The antioxidative effects of long-term treatment are more pronounced for carvedilol than for atenolol in post-myocardial infarction patients

Influence of carvedilol and thyroid hormones on inflammatory proteins and cardioprotective factor HIF-1α in the infarcted heart

Inflammatory pathways of Toll-like receptor 4 (TLR4) and NLRP3 inflammasome contribute to acute myocardial infarction (AMI) pathophysiology. The hypoxia-inducible factor 1α (HIF-1α), however, is a key transcription factor related to cardioprotection. This study aimed to compare the influence of carvedilol and thyroid hormones (TH) on inflammatory and HIF-1α proteins and on cardiac haemodynamics in the infarcted heart. Male Wistar rats were allocated into five groups: sham-operated group (SHAM), infarcted group (MI), infarcted treated with the carvedilol group (MI + C), infarcted treated with the TH group (MI + TH), and infarcted co-treated with the carvedilol and TH group (MI + C + TH). Haemodynamic analysis was assessed 15 days post-AMI. The left ventricle (LV) was collected for morphometric and Western blot analysis. The MI group presented LV systolic pressure reduction, LV end-diastolic pressure elevation, and contractility index decrease compared to the SHAM group. The MI + C, MI + TH, and MI + C + TH groups did not reveal such alterations compared to the SHAM group. The MI + TH and MI + C + TH groups presented reduced MyD88 and NLRP3 and increased HIF-1α levels. In conclusion, all treatments preserve the cardiac haemodynamic, and only TH, as isolated treatment or in co-treatment with carvedilol, was able to reduce MyD88 and NLRP3 and increase HIF-1α in the infarcted heart.

Ischemia and no obstructive coronary arteries (INOCA): A narrative review

Myocardial ischemia with no obstructive coronary arteries (INOCA) is a chronic coronary syndrome condition that is increasingly being recognized as a substantial contributor to adverse cardiovascular mortality and outcomes, including myocardial infarction and heart failure with preserved ejection fraction (HFpEF). While INOCA occurs in both women and men, women are more likely to have the finding of INOCA and are more adversely impacted by angina, with recurrent hospitalizations and a lower quality of life with this condition. Abnormal epicardial coronary vascular function and coronary microvascular dysfunction (CMD) have been identified in a majority of INOCA patients on invasive coronary function testing. CMD can co-exist with obstructive epicardial coronary artery disease (CAD), diffuse non-obstructive epicardial CAD, and with coronary vasospasm. Epicardial vasospasm can also occur with normal coronary arteries that have no atherosclerotic plaque on intravascular imaging. While all predisposing factors are not clearly understood, cardiometabolic risk factors, and endothelium dependent and independent mechanisms that increase oxidative stress and inflammation are associated with microvascular injury, CMD and INOCA. Cardiac autonomic dysfunction has also been implicated in abnormal vasoreactivity and persistent symptoms. INOCA is under-recognized and under-diagnosed, partly due to the heterogenous patient populations and mechanisms. However, diagnostic testing methods are available to guide INOCA management. Treatment of INOCA is evolving, and focuses on cardiac risk factor control, improving ischemia, reducing atherosclerosis progression, and improving angina and quality of life. This review focuses on INOCA, relations to HFpEF, available diagnostics, current and investigational therapeutic strategies, and knowledge gaps in this condition.

Three Generations of β-blockers: History, Class Differences and Clinical Applicability

BACKGROUND

Beta-adrenergic receptors are expressed in cardiomyocytes and activated by either noradrenaline released from sympathetic synapses or circulating catecholamines. Their corresponding receptors have three subtypes, namely, β1, β2 and β3, which are members of the G protein-coupled receptors (GPCRs) family. Activation of β1-adrenergic receptors causes various physiological reactions including cardiac contraction and renin secretion from juxtaglomerular cells of the kidney. Antagonists of β-adrenergic receptors, known as β-blockers, have been used effectively for over four decades and have beneficial effects in the treatment of cardiovascular diseases. There are three generations of β-blockers according to their pharmacological properties. Firstgeneration β-blockers are non-selective, blocking both β1- and β2-receptors; second-generation β- blockers are more cardioselective in that they are more selective for β1-receptors; and thirdgeneration β-blockers are highly selective drugs for β1-receptors. The latter also display vasodilator actions by blocking α1-adrenoreceptors and activating β3-adrenergic receptors. In addition, thirdgeneration β-blockers exhibit angiogenic, antioxidant, anti-proliferative, anti-hypertrophic and antiapoptotic activities among other effects that are still under investigation.

CONCLUSION

The objective of this review is to describe the evolution observed during the development of the three distinctive generations, thereby highlighting the advantages of third-generation β- blockers over the other two drug classes.

