Comparative effects of ivabradine, a selective heart rate-lowering agent, and propranolol on systemic and cardiac haemodynamics at rest and during exercise

Physiological effects of ivabradine in heart failure and beyond

Ivabradine is a pharmacologic agent that inhibits the funny current responsible for determining heart rate in the sinoatrial node. Ivabradine's clinical potential has been investigated in the context of heart failure since it is associated with reduced myocardial oxygen demand, enhanced diastolic filling, stroke volume, and coronary perfusion time; however, it is yet to demonstrate definitive mortality benefit. Alternative effects of ivabradine include modulation of the renin-angiotensin-aldosterone system, sympathetic activation, and endothelial function. Here, we review key clinical trials informing the clinical use of ivabradine and explore opportunities for leveraging its potential pleiotropic effects in other diseases, including treatment of hyperadrenergic states and mitigating complications of COVID-19 infection.

Comparison between the ECG Outcomes of Metoprolol and Bisoprolol

BACKGROUND

Beta-blockers are essential agents in the management of cardiovascular diseases, such as heart failure, acute myocardial infarction (MI), and cardiac arrhythmias. However, there are diurnal variations in the cardioprotective effects of the subgroups as a result of their different pharmacokinetic, pharmacodynamic, and pharmacogenetic profiles.

OBJECTIVES

We aimed to compare metoprolol and bisoprolol in terms of electrocardiogram (ECG) outcomes.

METHODS

A retrospective cross-sectional study was conducted at Prince Sultan Cardiac Center. The trial included 404 patients who met the inclusion criteria (204 in the metoprolol arm and 200 in the bisoprolol arm). Using case record forms that had already been created, information, such as patient demographics, medical histories, and treatment histories, was taken from their medical files. The most recent ECG records were also gathered. The ethical approval for this study was obtained from Qassim ethical committee (approval number: 45-44-902).

RESULTS

There was no significant difference found between the patients in both arms in terms of baseline characteristics, age, or sex.

CONCLUSION

In this retrospective cross-sectional study, we have compared the effects of metoprolol and bisoprolol beta blockers on ECG changes. The findings have indicated no difference between metoprolol and bisoprolol groups in terms of all ECG readings, particularly PR/ms, QTC-ms, and ventricular rate. Further studies are required to confirm these findings.

Effect of preoperative ivabradine on hemodynamics during elective off-pump CABG

Background

Ivabradine is a specific heart rate (HR)-lowering agent which blocks the cardiac pacemaker If channels. It reduces the HR without causing a negative inotropic or lusitropic effect, thus preserving ventricular contractility. The authors hypothesized that its usefulness in lowering HR can be utilized in patients undergoing off-pump coronary artery bypass (OPCAB) surgery.

Objective

To study the effects of preoperative ivabradine on hemodynamics (during surgery) in patients undergoing elective OPCAB surgery.

Methods

Fifty patients, New York Heart Association (NYHA) class I and II, were randomized into group I (control, n = 25) and group II (ivabradine group, n = 25). In group I, patients received the usual anti-anginal medications in the preoperative period, as per the institutional protocol. In group II, patients received ivabradine 5 mg twice daily for 3 days before surgery, in addition to the usual anti-anginal medications. Anesthesia was induced with fentanyl, thiopentone sodium, and pancuronium bromide as a muscle relaxant and maintained with fentanyl, midazolam, pancuronium bromide, and isoflurane. The hemodynamic parameters [HR and mean arterial pressure (MAP)] and pulmonary artery (PA) catheter-derived data were recorded at the baseline (before induction), 3 min after the induction of anesthesia at 1 min and 3 min after intubation and at 5 min and 30 min after protamine administration. Intraoperatively, hemodynamic data (HR and MAP) were recorded every 10 min, except during distal anastomosis of the coronary arteries when it was recorded every 5 min. Post-operatively, at 24 hours, the levels of troponin T and brain natriuretic peptide (BNP) were measured. This trial's CTRI registration number is CTRI/005858.

Results

The HR in group II was lower when compared to group I (range 59.6-72.4 beats/min and 65.8-80.2 beats/min, respectively) throughout the study period. MAP was comparable [range (78.5-87.8 mm Hg) vs. (78.9-88.5 mm Hg) in group II vs. group I, respectively] throughout the study period. Intraoperatively, 5 patients received metoprolol in group I to control the HR, whereas none of the patients in group II required metoprolol. The incidence of preoperative bradycardia (HR <60 beats/min) was higher in group II (20%) vs. group I (8%). There was no difference in both the groups in terms of troponin T and BNP level after 24 hours, time to extubation, requirement of inotropes, incidence of arrhythmias, in-hospital morbidity, and 30-day mortality.

Conclusion

Ivabradine can be safely used along with other anti-anginal agents during the preoperative period in patients undergoing OPCAB surgery. It helps to maintain a lower HR during surgery and reduces the need for beta-blockers in the intraoperative period, a desirable and beneficial effect in situations where the use of beta-blockers may be potentially harmful. Further studies are needed to evaluate the beneficial effects of perioperative Ivabradine in patients with moderate-to-severe left ventricular dysfunction.

