Antianginal and antiischemic effects of ivabradine, an I(f) inhibitor, in stable angina: a randomized, double-blind, multicentered, placebo-controlled trial

The Clinical Use of Ivabradine

The clinical use of ivabradine has and continues to evolve along channels that are predicated on its mechanism of action. It selectively inhibits the funny current (I_f) in sinoatrial nodal tissue, resulting in a decrease in the rate of diastolic depolarization and, consequently, the heart rate, a mechanism that is distinct from those of other negative chronotropic agents. Thus, it has been evaluated and is used in select patients with systolic heart failure and chronic stable angina without clinically significant adverse effects. Although not approved for other indications, ivabradine has also shown promise in the management of inappropriate sinus tachycardia. Here, the authors review the mechanism of action of ivabradine and salient studies that have led to its current clinical indications and use.

ANMCO/GICR-IACPR/SICI-GISE Consensus Document: the clinical management of chronic ischaemic cardiomyopathy

Stable coronary artery disease (CAD) is a clinical entity of great epidemiological importance. It is becoming increasingly common due to the longer life expectancy, being strictly related to age and to advances in diagnostic techniques and pharmacological and non-pharmacological interventions. Stable CAD encompasses a variety of clinical and anatomic presentations, making the identification of its clinical and anatomical features challenging. Therapeutic interventions should be defined on an individual basis according to the patient's risk profile. To this aim, management flow charts have been reviewed based on sustainability and appropriateness derived from recent evidence. Special emphasis has been placed on non-pharmacological interventions, stressing the importance of lifestyle changes, including smoking cessation, regular physical activity, and diet. Adherence to therapy as an emerging risk factor is also discussed.

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 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.

Using nationwide ‘big data’ from linked electronic health records to help improve outcomes in cardiovascular diseases: 33 studies using methods from epidemiology, informatics, economics and social science in the ClinicAl disease research using LInked Bespoke studies and Electronic health Records (CALIBER) programme

Background

Electronic health records (EHRs), when linked across primary and secondary care and curated for research use, have the potential to improve our understanding of care quality and outcomes.

Objective

To evaluate new opportunities arising from linked EHRs for improving quality of care and outcomes for patients at risk of or with coronary disease across the patient journey.

Design

Epidemiological cohort, health informatics, health economics and ethnographic approaches were used.

Setting

230 NHS hospitals and 226 general practices in England and Wales.

Participants

Up to 2 million initially healthy adults, 100,000 people with stable coronary artery disease (SCAD) and up to 300,000 patients with acute coronary syndrome.

Main outcome measures

Quality of care, fatal and non-fatal cardiovascular disease (CVD) events.

Data platform and methods

We created a novel research platform [ClinicAl disease research using LInked Bespoke studies and Electronic health Records (CALIBER)] based on linkage of four major sources of EHR data in primary care and national registries. We carried out 33 complementary studies within the CALIBER framework. We developed a web-based clinical decision support system (CDSS) in hospital chest pain clinics. We established a novel consented prognostic clinical cohort of SCAD patients.

Results

CALIBER was successfully established as a valid research platform based on linked EHR data in nearly 2 million adults with > 600 EHR phenotypes implemented on the web portal (seehttps://caliberresearch.org/portal). Despite national guidance, key opportunities for investigation and treatment were missed across the patient journey, resulting in a worse prognosis for patients in the UK compared with patients in health systems in other countries. Our novel, contemporary, high-resolution studies showed heterogeneous associations for CVD risk factors across CVDs. The CDSS did not alter the decision-making behaviour of clinicians in chest pain clinics. Prognostic models using real-world data validly discriminated risk of death and events, and were used in cost-effectiveness decision models.

Conclusions

Emerging ‘big data’ opportunities arising from the linkage of records at different stages of a patient’s journey are vital to the generation of actionable insights into the diagnosis, risk stratification and cost-effective treatment of people at risk of, or with, CVD.

Future work

The vast majority of NHS data remain inaccessible to research and this hampers efforts to improve efficiency and quality of care and to drive innovation. We propose three priority directions for further research. First, there is an urgent need to ‘unlock’ more detailed data within hospitals for the scale of the UK’s 65 million population. Second, there is a need for scaled approaches to using EHRs to design and carry out trials, and interpret the implementation of trial results. Third, large-scale, disease agnostic genetic and biological collections linked to such EHRs are required in order to deliver precision medicine and to innovate discovery.

