Heart rate reduction induced by the if current inhibitor ivabradine improves diastolic function and attenuates cardiac tissue hypoxia. J Cardiovasc Pharmacol. 2012;59:260-267. [PMID: 22075752 DOI: 10.1097/fjc.0b013e31823e5e01]

Evaluating the role of ivabradine in acute decompensated heart failure: A systematic review and meta-analysis

BACKGROUND

Acute decompensated heart failure (ADHF) presents a significant global health challenge, with high morbidity, mortality, and healthcare costs. The current therapeutic options for ADHF are limited. Ivabradine, a selective inhibitor of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, has emerged as a potential therapy for ADHF by reducing the heart rate (HR) without negatively affecting myocardial contractility. However, the evidence regarding the efficacy and safety of ivabradine in patients with ADHF is limited and inconsistent. This meta-analysis aimed to evaluate the efficacy and safety of ivabradine for ADHF based on observational studies.

METHODS

A systematic literature search was conducted following PRISMA guidelines to identify relevant observational studies comparing ivabradine with placebo in adult patients with ADHF. Data were pooled using a random-effects model, and heterogeneity was assessed. The risk of bias was evaluated using the Newcastle-Ottawa Scale.

RESULTS

Four observational studies comprising a total of 12034 patients. Meta-analysis revealed that ivabradine significantly reduced all-cause mortality (RR: 0.66, 95 % CI: 0.49-0.89, p < 0.01) and resting HR (MD: -12.54, 95 % CI: -21.66-3.42, p < 0.01) compared to placebo. However, no significant differences were observed in cardiovascular mortality, hospital readmission for all causes, changes in LVEF, or changes in LVEDD. Sensitivity and publication bias assessments were conducted for each outcome.

CONCLUSION

Ivabradine may be beneficial for reducing mortality and HR in patients with ADHF. However, its impact on other clinical outcomes such as cardiovascular mortality, hospital readmission, and cardiac function remains inconclusive. Further research, particularly well-designed RCTs with larger sample sizes and longer follow-up durations, are warranted.

Hyperpolarization-activated cyclic nucleotide-gated channel inhibitor in myocardial infarction: Potential benefits beyond heart rate modulation

Myocardial infarction (MI) and its associated complications including ventricular arrhythmias and heart failure are responsible for a significant incidence of morbidity and mortality worldwide. The ensuing cardiomyocyte loss results in neurohormone-driven cardiac remodeling, which leads to chronic heart failure in MI survivors. Ivabradine is a heart rate modulation agent currently used in treatment of chronic heart failure with reduced ejection fraction. The canonical target of ivabradine is the hyperpolarization-activated cyclic nucleotide-gated channels (HCN) in cardiac pacemaker cells. However, in post-MI hearts, HCN can also be expressed ectopically in non-pacemaker cardiomyocytes. There is an accumulation of intriguing evidence to suggest that ivabradine also possesses cardioprotective effects that are independent of heart rate reduction. This review aims to summarize and discuss the reported cardioprotective mechanisms of ivabradine beyond heart rate modulation in myocardial infarction through various molecular mechanisms including the prevention of reactive oxygen species-induced mitochondrial damage, improvement of autophagy system, modulation of intracellular calcium cycling, modification of ventricular electrophysiology, and regulation of matrix metalloproteinases.

Novel Targets for a Combination of Mechanical Unloading with Pharmacotherapy in Advanced Heart Failure

LVAD therapy is an effective rescue in acute and especially chronic cardiac failure. In several scenarios, it provides a platform for regeneration and sustained myocardial recovery. While unloading seems to be a key element, pharmacotherapy may provide powerful tools to enhance effective cardiac regeneration. The synergy between LVAD support and medical agents may ensure satisfying outcomes on cardiomyocyte recovery followed by improved quality and quantity of patient life. This review summarizes the previous and contemporary strategies for combining LVAD with pharmacotherapy and proposes new therapeutic targets. Regulation of metabolic pathways, enhancing mitochondrial biogenesis and function, immunomodulating treatment, and stem-cell therapies represent therapeutic areas that require further experimental and clinical studies on their effectiveness in combination with mechanical unloading.

Successful use of ivabradine in a 10-year-old patient with graft failure after heart transplantation

We encountered a paediatric case of graft failure due to antibody-mediated rejection after heart transplantation in which ivabradine was effective. Inappropriate sinus tachycardia in denervated transplanted hearts is a good indication for ivabradine administration as beta-blockers have a limited efficacy. To our knowledge, this is the first report on the effectiveness of ivabradine in a paediatric heart transplant rejection case.

Transient heart rate reduction improves acute decompensated heart failure-induced left ventricular and coronary dysfunction

Aims

Acute decompensated heart failure (ADHF), a live‐threatening complication of heart failure (HF), associates a further decrease of the already by HF‐impaired cardiac function with an increase in heart rate. We evaluated, using a new model of ADHF, whether heart rate reduction (HRR) opposes the acute decompensation‐related aggravation of cardiovascular dysfunction.