Rationale and Design of the Effect of Ivabradine on Exercise Tolerance in Patients With Chronic Heart Failure (EXCILE-HF) Trial ― Protocol for a Multicenter Randomized Controlled Trial ―

Background: A high resting heart rate is an independent risk factor for mortality and morbidity in patients with cardiovascular diseases. Ivabradine selectively inhibits the funny current (I _f) and decreases heart rate without affecting cardiac conduction, contractility, or blood pressure. The effect of ivabradine on exercise tolerance in patients with heart failure with reduced ejection fraction (HFrEF) on standard drug therapies remains unclear. Methods and Results: This multicenter interventional trial of patients with HFrEF and a resting heart rate ≥75 beats/min in sinus rhythm treated with standard drug therapies will consist of 2 periods: a 12-week open-label, randomized, parallel-group intervention period (standard drug treatment+ivabradine group and standard drug treatment group) to compare changes in exercise tolerance between the 2 groups; and a 12-week open-label ivabradine treatment period for all patients to evaluate the effect of adding ivabradine on exercise tolerance. The primary endpoint will be the change in peak oxygen uptake (V̇O₂) during the cardiopulmonary exercise test from Week 0 (baseline) to Week 12. Secondary endpoints will be time-dependent changes in peak V̇O₂ from Week 0 to Weeks 12 and 24. Adverse events will also be evaluated. Conclusions: The EXCILE-HF trial will provide meaningful information regarding the effects of ivabradine on exercise tolerance in patients with HFrEF receiving standard drug therapies and suggestions for the initiation of ivabradine treatment.

Adaptation of Arterial Wall Viscosity to the Short-Term Reduction of Heart Rate: Impact of Aging

Background Changes in arterial wall viscosity, which dissipates the energy stored within the arterial wall, may contribute to the beneficial effect of heart rate (HR) reduction on arterial stiffness and cardiovascular coupling. However, it has never been assessed in humans and could be altered by aging. We evaluated the effect of a selective HR-lowering agent on carotid arterial wall viscosity and the impact of aging on this effect. Methods and Results This randomized, placebo-controlled, double-blind, crossover study performed in 19 healthy volunteers evaluated the effects of ivabradine (5 mg BID, 1-week) on carotid arterial wall viscosity, mechanics, hemodynamics, and cardiovascular coupling. Arterial wall viscosity was evaluated by the area of the hysteresis loop of the pressure-lumen cross-sectional area relationship, representing the energy dissipated (W_V), and by the relative viscosity (W_V/W_E), with W_E representing the elastic energy stored. HR reduction by ivabradine increased W_V and W_E whereas W_V/W_E remained stable. In middle-aged subjects (n=11), baseline arterial stiffness and cardiovascular coupling were less favorable, and W_E was similar but W_V and therefore W_V/W_E were lower than in youth (n=8). HR reduction increased W_V/W_E in middle-aged but not in young subjects, owing to a larger increase in W_V than W_E. These results were supported by the age-related linear increase in W_V/W_E after HR reduction (P=0.009), explained by a linear increase in W_V. Conclusion HR reduction increases arterial wall energy dissipation proportionally to the increase in W_E, suggesting an adaptive process to bradycardia. This mechanism is altered during aging resulting in a larger than expected energy dissipation, the impact of which should be assessed. Registration URL: https://www.clinicaltrials.gov; Unique identifier: 2015/077/HP. URL: https://www. eudract.ema.europa.eu; Unique identifier: 2015-002060-17.

The Functional Role of Hyperpolarization Activated Current (I f) on Cardiac Pacemaking in Human vs. in the Rabbit Sinoatrial Node: A Simulation and Theoretical Study

The cardiac hyperpolarization-activated “funny” current (I_f), which contributes to sinoatrial node (SAN) pacemaking, has a more negative half-maximal activation voltage and smaller fully-activated macroscopic conductance in human than in rabbit SAN cells. The consequences of these differences for the relative roles of I_f in the two species, and for their responses to the specific bradycardic agent ivabradine at clinical doses have not been systematically explored. This study aims to address these issues, through incorporating rabbit and human I_f formulations developed by Fabbri et al. into the Severi et al. model of rabbit SAN cells. A theory was developed to correlate the effect of I_f reduction with the total inward depolarising current (I_total) during diastolic depolarization. Replacing the rabbit I_f formulation with the human one increased the pacemaking cycle length (CL) from 355 to 1,139 ms. With up to 20% I_f reduction (a level close to the inhibition of I_f by ivabradine at clinical concentrations), a modest increase (~5%) in the pacemaking CL was observed with the rabbit I_f formulation; however, the effect was doubled (~12.4%) for the human I_f formulation, even though the latter has smaller I_f density. When the action of acetylcholine (ACh, 0.1 nM) was considered, a 20% I_f reduction markedly increased the pacemaking CL by 37.5% (~27.3% reduction in the pacing rate), which is similar to the ivabradine effect at clinical concentrations. Theoretical analysis showed that the resultant increase of the pacemaking CL is inversely proportional to the magnitude of I_total during diastolic depolarization phase: a smaller I_f in the model resulted in a smaller I_total amplitude, resulting in a slower pacemaking rate; and the same reduction in I_f resulted in a more significant change of CL in the cell model with a smaller I_total. This explained the mechanism by which a low dose of ivabradine slows pacemaking rate more in humans than in the rabbit. Similar results were seen in the Fabbri et al. model of human SAN cells, suggesting our observations are model-independent. Collectively, the results of study explain why low dose ivabradine at clinically relevant concentrations acts as an effective bradycardic agent in modulating human SAN pacemaking.

Relief of Ischemia in Ischemic Cardiomyopathy

PURPOSE OF THE REVIEW

Ischemic heart disease is among the most common causes of morbidity and mortality worldwide. In its stable manifestation, obstructing coronary artery stenoses prevent myocardial blood flow from matching metabolic needs of the heart under exercise conditions, which manifests clinically as dyspnea or chest pain. Prolonged bouts of ischemia may result in permanent myocardial dysfunction, heart failure, and eventually reduced survival. The aim of the present work is to review currently available approaches to provide relief of ischemia in stable coronary artery disease (CAD).

