Antioxidant properties of carvedilol and metoprolol in heart failure: a double-blind randomized controlled trial

Which should you choose for post operative atrial fibrillation, carvedilol or metoprolol? A systemic review and meta-analysis

BACKGROUND

Postoperative atrial fibrillation (POAF) is the most common arrhythmic complication following cardiac surgery. Current guidelines suggest beta-blockers for the prevention of POAF. In comparing metoprolol succinate with carvedilol, the later has sparked interest in its usage as an important medication for POAF prevention.

METHODS

We considered randomized controlled studies (RCTs) and retrospective studies that evaluated the efficacy of carvedilol versus metoprolol for the prevention of POAF. After literature search, data extraction, and quality evaluation, pooled data were analyzed using either the fixed-effect or random-effect model using Review Manager 5.3. The Cochrane risk of bias tool was used to assess the bias of included studies. The incidence of POAF was the primary endpoint, while mortality rate and bradycardia were secondary outcomes.

RESULTS

In meta-analysis 5 RCTs and 2 retrospective studies with a total of 1000 patients were included. The overall effect did not favor the carvedilol over metoprolol groups in terms of mortality rate [risk ratio 0.45, 95 % CI (0.1-1.97), P=0.29] or incidence of bradycardia [risk ratio 0.63, 95 % CI (0.32-1.23), P=0.17]. However, the incidence of POAF was lower in patients who received carvedilol compared to metoprolol [risk ratio 0.54, 95 % CI (0.42-0.71), P < 0.00001].

CONCLUSION

In patients undergoing cardiac surgery, carvedilol may minimize the occurrence of POAF more effectively than metoprolol. To definitively establish the efficacy of carvedilol compared to metoprolol and other beta-blockers in the prevention of POAF, a large-scale, well-designed randomized controlled trials are required.

The Arrhythmogenicity of Sotalol and its Role in Heart Failure: A Literature Review

ABSTRACT

According to the American Heart Association, approximately 6 million adults have been afflicted with heart failure in the United States in 2020 and are more likely to have sudden cardiac death accounting for approximately 50% of the cause of mortality. Sotalol is a nonselective β-adrenergic receptor antagonist with class III antiarrhythmic properties that has been mostly used for atrial fibrillation treatment and suppressing recurrent ventricular tachyarrhythmias. The use of sotalol in patients with left ventricular dysfunction is not recommended by the American College of Cardiology or American Heart Association because studies are inconclusive with conflicting results regarding safety. This article aims to review the mechanism of action of sotalol, the β-blocking effects on heart failure, and provide an overview of clinical trials on sotalol use and its effects in patients with heart failure. Small- and large-scale clinical trials have been controversial and inconclusive about the use of sotalol in heart failure. Sotalol has been shown to reduce defibrillation energy requirements and reduce shocks from implantable cardioverter-defibrillators. Torsades de Pointes is the most life-threatening arrhythmia that has been documented with sotalol use and occurs more commonly in women and heart failure patients. Thus far, mortality benefits have not been demonstrated with sotalol use and larger multicenter studies are required going forward.

Comparison of new-onset post-operative atrial fibrillation between patients receiving carvedilol and metoprolol after off-pump coronary artery bypass graft surgery

OBJECTIVE

Post-operative atrial fibrillation (POAF) is a common complication of coronary artery bypass graft (CABG) surgery. Previous studies suggest carvedilol is more effective than metoprolol in preventing POAF in on-pump CABG. This study investigated if the same benefit would be seen in off-pump CABG.

METHODS

This single-center, retrospective review compared rates of new-onset POAF between adult patients who received carvedilol and metoprolol after off-pump CABG surgery. Safety endpoints included hypotension, bradycardia, dyspnea, and the composite. Multivariate logistic regression was conducted to identify associations between demographics, potential confounders, and beta-blocker dose and POAF. Kaplan-Meier plots and Cox proportional-hazards models examined differences in time-to-event for POAF.

RESULTS

134 patients were included (34 carvedilol and 100 metoprolol). The mean age was 63 years, 70.9% were male, 85% had history of hypertension, 3.7% had history of heart failure with reduced ejection fraction, and 38.8% were taking beta blockers prior to admission. POAF developed in 2 patients (5.8%) in the carvedilol group and 24 patients (24.0%) in the metoprolol group (odds ratio 0.17 [95% CI 0.03-0.83], p = 0.023). Safety endpoints occurred in 10 carvedilol (29.4%) and 44 metoprolol (44.0%) patients (p = 0.134). Hypotension and dyspnea rates were similar between groups; bradycardia occurred more commonly among metoprolol-treated patients (p = 0.040). Time-to-event analyses revealed a hazard ratio = 0.22 (95% CI 0.05-0.93, p = 0.040) for carvedilol use.

CONCLUSIONS

In this single-center, retrospective study of off-pump CABG patients, carvedilol was associated with reduced POAF risk and enhanced safety compared to metoprolol.

Heart Failure and Drug Therapies: A Metabolic Review

Cardiovascular disease is the leading cause of mortality globally with at least 26 million people worldwide living with heart failure (HF). Metabolism has been an active area of investigation in the setting of HF since the heart demands a high rate of ATP turnover to maintain homeostasis. With the advent of -omic technologies, specifically metabolomics and lipidomics, HF pathologies have been better characterized with unbiased and holistic approaches. These techniques have identified novel pathways in our understanding of progression of HF and potential points of intervention. Furthermore, sodium-glucose transport protein 2 inhibitors, a drug that has changed the dogma of HF treatment, has one of the strongest types of evidence for a potential metabolic mechanism of action. This review will highlight cardiac metabolism in both the healthy and failing heart and then discuss the metabolic effects of heart failure drugs.

A Novel Mechanism of Carvedilol Efficacy for Rosacea Treatment: Toll-Like Receptor 2 Inhibition in Macrophages

Background

Rosacea, a chronic inflammatory skin disorder etiologically associated with immune cells and the antibacterial peptide cathelicidin LL-37, can be effectively treated by oral carvedilol administration.

Objective

To investigate the molecular mechanisms underlying carvedilol efficacy in rosacea treatment.

Methods

Skin samples of patients with rosacea were subjected to histopathological (hematoxylin and eosin) and immunohistochemical (CD68, Toll-like receptor 2 (TLR2), kallikrein 5, cathelicidin, TNF-α, and IL-1β) evaluation. An in vivo murine rosacea-like inflammation model was established by LL-37 intradermal injection with or without carvedilol gavage-based pretreatment. Erythema proportion (Image J) and skin redness (L*a*b colorimetry) were quantified. Murine skin samples underwent pathological examination for inflammatory status and immunofluorescence staining. Murine skin and lipopolysaccharide-stimulated RAW 264.7 cells with or without carvedilol pretreatment were evaluated by quantitative reverse transcription-polymerase chain reaction and western blotting. Clinical facial images of patients were obtained using the VISIA skin analysis system before, 4, and 6 months following oral carvedilol administration.

Results

Rosacea skin lesions exhibited more pronounced inflammatory cell infiltration than peripheral areas, with profound macrophage infiltration and inflammatory cytokines (TLR2, kallikrein 5, cathelicidin, TNF-α, and IL-1β). In vivo, carvedilol alleviated inflammation in LL-37 mice, down-regulating TLR2, KLK5, and cathelicidin expression. In vitro, carvedilol decreased TLR2 expression in RAW 264.7 cells, further reducing KLK5 secretion and LL-37 expression and ultimately inhibiting rosacea-like inflammatory reactions. Clinical manifestations and facial redness obviously improved during 6-month follow-up with systemic carvedilol administration.

Conclusion

Carvedilol is effective against rosacea, with inhibition of macrophage TLR2 expression as a novel anti-inflammatory mechanism.