The use of medications in the secondary prevention of coronary artery disease in the Asian region

BACKGROUND

Cardiovascular diseases, to which coronary artery disease (CAD) is a significant contributor, are a leading cause of long-term morbidity and mortality worldwide. In the years ahead, it is estimated that approximately half of the world's cardiovascular burden will occur in the Asian region. Currently there is a large gap in secondary prevention, with unrealized health gains resulting from underuse of evidence-based medications, including beta-blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), aspirin and other antiplatelet agents, and lipid-lowering drugs. Despite the almost universal recommendation for these drugs in unstable CAD, their under-prescription is well documented for patients with acute heart failure, non-obstructive CAD, and for secondary prevention of CAD.

OBJECTIVE

This article reviews the burden of CAD in Asian countries together with guidelines supporting evidence-based medication use from a secondary prevention perspective.

METHODS

The MEDLINE database was searched from 2000 to 2013, inclusive, for country-specific data related to CAD and supplemented with unpublished registry data.

RESULTS

In the post-discharge setting following hospital admission for acute coronary syndromes, medication prescription rates were low. Beta-blocker prescription rates ranged from 49% in China to 99% in Singapore, ACE-inhibitor/ARB prescription rates ranged from 28% in China to 96% in Singapore, and lipid-lowering therapy rates ranged from 47% in China to 97% in Singapore. Aspirin/antiplatelet drug prescription rates ranged from 86% in Indonesia to 99.5% in Singapore. Recommendations are provided to improve patient outcomes and reduce the disease burden in Asia.

CONCLUSIONS

Despite recommendations issued in international and national guidelines, use of CAD medications in Asia remains suboptimal. In the absence of clear contraindications, all patients with unstable CAD should receive these agents as secondary prevention. This averts the need to target drug use according to risk, with high-risk features paradoxically associated with under-prescribing of such drugs.

BAC CGH-array identified specific small-scale genomic imbalances in diploid DMBA-induced rat mammary tumors

BACKGROUND

Development of breast cancer is a multistage process influenced by hormonal and environmental factors as well as by genetic background. The search for genes underlying this malignancy has recently been highly productive, but the etiology behind this complex disease is still not understood. In studies using animal cancer models, heterogeneity of the genetic background and environmental factors is reduced and thus analysis and identification of genetic aberrations in tumors may become easier. To identify chromosomal regions potentially involved in the initiation and progression of mammary cancer, in the present work we subjected a subset of experimental mammary tumors to cytogenetic and molecular genetic analysis.

METHODS

Mammary tumors were induced with DMBA (7,12-dimethylbenz[a]anthrazene) in female rats from the susceptible SPRD-Cu3 strain and from crosses and backcrosses between this strain and the resistant WKY strain. We first produced a general overview of chromosomal aberrations in the tumors using conventional kartyotyping (G-banding) and Comparative Genome Hybridization (CGH) analyses. Particular chromosomal changes were then analyzed in more details using an in-house developed BAC (bacterial artificial chromosome) CGH-array platform.

RESULTS

Tumors appeared to be diploid by conventional karyotyping, however several sub-microscopic chromosome gains or losses in the tumor material were identified by BAC CGH-array analysis. An oncogenetic tree analysis based on the BAC CGH-array data suggested gain of rat chromosome (RNO) band 12q11, loss of RNO5q32 or RNO6q21 as the earliest events in the development of these mammary tumors.

CONCLUSIONS

Some of the identified changes appear to be more specific for DMBA-induced mammary tumors and some are similar to those previously reported in ACI rat model for estradiol-induced mammary tumors. The later group of changes is more interesting, since they may represent anomalies that involve genes with a critical role in mammary tumor development. Genetic changes identified in this work are at very small scales and thus may provide a more feasible basis for the identification of the target gene(s). Identification of the genes underlying these chromosome changes can provide new insights to the mechanisms of mammary carcinogenesis.

