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.

Associations between resting heart rate and cognitive decline in Chinese oldest old individuals: a longitudinal cohort study

BACKGROUND

The trajectories of cognitive function in the oldest old individuals is unclear, and the relationship between resting heart rate (RHR) and cognitive decline is controversial.

METHODS

3300 participants who had cognitive function repeatedly measured 4 ~ 8 times were included, and latent class growth mixed models were used to identified the cognitive function trajectories. Cognitive decline was defined by the trajectory shapes, considering level and slope. After excluding individuals with sinus rhythm abnormal, 3109 subjects were remained and were divided into five groups by their RHR. Logistic regression models were used to estimate the relationship between RHR and cognitive decline.

RESULTS

Three distinct cognitive function trajectory groups were identified: high-stable (n = 1226), medium-decreasing (n = 1526), and rapid-decreasing (n = 357). Individuals of medium/rapid-decreasing group were defined as cognitive decline. Adjusting for covariates, the odds ratios (95% confidence intervals) of RHR sub-groups were 1.19 (0.69, 2.05), 1.27 (1.03, 1.56), 1.30 (1.01, 1.67) and 1.62 (1.07, 2.47) for those RHR < 60 bpm, 70 ~ 79 bpm, 80 ~ 89 bpm and > 90 bpm respectively, compared with those RHR 60 ~ 69 bpm. The interaction effect between RHR and physical activity (PA) on cognitive decline was found, and stratification analysis was presented that higher RHR would only show risk effects on cognitive decline in those with physical inactivity (P < 0.05 for all).

CONCLUSIONS

Our study demonstrates RHR more than 70 bpm present significant risk effect on cognitive decline, and this relationship is modified by PA. Elder population with physical inactivity and higher RHR should be paid more attention to prevent cognitive decline.

Construction of an immune-related signature for predicting the ischemic events in patients undergoing carotid endarterectomy

Background: Inflammatory responses have drawn more attention to atherosclerosis; however, the immune-related genes (IRGs) as a prognostic factor in atherosclerotic plaque remain to be fully elucidated. Here, the purpose of this study was to investigate whether the IRGs could be identified as a reliable biomarker for predicting ischemic events in patients undergoing carotid endarterectomy (CEA). Methods: Two datasets GSE97210 and GSE21545 were downloaded from the Gene Expression Omnibus (GEO) database. The dataset GSE97210 was used to explore the significant pathways and differentially expressed IRGs (DEIRGs) between plaques and controls, which were further screened to identify the prognostic DEIRGs in the GSE21545 dataset. The identification of molecular subgroups with the prognostic gene expression patterns was achieved through nonnegative matrix factorization (NMF) clustering. Functional analyses including GO, KEGG, GSVA, and GSEA analyses, and immune analyses including xCell and ssGSEA algorithms were conducted to elucidate the underlying mechanisms. The prognostic risk model was constructed using the LASSO algorithm and multivariate Cox regression analysis. Results: A total of 796 DEIRGs (including 588 upregulated and 208 downregulated) were identified. Nine prognostic DEIRGs were further screened with univariate Cox regression analysis. Two clusters with different prognosis were grouped based on the prognostic DEIRGs. Immune infiltration analysis shows that cluster 2 with a better prognosis presented with a higher immune response than cluster 1. A prognostic model based on seven IRGs (IL2RA, NR4A2, DES, ERAP2, SLPI, RASGRP1, and AGTR2) was developed and verified. Consistent with the immune analysis of the cluster, the immune infiltration in the low-risk group with a better prognosis was also more active than that in the high-risk group. Finally, a nomogram based on the seven genes was constructed, which might have future implications in clinical care. Conclusion: The expression of immune-related genes is correlated with the immune microenvironment of atherosclerotic patients and could be applied to predict the ischemic events in patients undergoing CEA accurately.

Ivabradine in the management of COVID-19-related cardiovascular complications: A perspective

Abstract:

Besides acute respiratory distress syndrome, acute cardiac injury is a major complication in severe coronavirus disease 2019 (COVID-19) and associates with a poor clinical outcome. Acute cardiac injury with COVID-19 can be of various etiologies, including myocardial ischemia or infarction and myocarditis, and may compromise cardiac function, resulting in acute heart failure or cardiogenic shock. Systemic inflammatory response increases heart rate (HR), which disrupts the myocardial oxygen supply/demand balance and worsens cardiac energy efficiency, thus further deteriorating the cardiac performance of the injured myocardium. In fact, the combination of elevated resting HR and markers of inflammation synergistically predicts adverse cardiovascular prognosis. Thus, targeted HR reduction may potentially be of benefit in cardiovascular pathologies associated with COVID-19. Ivabradine is a drug that selectively reduces HR via If current inhibition in the sinoatrial node without a negative effect on inotropy. Besides selective HR reduction, ivabradine was found to exert various beneficial pleiotropic effects, either HR-dependent or HR-independent, including anti-inflammatory, anti-atherosclerotic, anti-oxidant and antiproliferative actions and the attenuation of endothelial dysfunction and neurohumoral activation. Cardioprotection by ivabradine has already been indicated in cardiovascular pathologies that are prevalent with COVID-19, including myocarditis, acute coronary syndrome, cardiogenic shock or cardiac dysautonomia. Here, we suggest that ivabradine may be beneficial in the management of COVID-19-related cardiovascular complications.

With a Little Help From My Friends: the Role of the Renal Collateral Circulation in Atherosclerotic Renovascular Disease

The collateral circulation can adapt to bypass major arteries with limited flow and serves a crucial protective role in coronary, cerebral, and peripheral arterial disease. Emerging evidence indicates that the renal collateral circulation can similarly adapt and thereby limit kidney ischemia in atherosclerotic renovascular disease. These adaptations predominantly include recruitment of preexisting microvessels for arteriogenesis, with de novo vessel formation playing a limited role. Yet, adaptations of the renal collateral circulation in renovascular disease are often insufficient to fully compensate for the limited flow within an obstructed renal artery and may be hampered by the severity of obstruction or patient comorbidities. Experimental strategies have attempted to circumvent limitations of collateral formation and improve the prognosis of patients with various ischemic vascular territories. These have included pharmacological approaches such as endothelial growth factors, renin-angiotensin-aldosterone system blockade, and If-channel-blockers, as well as interventions like preconditioning, exercise, enhanced external counter-pulsation, and low-energy shock-wave therapy. However, few of these strategies have been implemented in atherosclerotic renovascular disease. This review summarizes current understanding regarding the development of renal collateral circulation in atherosclerotic renovascular disease. Studies are needed to apply lessons learned in other vascular beds in the setting of atherosclerotic renovascular disease to develop new treatment regimens for this patient group.