RECENT FINDINGS

Several pharmacological and interventional approaches have proven effectiveness in reducing the burden of ischemia in stable CAD and allow for symptom control and quality of life improvement. However, substantial evidence in favor of improved survival with ischemia relief is lacking, and recently published randomized controlled trial suggests that only selected groups of patients may substantially benefit from this approach. Pharmacological treatments aimed at reducing ischemia were shown to significantly reduce ischemic symptoms but failed to provide prognostic benefit. Myocardial revascularization is able to re-establish adequate coronary artery flow and was shown to improve survival in selected groups of patients, i.e., those with significant left main CAD or severe left ventricular dysfunction in multivessel CAD. Outside the previously mentioned categories, revascularization appears to improve symptoms control over medical therapy, but does not confer prognostic advantage. More studies are needed to elucidate the role of systematic invasive functional testing to identify individuals more likely to benefit from revascularization and to evaluate the prognostic role of chronic total occlusion recanalization.

Sex differences in blood pressure regulation during ischemic isometric exercise: the role of the β-adrenergic receptors

We sought to investigate whether the β-adrenergic receptors play a pivotal role in sex-related differences in arterial blood pressure (BP) regulation during isometric exercise. Sixteen volunteers (8 women) performed 2 min of ischemic isometric handgrip exercise (IHE) and 2 min of postexercise circulatory occlusion (PECO). Heart rate (HR) and beat-to-beat arterial BP were continuously measured. Beat-to-beat estimates of stroke volume (ModelFlow) were obtained and matched with HR to calculate cardiac output (Q̇) and total peripheral resistance (TPR). Two trials were randomly conducted between placebo and nonselective β-adrenergic blockade (40 mg propranolol). Under the placebo condition, the magnitude of the BP response in IHE was lower in women compared with men. During PECO, the BP remained elevated and the sex differences persisted. The β-blockade attenuated the BP response during IHE in men (∆57 ± 4 vs. ∆45 ± 7 mmHg, P = 0.025) due to a reduction in Q̇ (∆3.7 ± 0.5 vs. ∆1.8 ± 0.2 L/min, P = 0.012) while TPR was not affected. In women, however, the BP response during IHE was unchanged (∆27 ± 3 vs. ∆28 ± 3 mmHg, P = 0.889), despite attenuated Q̇ (∆2.7 ± 0.4 vs. ∆1.3 ± 0.2 L/min, P = 0.012). These responses were mediated by a robust increase in TPR under β-blockade (∆-0.2 ± 0.4 vs. ∆2.2 ± 0.7 mmHg·L^-1·min, P = 0.012). These findings demonstrate that the sex differences in arterial BP regulation during ischemic IHE are mediated by β-adrenergic receptors.NEW & NOTEWORTHY We found that the blood pressure response during isometric exercise in women is mediated by increases in cardiac output, whereas in men it is mediated by increases in both cardiac output and total peripheral resistance. In addition, women showed a robust increase in total peripheral resistance under β-blockade during isometric exercise and muscle metaboreflex activation. These findings demonstrate that sex differences in blood pressure regulation during isometric exercise are mediated by β-adrenergic receptors.

Ivabradine has a neutral effect on mortality in randomized controlled trials

BACKGROUND

It has long been a controversial hotspot whether resting heart rate (RHR) is a risk factor or a marker for death. Ivabradine, a specific inhibitor of the If current in the sinoatrial node, is a pure RHR lowering agent. The study was aimed to investigate whether ivabradine would reduce more RHR, cardiovascular disease (CVD) mortality, and all-cause mortality than those placebo or beta-blockers.

METHODS

The authors performed a meta-analysis of 8 randomized controlled clinical studies (with 40,357 participants), and 3 studies of those which were ivabradine versus placebo (36,069 participants) and other 5 studies ivabradine versus beta-blockers (4288 participants) were available. The authors compared the association of the RHR reduction with death from CVD causes (2674 in 40,285 participants) and the rate of all-cause death (3143 deaths in 38,037 participants), and assessed improvement in death rates with the use of ivabradine.

RESULTS

The change of RHR from baseline to endpoint was 8 to 16 beats/min (bpm) in ivabradine group, 1 to 8 bpm in placebo group, and 4 to 24 bpm in beta-blockers group. In ivabradine versus placebo, the reduced risks of CVD mortality and all-cause morbidity were not significantly (risk ratio [RR] 1.02; 95% confidence interval [CI] 0.91-1.14, P = .737; RR: 1.00, 95% CI: 0.92-1.09, P = .992, respectively). CVD and all-cause morbidity were similar for ivabradine versus beta-blockers (RR: 1.04; 95% CI: 0.80-1.37, P = .752; RR: 1.17, 95% CI: 0.53-2.60, P = .697, respectively).

CONCLUSIONS

Ivabradine had a neutral effect on mortality, suggesting that a pure RHR lowering agent did not reduce CVD mortality, all-cause mortality and improve the lifespan.

Heart rate manipulation in dilated cardiomyopathy: Assessing the role of Ivabradine

Background

Heart rate (HR) reduction is of benefit in chronic heart failure (HF). The effect of heart rate reduction using Ivabradine on various echocardiographic parameters in dilated cardiomyopathy has been less investigated.

Methods

Of 187 patients with HF (DCM, NYHA II–IV, baseline HR > 70/min), 125 patients were randomized to standard therapy (beta blockers, ACEI, diuretics, n = 62) or add-on Ivabradine (titrated to maximum 7.5 mg BD, n = 63). Beta-blockers were titrated in both the groups.