Targeting Adrenergic Receptors in Metabolic Therapies for Heart Failure

The heart has a reduced capacity to generate sufficient energy when failing, resulting in an energy-starved condition with diminished functions. Studies have identified numerous changes in metabolic pathways in the failing heart that result in reduced oxidation of both glucose and fatty acid substrates, defects in mitochondrial functions and oxidative phosphorylation, and inefficient substrate utilization for the ATP that is produced. Recent early-phase clinical studies indicate that inhibitors of fatty acid oxidation and antioxidants that target the mitochondria may improve heart function during failure by increasing compensatory glucose oxidation. Adrenergic receptors (α1 and β) are a key sympathetic nervous system regulator that controls cardiac function. β-AR blockers are an established treatment for heart failure and α1A-AR agonists have potential therapeutic benefit. Besides regulating inotropy and chronotropy, α1- and β-adrenergic receptors also regulate metabolic functions in the heart that underlie many cardiac benefits. This review will highlight recent studies that describe how adrenergic receptor-mediated metabolic pathways may be able to restore cardiac energetics to non-failing levels that may offer promising therapeutic strategies.

Carvedilol Promotes Retinal Ganglion Cell Survival Following Optic Nerve Injury via ASK1-p38 MAPK Pathway

BACKGROUND

Carvedilol, which is considered as a nonselective β-adrenoreceptor blocker, has many pleiotropic activities. It also causes great impact on neuroprotection because of its antioxidant ability, which suggested that carvedilol may be effective in protecting RGCs from increased oxidative stress.

OBJECTIVE

To examine the effects of carvedilol on preventing Retinal Ganglion Cell (RGC) death in a mouse model of Optic Nerve Injury (ONI).

METHODS

C57BL/6J mice were subjected to Optic Nerve Injury (ONI) model and treated with carvedilol or placebo. Histological and morphometric studies were performed; the RGC number, the amount of neurons in the ganglion cell layer and the thickness of the Inner Retinal Layer (IRL) was quantified. The average thickness of Ganglion Cell Complex (GCC) was determined by the Spectral- Domain OCT (SD-OCT) assay. Immunohistochemistry, western blot and quantitative real-time PCR analysis were also applied.

RESULTS

Daily treatment of carvedilol reduced RGC death following ONI, and in vivo retinal imaging revealed that carvedilol can effectively prevent retinal degeneration. The expression of chemokines important for micorglia recruitment was deceased with carvedilol ingestion and the accumulation of retinal microglia is reduced consequently. In addition, the ONI-induced expression of inducible nitric oxide synthase in the retina was inhibited with carvedilol treatment in the retina. We also discovered that carvedilol suppressed ONI-induced activation of Apoptosis Signal-regulating Kinase-1 (ASK1) and p38 Mitogen-Activated Protein Kinase (MAPK) pathway.

CONCLUSION

The results of this study indicate that carvedilol can stimulate neuroprotection and neuroregeneration, and may be useful for treatment of various neurodegenerative diseases.

Effect of carvedilol vs metoprolol succinate on mortality in heart failure with reduced ejection fraction

BACKGROUND

Beta blocker therapy is indicated in all patients with heart failure with reduced ejection fraction (HFrEF) as per current guidelines. The relative benefit of carvedilol to metoprolol succinate remains unknown. This study aimed to compare survival benefit of carvedilol to metoprolol succinate.

METHODS

The VA's databases were queried to identify 114,745 patients diagnosed with HFrEF from 2007 to 2015 who were prescribed carvedilol and metoprolol succinate. The study estimated the survival probability and hazard ratio by comparing the carvedilol and metoprolol patients using propensity score matching with replacement techniques on observed covariates. Sub-group analyses were performed separately for men, women, elderly, duration of therapy of more than 3 months, and diabetic patients.

RESULTS

A total of 43,941 metoprolol patients were matched with as many carvedilol patients. The adjusted hazard ratio of mortality for metoprolol succinate compared to carvedilol was 1.069 (95% CI: 1.046-1.092, P value: < .001). At six years, the survival probability was higher in the carvedilol group compared to the metoprolol succinate group (55.6% vs 49.2%, P value < .001). The sub-group analyses show that the results hold true separately for male, over or under 65 years old, therapy duration more than three months and non-diabetic patients.

CONCLUSION

Patients with HFrEF taking carvedilol had improved survival as compared to metoprolol succinate. The data supports the need for furthering testing to determine optimal choice of beta blockers in patients with heart failure with reduced ejection fraction.

Apoptosis in human liver carcinoma caused by gold nanoparticles in combination with carvedilol is mediated via modulation of MAPK/Akt/mTOR pathway and EGFR/FAAD proteins

In cancers, apoptosis signaling pathways and cell survival and growth pathways responsible for resistance to conventional treatments, such as Pi3K/Akt/mTOR and mitogen-activated protein kinase (MAPK) become dysregulated. Recently, alternative treatments to promote tumor cell death have become important. The present study reports on the antitumor and cytoprotective action of gold nanoparticles (GNPs) and carvedilol in combination and in isolated application. Apoptosis was analyzed by FITC/propidium iodide staining flow cytometry; caspase-3, caspase-8, Bcl-2 and MAPK/ERK activity by immunofluorescence microscopy; gene expression of proteins related to cell death as Akt, mTOR, EGFR, MDR1, survivin, FADD and Apaf, by the real-time PCR; and western blot analysis for MAPK/ERK, Akt and mTOR. Oxidative stress evaluation was performed by reduced glutathione (GSH) and malondialdehyde (MDA) levels. Intracellular GNPs targets were identified by transmission electron microscopy. After exposure to a combination of GNPs (6.25 µg/ml) and carvedilol (3 µM), death as promoted by apoptosis was detected using flow cytometry, for expression of pro-apoptotic proteins FADD, caspase-3, caspase-8 and sub-regulation of anti-apoptotic MAPK/ERK, Akt, mTOR, EGFR and MDR1 resistance. Non-tumor cell cytoprotection with GSH elevation and MDA reduction levels was detected. GNPs were identified within the cell near to the nucleus when combined with carvedilol. The combination of GNP and carvedilol promoted downregulation of anti-apoptotic and drug resistance genes, over-regulation of pro-apoptotic proteins in tumor cells, as well as cytoprotection of non-tumor cells with reduction of apoptosis and oxidative stress.

Carvedilol abrogates hypoxia-induced oxidative stress and neuroinflammation in microglial BV2 cells

Microglia initially undergo rapid activation in response to injury and stressful stimuli, such as hypoxia. Oxidative stress and the inflammatory response play critical roles in hypoxic-ischemic brain injury. Carvedilol is a β-blocker used to treat high blood pressure and heart failure. In this study, we investigated whether carvedilol had a protective effect against hypoxia-induced oxidative stress and inflammation in microglial BV2 cells. Our results indicate that hypoxic exposure significantly reduced mean cell viability of BV2 microglia, which was significantly restored by carvedilol (10 and 50μM). In addition, carvedilol treatment significantly inhibited the hypoxia-induced increase in reactive oxygen species (ROS) and 4-hydroxy-2-nonenal (4-HNE). Administration of carvedilol significantly inhibited expression of IL-1β, TNF-α, and IL-6 at both the mRNA and protein levels. Mechanistically, we found that hypoxia significantly increased phosphorylation of IKK, IκBα, and NF-κB p65. However, treatment with carvedilol inhibited phosphorylation of these molecules. Notably, hypoxia resulted in a significant nuclear translocation of NF-κB p65, which was inhibited by administration of carvedilol. Luciferase reporter assay results demonstrate that treatment with carvedilol inhibited the hypoxia-induced increase in NF-κB binding activity. These data suggest that carvedilol may be of potential use as a novel therapy against hypoxia or ischemia.