Pleiotropic vascular effects of ivabradine in streptozotocin-induced diabetes

AIMS

Ivabradine (IVA) reduces heart rate (HR) by inhibiting hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in sinoatrial node. Studies suggest that IVA has other beneficial effects on cardiovascular system that are not related to its effect on HR such as prevention of endothelial injury and the antioxidant effects. In addition to sinoatrial node, HCN channels exist in other tissues and their expression pattern differs in certain pathologies such as hypertension and hypertrophy. We investigated the mechanism of IVA effect in the setting of streptozotocin (STZ)-induced cardiovascular damage. Direct effects of IVA and their mechanism on thoracic aorta as well as possible prevention of vascular dysfunction in diabetes were investigated in this study.

METHODS AND RESULTS

The effects of IVA on vascular function were investigated in control and STZ-diabetic rats. Some control and diabetic rats were treated with IVA. IVA treatment prevented diabetes-induced increase in plasma p-selectin and vascular cell adhesion molecule-1 levels and the decrease in nitric oxide content in the aortas of diabetic animals. When added to isolated organ bath, IVA induced concentration-dependent relaxations in thoracic aorta. Pre-incubation with Nω-Nitro- L -arginine methyl ester reduced IVA-induced relaxations. Expression patterns of all isoforms of HCN proteins were affected by both diabetes and IVA treatment.

CONCLUSION

IVA improves vascular function in diabetes and HCN channels support vascular activity against damaging effects of diabetes. IVA may be added to prevent diabetic cardiovascular dysfunction with these beneficial effects that are unrelated to its primary mechanism of action.

Effect of Heart Rate on the Outcome of Renal Denervation in Patients With Uncontrolled Hypertension

BACKGROUND

Sham-controlled trials demonstrated safety and efficacy of renal denervation (RDN) to lower blood pressure (BP). Association of baseline heart rate with BP reduction after RDN is incompletely understood.

OBJECTIVES

The purpose of this analysis was to evaluate the impact of baseline heart rate on BP reduction without antihypertensive medications in the SPYRAL HTN-OFF MED (Global Clinical Study of Renal Denervation With the Symplicity Spyral Multi-electrode Renal Denervation System in Patients With Uncontrolled Hypertension in the Absence of Antihypertensive Medications) Pivotal trial.

METHODS

Patients removed from any antihypertensive medications were enrolled with office systolic blood pressure (SBP) ≥150 and <180 mm Hg and randomized 1:1 to RDN or sham control. Patients were separated according to baseline office heart rate <70 or ≥70 beats/min. BP changes from baseline to 3 months between treatment arms were adjusted for baseline SBP using analysis of covariance.

RESULTS

Scatter plots of 3-month changes in 24-hour and office SBP illustrate a wide range of changes in SBP for different baseline heart rates. Treatment difference at 3 months between RDN and sham control with baseline office heart rate ≥70 beats/min for 24-hour SBP was -6.2 mm Hg (95% CI: -9.0 to -3.5 mm Hg) (P < 0.001) and for baseline office heart rate <70 beats/min it was -0.1 mm Hg (-3.8 to 3.6 mm Hg) (P = 0.97) with an interaction P value of 0.008. Results were similar for changes in office, daytime, and nighttime SBP at 3 months, with a greater reduction in SBP with baseline office heart rate ≥70 beats/min.

CONCLUSIONS

Reduction in mean office, 24-hour, daytime, and nighttime SBP for RDN at 3 months was greater with baseline office heart rate ≥70 than <70 beats/min, suggesting an association between baseline heart rate and BP reduction after RDN. (SPYRAL PIVOTAL-SPYRAL HTN-OFF MED Study; NCT02439749).

Resting heart rate and cardiovascular outcomes in diabetic and non-diabetic individuals at high cardiovascular risk analysis from the ONTARGET/TRANSCEND trials

AIMS

Resting heart rate (RHR) has been shown to be associated with cardiovascular outcomes in various conditions. It is unknown whether different levels of RHR and different associations with cardiovascular outcomes occur in patients with or without diabetes, because the impact of autonomic neuropathy on vascular vulnerability might be stronger in diabetes.

METHODS AND RESULTS

We examined 30 937 patients aged 55 years or older with a history of or at high risk for cardiovascular disease and after myocardial infarction, stroke, or with proven peripheral vascular disease from the ONTARGET and TRANSCEND trials investigating ramipril, telmisartan, and their combination followed for a median of 56 months. We analysed the association of mean achieved RHR on-treatment with the primary composite outcome of cardiovascular death, myocardial infarction, stroke, hospitalization for heart failure, the components of the composite primary outcome, and all-cause death as continuous and categorical variables. Data were analysed by Cox regression analysis, ANOVA, and χ2 test. These trials were registered with ClinicalTrials.gov.number NCT00153101. Patients were recruited from 733 centres in 40 countries between 1 December 2001 and 31 July 2008 (ONTARGET) and 1 November 2001 until 30 May 2004 (TRANSCEND). In total, 19 450 patients without diabetes and 11 487 patients with diabetes were stratified by mean RHR. Patients with diabetes compared to no diabetes had higher RHRs (71.8 ± 9.0 vs. 67.9 ± 8.8, P < 0.0001). In the categories of <60 bpm, 60 ≤ 65 bpm, 65 ≤ 70 bpm, 70 ≤ 75 bpm, 75 ≤ 80 bpm and ≥80 bpm, non-diabetic patients had an increased hazard of the primary outcome with mean RHR of 75 ≤ 80 bpm (adjusted hazard ratio [HR] 1.17 (1.01-1.36)) compared to RHR 60 ≤ 65 bpm. For patients with in-trial RHR ≥80 bpm the hazard ratios were highest (diabetes: 1.96 (1.64-2.34), no diabetes: 1.73 (1.49-2.00), For cardiovascular death hazards were also clearly increased at RHR ≥80 bpm (diabetes [1.99, (1.53-2.58)], no diabetes [1.73 (1.38-2.16)]. Similar results were obtained for hospitalization for heart failure and all-cause death while the effect of RHR on myocardial infarction and stroke was less pronounced. Results were robust after adjusting for various risk indicators including beta-blocker use and atrial fibrillation. No significant association to harm was observed at lower RHR.

CONCLUSION

Mean RHR above 75-80 b.p.m. was associated with increased risk for cardiovascular outcomes except for stroke. Since in diabetes, high RHR is associated with higher absolute event numbers and patients have higher RHRs, this association might be of particular clinical importance in diabetes. These data suggest that RHR lowering in patients with RHRs above 75-80 b.p.m. needs to be studied in prospective trials to determine if it will reduce outcomes in diabetic and non-diabetic patients at high cardiovascular risk.

CLINICAL TRIAL REGISTRATION

http://clinicaltrials.gov.Unique identifier: NCT00153101.

Ivabradine, the hyperpolarization-activated cyclic nucleotide-gated channel blocker, elicits relaxation of the human corpus cavernosum: a potential option for erectile dysfunction treatment

OBJECTIVE

To evaluate the effect of the I_f channel inhibitor, ivabradine on human corpus cavernosum (HCC) smooth muscle tone.