Results

At 3 months both groups had improvement in NYHA class, 6 min walk test, Minnesota Living With Heart Failure (MLWHF) scores and fall in BNP, however the magnitude of change was greater in Ivabradine group. Those on Ivabradine also had lower LV volumes, higher LVEF (28.8 ± 3.6 vs 27.2 ± 0.5, p = 0.01) and more favorable LV global strain (11 ± 1.7vs 12.2 ± 1.1, p = <0.001), MPI (0.72 ± 0.1 vs 0.6 ± 0.1, p = <0.001), LV mass (115.2 ± 30 vs 131.4 ± 35, p = 0.007), LV wall stress (219.8 ± 46 vs 238 ± 54) and calculated LV work (366 ± 101 vs 401 ± 102, p = 0.05). The benefit of Ivabradine was sustained at 6 months follow up. The % change in HR was significantly higher in Ivabradine group (−32.2% vs −19.3%, p = 0.001) with no difference in blood pressure. Resting HR < 70/min was achieved in 96.8% vs 27.9%, respectively in the two groups.

Conclusion

Addition of Ivabradine to standard therapy in patients with DCM and symptomatic HF and targeting a heart rate < 70/min improves symptoms, quality of life and various echocardiographic parameters.

Newer Therapies for Management of Stable Ischemic Heart Disease With Focus on Refractory Angina

Ischemic heart disease remains a major public health problem nationally and internationally. Stable ischemic heart disease (SIHD) is one of the clinical manifestations of ischemic heart disease and is generally characterized by episodes of reversible myocardial demand/supply mismatch, related to ischemia or hypoxia, which are usually inducible by exercise, emotion, or other stress and reproducible-but which may also be occurring spontaneously. Improvements in the treatment of acute coronary syndromes along with increasing prevalence of cardiovascular risk factors, including diabetes and obesity, have led to increasing population of patients with SIHD. A significant number of these continue to have severe angina despite medical management and revascularization procedures performed and may progress to refractory angina. This article reviews the newer therapies in the treatment of SIHD with special focus in treating patients with refractory angina.

The role of Ivabradine in Diastolic Heart Failure with preserved Ejection Fraction. A Doppler-Echocardiographic study

Background:

Ivabradine (IVA) is effective in patients with coronary artery disease (CAD) or systolic heart failure in sinus rhythm. Its action consists in reducing heart rate (HR) and improving the time of left ventricular (LV) diastolic filling. The aim of this study was to evaluate the effects of IVA added to conventional therapy on patients with diastolic heart failure (DHF) and preserved ejection fraction (HFpEF).

Methods:

We evaluated 25 patients with DHF in the New York Heart Association (NYHA) Class II-III and sinus rhythm. In these, IVA per os (5 mg/twice a day) was added to the conventional medical therapy and given for 12 weeks. Immediately before the beginning of IVA therapy and 3 months later, patients underwent echocardiographic evaluation by two-dimensional (2D) ultrasound and tissue Doppler imaging (TDI). The patterns of diastolic mitral inflow and pulmonary venous flow were recorded using 2D echocardiography, while the diastolic phase of mitral flow was recorded by TDI, from the lateral mitral annulus.

Results:

Three months after the addition of IVA to conventional treatment, HR significantly decreased in comparison to the baseline values. On the contrary, the echocardiographic indexes of LV diastolic dysfunction improved.

Conclusions:

These results testify that the addition of IVA to conventional therapy in patients with HFpEF can improve LV diastolic function evaluated by 2D and tissue Doppler-echocardiographic patterns. These Doppler-echocardiographic results match with the clinical improvement of patients evaluated.

Cardiovascular symptoms in patients with systemic mast cell activation disease

Traditionally, mast cell activation disease (MCAD) has been considered as just one rare (neoplastic) disease, mastocytosis, focused on the mast cell (MC) mediators tryptase and histamine and the suggestive, blatant symptoms of flushing and anaphylaxis. Recently another form of MCAD, the MC activation syndrome, has been recognized featuring inappropriate MC activation with little to no neoplasia and likely much more heterogeneously clonal and far more prevalent than mastocytosis. Increasing expertise and appreciation has been established for the truly very large menagerie of MC mediators and their complex patterns of release, engendering complex, nebulous presentations of chronic and acute illness best characterized as multisystem polymorbidity of generally inflammatory ± allergic theme. We describe the pathogenesis of MCAD with a particular focus on clinical cardiovascular symptoms and the therapeutic options for MC mediator-induced cardiovascular symptoms.

Is Heart Rate a Norepiphenomenon in Heart Failure?

There has been an increased focus on heart rate as a target in the management of cardiovascular disease and more specifically in heart failure with preserved ejection fraction in recent years with several studies showing the benefit of a lower resting heart rate on outcomes. This review paper examines the pathophysiology behind the benefits of lowering heart rate in heart failure and also the evidence for and against the pharmacological agents available to achieve this.

HCN Channels Modulators: The Need for Selectivity

Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators.

Pharmacological and emerging therapies in the treatment of chronic angina

Chronic angina is a common manifestation of ischaemic heart disease. Medical treatments are the mainstay approach to reduce the occurrence of angina and improve patients' quality of life. This Series paper focuses on commonly used standard treatments (eg, nitrates, β blockers, and calcium-channel blockers), emerging anti-angina treatments (which are not available in all parts of the world), and experimental treatments. Although many emerging treatments are available, evidence is scarce about their ability to reduce angina and ischaemia.

