failure (HF), especially acute HF, has proven to be quite challenging; and therapies evaluated in HF have greatly outnumbered treatments that are eventually successful in obtaining regulatory approval. Thus, the development of therapies for HF remains a vexing problem for pharmaceutical and device companies, clinical trialists, and health care professionals. Nowhere is this more apparent than in the phase II HF clinical trial, in which the goal is to determine whether an investigational agent should move forward to a phase III trial. Recent advancements in noninvasive cardiovascular imaging have allowed a new era of comprehensive phenotyping of cardiac structure and function in phase II HF trials. Besides using imaging parameters to predict success of subsequent phase III outcome studies, it is essential to also use imaging in phase II HF trials in a way that increases understanding of drug or device mechanism. Determination of the patients who would benefit most from a particular drug or device could decrease heterogeneity of phase III trial participants and lead to more successful HF clinical trials. In this review, we outline advantages and disadvantages of imaging various aspects of cardiac structure and function that are potential targets for therapy in HF, compare and contrast imaging modalities, provide practical advice for the use of cardiovascular imaging in drug development, and conclude with some novel uses of cardiac imaging in phase II HF trials.

Prognostic significance of right ventricular dimension on acute decompensation in chronic left-sided heart failure

Right ventricular (RV) dysfunction has been discussed in relation to an adverse outcome in heart failure (HF). The aim of this study was to analyze the relationship between RV function with HF exacerbation and its subsequent long-term outcome in patients with chronic left-sided HF.We studied 122 consecutive patients who were admitted for dyspnea due to exacerbated left-sided HF with a left ventricular (LV) ejection fraction of less than 40%. Conventional echocardiography was performed in the study subjects on admission and at discharge. Cox proportional hazards analysis revealed that RV end-diastolic dimension (RVDd) (hazard ratio 1.131, P = 0.005, 95% confidence interval 1.039-1.231) and the serum level of creatinine on admission were independent predictors of subsequent cardiac-related death, but RVDd at discharge and other LV parameters were not. Thus, patients were divided into tertiles on the basis of RVDd on admission: < 32 mm (n = 37), 32-40 mm (n = 43), and ≥ 40 mm (n = 42). According to the increase in the RVDd category, the cardiac-related death-free rate significantly decreased. Among the 3 groups, the pulse pressure and serum total bilirubin levels that demonstrated low cardiac output syndrome (LOS) parameters had significant differences.RVDd on admission could be measured noninvasively and easily to predict a worse long-term prognosis of chronic left-sided HF on admission, and showed correlations with LOS parameters.

Effects of cilostazol in the heart

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

Current use of pimobendan in canine patients with heart disease

Pimobendan is a drug with both inotropic and vasodilatory properties and is widely used for the treatment of heart failure in dogs. The best evidence regarding its efficacy is derived from several clinical studies of dogs with the two most common conditions that result in heart failure: dilated cardiomyopathy (DCM) and degenerative mitral valve disease (DMVD). The main studies addressing the effectiveness of pimobendan in dogs with DCM and DVMD are discussed in this article.

Cilostazol attenuates ventricular arrhythmia induction and improves defibrillation efficacy in swine

Previous reports demonstrated that cilostazol, a phosphodiesterase 3 inhibitor, affected cellular electrophysiology and reduced episodes of ventricular fibrillation (VF) in patients with Brugada syndrome. However, its effects on VF induction and defibrillation efficacy have never been investigated. We tested the hypothesis that cilostazol increases the VF threshold (VFT) and decreases the upper limit of vulnerability (ULV) and the defibrillation threshold (DFT). A total of 48 pigs were randomly assigned to defibrillation and VF induction studies. The diastolic pacing threshold (DPT), VFT, ULV, DFT, and effective refractory period were determined before and after the infusion of cilostazol at 6 mg/kg, 3 mg/kg, or vehicle. The DPT was significantly increased after administration of 3 and 6 mg/kg cilostazol. The ULV and DFT were significantly decreased after administration of 6 mg/kg cilostazol only. The ULV in the 6 mg/kg group had 12% lower peak voltage and 25% lower total energy, and the DFT had 13% lower peak voltage and 25% lower total energy. The VFT was not altered in any experimental group. This study shows that cilostazol administration significantly increased the DPT, which was associated with significantly reduced DFT and ULV.