METHODS

HCC samples were obtained from erectile dysfunction(ED) patients (n = 12) undergoing penile prosthesis surgery. Concentration-response curves for ivabradine were exposed to various inhibitory and stimulatory agents. The relaxant and contractile responses to electrical field stimulation (EFS, 10 Hz and 80 Hz) were examined in the presence or absence of ivabradine (10 μM). HCN3 and HCN4 channel expression and localization were determined by Western blot and immunohistochemical analyses of HCC tissues.

RESULTS

Increasing ivabradine concentrations dependently reduced the maximal contractile responses of isolated HCC strips induced by KCl (59.5 ± 2.5%) and phenylephrine (84.0 ± 9.8%), which was not affected by nitric oxide synthase and soluble guanylyl cyclase inhibitors after phenylephrine-induced contraction. Nifedipine and tetraethylammonium inhibited the maximum relaxation to ivabradine by 75% and 39.3%, respectively. Fasudil and sildenafil increased the relaxation response to ivabradine without altering the maximum response. Pre-incubation with ivabradine significantly increased relaxant responses to EFS (p < 0.01) and reduced the contractile tension evoked by EFS (72.3%) (p < 0.001). Ivabradine incubation did not affect the expression and localization of HCN3 and HCN4 channels in the HCC smooth muscle cells.

CONCLUSIONS

Ivabradine exhibits a relaxant effect on HCC tissues, which is likely to be attributed to the blocking of L-type Ca²⁺ channels and the opening of K⁺ channels, independent of changes in the activation of the nitric oxide/cyclic guanosine monophosphate system. Inhibition of HCN channels localized in cavernosal smooth muscle cells may offer pharmacological benefits for patients with cardiovascular risk factors.

Effects of heart rate reduction with ivabradine on vascular stiffness and endothelial function in chronic stable coronary artery disease

INTRODUCTION

Epidemiological and clinical studies have shown a relevant association between heart rate and cardiovascular mortality. Experimental studies identified vascular effects of heart rate reduction with the If channel inhibitor ivabradine. Therefore, the effects of heart rate reduction on endothelial function and indices of arterial stiffness were examined in patients with stable coronary artery disease in a prospective, placebo-controlled clinical crossover study.

METHODS AND RESULTS

Twenty-three patients (18 men and 5 women) with a resting heart rate (HR) of at least 70 beats per minute (bpm) and stable coronary artery disease were enrolled in this study. In a cross-over design, all patients were treated with ivabradine (Iva, 7.5 mg b.i.d.) and placebo for 6 months each. Iva reduced heart rate by 11.4 bpm (Iva 58.8 ± 8.2 bpm vs. placebo 70.2 ± 8.3 bpm, P < 0.0001). Augmentation index (AIx75), carotid-femoral pulse wave velocity (cfPWV) and central aortic blood pressure were measured using applanation tonometry (SphygmoCor). HRR by Iva increased AIx75 by 12.4% (Iva 24.3 ± 10.5% vs. placebo 21.3 ± 10.1%, P < 0.05) and reduced cfPWV by 14.1% (Iva 6.3 ± 1.7 m/s vs. placebo 7.3 ± 1.4 m/s, P < 0.01). Iva increased mean central blood pressure by 7.8% (Iva 107.5 ± 15.4 mmHg vs. placebo 99.1 ± 12.2 mmHg, P < 0.001). Endothelial function was determined measuring the flow-mediated vasodilation (FMD) of the brachial artery. HRR by Iva increased FMD by 18.5% (Iva 7.3 ± 2.2% vs. placebo 6.0 ± 2.0%, P < 0.001). Aortic distensibility was characterized by MRI. HRR by Iva increased aortic distensibility by 33.3% (Iva 0.003 ± 0.001/mmHg vs. placebo 0.002 ± 0.010/mmHg, P < 0.01) and circumferential cyclic strain by 37.1% (Iva 0.062 ± 0.027 vs. placebo 0.039 ± 0.018, P < 0.0001).

CONCLUSION

Heart rate reduction with Iva increased endothelium-dependent vasodilation and reduced arterial stiffness in patients with stable CAD. These findings corroborate and expand the results collected in experimental studies and indicate the importance of heart rate as a determinant of vascular function.

Effects of edoxaban and warfarin on vascular remodeling: Atherosclerotic plaque progression and collateral artery growth

BACKGROUND AND PURPOSE

Oral anticoagulation prevents thromboembolism in atrial fibrillation. Factor Xa inhibitors, like edoxaban, are known to reduce inflammation and proliferation of smooth muscle cells, while vitamin K antagonism can cause vascular calcific damage. The influence of edoxaban compared to warfarin on vascular remodeling, atherosclerosis and arteriogenesis is unknown.

EXPERIMENTAL APPROACH

Apolipoprotein E knockout (ApoE ^-/-) mice were fed cholesterol-rich diet alone (control, co), with warfarin+vitamin K1 (warf) or with edoxaban (Edo) for 8 weeks. After 6 weeks, femoral artery ligation was performed.

KEY RESULTS

There was no difference in hind-limb perfusion restoration between the three groups after 14 days (Co 0.36 ± 0.05 vs. Warf 0.39 ± 0.09 (p = .39), Co vs. Edo 0.51 ± 0.06 (p = .089), Warf vs. Edo (p = .83)) after ligation. Immuno-histologically, there was no difference in smooth muscle cell count in both hindlimbs between the three groups or in the amount of perivascular macrophages in collateral-bearing hindlimb tissue. Edoxaban showed the lowest amount of plaque tissue in the aortic sinus tissue (Co 74 ± 11% vs. Edo 62 ± 12% (p = .024), Co vs. Warf 69 ± 14% (p = .30), Edo vs. Warf (p = .14)) as well as the least amount of fibrosis (Co 3.1 ± 0.9% vs. Edo 1.7 ± 0.6% (p = .027), Co vs. Warf 4.1 ± 0.7% (p = .081), Edo vs. Warf (p < .001)). No difference in mRNA content of inflammatory cytokines in muscle tissue or spleen was detected between the three groups.

CONCLUSION AND IMPLICATIONS

These data suggest that treatment with edoxaban unlike warfarin prevents vascular maladaptive remodeling, which may be clinically important.