Ivabradine and Bisoprolol on Doppler-derived Coronary Flow Velocity Reserve in Patients with Stable Coronary Artery Disease: Beyond the Heart Rate

Introduction

Coronary flow velocity reserve (CFVR) is an important prognostic marker in patients with stable coronary artery disease (CAD). Beta-blockers and ivabradine have been shown to improve CFVR in patients with stable CAD, but their effects were never compared. The aim of the current study was to compare the effects of bisoprolol and ivabradine on CFVR in patients with stable CAD.

Methods

Patients in sinus rhythm with stable CAD were enrolled in this prospective, randomized, double-blind trial. Patients had to be in a stable condition for at least 15 days before enrollment, on their usual therapy. Patients who were receiving beta-blockers or ivabradine entered a 2-week washout period from these drugs before randomization. Transthoracic Doppler-derived CFVR was assessed in left anterior descending coronary artery, and was calculated as the ratio of hyperemic to baseline diastolic coronary flow velocity (CFV). Hyperemic CFV was obtained using dipyridamole administration using standard protocols. After CFVR assessment, patients were randomized to ivabradine or bisoprolol and entered an up-titration phase, and CFVR was assessed again 1 month after the end of the up-titration phase.

Results

Fifty-nine patients (38 male, 21 female; mean age 69 ± 9 years) were enrolled. Transthoracic Doppler-derived assessment of CFV and CFVR was successfully performed in all patients. Baseline characteristics were similar between the bisoprolol and ivabradine groups. No patient dropped out during the study. At baseline, rest and hyperemic peak CFV as well as CFVR was not significantly different in the ivabradine and bisoprolol groups. After the therapy, resting peak CFV significantly decreased in both the ivabradine and bisoprolol groups, but there was no significant difference between the groups (ivabradine group 20.7 ± 4.6 vs. 22.8 ± 5.2, P < 0.001; bisoprolol group 20.1 ± 4.1 vs. 22.1 ± 4.3, P < 0.001). However, hyperemic peak CFV significantly increased in both groups, but to a greater extent in patients treated with ivabradine (ivabradine: 70.7 ± 9.4 vs. 58.8 ± 9.2, P < 0.001; bisoprolol: 65 ± 8.3 vs. 58.7 ± 8.2, P < 0.001). Accordingly, CFVR significantly increased in both groups (ivabradine 3.52 ± 0.64 vs. 2.67 ± 0.55, P < 0.001; bisoprolol 3.35 ± 0.70 vs. 2.72 ± 0.55, P < 0.001), but it was significantly higher in ivabradine group, despite a similar decrease in heart rate (63 ± 7 vs. 61 ± 6; P not significant).

Conclusion

Ivabradine improves hyperemic peak CFV and CFVR to a greater extent than bisoprolol in patients with stable CAD, despite a similar decrease in heart rate. These data demonstrate that the benefits from ivabradine therapy go beyond the heart rate. This could be due to a different mechanism such as diastolic perfusion time, isovolumic ventricular relaxation, end-diastolic pressure, and collaterals.

Funding

Servier.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-015-0237-x) contains supplementary material, which is available to authorized users.

The Effect of Ivabradine on the Heart Rate and Sympathovagal Balance in Postural Tachycardia Syndrome Patients

BACKGROUND

Postural tachycardia syndrome (POTS) is a common form of chronic orthostatic intolerance. The remarkable increase in heart rate (HR) upon standing is the hallmark of this syndrome. Treatment of POTS patients is challenging and includes drugs that slow the HR. Ivabradine is a selective If channel blocker designed to slow the HR, as an anti-anginal agent. In view of its ability to slow the HR, we posited that ivabradine may be an ideal medication for treating POTS patients. This report provides the results of an investigation in which we studied ivabradine's effect on the hemodynamics and sympathovagal balance in POTS patients.

METHODS

An open-label trial, without a placebo control, was performed in eight patients with POTS of two years' standing. Characterization of symptoms, hemodynamics, autonomic function tests, and HR and blood pressure (BP) variability were determined while patients were in a supine position and during a 20-minute head-up tilt before and after a single oral dose of 7.5 mg ivabradine.

RESULTS

Ivabradine slowed the HR of POTS patients at rest by 4±1 bpm (P<0.05). During a 5-minute head-up tilt, the HR decreased from 118±4 bpm to 101±5 bpm (P<0.01). Ivabradine did not affect the BP when patients were at rest in a supine position or in head-up tilt position. Cardiovascular vagal and sympathetic tone, extrapolated from the time and frequency domains of the HR and BP variability, were also not affected by ivabradine.

CONCLUSIONS

Ivabradine is an effective drug for slowing the HR of POTS patients at rest and during tilting, without producing significant adverse effects. Moreover, ivabradine exerts its effects without influencing the sympathovagal balance.

hERG potassium channel blockade by the HCN channel inhibitor bradycardic agent ivabradine

Background

Ivabradine is a specific bradycardic agent used in coronary artery disease and heart failure, lowering heart rate through inhibition of sinoatrial nodal HCN‐channels. This study investigated the propensity of ivabradine to interact with KCNH2‐encoded human Ether‐à‐go‐go–Related Gene (hERG) potassium channels, which strongly influence ventricular repolarization and susceptibility to torsades de pointes arrhythmia.

