Ranolazine for the treatment of heart failure with preserved ejection fraction: background, aims, and design of the RALI-DHF study

Efficacy of Ranolazine to Improve Diastolic Performance in Heart Failure with Preserved Ejection Fraction: A Systematic Review and Meta-analysis

This article evaluates the efficacy of using ranolazine to improve diastolic performance and exercise capacity in heart failure with preserved ejection fraction. A comprehensive literature review found eight trials where there are no significant difference in peak O2 (p=0.09) and exercise duration (p=0.18) between ranolazine and placebo. The ranolazine group had significantly higher and better diastolic parameters compared to placebo, with a mean difference of 0.45 (95% CI [27.18-39.50]). There were no significant differences for haemodynamic parameters (blood pressure and heart rate) and electrocardiography (QT interval) between ranolazine and placebo. The review found that ranolazine has good wefficacy to improve diastolic performance among heart failure with preserved ejection fraction patients and it does not affect blood pressure, heart rate and rate of ventricular repolarisation (shortening of the QT interval).

Microvascular Dysfunction in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is an increasingly studied entity accounting for 50% of all diagnosed heart failure and that has claimed its own dignity being markedly different from heart failure with reduced EF in terms of etiology and natural history (Graziani et al., 2018). Recently, a growing body of evidence points the finger toward microvascular dysfunction as the major determinant of the pathological cascade that justifies clinical manifestations (Crea et al., 2017). The high burden of comorbidities such as metabolic syndrome, hypertension, atrial fibrillation, chronic kidney disease, obstructive sleep apnea, and similar, could lead to a systemic inflammatory state that impacts the physiology of the endothelium and the perivascular environment, engaging complex molecular pathways that ultimately converge to myocardial fibrosis, stiffening, and dysfunction (Paulus and Tschope, 2013). These changes could even self-perpetrate with a positive feedback where hypoxia and locally released inflammatory cytokines trigger interstitial fibrosis and hypertrophy (Ohanyan et al., 2018). Identifying microvascular dysfunction both as the cause and the maintenance mechanism of this condition has opened the field to explore specific pharmacological targets like nitric oxide (NO) pathway, sarcomeric titin, transforming growth factor beta (TGF-β) pathway, immunomodulators or adenosine receptors, trying to tackle the endothelial impairment that lies in the background of this syndrome (Graziani et al., 2018;Lam et al., 2018). Yet, many questions remain, and the new data collected still lack a translation to improved treatment strategies. To further elaborate on this tangled and exponentially growing topic, we will review the evidence favoring a microvasculature-driven etiology of this condition, its clinical correlations, the proposed diagnostic workup, and the available/hypothesized therapeutic options to address microvascular dysfunction in the failing heart.

Therapy for heart failure with preserved ejection fraction: current status, unique challenges, and future directions

Heart failure (HF) with preserved ejection fraction (HFpEF) is the most common form of HF. Among elderly women, HFpEF comprises more than 80% of incident HF cases. Adverse outcomes-exercise intolerance, poor quality of life, frequent hospitalizations, and reduced survival-approach those of classic HF with reduced EF (HFrEF). However, despite its importance, our understanding of the pathophysiology of HFpEF is incomplete, and despite intensive efforts, optimal therapy remains uncertain, as most trials to date have been negative. This is in stark contrast to management of HFrEF, where dozens of positive trials have established a broad array of effective, guidelines-based therapies that definitively improve a range of clinically meaningful outcomes. In addition to providing an overview of current management status, we examine evolving data that may help explain this paradox, overcome past challenges, provide a roadmap for future success, and that underpin a wave of new trials that will test novel approaches based on these insights.

Ranolazine: Multifaceted Role beyond Coronary Artery Disease, a Recent Perspective

Ranolazine is a piperazine derivative approved as an antianginal. Primarily used as a second-line antianginal in stable coronary artery disease. Ranolazine blocks the late Na + current and prevents the rise of cytosolic calcium. It decreases myocardial wall tension and improves coronary blood flow. Ranolazine is effective in atrial fibrillation (AF) as an adjunct to electrical or pharmacological cardioversion. It can be used in combination with amiodarone or dronedarone. It has also been used in AF arising after coronary artery bypass grafting surgery. Role of ranolazine is also being evaluated in pulmonary arterial hypertension, diastolic dysfunction, and chemotherapy-induced cardiotoxicity. Ranolazine has some anti-glycemic effect and has shown a reduction of hemoglobin A1c in multiple trials. The antianginal effect of ranolazine has also been seen to be more in patients with diabetes compared to those without diabetes. Ranolazine is being evaluated in patients with the peripheral arterial disease with intermittent claudication and hypertrophic cardiomyopathy. Pilot studies have shown that ranolazine may be beneficial in neurological conditions with myotonia. The evidence-base on the use of ranolazine in various conditions is rapidly increasing with results of further trials eagerly awaited. Accumulating evidence may see ranolazine in routine clinical use for many conditions beyond its traditional role as an antianginal.