Perspectives and challenges of antioxidant therapy for atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia associated with significant morbidity and mortality. The mechanisms underlying the pathogenesis of AF are poorly understood, although electrophysiological remodeling has been described as an important initiating step. There is growing evidence that oxidative stress is involved in the pathogenesis of AF. Many known triggers of oxidative stress, such as age, diabetes, smoking, and inflammation, are linked with an increased risk of arrhythmia. Numerous preclinical studies and clinical trials reported the importance of antioxidant therapy in the prevention of AF, using vitamins C and E, polyunsaturated fatty acids, statins, or nitric oxide donors. The aim of our work is to give a current overview and analysis of opportunities, challenges, and benefits of antioxidant therapy in AF.

Older adults with heart failure treated with carvedilol, bisoprolol, or metoprolol tartrate: risk of mortality

PURPOSE

The long-term use of β-blockers has been shown to improve clinical outcomes among patients with heart failure (HF). However, a lack of data persists in assessing whether carvedilol or bisoprolol are superior to metoprolol tartrate in clinical practice. We endeavored to compare the effectiveness of β-blockers among older adults following a primary hospital admission for HF.

METHODS

We conducted a cohort study using Quebec administrative databases to identify patients who were using β-blockers, carvedilol, bisoprolol, or metoprolol tartrate after the diagnosis of HF. We characterized the patients by the type of β-blocker prescribed at discharge of their first HF hospitalization. An adjusted multivariate Cox proportional hazards model was used to compare the primary outcome of all-cause mortality. We also conducted analyses by matching for a propensity score for initiation of β-blocker therapy and assessed the effect on primary outcome.

RESULTS

Among 3197 patients with HF with a median follow-up of 2.8 years, the crude annual mortality rates (per 100 person-years) were at 16, 14.9, and 17.7 for metoprolol tartrate, carvedilol, and bisoprolol, respectively. Adjusted hazard ratios of carvedilol (hazard ratio 0.92; 0.78-1.09) and bisoprolol (hazard ratio 1.04; 0.93-1.16) were not significantly different from that of metoprolol tartrate in improving survival. After matching for propensity score, carvedilol and bisoprolol showed no additional benefit with respect to all-cause mortality compared with metoprolol tartrate.

CONCLUSIONS

Our evidence suggests no differential effect of β-blockers on all-cause mortality among older adults with HF. Copyright © 2016 John Wiley & Sons, Ltd.

Meta-analysis of the effects of carvedilol versus metoprolol on all-cause mortality and hospitalizations in patients with heart failure

Long-term treatment with appropriate doses of carvedilol or metoprolol is currently recommended for patients with heart failure with reduced ejection fraction (HFrEF) to decrease the risk of death, hospitalizations, and patients' symptoms. It remains unclear if the β blockers used in patients with HFrEF are equal or carvedilol is superior to metoprolol types. We performed a meta-analysis of the comparative effects of carvedilol versus metoprolol tartrate and succinate on all-cause mortality and/or hospitalization. We conducted an Embase and MEDLINE search for prospective controlled trials and cohort studies of patients with HFrEF who were received to treatment with carvedilol versus metoprolol. We identified 4 prospective controlled and 6 cohort studies with 30,943 patients who received carvedilol and 69,925 patients on metoprolol types (tartrate and succinate) with an average follow-up duration of 36.4 months. All-cause mortality was reduced in prospective studies with carvedilol versus metoprolol tartrate. Neither all-cause mortality nor hospitalizations were significantly different between carvedilol and metoprolol succinate in the cohort studies. In conclusion, in patients with HFrEF, carvedilol and metoprolol succinate have similar effects in reducing all-cause mortality.

The effects of anti-hypertensives and type 2 diabetes on salivary flow and total antioxidant capacity

OBJECTIVE

The present cross-sectional study aimed to determine the effect of first-line anti-hypertensive drugs (enalapril, metoprolol, and combinations of enalapril with metoprolol and/or hydrochlorothiazide) on salivary gland function and salivary total antioxidant capacity (TAC) in hypertensive patients with/without diabetes mellitus (DM) type 2.

MATERIALS AND METHODS

Salivary gland function was measured as xerostomia (interview) and unstimulated whole saliva flow rate (UWSFR) in 447 subjects (387 hypertensive and 60 healthy). Salivary TAC was evaluated by spectrophotometric assay.

RESULTS

Enalapril is not xerogenic, while metoprolol and drug combinations are. In the presence of DM type 2, all drugs, except metoprolol, had pronounced xerogenic effect. Binary logistic regression analysis found enalapril to be significantly associated with decreased risk of xerogenic effect development, while DM type 2 with increased risk. In the presence of enalapril in hypertensive patients with/without DM type 2 salivary TAC was similar to that in healthy subjects, while for metoprolol was reduced.

CONCLUSIONS

Enalapril is not xerogenic but is antioxidant, which moderately reduces the risk of xerogenic effect development even in the presence of DM type 2. However, metoprolol and drug combinations exhibit xerogenic effect. In DM type 2, xerogenic effect of all drugs was pronounced except of metoprolol.

β-Blockers in hypertension, diabetes, heart failure and acute myocardial infarction: a review of the literature

β-Blockers (BBs) are an essential class of cardiovascular medications for reducing morbidity and mortality in patients with heart failure (HF). However, a large body of data indicates that BBs should not be used as first-line therapy for hypertension (HTN). Additionally, new data have questioned the role of BBs in the treatment of stable coronary heart disease (CHD). However, these trials mainly tested the non-vasodilating β₁ selective BBs (atenolol and metoprolol) which are still the most commonly prescribed BBs in the USA. Newer generation BBs, such as the vasodilating BBs carvedilol and nebivolol, have been shown not only to be better tolerated than non-vasodilating BBs, but also these agents do not increase the risk of diabetes mellitus (DM), atherogenic dyslipidaemia or weight gain. Moreover, carvedilol has the most evidence for reducing morbidity and mortality in patients with HF and those who have experienced an acute myocardial infarction (AMI). This review discusses the cornerstone clinical trials that have tested BBs in the settings of HTN, HF and AMI. Large randomised trials in the settings of HTN, DM and stable CHD are still needed to establish the role of BBs in these diseases, as well as to determine whether vasodilating BBs are exempt from the disadvantages of non-vasodilating BBs.

Addition of N-acetyl cysteine to carvedilol decreases the incidence of acute renal injury after cardiac surgery

BACKGROUND

Oxidative stress and inflammation during cardiac surgery may be associated with acute renal injury (ARI). N-acetyl cysteine (NAC) and carvedilol have antioxidant and anti-inflammatory properties.

HYPOTHESIS

A combination of carvedilol and NAC should decrease the incidence of ARI more than metoprolol or carvedilol.

METHODS

Patients undergoing cardiac surgery were randomized to metoprolol, carvedilol, or carvedilol plus NAC. End points were occurrence of ARI and change in preoperative to postoperative peak creatinine levels.

RESULTS

ARI incidence was lower in the carvedilol plus NAC group compared with the metoprolol (21.0% vs 42.1%; P = 0.002) or carvedilol (21.0% vs 38.6%; P = 0.006) groups, but was similar between the metoprolol and carvedilol groups (P = 0.62). Preoperative and postoperative day 1 creatinine levels were similar among the metoprolol (1.02 [0.9-1.2] and 1.2 [0.92-1.45]) the carvedilol (1.0 [0.88-1.08] and 1.2 [0.9-1.5]) and the carvedilol plus NAC groups (1.06 [0.9-1.18] and 1.1 [1.0-1.21] mg/dL; all P values >0.05). Postoperative day 3, day 5, and peak creatinine levels were lower in the carvedilol plus NAC group (1.11 [1.0-1.23], 1.14 [1.0-1.25] and 1.15 [1.0-1.25]) as compared with the metoprolol (1.4 [1.3-1.49], 1.3 [1.0-1.54] and 1.3 [1.0-1.54]) or carvedilol groups (1.2 [1.0-1.52], 1.25 [1.0-1.52] and 1.25 [1.0-1.55] mg/dL; all P values <0.05), but were similar between the metoprolol and carvedilol groups (all P values >0.05).