[The Use of Selective Inhibitor of If-Channels Ivabradine in Patients with Ischemic Heart Disease, Heart Failure with High Heart Rate]

Ischemic heart disease (IHD) and chronic heart failure (CHF) belong to leading causes of death among patients with cardiovascular diseases (CVD). Modern medical approaches to the treatment of patients with CHF do not always provide a significant improvement in the quality of life, a decrease in the frequency of CHF exacerbations and hospitalizations, and an improvement of the long-term prognosis. According to the neurohumoral theory of IHD and CHF development, the blockade of the sympathoadrenal system with β-adrenoblockers (β-AB) is pathogenetically substantiated, and preparations of this group are recommended as one of the main classes of drugs for the treatment of patients with CHF. However, selection of heart rhythm slowing therapy in patients with CHF of ischemic genesis is often difficult due to the development of undesirable side effects of β-AB, intolerance and/or due to the presence of contraindications for their use. Randomized studies have shown that prescribing a combination of β-AB and If-channel blocker ivabradine for heart rate (HR) reduction or solely ivabradine when use of β-AB is impossible in complex CHF therapy, improves the left ventricle (LV) diastolic function, reducing mortality from CHF decompensation. However, the prognostic significance of the use of ivabradine in patients with CHF with preserved left ventricular ejection fraction of ischemic genesis with heart rate higher than 70 beats/min receiving maximum tolerated doses of β-AB remains not fully investigated.

Exercise Training as a Mediator for Enhancing Coronary Collateral Circulation: A Review of the Evidence

Coronary collateral vessels supply blood to areas of myocardium at risk after arterial occlusion. Flow through these channels is driven by a pressure gradient between the donor and the occluded artery. Concomitant with increased collateral flow is an increase in shear force, a potent stimulus for collateral development (arteriogenesis). Arteriogenesis is self-limiting, often ceasing prematurely when the pressure gradient is reduced by the expanding lumen of the collateral vessel. After the collateral has reached its self-limited maximal conductance, the only way to drive further increases is to re-establish the pressure gradient.

During exercise, the myocardial oxygen demand is increased, subsequently increasing coronary flow. Therefore, exercise may represent a means of driving augmented arteriogenesis in patients with stable coronary artery disease. Studies investigating the ability of exercise to drive collateral development in humans are inconsistent. However, these inconsistencies may be due to the heterogeneity of assessment methods used to quantify change. This article summarises current evidence pertaining to the role of exercise in the development of coronary collaterals, highlighting areas of future research.

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

BACKGROUND

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

PURPOSE

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Cardiovascular drugs attenuated myocardial resistance against ischaemia-induced and reperfusion-induced injury in a rat model of repetitive occlusion

Objective

We investigated the impact of cardioprotective drugs on ST-elevation, arrhythmias and infarct size in a rat model of repetitive coronary artery occlusion.

Methods

Seventy Sprague-Dawley rats were randomised to two control and five treatment groups. Placebo was either implantation of a pneumatic occluder onto the left anterior descending coronary artery (LAD) without starting repetitive occlusion (SHAM) or subsequent RO of the LAD over 10 days without medication (ROP). Treatment groups underwent RO and additionally received nitroglycerin (NTG), metoprolol, verapamil (VER), ranolazine (RAN) or candesartan (CAN). Two weeks after the intervention, rats underwent a single, sustained LAD occlusion followed by reperfusion. To evaluate differences in cardiac resistance against myocardial ischaemia and reperfusion injury, cardiac surrogate parameters including maximal ST-elevation, arrhythmias and infarct size were assessed.

Results

Compared with sham, RO alone and RO plus nitroglycerin were associated with significantly lower maximal ST-elevation and percentage of infarcted myocardium (SHAM 0.12 mV, ROP 0.06 mV (p=0.004), NTG 0.05 mV (p=0.005); SHAM 16.2%, ROP 6.6% (p=0.008), NTG 5.9% (p=0.006). Compared with RO alone, RO plus RAN was accompanied by increased ST-elevation (0.13 mV, p=0.018) and RO plusVER or CAN by more infarcted myocardium (14.2%, p=0.004% and 15.5%, p=0.003, respectively). Rats treated with VER, RAN or CAN tended to severe arrhythmias more frequently than those of the control groups.

Conclusions

RO led to an increased myocardial resistance against ischaemia and reperfusion injury. Concomitant administration of nitroglycerin did not affect the efficacy of RO. Cardiovascular channel or receptor blockers reduced the efficacy of RO.

ABILITY TO PREVENT AND TREAT THE CARDIOVASCULAR SYSTEM DAMAGES, CAUSED BY THE USE OF ANTI-CANCER DRUGS

This review presents modern strategies for the prevention and treatment of cardiotoxicity induced by the most commonly used anticancer drugs such as anthracycline antibiotics, monoclonal antibodies, tyrosine kinase inhibitors. There are a large number of conflicting data on ways to overcome the cardiotoxicity of anticancer drugs. The creation of a complex of diagnostic measures will allow to identify the earliest signs of heart damage during chemotherapy and to develop timely preventive measures to prevent cardiotoxicity, improve the quality of life and prognosis of patients. Currently, a large number of small publications on the prevalence, prediction and prevention of cardiotoxicity in cancer patients, including the primary and secondary prevention of cardiotoxicity, are available. Beta-blockers and inhibitors of angiotensin-converting enzyme most often use as cardioprotective agents. There is evidence of poor tolerability of treatment with these drugs for young patients. Most drugs reduce blood pressure, which can adversely affect the health of patients without associated hypertension. Coordinated work between cardiologists and oncologists is needed to create common terminology, to define cardiovascular events and create registers, meta-analyzes, generally accepted recommendations, guidelines for the management of patients at risk of developing cardiotoxicity. This review used published articles the Scopus, Pubmed database, articles from The New England Journal of Medicine, Annals of Oncology, and periodicals of the Russian Federation over the past 10 years, as well as publications from previous years.

ROS and NO Dynamics in Endothelial Cells Exposed to Exercise-Induced Wall Shear Stress

Introduction

Intracellular reactive oxygen species (ROS) and nitric oxide (NO) levels are associated with vascular homeostasis and diseases. Exercise can modulate ROS and NO production through increasing frequency and magnitude of wall shear stress (WSS). However, the details of ROS and NO production in endothelial cells and their interplay under WSS induced by exercise at different intensities remain unclear.

Methods

In this study, we developed an in vitro multicomponent nonrectangular flow chamber system to simulate pulsatile WSS waveforms induced by moderate and high intensity exercise. Furthermore, the dynamic responses of ROS and NO in endothelial cells and the relationship between ROS and NO were investigated under the WSS induced by different intensity exercise.

Results

After exposing to WSS induced by moderate intensity exercise, endothelial cells produced more NO than those under high intensity exercise-induced WSS. In this process, ROS was found to play a dual role in the generation of intracellular NO. Under WSS induced by moderate intensity exercise, modest elevated ROS promoted NO production, whereas excessive ROS in endothelial cells exposed to WSS induced by high intensity exercise attenuated NO bioavailability. Interestingly, antioxidant N-acetylcysteine (NAC) could increase NO production under WSS induced by high intensity exercise.

Conclusions

Our results provide some cues for selecting appropriate exercise intensities and elevating benefits of exercise on endothelial function. Additionally, owing to the consistency of our results and some in vivo phenomena, this flow chamber system may serve as an in vitro exercise model of arterial vessel for future studies.