Treatment of Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a growing epidemiologic problem affecting more than half of the patients with heart failure (HF). HFpEF has a significant morbidity and mortality and so far no treatment has been clearly demonstrated to improve the outcomes in HFpEF, in contrast to the efficacy of treatment in heart failure with reduced ejection fraction (HFrEF).The failure of proven beneficial drugs in HFrEF to influence the outcome of patients with HFpEF could be related to the heterogeneity of the disease, its various phenotypes and multifactorial pathophysiology, incompletely elucidated yet. The diagnosis of HFpEF could be demanding or even inaccurate. Moreover, the therapeutic strategies were influenced by different cut-offs used to define preserved ejection fraction (EF). From this perspective, the current guidelines have classified HFpEF by an EF ≥ 50%, together with a distinct entity, heart failure with mid-range ejection fraction (HFmrEF), defined by an EF ranging from 41-49%.New therapies have been developed to interfere with the mediator pathways of HFpEF at the cellular and molecular level, including mineralocorticoid receptor antagonists, soluble guanylate cyclase stimulators, or angiotensin receptor-neprilysin inhibitors. A number of antidiabetic drugs, such as sodium/glucose cotransporter 2 inhibitors and dipeptidyl peptidase-4 inhibitors are promising options, being under research in large clinical trials. Until the results of ongoing trials shed light on these therapies, guidelines recommend empirical treatment for established HFpEF, and emphasize the crucial role of addressing cardiovascular comorbidities leading to HFpEF, in particular arterial hypertension.

Biological Phenotypes of Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) involves multiple pathophysiological mechanisms, which result in the heterogeneous phenotypes that are evident clinically, and which have potentially confounded previous HFpEF trials. A greater understanding of the in vivo human processes involved, and in particular, which are the causes and which are the downstream effects, may allow the syndrome of HFpEF to be distilled into distinct diagnoses based on the underlying biology. From this, specific interventions can follow, targeting individuals identified on the basis of their biological phenotype. This review describes the biological phenotypes of HFpEF and therapeutic interventions aimed at targeting these phenotypes.

Management of Heart Failure with Preserved Ejection Fraction: Current Challenges and Future Directions

Heart failure (HF) with preserved ejection fraction (HFpEF) is the most common form of HF in patients older than 65 years. Among elderly women living in the community, HFpEF comprises nearly 90% of incident HF cases. The health and economic impact of HFpEF is at least as great as that of HF with reduced ejection fraction (HFrEF), with similar severity of acute hospitalization rates and substantial mortality. Despite the importance of HFpEF, our understanding of its pathophysiology is incomplete, and optimal treatment remains largely undefined. Unlike the management of HFrEF, there is a paucity of large evidence-based trials demonstrating morbidity and mortality benefit for the treatment of HFpEF. The agents tested in trials to date, which were based upon an incomplete understanding of the pathophysiology of HFpEF, have not been positive. There is an urgent need to understand HFpEF pathophysiology and to focus on developing novel therapeutic targets.

Heart Failure with Preserved Ejection Fraction in Older Adults

Most elderly patients, particularly women, who have heart failure, have a preserved ejection fraction. Patients with this syndrome have severe symptoms of exercise intolerance, frequent hospitalizations, and increased mortality. Despite the importance of heart failure with preserved ejection fraction (HFpEF), the understanding of its pathophysiology is incomplete, and optimal treatment remains largely undefined. Unlike the management of HFrEF, there is a paucity of large evidence-based trials demonstrating morbidity and mortality benefit for the treatment of HFpEF. An update is presented on information regarding pathophysiology, diagnosis, management, and future directions in this important and growing disorder.

Role of Ranolazine in cardiovascular disease and diabetes: Exploring beyond angina

Ranolazine was FDA approved for chronic angina in 2006. Since then, there has been extensive research involving this drug. The mechanism of action, debatable at the time of approval, has been demonstrated. Ranolazine acts via inhibition of late sodium channel current in the myocardium. This acts by lowering abnormally high cytosolic calcium levels. Other possible clinical applications of Ranolazine have also been explored. Out of many lines of investigation, its effects in atrial fibrillation, especially post-CABG and recurrent atrial fibrillation show promise. It has also shown definite HbA1c lowering effects when used in diabetics with coronary artery disease. Other possible indications for the drug include pulmonary arterial hypertension, diastolic dysfunction and chemotherapy-induced cardiotoxicity. This review aims to summarize major research regarding Ranolazine in potential applications beyond chronic angina. There are few dedicated large, randomized, phase III trials exploring the newer effects of Ranolazine. There are a few such trials underway, but more are needed.