Methods and results

Cardiac output (echocardiography), cardiac tissue perfusion (magnetic resonance imaging), pulmonary wet weight, and in vitro coronary artery relaxation (Mulvany) were assessed 1 and 14 days after acute decompensation induced by salt‐loading (1.8 g/kg, PO) in rats with well‐established HF due to coronary ligation. HRR was induced by administration of the I_f current inhibitor S38844, 12 mg/kg PO twice daily for 2.5 days initiated 12 h or 6 days after salt‐loading (early or delayed treatment, respectively). After 24 h, salt‐loading resulted in acute decompensation, characterized by a reduction in cardiac output (HF: 130 ± 5 mL/min, ADHF: 105 ±  8 mL/min; P < 0.01), associated with a decreased myocardial perfusion (HF: 6.41 ± 0.53 mL/min/g, ADHF: 4.20 ± 0.11 mL/min/g; P < 0.01), a slight increase in pulmonary weight (HF: 1.68 ± 0.09 g, ADHF: 1.81 ± 0.15 g), and impaired coronary relaxation (HF: 55 ± 1% of pre‐contraction at acetylcholine 4.5 10⁻⁵ M, ADHF: 27 ± 7 %; P < 0.01). Fourteen days after salt‐loading, cardiac output only partially recovered (117 ± 5 mL/min; P < 0.05), while myocardial tissue perfusion (4.51 ± 0.44 mL/min; P < 0.01) and coronary relaxation (28 ± 4%; P < 0.01) remained impaired, but pulmonary weight further increased (2.06 ± 0.15 g, P < 0.05). Compared with untreated ADHF, HRR induced by S38844 improved cardiac output (125 ± 1 mL/min; P < 0.05), myocardial tissue perfusion (6.46 ± 0.42 mL/min/g; P < 0.01), and coronary relaxation (79 ± 2%; P < 0.01) as soon as 12 h after S38844 administration. These effects persisted beyond S38844 administration, illustrated by the improvements in cardiac output (130 ± 6 mL/min; P < 0.05), myocardial tissue perfusion (6.38 ± 0.48 mL/min/g; P < 0.01), and coronary relaxation (71 ± 4%; P < 0.01) at Day 14. S38844 did not modify pulmonary weight at Day 1 (1.78 ± 0.04 g) but tended to decrease pulmonary weight at Day 14 (1.80 ± 0.18 g). While delayed HRR induced by S38844 never improved cardiac function, early HRR rendered less prone to a second acute decompensation.

Conclusions

In a model mimicking human ADHF, early, but not delayed, transient HRR induced by the I_f current inhibitor S38844 opposes acute decompensation by preventing the decompensated‐related aggravation of cardiovascular dysfunction as well as the development of pulmonary congestion, and these protective effects persist beyond the transient treatment. Whether early transient HRR induced by I_f current inhibitors or other bradycardic agents, i.e. beta‐blockers, exerts beneficial effects in human ADHF warrants further investigation.

A Novel Approach to Medical Management of Heart Failure With Reduced Ejection Fraction

The advent of newly available medical therapies for heart failure with reduced ejection fraction (HFrEF) has resulted in many potential therapeutic combinations, increasing treatment complexity. Publication of expert consensus guidelines and initiatives aimed to improve implementation of treatment has emphasized sequential stepwise initiation and titration of medical therapy, which is labour intensive. Data taken from heart failure registries show suboptimal use of medications, prolonged titration times, and consequently little change in dose intensity, all of which indicate therapeutic inertia. Recently published evidence indicates that 4 medication classes-renin-angiotensin-neprilysin inhibitors, β-blockers, mineralocorticoid antagonists, and sodium-glucose cotransporter inhibitors-which we refer to as Foundational Therapy, confer rapid and robust reduction in both morbidity and mortality in most patients with HFrEF and that they work in additive fashion. Additional morbidity and mortality may be observed following addition of several personalized therapies in specific subgroups of patients. In this review, we discuss mechanisms of action of these therapies and propose a framework for their implementation, based on several principles. These include the critical importance of rapid initiation of all 4 Foundational Therapies followed by their titration to target doses, emphasis on multiple simultaneous drug changes with each patient encounter, attention to patient-specific factors in choice of medication class, leveraging inpatient care, use of the entire health care team, and alternative (ie, virtual visits) modes of care. We have incorporated these principles into a Cluster Scheme designed to facilitate timely and optimal medical treatment for patients with HFrEF.

Hemodynamic effects of ivabradine use in combination with intravenous inotropic therapy in advanced heart failure

Intravenous inotropic therapy can be used in patients with advanced heart failure, as palliative therapy or as a bridge to cardiac transplantation or mechanical circulatory support, as well as in cardiogenic shock. Their use is limited to increasing cardiac output in low cardiac output states and reducing ventricular filling pressures to alleviate patient symptoms and improve functional class. Many advanced heart failure patients have sinus tachycardia as a compensatory mechanism to maintain cardiac output. However, excessive sinus tachycardia caused by intravenous inotropes can increase myocardial oxygen consumption, decrease coronary perfusion, and at extreme heart rates decrease ventricular filling and stroke volume. The limited available hemodynamic studies support the hypothesis that adding ivabradine, a rate control agent without negative inotropic effect, may blunt inotrope-induced tachycardia and its associated deleterious effects, while optimizing cardiac output by increasing stroke volume. This review analyzes the intriguing pathophysiology of combined intravenous inotropes and ivabradine to optimize the hemodynamic profile of patients in advanced heart failure. Graphical abstract Illustration of the beneficial and deleterious hemodynamic effects of intravenous inotropes in advanced heart failure, and the positive effects of adding ivabradine.