Methods and Results

Patch clamp recordings of hERG current (I_hERG) were made from hERG expressing cells at 37°C. I_hERG was inhibited with an IC₅₀ of 2.07 μmol/L for the hERG 1a isoform and 3.31 μmol/L for coexpressed hERG 1a/1b. The voltage and time‐dependent characteristics of I_hERG block were consistent with preferential gated‐state‐dependent channel block. Inhibition was partially attenuated by the N588K inactivation‐mutant and the S624A pore‐helix mutant and was strongly reduced by the Y652A and F656A S6 helix mutants. In docking simulations to a MthK‐based homology model of hERG, the 2 aromatic rings of the drug could form multiple π‐π interactions with the aromatic side chains of both Y652 and F656. In monophasic action potential (MAP) recordings from guinea‐pig Langendorff‐perfused hearts, ivabradine delayed ventricular repolarization and produced a steepening of the MAPD₉₀ restitution curve.

Conclusions

Ivabradine prolongs ventricular repolarization and alters electrical restitution properties at concentrations relevant to the upper therapeutic range. In absolute terms ivabradine does not discriminate between hERG and HCN channels: it inhibits I_hERG with similar potency to that reported for native I_f and HCN channels, with S6 binding determinants resembling those observed for HCN4. These findings may have important implications both clinically and for future bradycardic drug design.

Addition of ivabradine to β-blocker improves exercise capacity in systolic heart failure patients in a prospective, open-label study

INTRODUCTION

Difficulties initiating and uptitrating β-blockers due to tolerability can complicate management of heart failure. Among other actions, β-blockers reduce heart rate, which is an important cardiovascular risk factor in heart failure. A new therapeutic strategy is ivabradine, which reduces resting heart rate and is associated with improved outcomes.

METHODS

A 5-month, prospective, open-label, nonrandomized single-center study was performed in 69 patients. All patients had chronic heart failure with left ventricular systolic dysfunction in sinus rhythm, each were initiated on 3.125 mg twice daily (bid) carvedilol alone (n = 36) or 3.125 mg bid carvedilol/5 mg bid ivabradine (n = 33), on top of background therapy including angiotensin-converting enzyme inhibitor (88%), diuretics (86%), antiplatelet agents (91%), and statins (90%). Dosages were uptitrated every 2 weeks to 25 mg bid carvedilol in both groups and 7.5 mg bid ivabradine maximum in the carvedilol/ivabradine group. Uptitration of carvedilol lasted 1.9 ± 0.4 months with carvedilol/ivabradine and 2.8 ± 0.6 months with carvedilol alone (P < 0.05).

RESULTS

The patients receiving ivabradine had lower resting heart rate at 5 months (61.6 ± 3.1 versus 70.2 ± 4.4 bpm, P < 0.05). Adding ivabradine to carvedilol in patients with heart failure was associated with increases in the 6-min walk test and ejection fraction (all P < 0.05). Treatment tolerability was satisfactory. Patients receiving ivabradine and carvedilol had lower heart rates and better exercise capacity than those on carvedilol alone.

CONCLUSION

Adding ivabradine to carvedilol in patients with chronic heart failure improves the uptitration of β-blocker. The results merit further verification in a prospective double-blind study.

Stable angina pectoris

The stable coronary artery disease (SCAD) population is a heterogeneous group of patients both for clinical presentations and for different underlying mechanisms. The recent European Society of Cardiology guidelines extensively review SCAD from its definition to patients' diagnostic and therapeutic management. In this review, we deal with five topics that, in our opinion, represent the most intriguing, novel and/or clinically relevant aspects of this complex coronary condition. Firstly, we deal with a peculiar SCAD population: patients with angina and 'normal' coronary arteries. Secondly, we reinforce the clinical importance of a diagnostic approach based on the pretest probability of disease. Thirdly, we review and critically discuss the novel pharmacological therapies for SCAD patients. Finally, we analyse the results of the most recent clinical trials comparing revascularization versus optimal medical therapy in SCAD patients and review the currently recommended use of intracoronary functional evaluation of stenosis.

Use of ivabradine and atorvastatin in emergent orthopedic lower limb surgery and computed tomography coronary plaque imaging and novel biomarkers of cardiovascular stress and lipid metabolism for the study and prevention of perioperative myocardial infarction: study protocol for a randomized controlled trial

Background

The incidence of perioperative myocardial infarction (PMI) globally is known to be around 2 to 3% and can prolong hospitalization, increased morbidity and mortality. Little is known about the pathophysiology and risk factors for PMI. We investigate the presence of elevated novel cardiac markers and preoperative coronary artery plaque through contemporary laboratory techniques to determine the correlation with PMI, as well as studying ivabradine and atorvastatin as protective pharmacotherapies against PMI in the context of orthopedic surgery.

Methods/Design

We aim to enroll 200 patients aged above 60 years who suffer from neck of femur fracture requiring surgery. Patients will be randomized to four arms (no study drugs, atorvastatin only, ivabradine only and ivabradine and atorvastatin). Our primary outcome is incidence of PMI. All patients will receive an electrocardiogram, cardiac echocardiography, measurement of novel cardiac biomarkers and computed tomography (CT) coronary angiography. A telephone interview post discharge will be conducted at 30 days, 60 days and 1 year.

Discussion

We postulate that ivabradine and atorvastatin will reduce the rate and magnitude of PMI following surgery by reducing heart rate and attenuating catecholamine-induced tachycardia postoperatively. Secondly, we postulate that postoperative reduction in heart rate and catecholamine-induced tachycardia with ivabradine will correlate with a reduction in cardiovascular novel biomarkers which will reduce atrial stretch and postoperative incidence of arrhythmia. We aim to demonstrate that treatment with ivabradine and atorvastatin will cause a reduction in the incidence and magnitude of PMI, the benefit of which is derived primarily in patients with greater atherosclerotic burden as measured by higher CT coronary calcium scores.