Association between left ventricular end-diastolic pressure and coronary artery disease as well as its extent and severity

Patients with myocardial ischemia exhibit increased left ventricular end-diastolic pressure (LVEDP). The study was to evaluate the relationship between LVEDP measured by left cardiac catheterization and coronary artery disease (CAD) as well as its extent and severity evaluated by coronary angiography (CAG). 912 patients who underwent CAG and left cardiac catheterization were enrolled. There were 313 patients without CAD and 599 with CAD according to CAG. The extent and severity of coronary artery was evaluated by number of vessels and Gensini score. Analyze the correlation of LVEDP and CAD as well as its extent and severity. LVEDP was significantly higher in CAD patients than non-CAD (9.58±5.78 mmHg vs 10.9±5.46 mmHg, P<0.001), and was correlated independently with the presence of CAD (OR = 0.11, per 5 mmHg increase, 95% CI 1.02-1.29, P = 0.02). LVEDP was increased with an increase of number of vessels. By linear regression analysis, LVEDP was significantly associated with Gensini score (standardized β = 0.034, P = 0.001). In non-CAD group, LVEDP was only correlated with age (r = 0.123, P = 0.030). In conclusion, our findings suggest that elevated LVEDP was significantly associated with CAD as well as its extent and severity. LVEDP was only correlated with age in non-CAD patients. LVEDP measurement provides incremental clinical value for CAD and non-CAD patients.

Cardiac energy metabolic alterations in pressure overload-induced left and right heart failure (2013 Grover Conference Series)

Pressure overload of the heart, such as seen with pulmonary hypertension and/or systemic hypertension, can result in cardiac hypertrophy and the eventual development of heart failure. The development of hypertrophy and heart failure is accompanied by numerous molecular changes in the heart, including alterations in cardiac energy metabolism. Under normal conditions, the high energy (adenosine triphosphate [ATP]) demands of the heart are primarily provided by the mitochondrial oxidation of fatty acids, carbohydrates (glucose and lactate), and ketones. In contrast, the hypertrophied failing heart is energy deficient because of its inability to produce adequate amounts of ATP. This can be attributed to a reduction in mitochondrial oxidative metabolism, with the heart becoming more reliant on glycolysis as a source of ATP production. If glycolysis is uncoupled from glucose oxidation, a decrease in cardiac efficiency can occur, which can contribute to the severity of heart failure due to pressure-overload hypertrophy. These metabolic changes are accompanied by alterations in the enzymes that are involved in the regulation of fatty acid and carbohydrate metabolism. It is now becoming clear that optimizing both energy production and the source of energy production are potential targets for pharmacological intervention aimed at improving cardiac function in the hypertrophied failing heart. In this review, we will focus on what alterations in energy metabolism occur in pressure overload induced left and right heart failure. We will also discuss potential targets and pharmacological approaches that can be used to treat heart failure occurring secondary to pulmonary hypertension and/or systemic hypertension.

Heart failure with preserved ejection fraction in the elderly: scope of the problem

Heart failure with preserved ejection fraction (HFpEF) is the most common form of heart failure (HF) in older adults, particularly women, and is increasing in prevalence as the population ages. With morbidity and mortality on par with HF with reduced ejection fraction, it remains a most challenging clinical syndrome for the practicing clinician and basic research scientist. Originally considered to be predominantly caused by diastolic dysfunction, more recent insights indicate that HFpEF in older persons is typified by a broad range of cardiac and non-cardiac abnormalities and reduced reserve capacity in multiple organ systems. The globally reduced reserve capacity is driven by: 1) inherent age-related changes; 2) multiple, concomitant co-morbidities; 3) HFpEF itself, which is likely a systemic disorder. These insights help explain why: 1) co-morbidities are among the strongest predictors of outcomes; 2) approximately 50% of clinical events in HFpEF patients are non-cardiovascular; 3) clinical drug trials in HFpEF have been negative on their primary outcomes. Embracing HFpEF as a true geriatric syndrome, with complex, multi-factorial pathophysiology and clinical heterogeneity could provide new mechanistic insights and opportunities for progress in management. This article is part of a Special Issue entitled CV Aging.

New strategies for heart failure with preserved ejection fraction: the importance of targeted therapies for heart failure phenotypes

The management of heart failure with reduced ejection fraction (HF-REF) has improved significantly over the last two decades. In contrast, little or no progress has been made in identifying evidence-based, effective treatments for heart failure with preserved ejection fraction (HF-PEF). Despite the high prevalence, mortality, and cost of HF-PEF, large phase III international clinical trials investigating interventions to improve outcomes in HF-PEF have yielded disappointing results. Therefore, treatment of HF-PEF remains largely empiric, and almost no acknowledged standards exist. There is no single explanation for the negative results of past HF-PEF trials. Potential contributors include an incomplete understanding of HF-PEF pathophysiology, the heterogeneity of the patient population, inadequate diagnostic criteria, recruitment of patients without true heart failure or at early stages of the syndrome, poor matching of therapeutic mechanisms and primary pathophysiological processes, suboptimal study designs, or inadequate statistical power. Many novel agents are in various stages of research and development for potential use in patients with HF-PEF. To maximize the likelihood of identifying effective therapeutics for HF-PEF, lessons learned from the past decade of research should be applied to the design, conduct, and interpretation of future trials. This paper represents a synthesis of a workshop held in Bergamo, Italy, and it examines new and emerging therapies in the context of specific, targeted HF-PEF phenotypes where positive clinical benefit may be detected in clinical trials. Specific considerations related to patient and endpoint selection for future clinical trials design are also discussed.