CONCLUSIONS

Combined carvedilol and NAC decreased ARI incidence as compared with carvedilol or metoprolol. No difference was detected between carvedilol and metoprolol.

Meta-analysis comparing carvedilol versus metoprolol for the prevention of postoperative atrial fibrillation following coronary artery bypass grafting

A systematic review and meta-analysis was performed to evaluate the effects of carvedilol versus metoprolol on the incidence of postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting in randomized controlled trials. Ovid MEDLINE, PubMed, CENTRAL, and Excepta Medica (EMBASE) were searched up to March 2013 for suitable randomized controlled trials. Data were pooled using random-effects model for pairwise analyses. A total of 4 trials with 601 patients were included in this analysis. Pairwise analyses showed that compared with metoprolol, carvedilol significantly reduced the incidence of postoperative atrial fibrillation (odds ratio 0.50, 95% confidence interval 0.32 to 0.80). In conclusion, compared with metoprolol, carvedilol significantly reduces the incidence of postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting.

Oxidative status, inflammation, and postoperative atrial fibrillation with metoprolol vs carvedilol or carvedilol plus N-acetyl cysteine treatment

BACKGROUND

Atrial fibrillation is associated with inflammation and oxidative stress.

HYPOTHESIS

Carvedilol and N-acetyl cysteine (NAC) combination decreases inflammation, oxidative stress, and postoperative atrial fibrillation (POAF) rates more than metoprolol or carvedilol.

METHODS

Preoperative and postoperative total oxidative stress (TOS), total antioxidant capacity (TAC), and white blood cells (WBC) were measured in metoprolol, carvedilol, or carvedilol plus NAC groups, and association with POAF was evaluated.

RESULTS

Preoperative TAC, TOS, and WBC levels were similar among the groups. Postoperative TAC levels were lower in the metoprolol group compared with the carvedilol group (1.0 vs 1.4) or the carvedilol plus NAC group (1.0 vs 1.9) and were also lower in the carvedilol group compared with the carvedilol plus NAC group (all P < 0.0001). Postoperative TOS levels were higher in the metoprolol group as compared with the carvedilol (29.6 vs 24.2; P < 0.0001) or the carvedilol plus NAC groups (P < 0.0001), and were also higher in the carvedilol group as compared with the carvedilol plus NAC group (24.2 vs 19.3; P < 0.0001). Postoperative WBC counts were lower in the carvedilol plus NAC group compared with the metoprolol group (12.9 vs 14.8; P = 0.004), were similar between the carvedilol and the metoprolol groups (13 vs 14.8) and between the carvedilol plus NAC group and the carvedilol group (both P > 0.05). Postoperative TAC, TOS, and WBC were associated with POAF.

CONCLUSIONS

Carvedilol plus NAC reduced oxidative stress and inflammation compared with metoprolol and decreased oxidative stress compared with carvedilol. Postoperative TAC, TOS, and WBC were associated with POAF.

Circulating levels of linoleic acid and HDL-cholesterol are major determinants of 4-hydroxynonenal protein adducts in patients with heart failure

OBJECTIVE

Measurements of oxidative stress biomarkers in patients with heart failure (HF) have yielded controversial results. This study aimed at testing the hypothesis that circulating levels of the lipid peroxidation product 4-hydroxynonenal bound to thiol proteins (4HNE-P) are strongly associated with those of its potential precursors, namely n-6 polyunsaturated fatty acids (PUFA).

METHODS AND RESULTS

Circulating levels of 4HNE-P were evaluated by gas chromatography-mass spectrometry in 71 control subjects and 61 ambulatory symptomatic HF patients along with various other clinically- and biochemically-relevant parameters, including other oxidative stress markers, and total levels of fatty acids from all classes, which reflect both free and bound to cholesterol, phospholipids and triglycerides. All HF patients had severe systolic functional impairment despite receiving optimal evidence-based therapies. Compared to controls, HF patients displayed markedly lower circulating levels of HDL- and LDL-cholesterol, which are major PUFA carriers, as well as of PUFA of the n-6 series, specifically linoleic acid (LA; P=0.001). Circulating 4HNE-P in HF patients was similar to controls, albeit multiple regression analysis revealed that LA was the only factor that was significantly associated with circulating 4HNE-P in the entire population (R (2)=0.086; P=0.02). In HF patients only, 4HNE-P was even more strongly associated with LA (P=0.003) and HDL-cholesterol (p<0.0002). Our results demonstrate that 4HNE-P levels, expressed relative to HDL-cholesterol, increase as HDL-cholesterol plasma levels decrease in the HF group only.

CONCLUSION

Results from this study emphasize the importance of considering changes in lipids and lipoproteins in the interpretation of measurements of lipid peroxidation products. Further studies appear warranted to explore the possibility that HDL-cholesterol particles may be a carrier of 4HNE adducts.

Oxidative stress in atrial fibrillation: an emerging role of NADPH oxidase

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Patients with AF have up to seven-fold higher risk of suffering from ischemic stroke. Better understanding of etiologies of AF and its thromboembolic complications are required for improved patient care, as current anti-arrhythmic therapies have limited efficacy and off target effects. Accumulating evidence has implicated a potential role of oxidative stress in the pathogenesis of AF. Excessive production of reactive oxygen species (ROS) is likely involved in the structural and electrical remodeling of the heart, contributing to fibrosis and thrombosis. In particular, NADPH oxidase (NOX) has emerged as a potential enzymatic source for ROS production in AF based on growing evidence from clinical and animal studies. Indeed, NOX can be activated by known upstream triggers of AF such as angiotensin II and atrial stretch. In addition, treatments such as statins, antioxidants, ACEI or AT1RB have been shown to prevent post-operative AF; among which ACEI/AT1RB and statins can attenuate NOX activity. On the other hand, detailed molecular mechanisms by which specific NOX isoform(s) are involved in the pathogenesis of AF and the extent to which activation of NOX plays a causal role in AF development remains to be determined. The current review discusses causes and consequences of oxidative stress in AF with a special focus on the emerging role of NOX pathways.

Prevention of post-coronary artery bypass grafting (CABG) atrial fibrillation: efficacy of prophylactic beta-blockers in the modern era: a meta-analysis of latest randomized controlled trials

BACKGROUND

Atrial fibrillation/flutter (AF) is a common complication of open heart surgery and ACC/AHA guidelines strongly recommend the use of prophylactic beta-blockers (BB) for its prevention. Several recent studies, however, have failed to show the desired protective effects of BB against post-coronary artery bypass grafting (CABG) AF. As the protocols of CABG, medical management of CAD (coronary artery disease) and demographic features of the patients undergoing open heart surgery have evolved significantly over the last two decades, we decided to perform a review of evidence from latest randomized controlled trials (RCTs) to confirm the efficacy of prophylactic BB.

METHODS

We searched for RCTs comparing the efficacy of prophylactic BB versus placebo/control against post-CABG AF. We limited our search to 1995 till present to reflect ongoing advancements in the protocols of CABG and the medical management of CAD. Initially, 34 trials were selected; however after certain exclusions only 10 RCTs were included in the final analysis.

RESULTS

Prophylactic BB decreased the incidence of post-CABG AF from 32.8% in the control group to 20% in the prophylactic group with risk ratio (RR) of 0.50 with 95% CI of 0.36-0.69, P value < 0.001. In a subgroup analysis, carvedilol appears to be superior to metoprolol for the prevention of postoperative AF.