Trial registration

This study protocol has been listed in the Australia New Zealand Clinical Trial Registry (registration number: ACTRN12612000340831) on 23 March 2012.

Efficacy and safety of ivabradine in patients with chronic systolic heart failure according to blood pressure level in SHIFT

AIMS

Low systolic blood pressure (SBP) is associated with poor outcomes in heart failure and complicates management. In a post hoc analysis, we investigated the efficacy and safety of ivabradine in the SHIFT population divided by tertiles of baseline SBP.

METHODS AND RESULTS

The analysis comprised 2110 patients with SBP <115 mmHg, 1968 with 115≤ SBP <130 mmHg, and 2427 with SBP ≥130 mmHg. Patients with low SBP were younger, had lower ejection fraction, and were less likely to be at target beta-blocker dose than patients in the other SBP groups. Ivabradine was associated with a similar relative risk reduction of the composite outcome in the three SBP groups [SBP <115 mmHg, hazard ratio (HR) = 0.84, 95% confidence interval (CI) 0.72-0.98; 115≤ SBP <130 mmHg, HR = 0.86, 95% CI 0.72 to 1.03; SBP ≥130 mmHg, HR = 0.77, 95% CI 0.66 to 0.92; P interaction = 0.68]. Similar results were found for cardiovascular mortality (P interaction = 0.91), hospitalization because of heart failure (P interaction = 0.79), all-cause mortality (P interaction = 0.90), and heart failure mortality (P interaction = 0.18). There was no evidence for a difference in safety profile according to SBP group.

CONCLUSION

The efficacy and safety of ivabradine is independent of SBP. This may have implications for the management of HF patients with low SBP and elevated heart rate.

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.

Effect of ivabradine-induced heart rate reduction on flow-mediated dilation measured with high-sensitivity ultrasound in patients with stable coronary heart disease

Background

Experimental data suggests that exclusive heart rate reduction with ivabradine is associated with the amelioration of the endothelial function. Since it is presently unknown whether this also applies to humans, the aim of this pilot study was to investigate whether heart rate reduction with ivabradine modulates the endothelial function in humans with an established coronary heart disease.

Methods

Using high-sensitivity ultrasound, we analysed the flow-mediated (FMD) and nitro-mediated dilation (NMD) of the brachial artery in 25 patients (62.9 ± 8.4 years) with a stable coronary heart disease and a resting heart rate of ≥70 beats per minute (bpm). To assess acute effects, measurements were performed before and 4 hours after the first intake of ivabradine 7.5 mg. Sustained effects of an ivabradine therapy (5 mg to 7.5 mg twice daily) were investigated after 4 weeks.

Results

We found a significant decrease in heart rate, both 4 hours after the intake of 7.5 mg of ivabradine (median -8 [interquartile range (IQR) -14 to -4] bpm) and after 4 weeks of twice daily intake (median -10 [IQR-17 to -5] bpm) (p < 0.05). However, the FMD did not change significantly: neither after first dose of ivabradine nor after sustained therapy (baseline FMD: median 5.0 [IQR 2.4 to 7.9]%; FMD 4 hours after 7.5 mg of ivabradine: median 4.9 [IQR 2.7 to 9.8]%; FMD after 4 weeks of ivabradine therapy: median 6.1 [IQR 4.3 to 8.2]%). No significant changes of the NMD were observed. In regression analysis, the heart rate and FMD did not correlated, irrespective of the ivabradine intake (r² = 0.086).

Conclusion

In conclusion, in our study heart rate reduction through ivabradine does not improve the endothelial function in patients with a stable coronary heart disease. Moreover, we found no correlation between the heart rate and the endothelial function.

Impaired signaling intrinsic to sinoatrial node pacemaker cells affects heart rate variability during cardiac disease

The normal heart beat intervals are neither strictly stationary nor completely random, and continuously shift from one period to another. Decoding the ECG identifies this "hidden" information that imparts inherent complexity to the heart-beating interval time series. Loss of this complexity in cardiovascular disease is manifested as a reduction in heart rate variability (HRV) and this reduction correlates with an increase in both morbidity and mortality. Because HRV measurements are noninvasive and easy to perform, they have emerged as an important tool in cardiology. However, the identities of specific mechanisms that underline the changes in HRV that occur in cardiovascular diseases remain largely unknown. Changes in HRV have mainly been interpreted on a neural basis, ie due to changes in autonomic impulses to the heart: sympathetic activity decreases both the average heart beat interval and HRV, and parasympathetic activity increases both. It has now become clear, however, that the heart rate and HRV are also determined by intrinsic properties of the pacemaker cells that comprise the sinoatrial node, and the responses of these properties to autonomic receptor stimulation. Here we review how changes in the properties of coupled-clock mechanisms intrinsic to pacemaker cells that comprise the sinoatrial node and their impaired response to autonomic receptor stimulation are implicated in the changes of HRV observed in heart diseases.

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.