Postextrasystolic blood pressure potentiation predicts poor outcome of cardiac patients

Background

Postextrasystolic blood pressure potentiation (PESP), the pulse wave augmentation after an extrasystolic beat, is typically enhanced in heart failure (HF) patients. This study prospectively tested the association of PESP and mortality in cardiac patients.

Methods and Results

Consecutive patients (n=941; mean age, 61 years; 19% female) presenting with acute myocardial infarction were enrolled between May 2000 and March 2005 and followed up until August 2010. The main study outcome was 5‐year all‐cause mortality. Patients underwent noninvasive 30‐minute recordings of ECG and continuous blood pressure. PESP presence was based on the ratio between the first postectopic pulse wave amplitude and the mean of the subsequent 9 pulse wave amplitudes. A ratio above 1 was prospectively defined as PESP present. Ventricular premature complexes (VPCs) suitable for PESP quantification were present in recordings of 220 patients. PESP was present in 62 of these patients. Patients without suitable VPCs were classified as PESP absent.

During the follow‐up, 72 patients died. Among the 220 patients in whom PESP was measurable, 27 died. Under univariable analysis, PESP was a significant predictor of death (P<0.001) as were GRACE score (P<0.001), left ventricular ejection fraction (LVEF) (P<0.001), and the number of recorded VPCs (P<0.001). Under multivariable analysis, PESP (P<0.001), GRACE score (P<0.001), and LVEF (P=0.001) were independently associated with outcome. The combination of PESP presence and LVEF ≤35% identified a subgroup of patients with a particularly high mortality of 46.7%. Separate validation reproduced the finding in an unrelated population of 146 HF patients.

Conclusions

PESP, which likely reflects abnormalities of myocardial calcium cycling, predicts the mortality risk in postinfarction patients.

Clinical Trial Registration

URL: ClinicalTrials.gov. Unique identifier: NCT00196274.

Therapeutic interventions for heart failure with preserved ejection fraction: A summary of current evidence

Heart failure with preserved ejection fraction (HFPEF) is common and represents a major challenge in cardiovascular medicine. Most of the current treatment of HFPEF is based on morbidity benefits and symptom reduction. Various pharmacological interventions available for heart failure with reduced ejection fraction have not been supported by clinical studies for HFPEF. Addressing the specific aetiology and aggressive risk factor modification remain the mainstay in the treatment of HFPEF. We present a brief overview of the currently recommended therapeutic options with available evidence.

Ranolazine improves diastolic function in spontaneously hypertensive rats

Diastolic dysfunction can lead to heart failure with preserved ejection fraction, for which there is no effective therapeutic. Ranolazine has been reported to reduce diastolic dysfunction, but the specific mechanisms of action are unclear. The effect of ranolazine on diastolic function was examined in spontaneously hypertensive rats (SHRs), where left ventricular relaxation is impaired and stiffness increased. The objective of this study was to determine whether ranolazine improves diastolic function in SHRs and identify the mechanism(s) by which improvement is achieved. Specifically, to test the hypothesis that ranolazine, by inhibiting late sodium current, reduces Ca(2+) overload and promotes ventricular relaxation and reduction in diastolic stiffness, the effects of ranolazine or vehicle on heart function and the response to dobutamine challenge were evaluated in aged male SHRs and Wistar-Kyoto rats by echocardiography and pressure-volume loop analysis. The effects of ranolazine and the more specific sodium channel inhibitor tetrodotoxin were determined on the late sodium current, sarcomere length, and intracellular calcium in isolated cardiomyocytes. Ranolazine reduced the end-diastolic pressure-volume relationship slope and improved diastolic function during dobutamine challenge in the SHR. Ranolazine and tetrodotoxin also enhanced cardiomyocyte relaxation and reduced myoplasmic free Ca(2+) during diastole at high-stimulus rates in the SHR. The density of the late sodium current was elevated in SHRs. In conclusion, ranolazine was effective in reducing diastolic dysfunction in the SHR. Its mechanism of action, at least in part, is consistent with inhibition of the increased late sodium current in the SHR leading to reduced Ca(2+) overload.