CONCLUSIONS

Despite several limitations, this analysis confirms the efficacy of prophylactic BB against post-CABG AF in this era. We recommend continuing perioperative BB in the open heart surgery patients in the absence of contraindications.

Oxidative stress and left ventricular remodelling after myocardial infarction

In acute myocardial infarction (MI), reactive oxygen species (ROS) are generated in the ischaemic myocardium especially after reperfusion. ROS directly injure the cell membrane and cause cell death. However, ROS also stimulate signal transduction to elaborate inflammatory cytokines, e.g. tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta and -6, in the ischaemic region and surrounding myocardium as a host reaction. Inflammatory cytokines also regulate cell survival and cell death in the chain reaction with ROS. Both ROS and inflammatory cytokines are cardiodepressant mainly due to impairment of intracellular Ca(2+) homeostasis. Inflammatory cytokines stimulate apoptosis through a TNF-alpha receptor/caspase pathway, whereas Ca(2+) overload induced by extensive ROS generation causes necrosis through enhanced permeability of the mitochondrial membrane (mitochondrial permeability transition). Apoptosis signal-regulating kinase-1 (ASK1) is an ROS-sensitive, mitogen-activated protein kinase kinase kinase that is activated by many stress signals and can activate nuclear factor kappaB and other transcription factors. ASK1-deficient mice demonstrate that the ROS/ASK1 pathway is involved in necrotic as well as apoptotic cell death, indicating that ASK1 may be a therapeutic target to reduce left ventricular (LV) remodelling after MI. ROS and inflammatory cytokines activate matrix metalloproteinases which degrade extracellular matrix, causing a slippage of myofibrils and hence LV dilatation. Consequently, collagen deposition is increased and tissue repair is enhanced with myocardial fibrosis and angiogenesis. Since the extent of LV remodelling is a major predictor of prognosis of the patients with MI, the therapeutic approach to attenuating LV remodelling is critically important.

Effects of carvedilol on left ventricular function and oxidative stress in infants and children with idiopathic dilated cardiomyopathy: a 12-month, two-center, open-label study

OBJECTIVES

This study was conducted to determine the effects of carvedilol adjunct to standard treatment on left ventricular function (LVF), estimated as ejection fraction (EF) and fractional shortening (FS) on echocardiography, in children with idiopathic dilated cardiomyopathy (DCM). A secondary end point was to characterize the antioxidant potential of carvedilol.

METHODS

Hospitalized children aged <or=16 years with clinically stable DCM and advanced congestive heart failure (HF) with modified New York Heart Association Classification for Children (NYHAC) functional classes II to IV and EF <40% were enrolled in this prospective, 12-month, 2-center, open-label study. Oral carvedilol was added to a standard regimen of an angiotensin-converting enzyme inhibitor, a diuretic, and digoxin in a dose-escalation design. Systolic and diastolic blood pressure (BP), heart rate (HR), and modified NYHAC were assessed before (baseline) and at 1, 3, 6, and 12 months of adjunct carvedilol treatment. EF and FS were analyzed before and at 6 and 12 months of carvedilol treatment. At each study visit, tolerability was assessed in terms of adverse events (AEs), treatment emergent signs and symptoms, physical examination including vital sign measurement (BP, HR, and body temperature), and laboratory analysis. Antioxidative enzyme activity was evaluated by measuring erythrocyte copper/zinc superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione reductase (GR) activity at baseline and 1, 3, 6, and 12 months of adjunct carvedilol treatment. For assessment of antioxidative enzyme activity, a control group comprised 29 age-matched healthy children.

RESULTS

Twenty-one children (12 boys, 9 girls; age range, 7 months to 16 years; 100% white) completed the study. Four patients discontinued carvedilol at the beginning of the study due to severe arrhythmia which required amiodarone therapy (2 patients), bradycardia and hypotension (1), and bronchospasm (1). Carvedilol (0.4 mg/kg/d in children <or=62.5 kg or 25 mg/d in children >62.5 kg) was associated with significant decreases from baseline in systolic BP (130 [4] vs 123 [3] mm Hg; P<0.05), diastolic BP (85 [4] vs 77 [4] mm Hg; P<0.05), and HR (81 [4] vs 65 [4] bpm; P<0.001) after the first month of addition to standard therapy. At 6 months, there were significant improvements from baseline in EF (37.2% [2.4%] vs 50.2% [2.3%]; P<0.001) and FS (18.37% [2.00%] vs 23.58% [0.90%]; P<0.001). Modified NYHAC class was significantly improved in 80% of children (2.9 vs 2.3; P<0.001) at 12 months. The highest dose of carvedilol (0.8 mg/kg/d in children <or=62.5 kg or 50 mg/d in children >62.5 kg) was well tolerated in all 21 children. No serious AEs that necessitated study drug discontinuation (tiredness, headache, vomiting) were observed. At baseline, mean (SE) erythrocyte SOD activity (2781 [116] vs 2406 [102] U/g Hb; P<0.05) and GR activity (5.3 [0.3] vs 3.0 [0.2] micromol nicotinamide adenine dinucleotide phosphate [NADPH]/min/g Hb; P<0.001) were significantly higher in children with DCM who received standard therapy compared with healthy controls.CAT activity (12.7[0.9] vs 18.5 [1.0]U/g Hb; P<0.001) was significantly lower, while GSH-Px was unchanged. At 6 and 12 months of therapy, carvedilol plus standard treatment was associated with significant decreases from baseline in SOD (2516 [126] and 2550 [118], respectively, vs 2781 [116] U/g Hb; both, P<0.001) and GR (4.7 [0.3] and 4.1 [0.2], respectively, vs 5.3 [0.2] micromol NADPH/min/g Hb; P<0.05 and P<0.001) and increased CAT (16.9 [1.0] and 16.4 [0.7], respectively, vs 12.7 [0.9] U/g Hb; both, P<0.001).

CONCLUSIONS

These pediatric patients with DCM treated for 12 months with carvedilol (up to 0.8 mg/kg/d in children <or=62.5 kg or 50 mg/d in children >62.5 kg) were found to have significant improvements in LVF and symptoms of HF. Twelve months of carvedilol therapy was associated with antioxidant enzyme activities near those observed in healthy children.

Comparison of the efficacy of metoprolol and carvedilol for preventing atrial fibrillation after coronary bypass surgery

BACKGROUND

Atrial fibrillation (AF) occurs frequently after coronary artery bypass grafting (CABG) and often results in prolonged postsurgical hospital stays and increased mortality and morbidity. Beta blockers are known to prevent postoperative AF. In this prospective study, we investigated the efficacy of carvedilol compared with metoprolol succinate in preventing postoperative AF.

METHODS

Subjects included 110 patients (31 women, 79 men; mean age, 60+/-10 years, range, 39-82 years) who had undergone CABG. Patients were randomized to receive either metoprolol or carvedilol, and all patients received the drugs 3 days prior to surgery. Metoprolol was started at 50 mg twice daily and carvedilol was started at 12.5 mg twice daily. The doses were titrated according to the patients' hemodynamic responses. All patients were monitored for 3 days after the surgery.

RESULTS

Of the 110 patients, 55 (50%) were treated with metoprolol succinate, and 55 (50%) were treated with carvedilol. Baseline characteristics and operative data of the patients did not differ between groups. During follow-up, 20 patients (36%) in the metoprolol group and 9 patients (16%) in the carvedilol group developed AF (P=0.029). Multiple stepwise logistic regression analysis showed that metoprolol use, older age, and impaired left ventricular ejection fraction were independent risk factors for developing AF, and carvedilol use was found to be independently related to sinus rhythm maintenance after CABG (P=0.02).

CONCLUSIONS

These results show that carvedilol is superior to metoprolol in decreasing development of early postoperative AF.