Short-and long-term administration of imeglimin counters cardiorenal dysfunction in a rat model of metabolic syndrome

INTRODUCTION

Imeglimin, a glucose-lowering agent targeting mitochondrial bioenergetics, decreases reactive oxygen species (ROS) overproduction and improves glucose homeostasis. We investigated whether this is associated with protective effects on metabolic syndrome-related left ventricular (LV) and vascular dysfunctions.

METHODS

We used Zucker fa/fa rats to assess the effects on LV function, LV tissue perfusion, LV oxidative stress and vascular function induced by imeglimin administered orally for 9 or 90 days at a dose of 150 mg/kg twice daily.

RESULTS

Compared to untreated animals, 9- and 90-day imeglimin treatment decreased LV end-diastolic pressure and LV end-diastolic pressure-volume relation, increased LV tissue perfusion and decreased LV ROS production. Simultaneously, imeglimin restored acetylcholine-mediated coronary relaxation and mesenteric flow-mediated dilation. One hour after imeglimin administration, when glucose plasma levels were not yet modified, imeglimin reduced LV mitochondrial ROS production and improved LV function. Ninety-day imeglimin treatment reduced related LV and kidney fibrosis and improved kidney function.

CONCLUSION

In a rat model, mimicking Human metabolic syndrome, imeglimin immediately countered metabolic syndrome-related cardiac diastolic and vascular dysfunction by reducing oxidative stress/increased NO bioavailability and improving myocardial perfusion and after 90-day treatment myocardial and kidney structure, effects that are, at least in part, independent from glucose control.

Effect of Ivabradine on Left Ventricular Diastolic Function, Exercise Tolerance and Quality of Life in Patients With Heart Failure: A Systemic Review and Meta-Analysis of Randomized Controlled Trials

Background

Ivabradine is a heart rate-lowering drug that selectively inhibits the funny (I_f) current of the sinoatrial node. It is currently recommended in patients with heart failure (HF) with reduced ejection fraction (HFrEF) in sinus rhythm and a heart rate of ≥ 70 beats per minute (bpm) at rest. To investigate whether ivabradine has an effect on diastolic dysfunction, exercise tolerance and quality of life (QOL), we conducted a systemic review and meta-analysis of randomized controlled trials (RCTs).

Methods

We searched PubMed, EMBASE and Cochrane Central Register of Clinical Trials for studies on the effect of ivabradine on left ventricular (LV) diastolic dysfunction, exercise tolerance, QOL, readmission for worsening HF and mortality in both patients with HF with preserved ejection fraction (HFpEF) and HFrEF.

Results

Thirteen RCTs with 881 patients met the inclusion criteria. According to the pooled analysis, for the HFpEF subgroup, treatment with ivabradine resulted in a decrease in early diastolic mitral inflow to late diastolic flow ratio (E/A) (standardized mean difference (SMD): -0.53; 95% confidence interval (CI): -0.99, -0.07; P < 0.000) and increase in peak oxygen uptake during exercise (VO₂) (SMD: 0.05; 95% CI: -0.35, 0.45; P < 0.00; I² = 95.1%). Similar effect was seen in the HFrEF subgroup with decrease in E/A ratio (SMD: -0.33; 95% CI: -0.59, -0.06; P < 0.000) and early diastolic mitral inflow to annular velocity ratio (E/e’) (SMD: -1.01; 95% CI: -1.49, -0.54; P < 0.012). Ivabradine therapy increased peak VO₂ and 6-min walk test (6MWT) in HFrEF patients (SMD: 0.83; 95% CI: 0.35, 1.32; P < 0.00; I² = 97.5% and SMD: 1.11; 95% CI: 0.82, 1.41; P < 0.000, respectively). There was also significant reduction in Minnesota Living with Heart Failure Questionnaire (MLHFQ) score (SMD: -0.68; 95% CI: -0.91, -0.45; P < 0.000). However, there was no significant difference in readmission for worsening HF and all-cause mortality between ivabradine and control (risk ratio (RR): 1.44; 95% CI: 0.73, 2.16; P < 0.148 and RR: 0.76; 95% CI: 0.19, 1.33; P < 0.907, respectively).

Conclusions

Ivabradine therapy is associated with improved LV diastolic function, increases exercise tolerance and hence QOL, but it has no significant effect on readmission for worsening HF and all-cause mortality.

Ivabradine promotes angiogenesis and reduces cardiac hypertrophy in mice with myocardial infarction

OBJECTIVE

We investigated the underlying mechanism of ivabradine (IVA) in promoting angiogenesis and reducing cardiac hypertrophy in mice with myocardial infarction (MI).

METHODS

Nineteen mice were randomly assigned into three groups as follows: sham group (10 ml/kg/day phosphate buffer saline (PBS), n=6), model group (MI and 10 ml/kg/day PBS, n=6) and IVA group (MI and 10 mg/kg/day IVA, n=7). All groups received an intragastric gavage for four weeks. Heart and body mass were measured. Cardiac function and heart rate were assessed by echocardiography and electrocardiography, respectively. The collagen deposition, area of cardiomyocytes, and number of capillaries were evaluated using Masson's staining, anti-wheat germ agglutinin (WGA) staining, and platelet endothelial cell adhesion molecule-1 (CD31) staining, respectively. The protein kinase B (Akt)- endothelial nitric oxide synthase (eNOS) signaling and p-38 mitogen-activated protein kinase (MAPK) family in myocardium were determined by western blot.