Study registration

CALIBER studies are registered as follows: study 2 – NCT01569139, study 4 – NCT02176174 and NCT01164371, study 5 – NCT01163513, studies 6 and 7 – NCT01804439, study 8 – NCT02285322, and studies 26–29 – NCT01162187. Optimising the Management of Angina is registered as Current Controlled Trials ISRCTN54381840.

Funding

The National Institute for Health Research (NIHR) Programme Grants for Applied Research programme (RP-PG-0407-10314) (all 33 studies) and additional funding from the Wellcome Trust (study 1), Medical Research Council Partnership grant (study 3), Servier (study 16), NIHR Research Methods Fellowship funding (study 19) and NIHR Research for Patient Benefit (study 33).

Benefits of Heart Rate Slowing With Ivabradine in Patients With Systolic Heart Failure and Coronary Artery Disease

Heart rate (HR) is a risk factor in patients with chronic systolic heart failure (HF) that, when reduced, provides outcome benefits. It is also a target for angina pectoris prevention and a risk marker in chronic coronary artery disease without HF. HR can be reduced by drugs; however, among those used clinically, only ivabradine reduces HR directly in the sinoatrial nodal cells without other known effects on the cardiovascular system. This review provides current information regarding the safety and efficacy of HR reduction with ivabradine in clinical studies involving >36,000 patients with chronic stable coronary artery disease and >6,500 patients with systolic HF. The largest trials, Morbidity-Mortality Evaluation of the I_f Inhibitor Ivabradine in Patients With Coronary Disease and Left Ventricular Dysfunction and Study Assessing the Morbidity-Mortality Benefits of the I_f Inhibitor Ivabradine in Patients With Coronary Artery Disease, showed no effect on outcomes. The Systolic Heart Failure Treatment With the I_f Inhibitor Ivabradine Trial, a randomized controlled trial in >6,500 patients with HF, revealed marked and significant HR-mediated reduction in cardiovascular mortality or HF hospitalizations while improving quality of life and left ventricular mechanical function after treatment with ivabradine. The adverse effects of ivabradine predominantly included bradycardia and atrial fibrillation (both uncommon) and ocular flashing scotomata (phosphenes) but otherwise were similar to placebo. In conclusion, ivabradine improves outcomes in patients with systolic HF; rates of overall adverse events are similar to placebo.

Angina and Its Management

Angina pectoris is defined as substernal chest pain, pressure, or discomfort that is typically exacerbated by exertion and/or emotional stress, lasts greater than 30 to 60 seconds, and is relieved by rest and nitroglycerin. There are approximately 10 million people in the United States who have angina, and there are over 500 000 cases diagnosed per year. Several studies now show that angina itself is a predictor of major adverse cardiac events. In addition, angina is a serious morbidity that impedes quality of life and should be treated. In the United States, pharmacologic therapy for angina includes β-blockers, nitrates, calcium channel blockers, and the late sodium current blocker ranolazine. In other countries, additional pharmacologic agents include trimetazidine, ivabradine, nicorandil, fasudil, and others. Revascularization is indicated in certain high-risk individuals and also has been shown to improve angina. However, even after revascularization, a substantial percentage of patients return with recurrent or continued angina, requiring newer and better therapies. Treatment for refractory angina not amenable to usual pharmacologic therapies or revascularization procedures, includes enhanced external counterpulsation, transmyocardial revascularization, and stem cell therapy. Angina continues to be a significant cause of morbidity. Therapy should be geared not only to treating the risk factors for atherosclerotic disease and improving survival but should also be aimed at eliminating or reducing the occurrence of angina and improving the ability of patients to be active.

Management standards for stable coronary artery disease in India

Coronary artery disease (CAD) is one of the important causes of cardiovascular morbidity and mortality globally, giving rise to more than 7 million deaths annually. An increasing burden of CAD in India is a major cause of concern with angina being the leading manifestation. Stable coronary artery disease (SCAD) is characterised by episodes of transient central chest pain (angina pectoris), often triggered by exercise, emotion or other forms of stress, generally triggered by a reversible mismatch between myocardial oxygen demand and supply resulting in myocardial ischemia or hypoxia. A stabilised, frequently asymptomatic phase following an acute coronary syndrome (ACS) is also classified as SCAD. This definition of SCAD also encompasses vasospastic and microvascular angina under the common umbrella.