Prevention of atrial fibrillation following cardiac surgery: basis for a novel therapeutic strategy based on non-hypoxic myocardial preconditioning

Atrial fibrillation is the most common complication of cardiac surgical procedures performed with cardiopulmonary bypass. It contributes to increased hospital length of stay and treatment costs. At present, preventive strategies offer only suboptimal benefits, despite improvements in anesthesia, surgical technique, and medical therapy. The pathogenesis of postoperative atrial fibrillation is considered to be multifactorial. However oxidative stress is a major contributory factor representing the unavoidable consequences of ischemia/reperfusion cycle occurring in this setting. Considerable evidence suggests the involvement of reactive oxygen species (ROS) in the pathogenic mechanism of this arrhythmia. Interestingly, the deleterious consequences of high ROS exposure, such as inflammation, cell death (apoptosis/necrosis) or fibrosis, may be abrogated by a myocardial preconditioning process caused by previous exposure to moderate ROS concentration known to trigger survival response mechanisms. The latter condition may be created by n-3 PUFA supplementation that could give rise to an adaptive response characterized by increased expression of myocardial antioxidant enzymes and/or anti-apoptotic pathways. In addition, a further reinforcement of myocardial antioxidant defenses could be obtained through vitamins C and E supplementation, an intervention also known to diminish enzymatic ROS production. Based on this paradigm, this review presents clinical and experimental evidence supporting the pathophysiological and molecular basis for a novel therapeutic approach aimed to diminish the incidence of postoperative atrial fibrillation through a non-hypoxic preconditioning plus a reinforcement of the antioxidant defense system in the myocardial tissue.

Cardiovascular disease in dialysis patients: do some antihypertensive drugs have specific antioxidant effects or is it just blood pressure reduction? Does antioxidant treatment reduce the risk for cardiovascular disease?

PURPOSE OF REVIEW

Patients with end-stage renal disease have an extremely high cardiovascular disease mortality. Oxidative stress is one of the 'nontraditional' risk factors for cardiovascular disease mortality in dialysis patients. This review discusses antioxidant activity of the commonly prescribed antihypertensive agents and the effects of antioxidant interventions on cardiovascular disease mortality in patients with end-stage renal disease.

RECENT FINDINGS

Several lines of evidence confirm antioxidant activity of the renin-angiotensin-aldosterone antagonists, some of the calcium channel blockers, carvedilol, and hydralazine. This appears to be independent of their antihypertensive activity. Clinical evidence of their superiority in improving cardiovascular disease endpoints in end-stage renal disease, however, is lacking. There are no randomized trials that have examined the effect of correcting oxidative stress on clinical endpoints. One randomized study in patients on hemodialysis reported a reduction in oxidative stress and the plasma methylarginines with valsartan and amlodipine but no clinical endpoints were examined.

SUMMARY

The effects of the antihypertensive agents with antioxidant activity on cardiovascular disease mortality in end-stage renal disease have not been examined in randomized clinical trials. These agents may offer specific clinical advantage in addition to lowering the blood pressure, but this remains to be proven. Two studies show a reduction in cardiovascular disease events with vitamin E and N-acetylcysteine in patients on hemodialysis without an effect on overall mortality.

Vascular effects of long-term propranolol administration after chronic nitric oxide blockade

Long-term propranolol treatment reduces arterial blood pressure in hypertensive individuals mainly by reducing peripheral vascular resistance, but mechanisms underlying their vasodilatory effect remain poorly investigated. This study aimed to investigate whether long-term propranolol administration ameliorates the impairment of relaxing responses of aorta and mesenteric artery from rats made hypertensive by chronic nitric oxide (NO) deficiency, and underlying mechanisms mediating this phenomenon. Male Wistar rats were treated with N(omega)-Nitro-L-arginine methyl ester (L-NAME; 20 mg/rat/day) for four weeks. DL-Propranolol (30 mg/rat/day) was given concomitantly to L-NAME in the drinking water. Treatment with L-NAME markedly increased blood pressure, an effect largely attenuated by DL-propranolol. In phenylephrine-precontracted aortic rings, the reduction of relaxing responses for acetylcholine (0.001-10 microM) in L-NAME group was not modified by DL-propranolol, whereas in mesenteric rings the impairment of acetylcholine-induced relaxation by L-NAME was significantly attenuated by DL-propranolol. In mesenteric rings precontracted with KCl (80 mM), DL-propranolol failed to attenuate the impairment of acetylcholine-induced relaxation by L-NAME. The contractile responses to extracellular CaCl2 (1-10 mM) were increased in L-NAME group, and co-treatment with DL-propranolol reduced this response in both preparations in most Ca2+ concentrations used. The NO2/NO3 plasma levels and superoxide dismutase (SOD) activity were reduced in L-NAME-treated rats, both of which were significantly prevented by DL-propranolol. In conclusion, propranolol-induced amplification of the relaxation to acetylcholine in mesenteric arteries from L-NAME-treated rats is sensitive to depolarization. Additional mechanisms involving blockade of Ca2+ entry in the vascular smooth muscle and increase in NO bioavailability contributes to beneficial effects of long-term propranolol treatment.

Vasorelaxing effects of propranolol in rat aorta and mesenteric artery: a role for nitric oxide and calcium entry blockade

1. Propranolol has been prescribed successfully to patients with cardiovascular diseases, but the exact mechanisms by which it reduces peripheral vascular resistance have been poorly investigated. 2. The present study was designed to investigate the relaxing effects of propranolol in the rat isolated aorta and mesenteric artery, focusing on the contribution of the nitric oxide (NO)-cGMP pathway and calcium entry blockade. Relaxation responses to propranolol were obtained in precontracted rat aortic and mesenteric artery rings. 3. DL-Propranolol (10-100 micromol/L) produced concentration-dependent relaxations in the aorta and mesenteric artery rings with intact endothelium. The isomers D- and L-propranolol produced relaxation responses that were equipotent to the racemic mixture. 4. Metoprolol (10-100 micromol/L) produced slight relaxations, whereas atenolol (10-100 micromol/L) had no relaxant activity. 5. The NO inhibitor N(G)-nitro-L-arginine methyl ester (100 micromol/L) and the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (1 micromol/L), as well as removal of the endothelium, significantly reduced the relaxation responses induced by the lower concentrations of propranolol without affecting maximal responses. In addition, DL-propranolol markedly increased cGMP levels in endothelium-intact preparations. 6. In Ca(2+)-free Krebs' solution, DL-propranolol (10-100 micromol/L) caused marked rightward shift in the concentration-response curves to CaCl(2), with a decrease of maximal responses in tissues with either intact or denuded endothelium. Nifedipine (1 micromol/L) in combination with DL-propranolol virtually abolished the CaCl(2)-induced contractile responses. 7. The relaxation responses induced by DL-propranolol were significantly reduced in aortic and mesenteric rings precontracted with phorbol-12,13-dibutyrate (1 micromol/L). 8. In conclusion, DL-propranolol relaxes arterial smooth muscle by mechanisms involving activation of the NO-cGMP pathway and calcium influx blockade, independent of beta-adrenoceptor blockade.

Antioxidant activity of carvedilol in cardiovascular disease

Oxidative and inflammatory stresses are cardinal in the pathogenesis of hypertension and atherosclerosis. Oxidative stress also leads to the induction of inflammation through the activation of proinflammatory transcription factors. Understanding the mechanisms leading to oxidative stress and the means of suppressing it are important in controlling complications related to atherogenesis, since oxidative and inflammatory stress are important in the pathogenesis of atherosclerosis. The failure of chemical antioxidants [which scavenge reactive oxygen species (ROS)], such as vitamins E and C, has led to further exploration of the ROS-suppressive effects of drugs used in the treatment of cardiovascular disease. Carvedilol has been shown to possess both ROS-scavenging and ROS-suppressive effects, and its use is associated with a reduction in oxidative stress. Furthermore, anti-inflammatory effects of carvedilol have now been described. Although further clinical investigations are required, these properties may contribute to the improvement in clinical outcomes observed with carvedilol.