Inhibition of cardiac pacemaker channel hHCN2 depends on intercalation of lipopolysaccharide into channel-containing membrane microdomains

Depressed heart rate variability in severe inflammatory diseases can be partially explained by the lipopolysaccharide (LPS)-dependent modulation of cardiac pacemaker channels. Recently, we showed that LPS inhibits pacemaker current in sinoatrial node cells and in HEK293 cells expressing cloned pacemaker channels, respectively. The present study was designed to verify whether this inhibition involves LPS-dependent intracellular signalling and to identify structures of LPS responsible for pacemaker current modulation. We examined the effect of LPS on the activity of human hyperpolarization-activated cyclic nucleotide-gated channel 2 (hHCN2) stably expressed in HEK293 cells. In whole-cell recordings, bath application of LPS decreased pacemaker current (IhHCN2) amplitude. The same protocol had no effect on channel activity in cell-attached patch recordings, in which channels are protected from the LPS-containing bath solution. This demonstrates that LPS must interact directly with or close to the channel protein. After cleavage of LPS into lipid A and the polysaccharide chain, neither of them alone impaired IhHCN2, which suggests that modulation of channel activity critically depends on the integrity of the entire LPS molecule. We furthermore showed that β-cyclodextrin interfered with LPS-dependent channel modulation predominantly via scavenging of lipid A, thereby abrogating the capability of LPS to intercalate into target cell membranes. We conclude that LPS impairs IhHCN2 by a local mechanism that is restricted to the vicinity of the channels. Furthermore, intercalation of lipid A into target cell membranes is a prerequisite for the inhibition that is suggested to depend on the direct interaction of the LPS polysaccharide chain with cardiac pacemaker channels.

Heart rate and heart failure: the role of ivabradine therapy

PURPOSE OF REVIEW

The clinical data about the impact of heart rate reduction in heart failure therapy will be reviewed.

RECENT FINDINGS

Clinical and experimental studies showed an association between elevated resting heart rate and mortality risk in heart failure patients. This review summarizes that heart rate level at rest and its extent of reduction is a sensitive indicator for outcome in heart failure. In addition to the nonspecific heart rate reducing drugs like β-blockers, cardiac glycosides and Ca(2+) antagonists, ivabradine is a highly selective heart rate reducing agent without modifying ventricular contractility and atrioventricular conduction in humans and animals, and has recently been shown to improve cardiovascular outcomes in patients with systolic heart failure by lowering the heart rate only. The present and future role of heart rate reduction in the spectrum of heart failure disease and therapy will be outlined and evaluated.

SUMMARY

Elevated heart rate at rest represents a key indicator of adverse outcome in heart failure and implies a major treatment target in these 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).

'Inappropriate' sinus tachycardia: does the 100 beats per min cut-off matter?

Sinus tachycardia is commonly encountered in clinical practice and when persistent, can result in significant symptoms and impaired quality of life, warranting further evaluation. On the other hand, a growing body of epidemiological and clinical evidence has shown that high resting heart rate (HR) within the accepted normal range is independently associated with increased risk of all-cause and cardiovascular mortality. However, higher HR as a risk factor for adverse cardiovascular outcomes is frequently underappreciated. In this review, we focus on two challenging problems that span the spectrum of abnormally fast sinus HR. The first section reviews inappropriate sinus tachycardia, a complex disorder characterized by rapid sinus HR without a clear underlying cause, with particular emphasis on current management options. The latter section discusses the prognostic significance of elevated resting HR and reviews clinical evidence aimed at modifying this simple, yet highly important risk factor.

Ivabradine in Combination With Metoprolol Succinate in the Treatment of Inappropriate Sinus Tachycardia

Background:

Inappropriate sinus tachycardia (IST) is a clinical syndrome characterized by excessive resting heart rate (HR) or a disproportional increase in HR during exercise. β-blocker or calcium channel-blocker therapy is often noneffective or not well tolerated. The HR reduction on ivabradine is similar to β-blockers but in some patients its efficacy to resolve all IST-related symptoms is limited. The aim of the study was to assess the efficacy and safety of combining ivabradine with metoprolol succinate in patients with refractory highly symptomatic IST.

Methods:

Twenty patients (36 ± 10 years; 16 women) with IST were enrolled. All patients received metoprolol succinate 95 mg single dose during the first month of the study. After 4 weeks of treatment with metoprolol, ivabradine was administered as adjuvant therapy up to 7.5 mg twice daily. Holter monitoring and treadmill stress test were performed at baseline, after 4, and 8 weeks of the study, respectively.

Results:

We observed significant and similar reduction in resting HR both for metoprolol and for combined therapy compared to the baseline. The mean HR during daily activity was significantly lower on ivabradine and metoprolol compared to monotherapy with β-blocker. The combined treatment yielded a significant increase in exercise capacity as assessed by treadmill stress test. After 4 weeks of combined therapy a significant reduction in IST-related symptoms, measured by means of the European Heart Rhythm Association score, was observed.

Conclusion:

Combining ivabradine with metoprolol is an effective and well-tolerated treatment option for IST in patients with refractory to monotherapy.

Intracardiac origin of heart rate variability, pacemaker funny current and their possible association with critical illness

Heart rate variability (HRV) is an indirect estimator of autonomic modulation of heart rate and is considered a risk marker in critical illness, particularly in heart failure and severe sepsis. A reduced HRV has been found in critically ill patients and has been associated with neuro-autonomic uncoupling or decreased baroreflex sensitivity. However, results from human and animal experimental studies indicate that intracardiac mechanisms might also be responsible for interbeat fluctuations. These studies have demonstrated that different membrane channel proteins and especially the so-called 'funny' current (If), an hyperpolarization-activated, inward current that drives diastolic depolarization resulting in spontaneous activity in cardiac pacemaker cells, are altered during critical illness. Furthermore, membrane channels kinetics seem to have significant impact upon HRV, whose early decrease might reflect a cellular metabolic stress. In this review article we present research findings regarding intracardiac origin of HRV, at the cellular level and in both isolated sinoatrial node and whole ex vivo heart preparations. In addition, we will review results from various experimental studies that support the interrelation between If and HRV during endotoxemia. We suggest that reduced HRV during sepsis could also be associated with altered pacemaker cell membrane properties, due to ionic current remodeling.