The effect of the heart rate lowering drug Ivabradine on hemodynamics in atherosclerotic mice

The heart rate lowering drug Ivabradine was shown to improve cardiac outcome in patients with previous heart failure. However, in patients without heart failure, no beneficial effect of Ivabradine was observed. Animal studies suggested a preventive effect of Ivabradine on atherosclerosis which was due to an increase in wall shear stress (WSS), the blood flow-induced frictional force exerted on the endothelium, triggering anti-inflammatory responses. However, data on the effect of Ivabradine on WSS is sparse. We aim to study the effect of Ivabradine on (i) the 3D WSS distribution over a growing plaque and (ii) plaque composition. We induced atherosclerosis in ApoE-/- mice by placing a tapered cast around the right common carotid artery (RCCA). Five weeks after cast placement, Ivabradine was administered via drinking water (15 mg/kg/day) for 2 weeks, after which the RCCA was excised for histology analyses. Before and after Ivabradine treatment, animals were imaged with Doppler Ultrasound to measure blood velocity. Vessel geometry was obtained using contrast-enhanced micro-CT. Time-averaged WSS during systole, diastole and peak WSS was subsequently computed. Ivabradine significantly decreased heart rate (459 ± 28 bpm vs. 567 ± 32 bpm, p < 0.001). Normalized peak flow significantly increased in the Ivabradine group (124.2% ± 40.5% vs. 87.3% ± 25.4%, p < 0.05), reflected by an increased normalized WSS level during systole (110.7% ± 18.4% vs. 75.4% ± 24.6%, p < 0.05). However, plaque size or composition including plaque area, relative necrotic core area and macrophage content were not altered in mice treated with Ivabradine compared to controls. We conclude that increased WSS in response to Ivabradine treatment did not affect plaque progression in a murine model.

Reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion

BACKGROUND

The extent of coronary collateral formation is a primary determinant of the severity of myocardial damage and mortality after coronary artery occlusion. Type 2 diabetes mellitus (T2DM) represents an important risk factor for impaired collateral vessel growth. However, the mechanism of reduced coronary collateralization in type 2 diabetic patients remains unclear.

METHODS

With the reference to the recent researches, this review article describes the pathogenic effects of T2DM on collateral development and outlines possible clinical and biochemical markers associated with reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion (CTO).

RESULTS

Diffuse coronary atherosclerosis in T2DM reduces pressure gradient between collateral donor artery and collateral recipient one, limiting collateral vessel growth and function. An interaction between advanced glycation end-products and their receptor activates several intracellular signaling pathways, enhances oxidative stress and aggravates inflammatory process. Diabetic condition decreases pro-angiogenic factors especially vascular endothelial growth factor and other collateral vessel growth related parameters. Numerous clinical and biochemical factors that could possibly attenuate the development of coronary collaterals have been reported. Increased serum levels of glycated albumin, cystatin C, and adipokine C1q tumor necrosis factor related protein 1 were associated with poor coronary collateralization in type 2 diabetic patients with stable coronary artery disease and CTO. Diastolic blood pressure and stenosis severity of the predominant collateral donor artery also play a role in coronary collateral formation.

CONCLUSIONS

T2DM impairs collateral vessel growth through multiple mechanisms involving arteriogenesis and angiogenesis, and coronary collateral formation in patients with T2DM and CTO is influenced by various clinical, biochemical and angiographic factors. This information provides insights into the understanding of coronary pathophysiology and searching for potential new therapeutic targets in T2DM.

The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels

Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets.

Low shear stress induces endothelial reactive oxygen species via the AT1R/eNOS/NO pathway

Reactive oxygen species (ROS) contribute to many aspects of physiological and pathological cardiovascular processes. However, the underlying mechanism of ROS induction by low shear stress (LSS) remains unclear. Accumulating evidence has shown that the angiotensin II type 1 receptor (AT1R) is involved in inflammation, apoptosis, and ROS production. Our aim was to explore the role of AT1R in LSS-mediated ROS induction. We exposed human umbilical vein endothelial cells (HUVECs) to LSS (3 dyn/cm² ) for different periods of time. Western blotting and immunofluorescence showed that LSS significantly induced AT1R expression in a time-dependent manner. Using immunohistochemistry, we also noted a similar increase in AT1R expression in the inner curvature of the aortic arch compared to the descending aorta in C57BL/6 mice. Additionally, HUVECs were cultured with a fluorescent probe, either DCFH, DHE or DAF, after being subjected to LSS. Cell chemiluminescence and flow cytometry results revealed that LSS stimulated ROS levels and suppressed nitric oxide (NO) generation in a time-dependent manner, which was reversed by the AT1R antagonist Losartan. We also found that Losartan markedly increased endothelial NO synthase (eNOS) phosphorylation at Ser(633,1177) and dephosphorylation at Thr(495), which involved AKT and ERK. Moreover, the ROS level was significantly reduced by endogenous and exogenous NO donors (L-arginine, SNP) and increased by the eNOS inhibitor L-NAME. Overall, we conclude that LSS induces ROS via AT1R/eNOS/NO.

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.

Different transcriptional profiling between senescent and non-senescent human coronary artery endothelial cells (HCAECs) by Omeprazole and Lansoprazole treatment

Recent evidence suggests that high dose and/or long term use of proton pump inhibitors (PPIs) may increase the risk of adverse cardiovascular events in older patients, but mechanisms underlying these detrimental effects are not known. Taking into account that the senescent endothelial cells have been implicated in the genesis or promotion of age-related cardiovascular disease, we hypothesized an active role of PPIs in senescent cells. The aim of this study is to investigate the changes in gene expression occurring in senescent and non-senescent human coronary artery endothelial cells (HCAECs) following Omeprazole (OPZ) or Lansoprazole (LPZ) treatment. Here, we show that atherogenic response is among the most regulated processes in PPI-treated HCAECs. PPIs induced down-regulation of anti-atherogenic chemokines (CXCL11, CXCL12 and CX3CL1) in senescent but not in non-senescent cells, while the same chemokines were up-regulated in untreated senescent cells. These findings support the hypothesis that up-regulated anti-atherogenic chemokines may represent a defensive mechanism against atherosclerosis during cellular senescence, and suggest that PPIs could activate pro-atherogenic pathways by changing the secretory phenotype of senescent HCAECs. Moreover, the genes coding for fatty acid binding protein 4 (FABP4) and piezo-type mechanosensitive ion channel component 2 (PIEZO2) were modulated by PPIs treatment with respect to untreated cells. In conclusions, our results show that long-term and high dose use of PPI could change the secretory phenotype of senescent cells, suggesting one of the potential mechanisms by which use of PPI can increase adverse outcomes in older subjects.

Heart Rate reduction by IVabradine for improvement of ENDothELial function in patients with coronary artery disease: the RIVENDEL study

AIMS

Data from experimental studies suggest that the _f current-inhibitor ivabradine may reduce oxidative stress and improve endothelial function. We aimed to evaluate the effect of ivabradine on endothelial function in patients with coronary artery disease (CAD) after complete revascularization with percutaneous coronary angioplasty (PCI).