β-Adrenergic Blockers as Antiarrhythmic and Antifibrillatory Compounds: An Overview

β-Adrenergic blockers have a wide spectrum of action for controlling cardiac arrhythmias that is larger than initially thought. Data from the past several decades indicate that, as an antiarrhythmic class, β-blockers remain among the very few pharmacologic agents that reduce the incidence of sudden cardiac death, prolong survival, and ameliorate symptoms caused by arrhythmias in patients with cardiac disease. As a class of compounds, β-blockers have a fundamental pharmacologic property that attenuates the effects of competitive adrenergic receptors. However, the net clinical effects of the different β-receptor blockers may vary quantitatively because of variations in associated intrinsic sympathomimetic agonism and in their intrinsic potency for binding to β-receptors. These individual compounds also differ in their selectivity for β1- and β2-receptors. Metoprolol is a β1-selective blocker, whereas carvedilol is a nonselective β1- and β2-blocker, an antioxidant, and has a propensity to inhibit α1-receptors and endothelin. Evolving data from controlled and uncontrolled clinical trials suggest that there are clinically significant differences among this class of drugs. Recent evidence also suggests that the antiarrhythmic actions of certain β-receptor blockers such as carvedilol and metoprolol extend beyond the ventricular tissue to encompass atrial cells and help maintain sinus rhythm in patients with atrial fibrillation, especially in combination with potent antifibrillatory agents such as amiodarone. This introduction provides a current perspective on these newer developments in the understanding of the antiarrhythmic and antifibrillatory actions of β-blockers.

The effect of ivabradine on functional capacity in patients with chronic obstructive pulmonary disease

Increased sympathetic tone and use of bronchodilators increase heart rate and this may worsen functional capacity in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to look at the short-term effect of the heart rate lowering drug ivabradine on clinical status in COPD patients.We randomised 80 COPD patients with sinus heart rate ≥90 bpm into either taking ivabradine 7.5 mg twice per day or placebo for two weeks. We assessed all patients using the modified Borg scale and 6-minute walk test at baseline and then again 2 weeks after randomisation.There were no significant differences in age, sex, severity of airway obstruction (measured using forceful exhalation), severity of diastolic dysfunction or pulmonary artery systolic pressure between the two groups. The ivabradine group showed significant improvement in 6-minute walk distance (from 192.6±108.8 m at baseline to 285.1±88.9 m at the end of the study) compared with the control group (230.6±68.4 at baseline and 250.4±65.8 m at the end of study) (p<0.001). This improvement in the drug group was associated with significant improvement of dyspnea on modified Borg scale (p=0.007).Lowering heart rate with ivabradine can improve exercise capacity and functional class in COPD patients with resting heart rate >90 bpm.

The risk of cardiovascular side effects with anti-anginal drugs

INTRODUCTION

Angina pectoris is a common presenting symptom of underlying coronary artery disease or reduced coronary flow reserve. Patients with angina have impaired quality of life; and need to be treated optimally with antianginal drugs to control symptoms and improve exercise performance. A wide range of antianginal medications are approved for the treatment of angina, and often more than one class of antianginal drugs are used to adequately control the symptoms. This expert opinion highlights the likely cardiac adverse effects of available antianginal drugs, and how to minimize these in individual patients and especially during combination treatment. Areas covered: All approved antianginal drugs, including the older and newly approved medications with different mechanism of action to the older drugs as well as some of the unapproved herbal medications. The safety profiles and potential cardiac side effects of these medications when used as monotherapy or as combination therapy are discussed and highlighted. Expert opinion: Because of the different cardiac safety profiles and possible side effects, we recommend selection of initial drug or adjustment of therapy based on the resting heart rate; blood pressure, hemodynamic status; and resting left ventricular function, concomitant medications and any associated comorbidities.

Economic evaluation of trimetazidine in the management of chronic stable angina in Greece

Background

To evaluate the cost-effectiveness of trimetazidine (TMZ) as add-on therapy to standard-of-care (SoC) compared to SoC alone in patients with chronic stable angina who did not respond adequately to first line therapy with b-blockers, nitrates or calcium channel antagonists in Greece.

Methods

A Markov model with 3-month cycles and 1-year time horizon was developed to assess the comparators. The analysis was conducted from a third-party payer perspective. The clinical inputs and utility values were extracted from the published literature. Resource consumption data were obtained from local experts, using a questionnaire developed for the purpose of the study and were combined with unit cost data (in €2016) obtained from official sources. Cost effectiveness was assessed by calculating the incremental cost effectiveness ratio (ICER). Probabilistic sensitivity analysis (PSA) was performed to account for uncertainty and variation in the input parameters of the model.

Results

The analysis showed that the cost of TMZ plus SoC was €1755.57 versus €1751.76 of SoC alone. In terms of health outcomes, TMZ plus SoC was associated with 0.6650 QALYs versus 0.6562 QALYs for SoC alone. The incremental analysis resulted in an ICER of €430.67 per QALY gained. PSA revealed that the probability of TMZ plus SoC being cost-effective over SoC was 89 %, at a threshold of €34,000 per QALY gained.