RESULTS

IVA treatment greatly improved cardiac dysfunction and suppressed cardiac hypertrophy at 4 weeks after MI (p<0.05). Heart rate and fibrotic area of IVA group declined notably compared to those of the model group (p<0.05). IVA administration substantially reduced cardiomyocyte size and increased capillary formation (p<0.05). Besides, IVA medication can enhance Akt-eNOS signaling and inhibit p38 MAPK phosphorylation in the heart of mice with MI (p<0.05).

CONCLUSION

IVA can perform two functions, the promotion of angiogenesis and the reduction of cardiac hypertrophy, both of which were closely associated with Akt-eNOS signaling activation and p38 MAPK inhibition.

Modulation of Sympathetic Activity and Innervation With Chronic Ivabradine and β-Blocker Therapies: Analysis of Hypertensive Rats With Heart Failure

BACKGROUND

Whether the reduction of heart rate with ivabradine (IVA) could affect sympathetic activation and cardiac innervation in heart failure (HF) remains unknown.

PURPOSE

The present study assessed the chronic effects of IVA and β-blocker on the systemic and local sympathetic nervous systems of hypertensive animals with HF.

METHODS AND RESULTS

The Dahl salt-sensitive rats received chronic IVA, bisoprolol (BIS), or placebo (CTL) therapy. The survival of the animal models with IVA and BIS significantly improved (median; 19.7 in IVA and 19.7 in BIS vs 17.0 weeks in CTL, P < .001). A similar decrease in 24-hour heart rate (mean; 305 in IVA and 329 in BIS vs 388 beats/min in CTL, P < .001) without effect on blood pressure, and an improvement in the left ventricular dysfunction (mean fractional shortening; 56.7% in IVA and 47.8% in BIS vs 39.0% in CTL, P < .001) were observed in the animals with IVA and BIS. However, a negative inotropic effect was only observed in the animals with BIS. Excessive urinary noradrenaline excretion in animals with CTL was only suppressed with the use of IVA (mean; 1.35 μg/d in IVA and 1.95 μg/d in BIS vs 2.27 μg/d in CTL, P = .002). In contrast, atrial noradrenaline and acetylcholine depletion in the animals with CTL improved and the tyrosine hydroxylase expression in the both atria were restored with the use of both IVA and BIS.

CONCLUSIONS

IVA therapy improved the survival of hypertensive animals with HF. Furthermore, it was associated with the amelioration of systemic sympathetic activation and cardiac sympathetic and parasympathetic nerve innervations. Chronic β-blocker therapy with negative inotropic effects had beneficial effects only on cardiac innervations.

Effect of exercise on passive myocardial stiffness in mice with diastolic dysfunction

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome, characterized by increased diastolic stiffness and a preserved ejection fraction, with no effective treatment options. Here we studied the therapeutic potential of exercise for improving diastolic function in a mouse model with HFpEF-like symptoms, the TtnΔIAjxn mouse model. TtnΔIAjxn mice have increased diastolic stiffness and reduced exercise tolerance, mimicking aspects of HFpEF observed in patients. We investigated the effect of free-wheel running exercise on diastolic function. Mechanical studies on cardiac muscle strips from the LV free wall revealed that both TtnΔIAjxn and wildtype (WT) exercised mice had a reduction in passive stiffness, relative to sedentary controls. In both genotypes, this reduction is due to an increase in the compliance of titin whereas ECM-based stiffness was unaffected. Phosphorylation of titin's PEVK and N2B spring elements were assayed with phospho-site specific antibodies. Exercised mice had decreased PEVK phosphorylation and increased N2B phosphorylation both of which are predicted to contribute to the increased compliance of titin. Since exercise lowers the heart rate we examined whether reduction in heart rate per se can improve passive stiffness by administering the heart-rate-lowering drug ivabradine. Ivabradine lowered heart rate in our study but it did not affect passive tension, in neither WT nor TtnΔIAjxn mice. We conclude that exercise is beneficial for decreasing passive stiffness and that it involves beneficial alterations in titin phosphorylation.

The Role of Ivabradine in the Management of Angina Pectoris

Stable angina pectoris affects 2–4 % of the population in Western countries and entails an annual risk of death and nonfatal myocardial infarction of 1–2 % and 3 %, respectively. Heart rate (HR) is linearly related to myocardial oxygen consumption and coronary blood flow, both at rest and during stress. HR reduction is a key target for the prevention of ischemia/angina and is an important mechanism of action of drugs which are recommended as first line therapy for the treatment of angina in clinical guidelines. However, many patients are often unable to tolerate the doses of beta blocker or non-dihydropyridine calcium antagonists required to achieve the desired symptom control. The selective pacemaker current inhibitor ivabradine was developed as a drug for the management of patients with angina pectoris, through its ability to reduce HR specifically. The available data suggest that ivabradine is a well-tolerated and effective anti-anginal agent and it is recommended as a second-line agent for relief of angina in guidelines. However, recent clinical trials of ivabradine have failed to show prognostic benefit and have raised potential concerns about safety. This article will review the available evidence base for the current role of ivabradine in the management of patients with symptomatic angina pectoris in the context of stable coronary artery disease.