Targeting sodium channels in cardiac arrhythmia

Cardiac voltage-gated sodium channels are responsible for proper electrical conduction in the heart. During acquired pathological conditions and inherited sodium channelopathies, altered sodium channel function causes conduction disturbances and ventricular arrhythmias. Although the clinical, genetic and biophysical characteristics of cardiac sodium channel disease have been extensively studied, limited progress has been made in the development of treatment strategies targeting sodium channels. Classical non-selective sodium channel blockers have only limited clinical applicability, while more selective inhibitors of the late sodium current constitute a more promising treatment option. Because of our insufficient understanding of their complexity and subcellular diversity, other specific therapeutic targets for modulating sodium channels remain elusive. The current status and future potential of targeting sodium channels in cardiac arrhythmias are discussed.

Update on heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFPEF) is the most common form of heart failure (HF) in older adults, and is increasing in prevalence as the population ages. Morbidity and long-term mortality in HFPEF are substantial and can be similar to HF with reduced ejection fraction (HFREF), yet HFPEF therapy remains empirical and treatment guidelines are based primarily on expert consensus. Neurohormonal blockade has revolutionized the management of HFREF, but trials in HFPEF based on this strategy have been disappointing to date. However, many recent studies have increased knowledge about HFPEF. The concept of HFPEF has evolved from a 'cardio-centric' model to a syndrome that may involve multiple cardiovascular and non-cardiovascular mechanisms. Emerging data highlight the importance of non-pharmacological management strategies and assessment of non-cardiovascular comorbidities. Animal models, epidemiological cohorts, and small human studies suggest that oxidative stress and inflammation contribute to HFPEF, potentially leading to development of new therapeutic targets.

Pre-clinical diastolic dysfunction

Pre-clinical diastolic dysfunction (PDD) has been broadly defined as left ventricular diastolic dysfunction without the diagnosis of congestive heart failure (HF) and with normal systolic function. PDD is an entity that remains poorly understood, yet has definite clinical significance. Although few original studies have focused on PDD, it has been shown that PDD is prevalent, and that there is a clear progression from PDD to symptomatic HF including dyspnea, edema, and fatigue. In diabetic patients and in patients with coronary artery disease or hypertension, it has been shown that patients with PDD have a significantly higher risk of progression to heart failure and death compared with patients without PDD. Because of these findings and the increasing prevalence of the heart failure epidemic, it is clear that an understanding of PDD is essential to decreasing patients' morbidity and mortality. This review will focus on what is known concerning pre-clinical diastolic dysfunction, including definitions, staging, epidemiology, pathophysiology, and the natural history of the disease. In addition, given the paucity of trials focused on PDD treatment, studies targeting risk factors associated with the development of PDD and therapeutic trials for heart failure with preserved ejection fraction will be reviewed.

Current treatment of heart failure with preserved ejection fraction: should we add life to the remaining years or add years to the remaining life?

According to the ejection fraction, patients with heart failure may be divided into two different groups: heart failure with preserved or reduced ejection fraction. In recent years, accumulating studies showed that increased mortality and morbidity rates of these two groups are nearly equal. More importantly, despite decline in mortality after treatment in regard to current guideline in patients with heart failure with reduced ejection fraction, there are still no trials resulting in improved outcome in patients with heart failure with preserved ejection fraction so far. Thus, novel pathophysiological mechanisms are under development, and other new viewpoints, such as multiple comorbidities resulting in increased non-cardiac deaths in patients with heart failure and preserved ejection fraction, were presented recently. In this review, we will focus on the tested as well as the promising therapeutic options that are currently studied in patients with heart failure with preserved ejection fraction, along with a brief discussion of pathophysiological mechanisms and diagnostic options that are helpful to increase our understanding of novel therapeutic strategies.

Late sodium current inhibition in acquired and inherited ventricular (dys)function and arrhythmias

The late sodium current has been increasingly recognized for its mechanistic role in various cardiovascular pathologies, including angina pectoris, myocardial ischemia, atrial fibrillation, heart failure and congenital long QT syndrome. Although relatively small in magnitude, the late sodium current (I(NaL)) represents a functionally relevant contributor to cardiomyocyte (electro)physiology. Many aspects of I(NaL) itself are as yet still unresolved, including its distribution and function in different cell types throughout the heart, and its regulation by sodium channel accessory proteins and intracellular signalling pathways. Its complexity is further increased by a close interrelationship with the peak sodium current and other ion currents, hindering the development of inhibitors with selective and specific properties. Thus, increased knowledge of the intricacies of the complex nature of I(NaL) during distinct cardiovascular conditions and its potential as a pharmacological target is essential. Here, we provide an overview of the functional and electrophysiological effects of late sodium current inhibition on the level of the ventricular myocyte, and its potential cardioprotective and anti-arrhythmic efficacy in the setting of acquired and inherited ventricular dysfunction and arrhythmias.