Use of carvedilol in hypertension: an update

β-blockers are effective antihypertensive agents and, together with diuretics, have been the cornerstone of pioneering studies showing their benefits on cardiovascular morbidity and mortality as a consequence of blood pressure reduction in patients with hypertension. However, evidence from recent meta-analyses have demonstrated no benefit afforded by atenolol compared with placebo in risk of mortality, myocardial infarction, or stroke, and a higher risk of mortality and stroke with atenolol/propranolol compared with other antihypertensive drug classes. Thus, the effect of these agents on cardiovascular morbidity and mortality in hypertensive patients, especially their use in uncomplicated hypertension, has remained largely controversial. However, it is recognized that the clinical studies used in these meta-analyses were mainly based on the older second-generation β-blockers, such as atenolol and metoprolol. Actually, considerable heterogeneity in, eg, pharmacokinetic, pharmacological, and physicochemical properties exists across the different classes of β-blockers, particularly between the second-generation and newer third-generation agents. Carvedilol is a vasodilating noncardioselective third-generation β-blocker, without the negative hemodynamic and metabolic effects of traditional β-blockers, which can be used as a cardioprotective agent. Compared with conventional β-blockers, carvedilol maintains cardiac output, has a reduced prolonged effect on heart rate, and reduces blood pressure by decreasing vascular resistance. Studies have also shown that carvedilol exhibits favorable effects on metabolic parameters, eg, glycemic control, insulin sensitivity, and lipid metabolism, suggesting that it could be considered in the treatment of patients with metabolic syndrome or diabetes. The present report provides an overview of the main clinical studies concerning carvedilol administered as either monotherapy or in combination with another antihypertensive or more frequently a diuretic agent, with particular focus on the additional benefits beyond blood pressure reduction.

Effect of felodipine with irbesartan or metoprolol on sexual function and oxidative stress in women with essential hypertension

OBJECTIVE

To evaluate the impact of felodipine with irbesartan on sexual function compared with felodipine with metoprolol in hypertensive women.

METHODS

This was a prospective, randomized, parallel, active-controlled, open-label study (ClinicalTrials.org: NCT01238705) in 160 women (18-60 years) with mild or moderate hypertension, randomized to a once-daily treatment with felodipine combined with irbesartan or metoprolol for 48 weeks. Patients' sexual function was evaluated using a female sexual function index (FSFI) questionnaire at baseline and after 24 and 48 weeks of therapy. Levels of serum estradiol, testosterone, 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA) were measured.

RESULTS

The two combination regimens were similarly effective in lowering blood pressure. After 48 weeks, in felodipine-irbesartan group, total scores of FSFI improved (P < 0.001). Items showing improvement in scores corresponded to desire, arousal and orgasm (P < 0.001; P = 0.002; P = 0.049, respectively). Levels of estradiol increased under treatment with felodipine-irbesartan (P = 0.003) and decreased under felodipine-metoprolol treatment (P < 0.001). The concentration of testosterone declined after felodipine-irbesartan therapy (P < 0.001) and increased under felodipine-metoprolol treatment (P < 0.001). In the felodipine-irbesartan group, decreases of 8-OHdG, 4-HNE (P < 0.001) and MDA (P < 0.001) were observed. The felodipine-irbesartan combination resulted in less oxidative stress. The differences in changes in 8-OHdG, 4-HNE and MDA between the two groups were significant (P < 0.05).

CONCLUSION

These results suggested that the felodipine-irbesartan combination regimen improved sexual function in hypertensive women, whereas felodipine-metoprolol regiment did not. The reason for the different influence of these two combination therapy on female sexual function might be their different impacts on oxidative stress and hormone levels.

Oxidative stress and vascular function: implications for pharmacologic treatments

Production of considerable amounts of reactive oxygen species (ROS) eventually leads to oxidative stress. A key role of oxidative stress is evident in the pathologic mechanisms of endothelial dysfunction and associated cardiovascular diseases. Vascular enzymes such as NADPH oxidases, xanthine oxidase, and uncoupled endothelial nitric oxide synthase are involved in the production of ROS. The question remains whether pharmacologic approaches can effectively combat the excessive ROS production in the vasculature. Interestingly, existing registered cardiovascular drugs can directly or indirectly act as antioxidants, thereby preventing the damaging effects of ROS. Moreover, new compounds targeting NADPH oxidases have been developed. Finally, food-derived compounds appear to be effective inhibitors of oxidative stress and preserve vascular function.

Coadministration of carvedilol attenuates nitrate tolerance by preventing cytochrome p450 depletion

BACKGROUND

Long-term administration of nitroglycerin (NTG) causes tolerance secondary to increased vascular formation of reactive oxygen species. Carvedilol, which has potent antioxidant activity in addition to functioning as an adrenergic blocker, prevents nitrate tolerance by a still to be elucidated mechanism. The present study investigated how carvedilol attenuates nitrate tolerance, particularly with reference to cytochrome P450 (CYP), an enzyme involved in the development of tolerance.