METHODS AND RESULTS

At least 30 days after PCI, 70 patients were randomized (T0) to receive ivabradine 5 mg twice daily (ivabradine group, n = 36) or to continue with standard medical therapy (control group, n = 34). After 4 weeks (T1), ivabradine dose was adjusted up to 7.5 mg twice daily in patients with heart rate (HR) at rest >60 bpm, and thereafter continued for additional 4 weeks (T2). At all timings, brachial artery reactivity was assessed by flow-mediated dilatation (FMD) and nitroglycerin-mediated dilatation (NMD). No significant differences were observed at T0 between ivabradine and control groups in terms of HR (68.0 ± 6.4 vs. 67.6 ± 6.4 bpm; p = 0.803), FMD (8.7 ± 4.9 vs. 8.0 ± 5.5 %; p = 0.577) and NMD (12.7 ± 6.7 vs. 13.3 ± 6.2 %; p = 0.715). Over the study period, a significant reduction of HR (65.2 ± 5.9 bpm at T1, 62.2 ± 5.7 bpm at T2; p < 0.001), and improvement of FMD (12.2 ± 6.2 % at T1, 15.0 ± 7.7 % at T2; p < 0.001) and NMD (16.6 ± 10.4 % at T1, 17.7 ± 10.8 at T2; p < 0.001) were observed in the ivabradine group, while no significant changes were observed in the control group. In the ivabradine group, a moderate negative correlation was observed between the HR variation and FMD variation from T1 to T3 (r = -0.448; p = 0.006).

CONCLUSIONS

In patients with CAD undergoing complete revascularization with PCI, addition of ivabradine to the standard medical therapy produces a significant improvement in endothelial function. This effect seems to be related to HR reduction. ClinicalTrials.gov number, NCT02681978.

Ivabradine and metoprolol differentially affect cardiac glucose metabolism despite similar heart rate reduction in a mouse model of dyslipidemia

While heart rate reduction (HRR) is a target for the management of patients with heart disease, contradictory results were reported using ivabradine, which selectively inhibits the pacemaker I_f current, vs. β-blockers like metoprolol. This study aimed at testing whether similar HRR with ivabradine vs. metoprolol differentially modulates cardiac energy substrate metabolism, a factor determinant for cardiac function, in a mouse model of dyslipidemia (hApoB^+/+;LDLR^-/-). Following a longitudinal study design, we used 3- and 6-mo-old mice, untreated or treated for 3 mo with ivabradine or metoprolol. Cardiac function was evaluated in vivo and ex vivo in working hearts perfused with ¹³C-labeled substrates to assess substrate fluxes through energy metabolic pathways. Compared with 3-mo-old, 6-mo-old dyslipidemic mice had similar cardiac hemodynamics in vivo but impaired (P < 0.001) contractile function (aortic flow: -45%; cardiac output: -34%; stroke volume: -35%) and glycolysis (-24%) ex vivo. Despite inducing a similar 10% HRR, ivabradine-treated hearts displayed significantly higher stroke volume values and glycolysis vs. their metoprolol-treated counterparts ex vivo, values for the ivabradine group being often not significantly different from 3-mo-old mice. Further analyses highlighted additional significant cardiac alterations with disease progression, namely in the total tissue level of proteins modified by O-linked N-acetylglucosamine (O-GlcNAc), whose formation is governed by glucose metabolism via the hexosamine biosynthetic pathway, which showed a similar pattern with ivabradine vs. metoprolol treatment. Collectively, our results emphasize the implication of alterations in cardiac glucose metabolism and signaling linked to disease progression in our mouse model. Despite similar HRR, ivabradine, but not metoprolol, preserved cardiac function and glucose metabolism during disease progression.

Improvement of endothelial function in a murine model of mild cholesterol-induced atherosclerosis by mineralocorticoid antagonism

BACKGROUND AND AIMS

The renin-angiotensin-aldosterone-system (RAAS) plays a role in endothelial dysfunction and atherosclerosis. During treatment with RAAS-inhibitors, elevated aldosterone may sustain "aldosterone escape".

METHODS

We investigated the effects of treatment with the mineralocorticoid antagonist eplerenone (Ep) compared with ramipril (Rami) or the combination of both on oxidative stress, plaque formation and endothelial function, in atherosclerotic apolipoprotein E deficient mice (ApoE(-/-)-mice). ApoE(-/-)-mice were fed a cholesterol rich diet (21% fat, 19.5% casein, 1.25% cholesterol) for 8 weeks to produce mild atherosclerosis (i.e. plaque load 20-30%). ApoE(-/-)-mice (control), ApoE(-/-)-mice treated with Ep (25 mg/kg/day), Rami (2.5 mg/kg/day) and their combination were compared. Heart rate (HR) and blood pressure (BP) were measured using the tail-cuff-method. Endothelial function was measured in aortic rings and corpora cavernosal strips (CCs). Atherosclerotic plaque burden, collagen content, oxidative stress (Dihydroethidium (DHE) staining) and macrophages were determined.

RESULTS

Treatments had no effects on HR and slightly reduced BP in ApoE(-/-)-mice treated with the combination of eplerenone and ramipril. Endothelium-dependent relaxation of aortic rings and CCs with carbachol was significantly improved in animals treated with Ep, Rami or their combination (p = 0.05 - p = 0.001). DHE-stained penile and aortic sections revealed a significant reduction in superoxide production in all treated groups (p = 0.035 - p = 0.001). In parallel, aortic and penile collagen content in ApoE(-/-)-mice was significantly decreased (p = 0.035 - p < 0.001) in animals treated with Ep, Rami or their combination. In agreement, there was a trend towards a reduction of aortic plaque area by treatment with Ep (-9.0 ± 3.2%) and Rami (-11.9 ± 4%). Only the treatment with the combination induced a significant reduction of the atherosclerotic plaque burden (p = 0.045). Moreover, the treatment of ApoE(-/-)-mice with Ep, Rami and their combination significantly reduced the count macrophage count in atherosclerotic plaque lesions. Ep restored endothelial function by reduction of oxidative stress, atherosclerotic macrophage content, atherosclerotic lesion size and fibrosis to the same extent as treatment with Rami or the combination.

CONCLUSIONS

Mineralocorticoid antagonism provides vasculoprotective effects and should be clinically evaluated for vascular disease such as erectile dysfunction.

Resting heart rate is an independent predictor of all-cause mortality in the middle aged general population

BACKGROUND

High resting heart rate (RHR) predicts cardiovascular outcomes in patients with vascular disease and heart failure. We evaluated the prognostic value of RHR in a large contemporary population-based, prospective cohort of individuals without known coronary artery disease.