Conclusion

The results indicate that TMZ as add –on treatment may be a highly cost-effective option for the symptomatic treatment of patients with chronic stable angina in Greece relative to SoC alone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-016-1779-6) contains supplementary material, which is available to authorized users.

Effectiveness of Ivabradine Treatment in Different Subpopulations with Stable Angina in Clinical Practice: A Pooled Analysis of Observational Studies

Objectives: The efficacy of ivabradine has been demonstrated in different subpopulations of stable angina patients in randomized clinical trials. This study explored its effectiveness in subpopulations seen in clinical practice as they often differ from those of randomized trials. Methods: Data were pooled from three German observational studies with similar inclusion criteria (stable angina and heart rate ≥60 bpm). All patients received 2.5, 5, or 7.5 mg b.i.d. of ivabradine for 4 months, with or without concomitant beta-blocker. Antianginal effectiveness was analyzed in subpopulations defined by gender, age, heart rate, angina severity, use of concomitant beta-blocker, previous percutaneous coronary intervention procedure, and comorbidities (including previous myocardial infarction and diabetes). Results: Treatment data were available on 8,555 patients, where therapy with ivabradine was associated with a significant reduction in the frequency of angina attacks and consumption of short-acting nitrates of 87%. Effectiveness was maintained in all investigated subpopulations, with a reduction in antianginal parameters of 82-90%. Clinical status (Canadian Cardiovascular Society class) and quality of life were also improved. Ivabradine was well tolerated in all subgroups. Conclusions: Ivabradine is effective and safe in all subpopulations of angina patients seen in clinical practice, independent of age, comorbidities, and use of beta-blocker.

A computational model of a human single sinoatrial node cell

For the investigation of the spontaneous rhythmical activity response in the application of cardiac neuromodulation, we formulated a human sinoatrial node (SAN) cell model. With the aim of decreasing elevated heart rate (HR), we want to establish a hardware-in-the-loop system including this model for the analysis of optimal stimulation patterns of the neurostimulation system. Base model structures are adopted from rabbit SAN cell models available in literature and conveyed with Hodgkin-Huxley-type model equations describing the complex time and voltage dependent activation and deactivation processes of individual ion channels. The resulting model consists of 15 currents which are currently known to be responsible for the generation of the membrane action potential (AP). The model reproduces AP frequencies equivalent to those measured in isolated human SAN cells with a resulting HR of 71.8 bpm. Model validation via simulation of the inhibitory effect of ivabradine showed accordance with experimental results obtained in human studies. Furthermore, we could validate the model in regard to its HR effects upon parasympathetic stimulation with results obtained in a human trial study.

Effectiveness of Ivabradine in Treating Stable Angina Pectoris

Many studies show that ivabradine is effective for stable angina.This meta-analysis was performed to determine the effect of treatment duration and control group type on ivabradine efficacy in stable angina pectoris.Relevant articles in the English language in the PUBMED and EMBASE databases and related websites were identified by using the search terms "ivabradine," "angina," "randomized controlled trials," and "Iva." The final search date was November 2, 2015.Articles were included if they were published randomized controlled trials that related to ivabradine treatment of stable angina pectoris.Patients with stable angina pectoris were included.The patients were classified according to treatment duration (<3 vs ≥3 months) or type of control group (placebo vs beta-receptor blocker). Angina outcomes were heart rate at rest or peak, exercise duration, and time to angina onset.Seven articles were selected. There were 3747 patients: 2100 and 1647 were in the ivabradine and control groups, respectively. The ivabradine group had significantly longer exercise duration when they had been treated for at least 3 months, but not when treatment time was less than 3 months. Ivabradine significantly improved time to angina onset regardless of treatment duration. Control group type did not influence the effect of exercise duration (significant) or time to angina onset (significant).Compared with beta-blocker and placebo, ivabradine improved exercise duration and time to onset of angina in patients with stable angina. However, its ability to improve exercise duration only became significant after at least 3 months of treatment.

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.