Selective Heart Rate Reduction Improves Metabolic Syndrome-related Left Ventricular Diastolic Dysfunction

BACKGROUND

Enhanced heart rate observed in metabolic syndrome (MS) contributes to the deterioration of left ventricular (LV) function via impaired LV filling and relaxation, increased myocardial O2 consumption, and reduced coronary perfusion. However, whether heart rate reduction (HRR) opposes LV dysfunction observed in MS is unknown.

METHODS

We assessed in Zucker fa/fa rats, a rat model of MS, the cardiovascular effects of HRR induced by the If current inhibitor S38844 (3 mg · kg(-1) · d(-1)).

RESULTS

Delayed short-term (4 days) and long-term (90 days) HRR induced by S38844 reduced LV end-diastolic pressure and LV end-diastolic pressure-volume relation, increased myocardial tissue perfusion, decreased myocardial oxidized glutathione levels, and preserved cardiac output, without modifying LV end-systolic pressure and LV end-systolic pressure-volume relation, although only long-term S38844 opposed LV collagen accumulation. Long-term S38844 improved flow-induced endothelium-dependent dilatation of mesenteric arteries, while metabolic parameters, such as plasma glucose levels, and Hb1c, were never modified.

CONCLUSIONS

In rats with MS, HRR induced by the If inhibitor S38844 improved LV diastolic function and endothelium-dependent vascular dilatation, independent from modifications in metabolic status. Moreover, this improvement in cardiac function involves not only immediate effects such as improved myocardial perfusion and reduced oxidative stress but also long-term effects such as modifications in the myocardial structure.

Ranolazine and Ivabradine: two different modalities to act against ischemic heart disease

Among the innovative drugs recently introduced for the management of chronic stable angina, Ranolazine and ivabradine represent two most true innovations. In fact, even if both drugs act by reducing myocardial work and thus oxygen consumption, this happens by a peculiar mechanism unlike that of conventional antischemic drugs. Ranolazine mediates its antianginal effects by the inhibition of cardiac late sodium current. This improves myocardial relaxation favoring myocardial perfusion. Ivabradine is a selective If channel blocker and acts by reducing firing rate of pacemaker cells in the sinoatrial node, without affecting the duration of action potential. The reduction of heart rate causes a reduction of left ventricular end diastolic pressure and increases the time useful to coronary flow by a prolongation of the diastole. A body of evidence found that two drugs are useful in ischemic patients whether at rest or during exercise. In addition, they can be used in monotherapy or in association with other conventional anti-ischemic drugs. The two medications could be used with advantage also in microvascular angina when standard therapy is ineffective. Thus, the two drugs represent an adjunctive and powerful therapeutic modality for the treatment of chronic stable angina, especially when conventional antianginal drugs were insufficient or inadequate.

Selective Vascular Endothelial Protection Reduces Cardiac Dysfunction in Chronic Heart Failure

Background—

Chronic heart failure (CHF) induces endothelial dysfunction in part because of decreased nitric oxide (NO · ) production, but the direct link between endothelial dysfunction and aggravation of CHF is not directly established. We previously reported that increased NO production via inhibition of protein tyrosine phosphatase 1B (PTP1B) is associated with reduced cardiac dysfunction in CHF. Investigation of the role of endothelial PTP1B in these effects may provide direct evidence of the link between endothelial dysfunction and CHF.

Methods and Results—

Endothelial deletion of PTP1B was obtained by crossing LoxP-PTP1B with Tie2-Cre mice. CHF was assessed 4 months after myocardial infarction. In some experiments, to exclude gene extinction in hematopoietic cells, Tie2-Cre/LoxP-PTP1B mice were lethally irradiated and reconstituted with bone marrow from wild-type mice, to obtain mouse with endothelial-specific deletion of PTP1B. Vascular function evaluated ex vivo in mesenteric arteries showed that in wild-type mice, CHF markedly impaired NO-dependent flow-mediated dilatation. CHF-induced endothelial dysfunction was less marked in endoPTP1B −/− mice, suggesting restored NO production. Echocardiographic, hemodynamic, and histological evaluations demonstrated that the selectively improved endothelial function was associated with reduced left ventricular dysfunction and remodeling, as well as increased survival, in the absence of signs of stimulated angiogenesis or increased cardiac perfusion.

Conclusions—

Prevention of endothelial dysfunction, by endothelial PTP1B deficiency, is sufficient to reduce cardiac dysfunction post myocardial infarction. Our results provide for the first time a direct demonstration that endothelial protection per se reduces CHF and further suggest a causal role for endothelial dysfunction in CHF development.