Myocardial energetics in heart failure

It has become common sense that the failing heart is an "engine out of fuel". However, undisputable evidence that, indeed, the failing heart is limited by insufficient ATP supply is currently lacking. Over the last couple of years, an increasingly complex picture of mechanisms evolved that suggests that potentially metabolic intermediates and redox state could play the more dominant roles for signaling that eventually results in left ventricular remodeling and contractile dysfunction. In the pathophysiology of heart failure, mitochondria emerge in the crossfire of defective excitation-contraction coupling and increased energetic demand, which may provoke oxidative stress as an important upstream mediator of cardiac remodeling and cell death. Thus, future therapies may be guided towards restoring defective ion homeostasis and mitochondrial redox shifts rather than aiming solely at improving the generation of ATP.

Redox-dependent regulation of the Na⁺-K⁺ pump: new twists to an old target for treatment of heart failure

By the time it was appreciated that the positive inotropic effect of cardiac glycosides is due to inhibition of the membrane Na(+)-K(+) pump, glycosides had been used for treatment of heart failure on an empiric basis for ~200 years. The subsequent documentation of their lack of clinical efficacy and possible harmful effect largely coincided with the discovery that a raised Na(+) concentration in cardiac myocytes plays an important role in the electromechanical phenotype of heart failure syndromes. Consistent with this, efficacious pharmacological treatments for heart failure have been found to stimulate the Na(+)-K(+) pump, effectively the only export route for intracellular Na(+) in the heart failure. A paradigm has emerged that implicates pump inhibition in the raised Na(+) levels in heart failure. It invokes protein kinase-dependent activation of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) and glutathionylation, a reversible oxidative modification, of the Na(+)-K(+) pump molecular complex that inhibits its activity. Since treatments of proven efficacy reverse the oxidative Na(+)-K(+) pump inhibition, the pump retains its status as a key pharmacological target in heart failure. Its role as a target is well integrated with the paradigms of neurohormonal abnormalities, raised myocardial oxidative stress and energy deficiency implicated in the pathophysiology of the failing heart. We propose that targeting oxidative inhibition of the pump is useful for the exploration of future treatment strategies. This article is part of a Special Issue entitled "Na(+)Regulation in Cardiac Myocytes".

Intracellular Na⁺ and cardiac metabolism

In heart failure, alterations of excitation-contraction underlie contractile dysfunction. One important defect is an elevation of the intracellular Na(+) concentration in cardiac myocytes ([Na(+)]i), which has an important impact on cytosolic and mitochondrial Ca(2+) homeostasis. While elevated [Na(+)]i is thought to compensate for decreased Ca(2+) load of the sarcoplasmic reticulum (SR), it yet negatively affects energy supply-and-demand matching and can even induce mitochondrial oxidative stress. Here, we review the mechanisms underlying these pathophysiological changes. The chain of events may constitute a vicious cycle of ion dysregulation, oxidative stress and energetic deficit, resembling characteristic cellular deficits that are considered key hallmarks of the failing heart. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".

Positioning of inflammatory biomarkers in the heart failure landscape

The clinical syndrome of heart failure is characterized by a systemic inflammatory response that contributes to end organ damage in the heart and circulation and can thus lead to worsening heart failure. The ensemble of inflammatory mediators that have been detected in heart failure patients include pro-inflammatory cytokines and their cognate receptors, as well as molecules secreted/released by macrophages (galectin-3 and pentraxin-3). Inflammatory biomarkers correlate with disease severity and prognosis across the broad spectrum of heart failure syndromes. Given the proliferation of new biomarkers that predict disease severity and prognosis in heart failure, it is reasonable to ask whether there is a current role for measuring inflammatory mediators in heart failure. This review will attempt to address this question, as well as review several novel approaches that have utilized inflammatory biomarkers to enhance risk stratification and prognosis in heart failure patients.

Wenxin Keli suppresses ventricular triggered arrhythmias via selective inhibition of late sodium current

BACKGROUND

Wenxin Keli is a popular Chinese herb extract that approximately five million Asians are currently taking for the treatment of a variety of ventricular arrhythmias. However, its electrophysiological mechanisms remain poorly understood.

METHODS AND RESULTS

The concentration-dependent electrophysiological effects of Wenxin Keli were evaluated in the isolated rabbit left ventricular myocytes and wedge preparation. Wenxin Keli selectively inhibited late sodium current (INa) with an IC50 of 3.8 ± 0.4 mg/mL, which was significantly lower than the IC50 of 10.6 ± 0.9 mg/mL (n = 6, P < 0.05) for the fast INa. Wenxin Keli produced a small but statistically significant QT prolongation at 0.3 mg/mL, but shortened the QT and Tp-e interval at concentrations ≥ 1 mg/mL. Wenxin Keli increased QRS duration by 10.1% from 34.8 ± 1.0 ms to 38.3 ± 1.1 ms (n = 6, P < 0.01) at 3 mg/mL at a basic cycle length of 2,000 ms. However, its effect on the QRS duration exhibited weak use-dependency, that is, QRS remained less changed at increased pacing rates than other classic sodium channel blockers, such as flecainide, quinidine, and lidocaine. On the other hand, Wenxin Keli at 1-3 mg/mL markedly reduced dofetilide-induced QT and Tp-e prolongation by attenuation of its reverse use-dependence and abolished dofetilide-induced early afterdepolarization (EAD) in four of four left ventricular wedge preparations. It also suppressed digoxin-induced delayed after depolarization (DAD) and ventricular tachycardias without changing the positive staircase pattern in contractility at 1-3 mg/mL in a separate experimental series (four of four).