Addressing Major Unmet Needs in Patients with Systolic Heart Failure: The Role of Ivabradine

We reviewed clinical evidence for the use of ivabradine in systolic heart failure (HF), in which it appears to improve symptoms, improve quality of life, prevent hospitalization, and prolong survival, thereby addressing unmet needs in the management of HF. Ivabradine provides symptomatic benefits in HF on top of standard therapies, in terms of functional parameters and exercise capacity, and there is some evidence that this leads to improvements in quality of life in symptomatic HF patients, who may have dyspnea, altered exercise capacity, and fatigue. The SHIFT trial demonstrated that ivabradine has significant beneficial effects on major outcomes in HF. Ivabradine had a significant effect on pump failure death, which was reduced by 26 % (p = 0.014), with no effect on sudden cardiac death. This is an important result since pump failure death is currently the main cause of death in HF, and also because the reductions in mortality obtained with beta-blockers and spironolactone in the last 20 years appear to be mainly due to reduction in sudden death rather than reduction in pump failure death. Ivabradine also has a beneficial effect on hospital admissions (-26 %, p < 0.0001), which is clinically relevant since a quarter of HF patients can expect to be readmitted to hospital for HF within 1 month of discharge. Ivabradine-treated patients are also at significantly lower risk of experiencing a second or third hospitalization for worsening HF. Ivabradine clearly has a key role to play in the management of HF by covering the main therapeutic objectives of symptoms, quality of life, and outcomes.

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.

Role of Ivabradine in the Treatment of Patients With Cardiovascular Disease

OBJECTIVE

To review the role of heart rate in myocardial ischemia and heart failure with reduced ejection fraction (HFrEF) as well as ivabradine's pharmacology and pharmacokinetics, clinical trials, and place in therapy.

DATA SOURCES

We conducted MEDLINE searches from 1980 to October 2015 using the terms heart failure, HFrEF, angina, f-channel inhibitor, and ivabradine, with forward and backward citation tracking.

STUDY SELECTION AND DATA EXTRACTION

English-language trials assessing ivabradine were obtained. Studies and narrative reviews of the topic areas were incorporated if they provided relevant data to inform the practicing clinician.

DATA SYNTHESIS

In the SIGNIFY (Study Assessing the Morbidity-Mortality Benefits of the If Inhibitor Ivabradine in Patients with Coronary Artery Disease) trial, there was no difference in the primary composite end point of cardiovascular (CV) mortality or nonfatal myocardial infarction with ivabradine use in patients with stable coronary artery disease (CAD) versus placebo (P = 0.20). In the subgroup with Canadian Cardiovascular Society angina class ≥II, there was an 18% increase in the primary end point with ivabradine versus placebo (P = 0.02). In HFrEF patients, ivabradine reduced CV mortality or heart failure hospitalizations versus placebo, as seen in the SHIFT (Systolic Heart failure treatment with the If inhibitor ivabradine Trial; P < 0.05).

CONCLUSIONS

The SIGNIFY trial negated much of the enthusiasm for using ivabradine in CAD. Ivabradine is a promising therapy in HFrEF based on the results of the SHIFT, but it is an adjunctive therapy, not a substitute for drugs with proven mortality benefits.

Current Role of Ivabradine in Stable Coronary Artery Disease Without Heart Failure

Increase in heart rate represents a significant contribution in the pathophysiology of coronary artery disease and heart failure, by promoting atherosclerotic process and endothelial dysfunction. Thus, it negatively influences cardiovascular risk in the general population. The aim of this review is to analyze the current, controversial, and future role of ivabradine as an anti-anginal agent in the setting of coronary artery disease without heart failure. Ivabradine represents a selective heart rate-lowering agent that increased diastolic perfusion time and improving energetics in the ischemic myocardium.

Preserved Autonomic Cardiovascular Regulation With Cardiac Pacemaker Inhibition: A Crossover Trial Using High-Fidelity Cardiovascular Phenotyping

BACKGROUND

Sympathetic and parasympathetic influences on heart rate (HR), which are governed by baroreflex mechanisms, are integrated at the cardiac sinus node through hyperpolarization-activated cyclic nucleotide-gated channels (HCN4). We hypothesized that HCN4 blockade with ivabradine selectively attenuates HR and baroreflex HR regulation, leaving baroreflex control of muscle sympathetic nerve activity intact.

METHODS AND RESULTS

We treated 21 healthy men with 2×7.5 mg ivabradine or placebo in a randomized crossover fashion. We recorded electrocardiogram, blood pressure, and muscle sympathetic nerve activity at rest and during pharmacological baroreflex testing. Ivabradine reduced normalized HR from 65.9±8.1 to 58.4±6.2 beats per minute (P<0.001) with unaffected blood pressure and muscle sympathetic nerve activity. On ivabradine, cardiac and sympathetic baroreflex gains and blood pressure responses to vasoactive drugs were unchanged. Ivabradine aggravated bradycardia during baroreflex loading.

CONCLUSIONS

HCN4 blockade with ivabradine reduced HR, leaving physiological regulation of HR and muscle sympathetic nerve activity as well as baroreflex blood pressure buffering intact. Ivabradine could aggravate bradycardia during parasympathetic activation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00865917.