METHODS AND RESULTS

Male Wistar rats were subjected to 48-h continuous infusion of NTG alone (0.5 mg/h) or NTG with concomitant carvedilol (20 or 100 microg/h), and then compared with vehicle-treated rats (4 groups; n=6 in each group). Following the continuous administration, nitrate tolerance, assessed by bolus NTG injections, was hemodynamically prevented by coadministration of carvedilol. Levels of CYP1A1/1A2, superoxide production, and phosphorylated vasodilator-stimulated phosphoprotein at serine 239 (P-VASP) were examined in the aortic wall and heart tissue. When NTG alone was continuously administered, vascular superoxide was produced, there was a decrease in the cardiac CYP1A1/1A2 level, and depletion of P-VASP. However, each of these changes induced by continuous NTG administration was significantly attenuated by coadministration of carvedilol and the extent of attenuation was more pronounced at the higher dose (100 microg/h).

CONCLUSIONS

Coadministration of carvedilol attenuates nitrate tolerance through maintenance of NO/cGMP pathway activity by preventing free radical generation and CYP depletion.

Effect of carvedilol on coronary flow reserve in patients with hypertensive left-ventricular hypertrophy

OBJECTIVE

Patients with hypertensive left-ventricular hypertrophy (LVH) have lower coronary flow reserve (CFR). Whether carvedilol can improve CFR of patients with hypertensive LVH is unknown. We aimed to investigate the effects of carvedilol on CFR in patients with hypertensive LVH.

METHODS

Sixty-three patients were randomly divided into two groups for treatment with carvedilol or metoprolol. The peak diastolic coronary flow velocity in the left anterior descending coronary artery at rest and at maximal vasodilation with dipyridamole infusion was recorded by transesophageal echocardiography (TEE), then CFR was calculated at baseline and at the end of 6 months of therapy. Left-ventricular mass index (LVMI) was calculated by 2-D echocardiography. Endothelium-dependent and -independent reactivity of the brachial artery was measured. Levels of plasma endothelin-1 (ET1), nitric oxide (NO) and other metabolites were monitored and analyzed before and after 6-month therapy.

RESULTS

Both blood pressure and heart rate decreased significantly in the two treatment groups after therapy (p<0.05). With carvedilol treatment, LVMI was lower (p<0.05), endothelium function of the brachial artery was higher (p<0.05), and peak diastolic coronary flow velocity at rest and at maximal vasodilation after dipyridamole infusion was significantly higher (p<0.05) than with metoprolol treatment, which led to a significantly higher CFR (p<0.05). Changes in CFR and LVMI with carvedilol treatment were inversely correlated (R(2)=0.474, p=0.036). With carvedilol treatment, plasma level of ET-1 was lower, but that of NO was significantly higher than with metoprolol treatment (both p<0.05).

CONCLUSIONS

The CFR of patients with hypertensive LVH but not coronary artery disease could increase with 6-month carvedilol therapy.

Serum oxidative stress level correlates with clinical parameters in chronic systolic heart failure patients

BACKGROUND

Serum oxidative stress (OS) level has an important role in the inflammatory process of heart failure.

HYPOTHESIS

The study was designed to analyze serum OS levels in chronic heart failure (HF) patients and to examine the relation between OS levels and other clinical and prognostic parameters of HF.

METHODS

We studied 82 consecutive chronic symptomatic HF patients with systolic LV dysfunction (ejection fraction <45%). The serum OS level was determined using thermochemiluminescence assay. We compared the serum OS levels with patients' clinical and prognostic parameters.

RESULTS

Higher serum OS levels were associated with higher New York Heart Association class (P = .01), worse renal function (serum urea, creatinine, and creatinine clearance) (P<.001) and higher serum levels of hs-C-reactive protein and N-terminal pro brain natriuretic peptide (P = .001, P<.001, respectively).

CONCLUSIONS

In chronic systolic HF patients, high serum OS levels correlate with advanced disease and known markers of poor prognosis.

The effects of different beta-blockers on left-ventricular volume and function after primary coronary stenting in acute myocardial infarction

The beneficial effect of beta-blockers is reported in myocardial infarction (MI). This study compared the effects of propranolol and carvedilol on left-ventricular (LV) volume and function after acute MI. Serial echocardiographic studies were performed on acute MI patients who were treated with primary coronary stenting and medical treatment, including propranolol or carvedilol. Determinants of the changes in LV volume and function were identified by regression analyses. At 6 months, there was no significant difference in change in the LV end-diastolic volume between patients receiving 2 beta-blockers. The increase of LV ejection fraction was greater in patients receiving carvedilol. On multivariate analyses, it was found that the kind of beta-blocker had no significant influence on the changes in LV volume or ejection fraction, whereas gender and baseline LV ejection fraction were predictive of change in LV ejection fraction. Compared with propranolol, carvedilol did not have a significant benefit on LV remodeling or function after primary coronary stenting in acute MI.