CONCLUSIONS

Wenxin Keli suppressed EADs, DADs, and triggered ventricular arrhythmias via selective inhibition of late INa.

Ranolazine: clinical applications and therapeutic basis

Ranolazine is currently approved for use in chronic angina. The basis for this use is likely related to inhibition of late sodium channels with resultant beneficial downstream effects. Randomized clinical trials have demonstrated an improvement in exercise capacity and reduction in angina episodes with ranolazine. This therapeutic benefit occurs without the hemodynamic effects seen with the conventional antianginal agents. The inhibition of late sodium channels as well as other ion currents has a central role in the potential use of ranolazine in ischemic heart disease, arrhythmias, and heart failure. Despite its QTc-prolonging action, albeit minimal, clinical data have not shown a predisposition to torsades de pointes, and the medication has shown a reasonable safety profile even in those with structural heart disease. In this article we present the experimental and clinical data that support its current therapeutic role, and provide insight into potential future clinical applications.

Effect of ranolazine on left ventricular dyssynchrony in patients with coronary artery disease

We previously reported that ranolazine improves exercise myocardial perfusion. Ranolazine ameliorates myocardial ischemia by augmenting myocardial blood flow; likely by a reduction in the extravascular compression of small vessels. We hypothesized that ranolazine could improve left ventricular (LV) dyssynchrony as assessed by phase analysis of gated single photon emission computed tomographic myocardial perfusion imaging. Patients (n = 32) with known or suspected coronary artery disease and reversible perfusion defects on a clinically indicated stress myocardial perfusion imaging were restudied 4 weeks after ranolazine (500 to 1,000 mg orally twice daily) was added to their conventional treatment in an open-label trial (data previously reported). The LV systolic and diastolic dyssynchrony indexes were obtained using automated phase analysis before and after ranolazine. No significant changes were found in the heart rate or blood pressure (at rest or during stress) after treatment. The perfusion pattern improved in 13 of 18 patients who had undergone exercise testing, but in only 3 of 14 patients who had undergone vasodilator stress testing. No significant changes were seen in the LV ejection fraction or volume after treatment. The systolic and diastolic LV dyssynchrony improved after ranolazine therapy; there was a significant decrease in the systolic phase SD (21 ± 17 vs 18 ± 13, p = 0.04), systolic bandwidth (69 ± 60 vs 53 ± 38, p = 0.03), diastolic SD (29 ± 18 vs 24 ± 15, p = 0.047) and diastolic bandwidth (91 ± 61 vs 72 ± 45, p = 0.02). In conclusion, the present study is the first to show improvements in diastolic and systolic LV synchrony with ranolazine as measured by automated phase analysis of gated single photon emission computed tomographic myocardial perfusion imaging.

Management of myocardial ischemia. Is ranolazine needed? For all or some patients with myocardial ischemia?

This editorial refers to 'Should ranolazine be used for all patients with ischemic heart disease or only for symptomatic patients with stable angina or for those with refractory angina pectoris? A critical appraisal' by U Thadani also published in this issue.

Prevalence, clinical phenotype, and outcomes associated with normal B-type natriuretic peptide levels in heart failure with preserved ejection fraction

B-type natriuretic peptide (BNP) is used widely to exclude heart failure (HF) in patients with dyspnea. However, most studies of BNP have focused on diagnosing HF with reduced ejection fraction (EF). The aim of this study was to test the hypothesis that a normal BNP level (≤100 pg/ml) is relatively common in HF with preserved EF (HFpEF), a heterogenous disorder commonly associated with obesity. A total of 159 consecutive patients enrolled in the Northwestern University HFpEF Program were prospectively studied. All subjects had symptomatic HF with EF >50% and elevated pulmonary capillary wedge pressure. BNP was tested at baseline in all subjects. Clinical characteristics, echocardiographic parameters, invasive hemodynamics, and outcomes were compared among patients with HFpEF with normal (≤100 pg/ml) versus elevated (>100 pg/ml) BNP. Of the 159 patients with HFpEF, 46 (29%) had BNP ≤100 pg/ml. Subjects with normal BNP were younger, were more often women, had higher rates of obesity and higher body mass index, and less commonly had chronic kidney disease and atrial fibrillation. EFs and pulmonary capillary wedge pressures were similar in the normal and elevated BNP groups (62 ± 7% vs 61 ± 7%, p = 0.67, and 25 ± 8 vs 27 ± 9 mm Hg, p = 0.42, respectively). Elevated BNP was associated with enlarged left atrial volume, worse diastolic function, abnormal right ventricular structure and function, and worse outcomes (e.g., adjusted hazard ratio for HF hospitalization 4.0, 95% confidence interval 1.6 to 9.7, p = 0.003). In conclusion, normal BNP levels were present in 29% of symptomatic outpatients with HFpEF who had elevated pulmonary capillary wedge pressures, and although BNP is useful as a prognostic marker in HFpEF, normal BNP does not exclude the outpatient diagnosis of HFpEF.