METHODS AND RESULTS

Resting heart rate (RHR) was determined in 4091 individuals (mean age 59.2 ± 7.7; 53 % women) from the Heinz Nixdorf RECALL study, of whom, 3348 were free of heart rate lowering medication. During 10.5 years of follow-up (median), 159 (3.9 %) individuals developed a coronary event and 398 (9.7 %) died of any cause. Persons without any event (n = 3603) had similar heart rates as persons with coronary events (69.5 ± 11 versus 69.9 ± 11 bpm, p = 0.51) but lower heart rates than persons who died (72.3 ± 13 bpm, p < 0.0001). In individuals without heart rate lowering medication, an increase in heart rate by 5 bpm was associated with an increased hazard ratio (HR) for all-cause mortality of 13 % in unadjusted analysis and also upon adjustment for traditional cardiovascular risk factors, including coronary artery calcification [full model: HR (95 % CI) 1.13 (1.07-1.20), p < 0.0001], but not for coronary events [HR 1.02 (0.94-1.11), p = 0.60]. In individuals without heart rate lowering medication, the HR (full model) for heart rate ≥70 versus <70 bpm with regard to all-cause mortality and coronary events was 1.68 (1.30-2.18), p < 0.0001, and 1.20 (0.82-1.77), p = 0.35. Analysis of the entire cohort revealed a continuous relationship of heart rate with all-cause mortality [HR for lowest to highest heart rate quartile 1.64 (1.22-2.22), p = 0.001, full model] but not with coronary events [HR 1.04 (0.65-1.66), p = 0.86].

CONCLUSIONS

In the general population without known coronary artery disease and heart rate lowering medication, elevated RHR is an independent risk marker for all-cause mortality but not for coronary events.

Influence of Cardiovascular and Noncardiovascular Co-morbidities on Outcomes and Treatment Effect of Heart Rate Reduction With Ivabradine in Stable Heart Failure (from the SHIFT Trial)

Incidence of chronic heart failure (HF) increases with age and cardiovascular (CV) morbidity. Co-morbidities increase hospitalization and mortality in HF, and non-CV co-morbidities may lead to preventable hospitalizations. We studied the impact of co-morbidities on mortality and morbidity in Systolic Heart Failure Treatment with the I(f) Inhibitor Ivabradine Trial, and investigated whether the impact of ivabradine was affected by co-morbidities. We analyzed the Systolic Heart Failure Treatment with the I(f) Inhibitor Ivabradine Trialpopulation, with moderate-to-severe HF and left ventricular dysfunction (in sinus rhythm with heart rate at rest ≥70 beats/min), according to co-morbidity: chronic obstructive pulmonary disease, diabetes mellitus, anemia, stroke, impaired renal function, myocardial infarction, hypertension, and peripheral artery disease. Co-morbidity load was classed as 0, 1, 2, 3, 4+ or 1 to 2 co-morbidities, or 3+ co-morbidities. Co-morbidities were evenly distributed between the placebo and ivabradine groups. Patients with more co-morbidities were likely to be older, women, had more advanced HF, were less likely to be on β blockers, with an even distribution on ivabradine 2.5, 5, or 7.5 mg bid and placebo at all co-morbidity loads. Number of co-morbidities was related to outcomes. Cardiovascular death or HF hospitalization events significantly increased (p <0.0001) with co-morbidity load, with the most events in patients with >3 co-morbidities for both, ivabradine and placebo. There was no interaction between co-morbidity load and the treatment effects of ivabradine. Hospitalization rate was lower at all co-morbidity loads for ivabradine. In conclusion, cardiac and noncardiac co-morbidities significantly affect CV outcomes, particularly if there are >3 co-morbidities. The effect of heart rate reduction with ivabradine is maintained at all co-morbidity loads.

Effect of Ivabradine on Endothelial Function in Patients with Stable Angina Pectoris: Assessment with the Endo-PAT 2000 Device

INTRODUCTION

Ivabradine has opened up new possibilities for treating stable angina and chronic heart failure by lowering heart rate. Ivabradine lowers heart rate by selectively inhibiting the I f current in the sinoatrial node. This study aimed to determine whether the decrease in heart rate achieved with ivabradine was accompanied by hemodynamic changes that might lead to an enhancement of endothelial function.

METHODS

Thirty patients with stable angina pectoris were included in the study. Ivabradine (5 mg bid) was added to the recommended standard treatment. Endothelial function was assessed at baseline and after 3 months of ivabradine therapy, with an Endo-PAT 2000 device (Itamar Medical, Israel). This device was recently developed for the noninvasive assessment for endothelial dysfunction. We evaluated reactive hyperemia index (RHI), which reflects endothelial function, and augmentation index (AI), which provides an indication of arterial stiffness.

RESULTS

The study population consisted of 25 (83.3%) men and five (16.7%) women. The mean age of the patients was 65.4 ± 6.7 years. Twenty-eight (93.3%) patients had a history of myocardial infarction (ST-segment elevation myocardial infarction or non-ST-segment elevation myocardial infarction), 23 (76.6%) had undergone revascularization (percutaneous coronary intervention or coronary artery bypass graft), 16 (53.3%) had type 2 diabetes mellitus, and 29 (96.6%) had arterial hypertension. The mean resting heart rate decreased significantly, from 77 ± 7 bpm at the start of the study to 65 ± 6 bpm after treatment (P < 0.0001). Endothelial function was found to have improved significantly after 3 months of ivabradine therapy. Mean RHI before treatment was 1.54 ± 0.30, suggesting probable endothelial dysfunction, whereas mean RHI at the end of the study was 1.83 ± 0.36 (P < 0.0001). AI also improved significantly on treatment, from 21 ± 20% to 10 ± 21% (P < 0.0001).

CONCLUSION

The addition of ivabradine to the treatment regimen of patients with stable angina pectoris both lowered heart rate and improved endothelial function. However, broader, randomized, double-blind, placebo-controlled clinical trials are required to confirm these findings.

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.

Resting heart rate is associated with renal disease outcomes in patients with vascular disease: results of the ONTARGET and TRANSCEND studies

BACKGROUND

Resting heart rate (RHR) is associated with cardiovascular disease outcomes in high-risk patients. It is not known whether RHR is predictive of renal outcomes such as albuminuria, end-stage renal disease (ESRD) or doubling of creatinine. We evaluated whether RHR could predict renal endpoints in patients at a high risk of cardiovascular disease. We also tested the effects of RHR at different levels of systolic blood pressure (SBP).

METHODS

We analysed data from 28 757 patients in the ONTARGET and TRANSCEND trials. RHR and SBP were available for a mean of 4.9 ± 0.4 visits (range 3-5) within the first 2 years of the studies. Albuminuria was determined at baseline, at 2 years and at study end.