Recent advances in treatment of heart failure

With the total cases and economic burden of heart failure continuing to rise, there is an overwhelming need for novel therapies. Several drugs for heart failure have succeeded in preclinical and early-phase clinical trials, but most of them failed to show the real benefit in pivotal clinical trials. Meanwhile, the US Food and Drug Administration recently approved two promising new drugs to treat heart failure: ivabradine and sacubitril/valsartan. Furthermore, some of the newer agents in testing offer the potential for significant progress in addition to these drugs. Patiromer and zirconium cyclosilicate are attractive agents that are expected to prevent hyperkalemia during renin-angiotensin-aldosterone system inhibition, and serelaxin and urodilatin are promising drugs in the treatment of acute heart failure. Future clinical trials with more appropriate study designs, optimal clinical endpoints, and proper patient selection are mandatory to assess the true efficacy of these attractive compounds in clinical practice.

Ranolazine for the symptomatic treatment of patients with chronic angina pectoris in Greece: a cost-utility study

Background

To conduct an economic evaluation comparing ranolazine as add-on therapy to standard-of-care (SoC) with SoC alone in patients with stable angina who did not respond adequately to first line therapy, in Greece.

Methods

A decision tree model was locally adapted in the Greek setting to evaluate the cost-utility of ranolazine during a 6-month period. The analysis was conducted from a third-party payer perspective. The clinical inputs were extracted from the published literature. The cost inputs considered in the model reflect drug acquisition, hospitalizations, vascular interventions and monitoring of patients. The resource utilization data were obtained from 3 local experts. All costs refer to the year 2014. Cost-effectiveness was assessed by means of the incremental cost per quality adjusted life year (QALY) gained with the ranolazine as add-on therapy relative to SoC alone (ICER). Probabilistic sensitivity analysis (PSA) was performed.

Results

Ranolazine as add-on therapy was more costly compared to SoC alone, as the 6-month total cost per patient was €1170 and € 984, respectively. Patients received ranolazine plus SoC and SoC alone gained 0.3155 QALYs and 0.2752 QALYs, respectively. Ranolazine plus SoC resulted in an ICER equal to €4620 per QALY gained, well below the threshold of €34,000 per QALY gained. The PSA showed that the likelihood of ranolazine plus SoC being cost-effective at the threshold of €34,000 per QALY gained was 100 %.

Conclusions

Τhe results suggest that ranolazine as add–on treatment may be a cost-effective alternative for the symptomatic treatment of patients with chronic stable angina in Greece.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-015-1228-y) contains supplementary material, which is available to authorized users.

Ivabradine in Combination with Metoprolol Improves Symptoms and Quality of Life in Patients with Stable Angina Pectoris: A post hoc Analysis from the ADDITIONS Trial

OBJECTIVES

Elevated heart rate can increase myocardial oxygen demand and reduce myocardial perfusion, provoking myocardial ischemia and angina symptoms. We evaluated adding ivabradine to the therapy of patients on metoprolol.

METHODS

ADDITIONS (prActical Daily efficacy anD safety of Procoralan® In combinaTION with betablockerS) was a multicenter, 4-month, noninterventional, prospective, open-label trial that involved stable-angina patients. Along with metoprolol, patients received ivabradine (5 or 7.5 mg, b.i.d.). We investigated the effect of ivabradine on heart rate, angina attacks, nitrate consumption, quality of life (QoL) and tolerability as well as the influence of baseline heart rate.

RESULTS

Heart rate fell by 19.7 ± 11.2 bpm, with an 8-fold decrease in weekly angina attacks (1.7 ± 2.2 to 0.2 ± 0.7) and nitrate consumption (2.4 ± 3.4 to 0.3 ± 0.9). Patient numbers in Canadian Cardiovascular Society class I more than doubled (i.e. from 29 to 65%) and QoL improved (the EQ-5D index and visual analog scale scores rose from 0.68 ± 0.27 to 0.84 ± 0.20 and 58.1 ± 18.4 to 72.2 ± 15.5 mm, respectively). The effect of ivabradine was greater in patients with a baseline heart rate ≥70 bpm (mean reduction in heart rate -21.2 ± 10.4 bpm, with a relative reduction in angina attacks and short-acting nitrate consumption of 87.1 and 87.2%, respectively).

CONCLUSIONS

Ivabradine combined with metoprolol safely and effectively reduces heart rate, angina attacks and nitrate use, and improves QoL in stable-angina patients.