Carvedilol Increases Copper-Zinc Superoxide Dismutase Activity in Patients with Acute Myocardial Infarction

Balanced and coordinated antioxidant defence enzyme activities are of utmost importance for correct physiological function and for shielding against unwelcome pathological conditions. We determined the activities of copper-zinc superoxide dismutase (CuZnSOD), catalase, glutathione peroxidase and glutathione reductase in erythrocytes isolated from patients receiving different therapy (streptokinase alone or in combination with metoprolol or with carvedilol) for up to 168 hr after starting treatment for acute myocardial infarction. We observed increased CuZnSOD activity in erythrocytes isolated from patients treated with streptokinase-carvedilol (after 6, 24 and 168 hr) and in erythrocytes isolated from patients treated with streptokinase-metoprolol (after 24 hr). In addition, positive correlation between CuZnSOD and catalase activities was found in erythrocytes isolated from patients that received streptokinase-carvedilol after 168 hr. As metoprolol does not react directly with hydrogen peroxide, it would appear that combined streptokinase-metoprolol therapy exerted its effects primarily via by beta-blockade whereas combined streptokinase-carvedilol therapy appeared to function via both beta-blockade and direct antioxidant mechanisms.

Chronic treatment with carvedilol improves Ca(2+)-dependent ATP consumption in triton X-skinned fiber preparations of human myocardium

Evidence is given that beta-blocker treatment differentially influences gene expression and up-regulation of beta(1)-adrenoceptors in human myocardium. Here, we investigate whether long-term treatment with carvedilol or metoprolol may functionally alter myofibrillar function in end-stage human heart failure. Investigations were performed in Triton X (1%, 4 degrees C, 20 h)-skinned fiber preparations of explanted hearts from patients undergoing heart transplantation due to idiopathic dilative cardiomyopathy. Five patients were not on beta-adrenoceptor blocker treatment (DCM_NBB), and 5 patients received either carvedilol (DCM_CAR) or metoprolol (DCM_MET). Nonfailing (NF) donor hearts (n = 5), which could not be transplanted due to technical reasons, were investigated for comparison. Ca(2+)-dependent tension (DT) development and actomyosin-ATPase activity (MYO) were measured and tension-dependent ATP consumption was calculated by the ratio of DT and MYO ("tension cost"). In addition, we measured the phosphorylation of troponin I (TNI) by back phosphorylation. Maximal DT and TNI phosphorylation were reduced, with myofibrillar Ca(2+) sensitivity of DT and MYO as well as tension cost being increased in DCM_NBB compared with NF. Metoprolol treatment restored TNI phosphorylation, decreased Ca(2+) sensitivity of tension development and of myosin-ATPase activity, but did not alter the tension-dependent ATP consumption. Carvedilol treatment improved maximal DT and significantly decreased tension-dependent ATP consumption without altering myofibrillar Ca(2+) sensitivity. TNI dephosphorylation was increased in patients treated with carvedilol. In conclusion, chronic beta-adrenoceptor blockade functionally alters myofibrillar function. The more economic cross-bridge cycling in patients under carvedilol treatment may provide an explanation for the efficacy of carvedilol in the treatment of chronic heart failure patients.

Carvedilol Reduces Elevated B-type Natriuretic Peptide in Dialyzed Patients Without Heart Failure: Cardioprotective Effect of the β-blocker

Elevated plasma B-type natriuretic peptide (BNP) predicts future cardiovascular events in dialyzed patients without heart failure. We investigated whether carvedilol reduces the elevated BNP in these patients. Asymptomatic patients on chronic hemodialysis with elevated BNP but without clinical signs of heart failure were randomly assigned to receive either carvedilol (n = 10) or nothing (control group, n = 10). BNP and malondialdehyde-low density lipoprotein (MDA-LDL) were measured, and ultrasound cardiography was performed at baseline and at 3 months. Carvedilol reduced the concentrations of BNP (551 +/- 90 to 237 +/- 174 ng/L, P < 0.01) and MDA-LDL (174 +/- 63 to 85 +/- 23 U/L, P < 0.01) and increased the velocity ratio of E to A waves of the transmitral flow (E/A: 0.59 +/- 0.04 to 0.71 +/- 0.05, P < 0.05), while no such alterations were observed in the control group. The reduction in BNP concentration was correlated with that in MAD-LDL and the increase in the E/A. There was a significant correlation between the increase in the E/A and the reduction in MDA-LDL concentration. Thus, carvedilol reduces the elevated BNP by improving left ventricular diastolic function in dialyzed patients without heart failure, which may be attributable to the antioxidant property of the beta-blocker. Administering carvedilol may improve the prognosis in this population.

Bosentan: a review of its use in pulmonary arterial hypertension and systemic sclerosis

Bosentan (Tracleer), an orally administered dual endothelin (ET)(A) and ET(B) receptor antagonist, is indicated in the treatment of pulmonary arterial hypertension (PAH). The efficacy of oral bosentan 125 mg twice daily in improving exercise capacity has been demonstrated in well designed trials in adult patients with idiopathic PAH or PAH associated with connective tissue disease or congenital systemic-to-pulmonary shunts, and in other trials in patients with idiopathic PAH or PAH associated with congenital heart disease or HIV infection. The beneficial effects of first-line bosentan treatment may be maintained for up to 1 year in patients with idiopathic PAH or PAH associated with connective tissue disease. Despite the potential for treatment-related teratogenicity and hepatotoxicity, long-term data indicate that bosentan is generally well tolerated at the approved dosages. Although well designed trials are required to establish the efficacy of bosentan versus or in combination with other specific PAH therapies, especially sildenafil, the convenient oral administration and lack of serious injection-related adverse effects may render bosentan preferable to other PAH therapies. Preliminary data indicate that bosentan may be effective in pediatric PAH patients, although randomized trials are required. Furthermore, bosentan may be a useful option for the prevention of digital ulcer development in patients with systemic sclerosis. Thus, in accordance with current clinical guidelines, bosentan is a convenient, effective, and generally well tolerated agent for use in the first-line treatment of class III PAH or second-line treatment of class IV PAH.

Reducing the Risk of Sudden Death in Heart Failure With β-Blockers

BACKGROUND

Heart failure (HF) is a serious cardiovascular syndrome that affects nearly 5 million people in the United States. A review of clinical data demonstrates that sudden cardiac death (SCD) accounts for approximately one-third of all HF deaths. This fatal outcome typically involves an unexpected electrical event leading to sustained cardiac arrhythmias resulting in cardiovascular collapse.

METHODS AND RESULTS

A systematic review of the literature was performed to serve as the basis for this review. Factors contributing directly to incidence of SCD in the HF population may include significant remodeling of the left ventricle (hypertrophy, dilation, and fibrosis) in addition to increased sympathetic activation. Using specific therapies to limit these mechanisms are beneficial in the HF patient by preventing SCD. Beta-blockers play a key role in the prevention of SCD for patients with HF by limiting the effects of circulating norepinephrine and by reducing left ventricular remodeling.

CONCLUSIONS

This review outlines the potential mechanisms and contributing factors of SCD in patients with HF and the impact of beta-blocker usage in the prevention of this fatal outcome for this growing patient population.

Carvedilol Inhibits Mitochondrial Oxygen Consumption and Superoxide Production During Calcium Overload in Isolated Heart Mitochondria

BACKGROUND

The COMET study suggested the better effect of carvedilol to metoprolol in treating heart failure. However, its underlying mechanisms of action remain unclear. As a result, evaluation of the distinct effects of both drugs on the mitochondrial function and reactive oxygen species (ROS) production during Ca(2+) overload was investigated.