RESULTS

Mean RHR was predictive of incident micro-albuminuria [hazard ratio (HR) for RHR ≥80 vs. <60 beats min(-1) 1.49, 95% confidence interval (CI) 1.29-1.71, P < 0.0001], incident macro-albuminuria (HR 1.84, 95% CI 1.39-2.42, P < 0.0001), doubling of creatinine (HR 1.47, 95% CI 1.00-2.17, P = 0.050) and ESRD (HR 1.78, 95% CI 1.00-3.16, P = 0.050), and the combined renal end-point (HR 1.51, 95% CI 1.32-1.74, P < 0.0001). Associations were robust at SBPs from <120 to ≥150 mmHg, with the lowest risk at a SBP of 130-140 mmHg.

CONCLUSION

Resting heart rate is a potent predictor of these renal outcomes, as well as their combination, in patients with cardiovascular disease. RHR at all SBP levels should be considered as a possible renal disease risk predictor and should be investigated as a treatment target with RHR-reducing agents.

Cellular and pharmacological targets to induce coronary arteriogenesis

The formation of collateral vessels (arteriogenesis) to sustain perfusion in ischemic tissue is native to the body and can compensate for coronary stenosis. However, arteriogenesis is a complex process and is dependent on many different factors. Although animal studies on collateral formation and stimulation show promising data, clinical trials have failed to replicate these results. Further research to the exact mechanisms is needed in order to develop a pharmalogical stimulant. This review gives an overview of recent data in the field of arteriogenesis.

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.

Systolic blood pressure variation and mean heart rate is associated with cognitive dysfunction in patients with high cardiovascular risk

Elevated systolic blood pressure (SBP) correlates to cognitive decline and incident dementia. The effects of heart rate (HR), visit to visit HR variation, and visit to visit SBP variation are less well established. Patients without preexisting cognitive dysfunction (N=24 593) were evaluated according to mean SBP, SBP visit to visit variation (coefficient of variation [standard deviation/mean×100%], CV), mean HR, and visit to visit HR variation (HR-CV) in the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial and the Telmisartan Randomized Assessment Study in ACE Intolerant Subjects with Cardiovascular Disease. Cognitive function was assessed with mini mental state examination. Cognitive dysfunction (fall in mini mental state examination ≤24 points), important cognitive decline (drop of ≥5 points), and cognitive deterioration (drop of >1 point per year or decline to <24 points) were assessed. SBP and HR were measured over 10.7±2.2 (mean±SD) visits. Mean SBP, mean HR, and SBP-CV were associated with cognitive decline, dysfunction, and deterioration (all P<0.01, unadjusted). After adjustment, only SBP-CV (P=0.0030) and mean HR (P=0.0008) remained predictors for cognitive dysfunction (odds ratios [95% confidence intervals], 1.32 [1.10-1.58] for 5th versus 1st quintile of SBP-CV and 1.40 [1.18-1.66] for 5th versus 1st quintile of mean HR). Similar effects were observed for cognitive decline and deterioration. SBP-CV and mean HR showed additive effects. In conclusion, SBP-CV and mean HR are independent predictors of cognitive decline and cognitive dysfunction in patients at high CV risk.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT 00153101.

The dual PPARα/γ agonist aleglitazar increases the number and function of endothelial progenitor cells: implications for vascular function and atherogenesis

BACKGROUND AND PURPOSE

Aleglitazar is a dual PPARα/γ agonist but little is known about its effects on vascular function and atherogenesis. Hence, we characterized its effects on circulating angiogenic cells (CAC), neoangiogenesis, endothelial function, arteriogenesis and atherosclerosis in mice.

EXPERIMENTAL APPROACH

C57Bl/6 wild-type (WT, normal chow), endothelial NOS (eNOS)(-/-) (normal chow) and ApoE(-/-) (Western-type diet) mice were treated with aleglitazar (10 mg·kg(-1) ·day(-1) , i.p.) or vehicle.

KEY RESULTS

Aleglitazar enhanced expression of PPARα and PPARγ target genes, normalized glucose tolerance and potently reduced hepatic fat in ApoE(-/-) mice. In WT mice, but not in eNOS(-/-) , aleglitazar up-regulated Sca-1/VEGFR2-positive CAC in the blood and bone marrow and up-regulated diLDL/lectin-positive CAC. Aleglitazar augmented CAC migration and enhanced neoangiogenesis. In ApoE(-/-) mice, aleglitazar up-regulated CAC number and function, reduced markers of vascular inflammation and potently improved perfusion restoration after hindlimb ischaemia and aortic endothelium-dependent vasodilatation. This was associated with markedly reduced formation of atherosclerotic plaques. In human cultured CAC from healthy donors and patients with coronary artery disease with or without diabetes mellitus, aleglitazar increased migration and colony-forming units in a concentration-dependent manner. Furthermore, oxidative stress-induced CAC apoptosis and expression of p53 were reduced, while telomerase activity and expression of phospho-eNOS and phospho-Akt were elevated. Comparative agonist and inhibitor experiments revealed that aleglitazar's effects on CAC migration and colony-forming units were mediated by both PPARα and PPARγ signalling and required Akt.

CONCLUSIONS AND IMPLICATIONS

Aleglitazar augments the number, function and survival of CAC, which correlates with improved vascular function, enhanced arteriogenesis and prevention of atherosclerosis in mice.

Ivabradine improves left ventricular function during chronic hypertension in conscious pigs

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

Pharmacological Treatment of Patients with Chronic Systolic Heart Failure

Chronic heart failure is characterised by neuroendocrine activation as an attempt of the body to maintain pump function of the heart and blood pressure for the perfusion of peripheral tissues. While this neuroendocrine activation is beneficial in the short term, it induces maladaptive remodeling of the heart with continuous deterioration of left ventricular function. Accordingly, pharmacological treatment of patients with heart failure aims at protecting the heart from this neuroendocrine activation, which is represented in particular by the sympathetic nervous and the renin-angiotensin-aldosterone systems. While this concept is based on evidence from numerous large randomised placebo-controlled studies in patients with systolic heart failure, about half of the patients with heart failure have preserved systolic function, and most studies antagonising neuroendocrine activation were not successful in these latter patients. Here, we review the pathophysiological changes that occur in patients with heart failure and provide an overview on the mechanisms and clinical evidence of currently applied pharmacological treatment in patients with systolic heart failure.

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.

The collateral circulation of the heart

The coronary arteries have been regarded as end arteries for decades. However, there are functionally relevant anastomotic vessels, known as collateral arteries, which interconnect epicardial coronary arteries. These vessels provide an alternative source of blood supply to the myocardium in cases of occlusive coronary artery disease. The relevance of these collateral arteries is a matter of ongoing debate, but increasing evidence indicates a relevant protective role in patients with coronary artery disease. The collateral circulation can be assessed by different methods; the gold standard involves intracoronary pressure measurements. While the first clinical trials to therapeutically induce growth of collateral arteries have been unavailing, recent pilot studies using external counterpulsation or growth factors such as granulocyte colony stimulating factor (G-CSF) have shown promising results.