β₂ AR agonists in treatment of chronic heart failure: long path to translation

The main clinical manifestations of advanced chronic heart failure (CHF), e.g. in dilated cardiomyopathy (DCM), are reduced systolic and diastolic functions, increased arterial elastance and arterio-ventricular uncoupling, accompanied and exacerbated by an excessive sympathetic activation and extensive abnormalities in the βAR signaling. Loss of cardiomyocytes due to apoptosis is one mechanism that undoubtedly contributes to cardiac remodeling and functional deterioration associated with dilated cardiomyopathy (DCM). Research during the last decade on the single cardiomyocyte level strongly suggested that selective stimulation of β(1) AR activates the proapoptotic signaling pathways, while selective stimulation of β(2) AR is antiapoptotic, but its precise mechanisms remain to be elucidated. Extensive research in the rat model of DCM following induction of myocardial infarction (MI) showed that prolonged treatment with of β(2) AR agonist, fenoterol, in combination with a β(1) AR blocker, metoprolol, is more effective than β(1) AR blocker alone and as effective as β(1) AR blocker with ACE inhibitor with respect to survival and cardiac remodeling. This combined regimen of β(2) AR agonists and a β(1) AR blocker might be considered for clinical testing as alternative or adjunct therapy to currently acceptable CHF arsenal. This article is part of a special issue entitled "Key Signaling Molecules in Hypertrophy and Heart Failure."

Effect of levosimendan in experimental verapamil-induced myocardial depression

Background

Calcium antagonist overdose can cause severe deterioration of hemodynamics unresponsible to treatment with beta adrenergic inotropes. The aim of the study was to evaluate in an experimental model the effects of levosimendan during severe calcium antagonist intoxication.

Methods

Twelve landrace-pigs were intoxicated with intravenous verapamil at escalating infusion rates. The infusion containing 2.5 mg/ml verapamil was used aiming to a reduction of cardiac output by 40% from the baseline value. Intoxicated pigs were randomized into two groups: control (saline) and levosimendan (intravenous bolus). Inotropic effect was measured as a change in a maximum of the positive slope of the left ventricular pressure (LV dP/dt). The survival and hemodynamics of the animals were followed for 120 min after the targeted reduction of cardiac output.

Results

In the control group, five out of six pigs died during the experiment. In the levosimendan group, one pig died before completion of the experiment (p = 0.04). In the levosimendan group a change in LV dP/dt was positive in four out of six pigs compared to one out of six pigs in the control group (p = ns).

Conclusions

In this experimental model, the use of levosimendan was associated with improved survival.

Pharmacologic therapy for intermittent claudication

Peripheral artery disease, defined as atherosclerosis in the lower extremities, affects nearly 8.5 million people in the United States. Due to the frequent asymptomatic manifestation of peripheral artery disease, diagnosis may be delayed and its true incidence underestimated. However, some patients may experience aching pain, numbness, weakness, or fatigue, a condition termed intermittent claudication. Peripheral atherosclerosis is associated with cardiovascular risk and physical impairment; therefore, treatment goals are aimed at decreasing cardiovascular risk, as well as improving quality of life. Little debate exists regarding the management of cardiovascular risk reduction, which consists of both antiplatelet therapy and risk factor modification. Despite recently published guidelines, the treatment of intermittent claudication is less well established and the management remains controversial and uncertain. Exercise remains the first-line therapy for intermittent claudication; however, pharmacologic treatment is often necessary. Although only two prescription drugs have been approved by the U.S. Food and Drug Administration for the treatment of intermittent claudication, several supplements and investigational agents have been evaluated. Therapeutic optimization should balance the anticipated improvements in quality of life with the potential safety risks.

Left ventricular mechanical dyssynchrony as assessed by phase analysis of ECG-gated SPECT myocardial perfusion imaging

Cardiac resynchronization therapy (CRT) has shown benefits in patients with severe heart failure. The traditional criteria to select patients for CRT (NYHA class III or IV, depressed left ventricular (LV) ejection fraction, and prolonged QRS duration) result in at least 30% of the selected patients with no response to CRT. Recent studies with tissue Doppler imaging (TDI) have shown that the presence of LV dyssynchrony is an important predictor for response to CRT. Phase analysis has been developed to assess LV dyssynchrony from electrocardiography-gated single photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI). This technique uses Fourier harmonic functions to approximate regional wall thickening over the cardiac cycle and to calculate phases of regional onset of mechanical contraction (OMC). These OMC phases are obtained three-dimensionally over the left ventricle to generate an OMC phase distribution. Quantitative indices are calculated from the phase distribution to assess degree of LV dyssynchrony. This technique has been compared to other methods of measuring LV dyssynchrony and shown promising results in clinical evaluations. In this review, the phase analysis methodology is described and its up-to-date validations are summarized.