Molecular Mapping of Sinoatrial Node HCN Channel Expression in the Human Heart

BACKGROUND

The hyperpolarization-activated current, If, plays an important role in sinoatrial node (SAN) pacemaking. Surprisingly, the distribution of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in human SAN has only been investigated at the mRNA level. Our aim was to define the expression pattern of HCN proteins in human SAN and different atrial regions.

METHODS AND RESULTS

Entire SAN complexes were isolated from failing (n=5) and nonfailing (n=9) human hearts cardioplegically arrested in the operating room. Three-dimensional intramural SAN structure was identified as the fibrotic compact region around the SAN artery with Connexin 43-negative pacemaker cardiomyocytes visualized in Masson's trichrome and immunostained cryosections. SAN protein was precisely isolated from the adjacent frozen SAN tissue blocks using a 16G biopsy needle. The purity of the SAN protein was confirmed by Connexin 43 immunoblot. All 3 HCN isoform proteins were detected in SAN. HCN1 was predominantly distributed in the human SAN with a 125.1±40.2 (n=12) expression ratio of SAN to right atrium. HCN2 and HCN4 expression levels were higher in SAN than in atria, with SAN to right atrium ratios of 6.1±0.9 and 4.6±0.6 (n=12), respectively.

CONCLUSIONS

This is the first study to conduct precise 3D molecular mapping of the human SAN by isolating pure pacemaker SAN tissue. All 3 cardiac HCN isoforms had higher expression in the SAN than in the atria. HCN1 was almost exclusively expressed in SAN, emphasizing its utility as a new specific molecular marker of the human SAN and as a potential target of specific treatments intended to modify sinus rhythm.

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.

Heart Rate, Life Expectancy and the Cardiovascular System: Therapeutic Considerations

It has long been known that life span is inversely related to resting heart rate in most organisms. This association between heart rate and survival has been attributed to the metabolic rate, which is greater in smaller animals and is directly associated with heart rate. Studies have shown that heart rate is related to survival in apparently healthy individuals and in patients with different underlying cardiovascular diseases. A decrease in heart rate due to therapeutic interventions may result in an increase in survival. However, there are many factors regulating heart rate, and it is quite plausible that these may independently affect life expectancy. Nonetheless, a fast heart rate itself affects the cardiovascular system in multiple ways (it increases ventricular work, myocardial oxygen consumption, endothelial stress, aortic/arterial stiffness, decreases myocardial oxygen supply, other) which, in turn, may affect survival. In this brief review, the effects of heart rate on the heart, arterial system and survival will be discussed.

Pleiotropic, heart rate-independent cardioprotection by ivabradine

BACKGROUND AND PURPOSE

In pigs, ivabradine reduces infarct size even when given only at reperfusion and in the absence of heart rate reduction. The mechanism of this non-heart rate-related cardioprotection is unknown. Hence, in the present study we assessed the pleiotropic action of ivabradine in more detail.

EXPERIMENTAL APPROACH

Anaesthetized mice were pretreated with ivabradine (1.7 mg · kg(-1) i.v.) or placebo (control) before a cycle of coronary occlusion/reperfusion (30/120 min ± left atrial pacing). Infarct size was determined. Isolated ventricular cardiomyocytes were exposed to simulated ischaemia/reperfusion (60/5 min) in the absence and presence of ivabradine, viability was then quantified and intra- and extracellular reactive oxygen species (ROS) formation was detected. Mitochondria were isolated from mouse hearts and exposed to simulated ischaemia/reperfusion (6/3 min) in glutamate/malate- and ADP-containing buffer in the absence and presence of ivabradine respectively. Mitochondrial respiration, extramitochondrial ROS, mitochondrial ATP production and calcium retention capacity (CRC) were assessed.

KEY RESULTS

Ivabradine decreased infarct size even with atrial pacing. Cardiomyocyte viability after simulated ischaemia/reperfusion was better preserved with ivabradine, the accumulation of intra- and extracellular ROS decreased in parallel. Mitochondrial complex I respiration was not different without/with ivabradine, but ivabradine significantly inhibited the accumulation of extramitochondrial ROS, increased mitochondrial ATP production and increased CRC.

CONCLUSION AND IMPLICATIONS

Ivabradine reduces infarct size independently of a reduction in heart rate and improves ventricular cardiomyocyte viability, possibly by reducing mitochondrial ROS formation, increasing ATP production and CRC.