Ivabradine: A Unique and Intriguing Medication for Treating Cardiovascular Disease

There has been much research linking elevated resting heart rate to cardiovascular morbidity and mortality. Based on these findings, a lower resting heart rate would be of theoretical benefit in patients with cardiovascular disease. From a pathophysiologic perspective, a lower resting heart rate would be of particular benefit in patients with ischemic heart disease and/or heart failure. Although β-blockers and nondihydropyridine calcium channel blockers are effective at lowering heart rate, they have many other pharmacologic effects that may not be desirable in some patients, such as negative inotropy. Ivabradine is a drug designed to lower heart rate without any other demonstrable pharmacologic effects; in other words, a pure heart rate-lowering drug. It functions by blocking the hyperpolarization-activated cyclic nucleotide gated channels (f-channels) specific for the sinoatrial node and disrupting If ion current flow. This effectively prolongs diastolic depolarization and slows firing in the sinoatrial node, which lowers heart rate. The effects of ivabradine are most pronounced at higher heart rates (use-dependence), which is important in minimizing the development of symptomatic bradycardia. Clinical trials have demonstrated ivabradine to be an effective antianginal drug both alone and in combination with β-blocker therapy, although it has not been shown to produce a demonstrable effect on reducing major adverse cardiovascular events. In patients with heart failure, ivabradine has demonstrated many hemodynamic benefits, but its effect on clinical outcomes have been mixed and dependent on baseline heart rate, ie, the drug may be of benefit with higher baseline heart rates, but detrimental with low baseline heart rates. The adverse effects of ivabradine are not uncommon, but are rarely severe and include visual disturbances, bradycardia, and atrial fibrillation. Although ivabradine is a very interesting new agent, its variable benefits in large-scale clinical trials leave its exact place in therapy still somewhat nebulous. Unanswered questions include which patient populations would benefit most from this drug, and which concomitant medications would produce the best clinical outcomes when used with ivabradine.

Ivabradine Prevents Low Shear Stress Induced Endothelial Inflammation and Oxidative Stress via mTOR/eNOS Pathway

Ivabradine not only reduces heart rate but has other cardiac and vascular protective effects including anti-inflammation and anti-oxidation. Since endothelial nitric oxide synthase (eNOS) is a crucial enzyme in maintaining endothelial activity, we aimed to investigate the impact of ivabradine in low shear stress (LSS) induced inflammation and endothelial injury and the role of eNOS played in it. Endothelial cells (ECs) were subjected to LSS at 2dyne/cm², with 1 hour of ivabradine (0.04μM) or LY294002 (10μM) pre-treatment. The mRNA expression of IL-6, VCAM-1 along with eNOS were measured by QPCR. Reactive oxygen species (ROS) was detected by dihydroethidium (DHE) and DCF, and protein phosphorylation was detected by western blot. It demonstrated that ivabradine decreased LSS induced inflammation and oxidative stress in endothelial cells. Western blot showed reduced rictor and Akt-Ser473 as well as increased eNOS-Thr495 phosphorylation. However, mTORC1 pathway was only increased when LSS applied within 30 minutes. These effects were reversed by ivabradine. It would appear that ivabradine diminish ROS generation by provoking mTORC2/Akt phosphorylation and repressing mTORC1 induced eNOS-Thr495 activation. These results together suggest that LSS induced endothelial inflammation and oxidative stress are suppressed by ivabradine via mTORC2/Akt activation and mTORC1/eNOS reduction.

Ivabradine in Management of Heart Failure: a Critical Appraisal

Elevated resting heart rate has been linked to poor outcomes in patients with chronic systolic heart failure. Blockade of funny current channel with ivabradine reduces heart rate without inotropic effects. Ivabradine was recently approved by US Food and Drug Administration for patients with stable, symptomatic chronic heart failure (HF) with left ventricular ejection fraction (LVEF) ≤35 %, who are in sinus rhythm with resting heart rate (HR) ≥ 70 bpm and either are on maximally tolerated doses of beta-blockers, or have a contraindication to beta-blockers. This article will review and evaluate the data supporting the use of ivabradine in patients with HF and explore its mechanisms and physiologic effects.

Cardiac and Hemodynamic Benefits: Mode of Action of Ivabradine in Heart Failure

Heart failure has seen a number of therapeutic advances in recent years. Despite this, heart failure is still related to increasing rates of morbidity, repeated hospitalizations, and mortality. Ivabradine is a recent treatment option for heart failure. It has a mode of action that includes reduction in heart rate, and leads to improvement in outcomes related to heart failure mortality and morbidity, as demonstrated by the results of the SHIFT trial in patients with systolic heart failure, functional classes II and III on the New York Heart Association classification, and left ventricular ejection fraction ≤ 35%. These results are intriguing since many heart failure drugs reduce heart rate without such benefits, or with quite different effects, making it more difficult to understand the novelty of ivabradine in this setting. Many of the drugs used in heart failure modify heart rate, but most have other pathophysiological effects beyond their chronotropic action, which affect their efficacy in preventing morbidity and mortality outcomes. For instance, heart rate reduction at rest or exercise with ivabradine prolongs diastolic perfusion time, improves coronary blood flow, and increases exercise capacity. Another major difference is the increase in stroke volume observed with ivabradine, which may underlie its beneficial cardiac effects. Finally, there is mounting evidence from both preclinical and clinical studies that ivabradine has an anti-remodeling effect, improving left ventricular structures and functions. All together, these mechanisms have a positive impact on the prognosis of ivabradine-treated patients with heart failure, making a compelling argument for use of ivabradine in combination with other treatments.