New treatment options for late Na current, arrhythmias, and diastolic dysfunction

The late Na current is of pathophysiological importance for the heart. Ranolazine is an innovative anti-ischemic and antianginal agent that inhibits the late Na current, thereby reducing the Na-dependent Ca-overload, which improves diastolic tone and oxygen handling during myocardial ischemia. In addition, ranolazine seems to exert beneficial effects on diastolic cardiac function. Moreover, there are experimental and clinical data about its antiarrhythmic properties. A beneficial atrial selectivity of ranolazine has been suggested that may be helpful for the treatment of atrial fibrillation. The purpose of this review article is to discuss possible future clinical indications based on novel experimental and preclinical results and the significance of the available data.

18β-Glycyrrhetinic acid preferentially blocks late Na current generated by ΔKPQ Nav1.5 channels

AIM

To compare the effects of two stereoisomeric forms of glycyrrhetinic acid on different components of Na(+) current, HERG and Kv1.5 channel currents.

METHODS

Wild-type (WT) and long QT syndrome type 3 (LQT-3) mutant ΔKPQ Nav1.5 channels, as well as HERG and Kv1.5 channels were expressed in Xenopus oocytes. In addition, isolated human atrial myocytes were used. Two-microelectrode voltage-clamp technique was used to record the voltage-activated currents.

RESULTS

Superfusion of 18β-glycyrrhetinic acid (18β-GA, 1-100 μmol/L) blocked both the peak current (I(Na,P)) and late current (I(Na,L)) generated by WT and ΔKPQ Nav1.5 channels in a concentration-dependent manner, while 18α-glycyrrhetinic acid (18α-GA) at the same concentrations had no effects. 18β-GA preferentially blocked I(Na,L) (IC(50)=37.2 ± 14.4 μmol/L) to I(Na,P) (IC(50)=100.4 ± 11.2 μmol/L) generated by ΔKPQ Nav1.5 channels. In human atrial myocytes, 18β-GA (30 μmol/L) inhibited 47% of I(Na,P) and 87% of I(Na,L) induced by Anemonia sulcata toxin (ATX-II, 30 nmol/L). Superfusion of 18β-GA (100 μmol/L) had no effects on HERG and Kv1.5 channel currents.

CONCLUSION

18β-GA preferentially blocked the late Na current without affecting HERG and Kv1.5 channels.

Role of ranolazine in angina, heart failure, arrhythmias, and diabetes

Ranolazine which is currently approved as an antianginal agent reduces the Na-dependent Ca overload via inhibition of the late sodium current (late I(Na)) and thus improves diastolic tone and oxygen handling during myocardial ischemia. According to accumulating evidence ranolazine also exerts beneficial effects on diastolic and systolic heart failure where late I(Na) was also found to be elevated. Moreover, late I(Na) plays a crucial role as an arrhythmic substrate. Ranolazine has been described to have antiarrhythmic effects on ventricular as well as atrial arrhythmias without any proarrythmia or severe organ toxicity as it is common for several antiarrhythmic drugs. In patients with diabetes, treatment with ranolazine led to a significant improvement of glycemic control. In this article possible new clinical indications of the late I(Na)-inhibitor ranolazine are reviewed. We summarize novel experimental and clinical studies and discuss the significance of the available data.

Stable angina pectoris: antianginal therapies and future directions

Advances in pharmacotherapy for stable angina have produced a wide choice of drugs with various mechanisms of action, potentially enabling individualized, patient-specific treatment strategies to be developed. In this Review, the various treatment options for patients with stable angina are discussed. Data from randomized, clinical trials of established and novel drugs are reviewed, with particular emphasis on the proposed mechanisms of action, benefits of therapy, and adverse-effect profiles. The role of coronary revascularization in conjunction with optimal medical therapy as a treatment strategy is discussed, although drug therapy might reduce the need for prompt revascularization if the procedure is being considered solely for the purpose of alleviating angina. Finally, trials to investigate stimulation of angiogenesis using growth-factor, gene, and cell therapy are used to illustrate the challenges of chemically inducing the growth of adequate, durable blood vessels.