Chronotropic Modulation of the Source-Sink Relationship of Sinoatrial-Atrial Impulse Conduction and Its Significance to Initiation of AF: A One-Dimensional Model Study

Initiation and maintenance of atrial fibrillation (AF) is often associated with pharmacologically or pathologically induced bradycardic states. Even drugs specifically developed in order to counteract cardiac arrhythmias often combine their action with bradycardia and, in turn, with development of AF, via still largely unknown mechanisms. This study aims to simulate action potential (AP) conduction between sinoatrial node (SAN) and atrial cells, either arranged in cell pairs or in a one-dimensional strand, where the relative amount of SAN membrane is made varying, in turn, with junctional resistance. The source-sink relationship between the two membrane types is studied in control conditions and under different simulated chronotropic interventions, in order to define a safety factor for pacemaker-to-atrial AP conduction (SASF) for each treatment. Whereas antiarrhythmic-like interventions which involve downregulation of calcium channels or of calcium handling decrease SASF, the simulation of Ivabradine administration does so to a lesser extent. Particularly interesting is the increase of SASF observed when downregulation G Kr, which simulates the administration of class III antiarrhythmic agents and is likely sustained by an increase in I CaL. Also, the increase in SASF is accompanied by a decreased conduction delay and a better entrainment of repolarization, which is significant to anti-AF strategies.

Heart rate and use of β-blockers in Mexican stable outpatients with coronary artery disease

OBJECTIVE

To evaluate the use of β-blockers and to monitor heart rate in Mexican patients with coronary artery disease.

METHODS

CLARIFY is an outpatients registry with stable CAD. A total of 33,283 patients from 45 countries were enrolled between November 2009 and July 2010 from which 1342 were Mexican patients.

RESULTS

The mean HR pulse was 70 bpm (beats per minute). Patients in Mexico were compared with the remaining global CLARIFY population. Patients in Mexico had a higher incidence of acute myocardial infarction and percutaneous coronary intervention, and lower incidence of revascularization surgery compared with the remaining CLARIFY population. More often, Mexican patients presented with diabetes, but less often hypertension and stroke. These patients were split into three mutually exclusive groups of HR ≤ 60 (N=263), HR 61-69 (N=356) and HR ≥ 70 (N=722). Patients with elevated HR had a higher incidence of diabetes and higher diastolic blood pressure on average than those with controlled HR. Regarding the use of β-blockers, they were used in 63.3% of patients, 2.7% showed intolerance or contraindication to treatment to monitor heart rate, and ivabradine was used in 2.3%. Out of approximately 849 patients receiving treatment of β-blockers, 52.1% had ≥ 70 bpm HR.

CONCLUSIONS

In a large proportion of Mexican patients with stable coronary disease the HR remain elevated, > 70 bpm, even with the use of β-blockers; this requires further attention.

HCN4, Sinus Bradycardia and Atrial Fibrillation

Based on their established role in the generation of spontaneous activity in pacemaker cells and control of cardiac rate, funny/ hyperpolarisation-activated, cyclic nucleotide gated 4 (HCN4) channels are natural candidates in the search for causes of sinus arrhythmias. Investigation of funny current-related inheritable arrhythmias has led to the identification of several mutations of the HCN4 gene associated with bradycardia and/or more complex arrhythmias. More recently, the search has been extended to include auxiliary proteins such as the minK-related peptide 1 (MiRP1) β-subunit. All mutations described so far are loss-of-function and in agreement with the role of funny channels, the predominant type of arrhythmia found is bradycardia. Funny channel-linked arrhythmias, however, also include atrioventricular (AV) block and atrial fibrillation, in agreement with an emerging new concept according to which defective funny channels have a still unexplored role in impairing AV conduction and triggering atrial fibrillation. Also, importantly, recent work shows that HCN4 mutations can be associated with cardiac structural abnormalities. In this short review I briefly address the current knowledge of funny/HCN4 channel mutations and associated sinus and more complex arrhythmias.

Resting heart rate: risk indicator and emerging risk factor in cardiovascular disease

Resting heart rate is central to cardiac output and is influenced by changes occurring in numerous diseases. It predicts longevity and cardiovascular diseases, and current evidence suggests that it is also an important marker of outcome in cardiovascular disease, including heart failure. Beta-blockers improve outcomes in heart failure; however, they have effects outside reducing heart rate. Ivabradine has demonstrated efficacy in reducing rehospitalizations and mortality in heart failure and in improving exercise tolerance and reducing angina attacks in patients with coronary artery disease, whereas selective heart rate reduction may also prove to be beneficial in therapeutic areas outside those in which ivabradine has already demonstrated clinical efficacy. This review provides an update on the associations between heart rate and cardiovascular outcomes in various conditions, the experimental effects of heart rate reduction with ivabradine, and the potential new indications in cardiovascular disease.