Ivabradine improves left ventricular function during chronic hypertension in conscious pigs

During chronic hypertension, increases in heart rate (HR) or adrenergic stimulation are associated with maladaptive left ventricular responses as isovolumic contraction and relaxation durations failed to reduce, impeding filling. We, therefore, investigated the effects of acute selective HR reduction with ivabradine on left ventricular dysfunction during chronic hypertension. Accordingly, chronically instrumented pigs received angiotensin II infusion during 4 weeks to induce chronic hypertension. Left ventricular function was investigated while angiotensin II infusion was stopped. A single intravenous dose of ivabradine was administered at days 0 and 28. Dobutamine infusion was also performed. HR was increased at day 28 versus day 0. Paradoxically, both isovolumic contraction and relaxation times failed to reduce and remained unchanged (57±3 versus 58±3 ms and 74±3 versus 70±3 at day 28 versus day 0, respectively). At day 28, ivabradine significantly reduced HR by 27%. Concomitantly, abnormal ventricular responses were corrected because both isovolumic contraction and relaxation times were significantly reduced while filling time was improved. Similarly at day 28, maladaptive responses of isovolumic contraction and relaxation to dobutamine were no longer observed during HR reduction with ivabradine. Correction of HR reduction with pacing showed that non-HR-related mechanisms also participated to these beneficial effects. In this model of chronic hypertension and left ventricular hypertrophy, acute HR reduction with ivabradine corrects the maladaptive responses of cardiac cycle phases by restoring a normal profile for isovolumic contraction and relaxation both at rest and under adrenergic stimuli, ultimately favoring filling.

Effect of Chronic Heart Rate Reduction by If Current Inhibitor Ivabradine on Left Ventricular Remodeling and Systolic Performance in Middle-Aged Rats With Postmyocardial Infarction Heart Failure

Background:

A large myocardial infarction (MI) initiates progressive cardiac remodeling that leads to systolic heart failure (HF). Long-term heart rate reduction (HRR) induced by the I f current inhibitor ivabradine (IVA) ameliorates left ventricular (LV) remodeling and improves systolic performance in young post-MI rats. However, the beneficial effects of chronic IVA treatment in middle-aged rats remain to be determined.

Methods:

A large MI was induced in 12-month-old rats by left coronary artery ligation. Rats were treated with IVA via osmotic pumps intraperitoneal in a dose of 10.5 mg/kg/d (MI + IVA) and compared with MI and sham-operated animals 12 weeks after MI.

Results:

Heart rate in MI + IVA rats was on average 29% lower than that of rats in the MI group. Left ventricular remodeling was comparable between post-MI groups, although MI + IVA rats did not show the compensatory thickening of the noninfarcted myocardium. Chronic HRR had no effect on transverse cardiac myocyte size and capillary growth, but it reduced the collagen content in noninfarcted myocardium. Left ventricular systolic performance remained similarly impaired in MI and MI + IVA rats. Moreover, abrupt IVA withdrawal led to worsening HF and reduction of coronary reserve.

Conclusion:

Our data reveal that chronic IVA-induced HRR does not provide sustainable benefits for LV systolic performance in middle-aged rats with post-MI HF.

Ivabradine, coronary artery disease, and heart failure: beyond rhythm control

Elevated heart rate could negatively influence cardiovascular risk in the general population. It can induce and promote the atherosclerotic process by means of several mechanisms involving endothelial shear stress and biochemical activities. Furthermore, elevated heart rate can directly increase heart ischemic conditions because of its skill in unbalancing demand/supply of oxygen and decreasing the diastolic period. Thus, many pharmacological treatments have been proposed in order to reduce heart rate and ameliorate the cardiovascular risk profile of individuals, especially those suffering from coronary artery diseases (CAD) and chronic heart failure (CHF). Ivabradine is the first pure heart rate reductive drug approved and currently used in humans, created in order to selectively reduce sinus node function and to overcome the many side effects of similar pharmacological tools (ie, β-blockers or calcium channel antagonists). The aim of our review is to evaluate the role and the safety of this molecule on CAD and CHF therapeutic strategies.

The efficacy and safety of ivabradine hydrochloride versus atenolol in Chinese patients with chronic stable angina pectoris

PURPOSE

The aim of this study was to assess the efficacy and safety of ivabradine (Iva) noninferiority to atenolol (Aten) in Chinese patients with chronic stable angina pectoris.

METHODS

In this double-blind, double-dummy trial, patients with symptomatic angina pectoris and positive exercise tolerance test were randomized into the Iva [5 or 7.5 mg bis in die (BID)] or Aten group (12.5 or 25 mg BID) according to computer-generated random numbers for 12 weeks.

RESULTS

One hundred and sixty-eight patients were randomized to the Iva group and 166 to the Aten group. In a full analysis set, increases in the total exercise duration (TED) were 54.3 ± 120.1 seconds with Iva 5 mg and 58.8 ± 114.7 seconds with Aten 12.5 mg at the fourth week, and at the 12th week, TED improved by 84.1 ± 130.5 seconds with Iva and 77.8 ± 126.6 seconds with Aten (95%CI: -21.4-34.1 seconds, p = 0.0011 for noninferiority). The analysis of per protocol set yielded similar results (95%CI: -31.4-33.0 seconds, p = 0.0131 for noninferiority). Heart rate was reduced in both groups at rest and during peak exercise. There were small, nonsignificant differences in the number of adverse events between the two groups (66 in Iva and 73 in Aten, p > 0.05). Nine patients (5.42%) were reported to develop phosphenes/luminous phenomena and blurred vision in the Iva group (p = 0.0035).