METHODS AND RESULTS

The mitochondrial oxygen consumption (mVO(2)) and the mitochondrial ROS production in isolated rat heart mitochondria was measured. Ca(2+) overload from 10 to 100 micromol/L augmented mVO(2) was from 527+/-139 to 671 +/-138 nmol/mg (p<0.05), and this was then completely suppressed by carvedilol (1 micromol/L), but not by metoprolol (100 micromol/L). Ca(2+) overload augmented the ROS production upon complex I injury (9.7+/-1.2 to 11.4+/-1.4 nmol/mg, p<0.05). Carvedilol dose-dependently suppressed this ROS production, whereas metoprolol did not.

CONCLUSIONS

Carvedilol, but not metoprolol, was thus found to inhibit the calcium-dependent augmentation of mVO(2) and ROS production upon complex I injury. This new effect of carvedilol might partly explain the beneficial effect of carvedilol for the treatment of heart failure.

Carvedilol in chronic heart failure: past, present and future

Large randomized clinical trials of bisoprolol, carvedilol and metoprolol have conclusively demonstrated the efficacy and confirmed safety of β-blockers in patients with chronic heart failure. Recently, the beneficial effects of carvedilol in patients with heart failure soon after an acute myocardial infarction have also been shown. Despite this, β-blockers remain under-prescribed in this condition. This is of particular importance as heart failure is common and increasing in prevalence. In this article, when to start β-blockade and which β-blocker to use is considered. Since carvedilol is the most studied β-blocker in heart failure and has a broad range of activities that extend beyond β-blockade, whether it has possible advantages over other β-blockers is discussed. Also, how the use of β-blockade might evolve with the introduction of device-related therapy in heart failure is considered.

Do metoprolol and carvedilol have equivalent effects on diurnal heart rate in patients with chronic heart failure?

BACKGROUND

Carvedilol exerted a greater reduction in mortality than metoprolol tartrate in the Carvedilol or Metoprolol European Trial (COMET). However, it is unclear if the degree and time course of beta1-blockade during a 24-h period was similar with each agent at the doses used. Therefore we analyzed 24-h ECG Holter recordings from a study which compared the long-term clinical efficacy of metoprolol tartrate to carvedilol in chronic heart failure patients using the same dosing regimen as in COMET.

METHODS AND RESULTS

Fifty-one patients with chronic heart failure with a mean LVEF 26+/-1.8% were randomized in a double-blind fashion to receive metoprolol tartrate 50 mg bid or carvedilol 25 mg bid. 24-h ECG monitoring (Holter) was performed at baseline, 12 weeks and 1 year. Adequate quality recordings for analysis were obtained from 43 subjects at baseline, 42 at 12 weeks and 29 subjects at 1 year. Both drugs produced a fall in average 24-h heart rate from baseline at 12 weeks and at 1 year: metoprolol 88+/-3 to 71+/-2 and 69+/-3 bpm; carvedilol 83+/-3 to 70+/-2 and 70+/-3 bpm respectively (all p<0.001). The pattern of suppression of heart rate during the 24-h period was similar for both drugs.

CONCLUSION

Metoprolol tartrate 50 mg bid and carvedilol 25 mg bid had similar effects on 24-h heart rate. This result suggests that the degree of beta1-blockade produced by these two drugs in these doses is comparable and the superior survival effect of carvedilol compared to metoprolol seen in COMET is likely to be due to actions of carvedilol other than beta1-blockade.

Increased reactive oxygen species production and functional alterations in antioxidant enzymes in human failing myocardium

BACKGROUND

The nature of oxidative stress and the activity of antioxidant enzyme systems are incompletely characterized in the failing human heart.

METHODS AND RESULTS

We obtained ventricular myocardium from failing, explanted human hearts in patients with nonischemic dilated cardiomyopathy at the time of heart transplant to examine whether reactive oxygen species (ROS) production and antioxidant enzyme activity or expression were altered in end-stage human heart failure. Nonfailing myocardium was obtained from organ donors who were not eligible for transplantation. Electroparamagnetic resonance (EPR) with the O(2)(-) spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide demonstrated that formation of superoxide anion was increased more than 2-fold in the failing (P < .001 vs. nonfailing) myocardium. Manganese superoxide dismutase (MnSOD) mRNA and catalase mRNA expression were increased by 52% (P=.05) and 116% (P < .05), respectively, in failing vs. nonfailing hearts. Copper-zinc superoxide dismutase (CuZnSOD) mRNA and glutathione peroxidase-1 (GPx-1) mRNA were unchanged. The expression of MnSOD, CuZnSOD, and catalase mRNA showed moderate correlation, suggesting coordinate regulation of gene expression. Activity was no different with regard to catalase, GPx-1, and glucose-6-phosphate dehydrogenase. MnSOD activity accounted for approximately 90% of total SOD activity, and was markedly decreased in failing hearts (by 61%, P < .05). MnSOD protein expression by western blot analysis was decreased in the failing group (P < .05 vs. nonfailing).

CONCLUSION

The decrease in MnSOD activity in failing myocardium, in the setting of increased mRNA expression, may reflect decreased translation or processing, or a posttranslational modification of MnSOD. The increase in MnSOD mRNA in failing hearts is consistent with the thesis that there is increased oxidative stress in failing myocardium that leads to increase transcription of antioxidant enzymes. The source of this direct measure of ROS is likely superoxide. These observations have implications for the pathophysiology and treatment of heart failure.

Resistance training for chronic heart failure patients on beta blocker medications

BACKGROUND

Resistance training increases the skeletal muscle strength and functional ability of chronic heart failure patients. However, there is limited data regarding the effect of resistance training on the hemodynamic responses and peak oxygen consumption (peak VO(2)) of chronic heart failure patients treated with beta-blocker. This study examined the effect of resistance training on hemodynamics, peak aerobic capacity, muscle strength and quality of life of chronic heart failure patients on beta-blockers medication.

METHODS

Fifteen men diagnosed with chronic heart failure were matched to either a resistance training program or non-training control group. At baseline and after 8 weeks of resistance training patients performed both Balke incremental and maximal strength tests and completed quality of life questionnaires.

RESULTS

The resistance training group demonstrated a significant increase of walking time and peak VO(2) by 11.7% (p=0.002) and approximately 19% (p<0.05), respectively. Peak VO(2) was significantly correlated with both walking time (r=0.54, p=0.038) and change in total weight lifted (r=0.55, p=0.034). Quality of life significantly increased by 87% (p=0.030). The improvement in quality of life was correlated with post training peak VO(2) (r=0.58, p=0.025) and total weight lifted during the post maximal strength test (r=-0.52, p=0.047).

CONCLUSIONS

The benefits from resistance training for chronic heart failure patients on beta-blocker medication included an increased aerobic and exercise capacity, skeletal muscle strength and most importantly, an improvement in the quality of life, which is the main goal of cardiac rehabilitation programs. Furthermore, with appropriate supervision, it is recommended that resistance exercise be added to the exercise rehabilitation program of these patients when possible.

Role of carvedilol in atrial fibrillation: insights from clinical trials

Atrial fibrillation affects approximately 2 million people in the United States and is a common comorbidity among patients with heart failure. Clinical studies indicate that the benefits of the beta-blocker carvedilol in patients with heart failure extend to patients with heart failure complicated by atrial fibrillation. The results of the Carvedilol in Atrial Fibrillation Evaluation (CAFE) trial provide support that carvedilol has incremental benefit when added to digoxin for the management of atrial fibrillation in patients with heart failure. Additional recent studies suggest that carvedilol may be useful in managing postsurgical atrial fibrillation and also may prevent recurrence of atrial fibrillation among patients who undergo cardioversion.