CONCLUSIONS

Iva is effective in reducing heart rates and improving exercise capacity and noninferior to Aten in Chinese patients with chronic stable angina pectoris. Iva is well tolerated and safe.

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.

An evaluation of the pharmacokinetics and pharmacodynamics of ivabradine for the treatment of heart failure

INTRODUCTION

Ivabradine is a new heart-rate-lowering drug; the aim of this review was to analyze its role in heart failure (HF).

AREAS COVERED

This systematic review on the role of ivabradine in HF is based on material searched and obtained through Pubmed and Medline up to September 2013.

EXPERT OPINION

Heart rate (HR) is a risk factor in patients with HF, and its reduction is considered an important goal of therapy. The BEAUTIFUL trial demonstrated the benefits of ivabradine on prognosis (only on ischemic endpoints) in patients with coronary artery disease (CAD) and left ventricular systolic dysfunction (LVSD) and HR ≥ 60 bpm. In the SHIFT trial, which enrolled patients with LVSD, HF and HR ≥ 70 bpm, ivabradine administration (on top of guideline-based therapy, including β-blockers [BB]) was associated with a reduction of cardiovascular death and hospitalizations for HF, but BB were underutilized. Further studies are needed to test the efficacy of ivabradine in CAD patients with high HR and to shed light on the comparison between ivabradine and a more aggressive therapy with higher doses of BB in HF patients.

Effect of If-channel inhibition on hemodynamic status and exercise tolerance in heart failure with preserved ejection fraction: a randomized trial

OBJECTIVES

The aim of this study was to test the effects of treatment with ivabradine on exercise capacity and left ventricular filling in patients with heart failure with preserved ejection fraction (HFpEF).

BACKGROUND

Because symptoms of HFpEF are typically exertional, optimization of diastolic filling time by controlling heart rate may delay the onset of symptoms.

METHODS

Sixty-one patients with HFpEF were randomly assigned to ivabradine 5 mg twice daily (n = 30) or placebo (n = 31) for 7 days in this double-blind trial. Cardiopulmonary exercise testing with echocardiographic assessment of myocardial function and left ventricular filling were undertaken at rest and after exercise.

RESULTS

The ivabradine group demonstrated significant improvement between baseline and follow-up exercise capacity (4.2 ± 1.8 METs vs. 5.7 ± 1.9 METs, p = 0.001) and peak oxygen uptake (14.0 ± 6.1 ml/min/kg vs. 17.0 ± 3.3 ml/min/kg, p = 0.001), with simultaneous reduction in exercise-induced increase in the ratio of peak early diastolic mitral flow velocity to peak early diastolic mitral annular velocity (3.1 ± 2.7 vs. 1.3 ± 2.0, p = 0.004). Work load-corrected chronotropic response (the difference in heart rate at the same exercise time at the baseline and follow-up tests) showed a slower increase in heart rate during exercise than in the placebo-treated group. Therapy with ivabradine (β = 0.34, p = 0.04) and change with treatment in exertional increase in the ratio of peak early diastolic mitral flow velocity to peak early diastolic mitral annular velocity (β = -0.30, p = 0.02) were independent correlates of increase in exercise capacity, and therapy with ivabradine (β = 0.32, p = 0.007) was independently correlated with increase in peak oxygen uptake.

CONCLUSIONS

In patients with HFpEF, short-term treatment with ivabradine increased exercise capacity, with a contribution from improved left ventricular filling pressure response to exercise as reflected by the ratio of peak early diastolic mitral flow velocity to peak early diastolic mitral annular velocity. Because this patient population is symptomatic on exertion, therapeutic treatments targeting abnormal exercise hemodynamic status may prove useful. (Use of Exercise and Medical Therapies to Improve Cardiac Function Among Patients With Exertional Shortness of Breath Due to Lung Congestion; ACTRN12610001087044).

Prognostic significance of heart rate in hospitalized patients presenting with myocardial infarction

AIM

To investigate the prognostic significance of resting heart rate in patients with acute coronary syndrome (ACS), independent of other known factors.

METHODS

Patients 40 years of age or older who had been admitted with acute coronary syndrome (ACS) to one of the 94 hospitals participating in the Prevalence of Peripheral Arterial Disease in Patients with Acute Coronary Syndrome (PAMISCA) study were included. Patients were divided into two groups based on their resting heart rate (HR ≥ or < 70 bpm). Complications were recording during a follow-up period of 1 year.

RESULTS

There were 1054 ACS patients analyzed (43.5% with ST segment elevation and 56.5% without elevation). Mean age was 66.6 ± 11.7 years, 70.6% were male and 29.4% of subjects were female. During follow-up, more patients in the HR ≥ 70 bpm group were hospitalized for heart failure and they also had a higher mortality rate. In the multivariate analysis, a heart rate of ≥ 70 bpm was independently related to overall mortality during the follow-up period (hazard ratio 2.5; 95% confidence interval, 1.26-4.97, P = 0.009).

CONCLUSION

A resting heart rate ≥ 70 bpm in patients who survive an ACS is an indicator of a high risk of suffering cardiovascular events during follow-up.