Calcium channel blocker nifedipine slows down progression of coronary calcification in hypertensive patients compared with diuretics

Interventions to Attenuate Cardiovascular Calcification Progression: A Systematic Review of Randomized Clinical Trials

BACKGROUND

Cardiovascular calcification, characterized by deposition of calcium phosphate in the arterial wall and heart valves, is associated with cardiovascular morbidity and mortality and is commonly seen in aging, diabetes, and chronic kidney disease. Whether evidence-based interventions could significantly attenuate cardiovascular calcification progression remains uncertain.

METHODS AND RESULTS

We conducted a systematic review of randomized controlled trials involving interventions, compared with placebo, another comparator, or standard of care, to attenuate cardiovascular calcification. Included clinical trials involved participants without chronic kidney disease, and the outcome was cardiovascular calcification measured using radiological methods. Quality of evidence was determined by the Cochrane risk of bias and Grading of Recommendations, Assessment, Development, and Evaluations assessment. Forty-nine randomized controlled trials involving 9901 participants (median participants 104, median duration 12 months) were eligible for inclusion. Trials involving aged garlic extract (n=6 studies) consistently showed attenuation of cardiovascular calcification. Trials involving 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (n=14), other lipid-lowering agents (n=2), hormone replacement therapies (n=3), vitamin K (n=5), lifestyle measures (n=4), and omega-3 fatty acids (n=2) consistently showed no attenuation of cardiovascular calcification with these therapies. Trials involving antiresorptive (n=2), antihypertensive (n=2), antithrombotic (n=4), and hypoglycemic agents (n=3) showed mixed results. Singleton studies involving salsalate, folate with vitamin B6 and 12, and dalcetrapib showed no attenuation of cardiovascular calcification. Overall, Cochrane risk of bias was moderate, and the Grading of Recommendations, Assessment, Development, and Evaluations assessment for a majority of analyses was moderate certainty of evidence.

CONCLUSIONS

Currently, there are insufficient or conflicting data for interventions evaluated in clinical trials for mitigation of cardiovascular calcification. Therapy involving aged garlic extract appears most promising, but evaluable studies were small and of short duration.

Vascular calcification: Molecular mechanisms and therapeutic interventions

Vascular calcification (VC) is recognized as a pathological vascular disorder associated with various diseases, such as atherosclerosis, hypertension, aortic valve stenosis, coronary artery disease, diabetes mellitus, as well as chronic kidney disease. Therefore, it is a life-threatening state for human health. There were several studies targeting mechanisms of VC that revealed the importance of vascular smooth muscle cells transdifferentiating, phosphorous and calcium milieu, as well as matrix vesicles on the progress of VC. However, the underlying molecular mechanisms of VC need to be elucidated. Though there is no acknowledged effective therapeutic strategy to reverse or cure VC clinically, recent evidence has proved that VC is not a passive irreversible comorbidity but an active process regulated by many factors. Some available approaches targeting the underlying molecular mechanism provide promising prospects for the therapy of VC. This review aims to summarize the novel findings on molecular mechanisms and therapeutic interventions of VC, including the role of inflammatory responses, endoplasmic reticulum stress, mitochondrial dysfunction, iron homeostasis, metabolic imbalance, and some related signaling pathways on VC progression. We also conclude some recent studies on controversial interventions in the clinical practice of VC, such as calcium channel blockers, renin-angiotensin system inhibitions, statins, bisphosphonates, denosumab, vitamins, and ion conditioning agents.

Subclinical Hypertension-Mediated Organ Damage (HMOD) in Hypertension: Atherosclerotic Cardiovascular Disease (ASCVD) and Calcium Score

Calcium controls numerous events within the vessel wall. Permeability of the endothelium is calcium dependent, as are platelet activation and adhesion, vascular smooth muscle proliferation and migration, and synthesis of fibrous connective tissue. Double-helix computerized tomography is a noninvasive technique that can detect, measure, and compare coronary calcification in the coronary arteries. Despite some convincing evidence about the prognostic value and usefulness of coronary artery calcium score (CACS) in the stratification of cardiovascular risk in the high risk general population and also in hypertensive patients, current guidelines for the management of hypertension, do not include such evaluation among the recommended procedures to be performed in the majority of patients even with the intent to detect hypertension-mediated organ damage (HMOD) in an early phase. On the contrary, the European Society of Cardiology guidelines for the diagnosis and management of chronic coronary syndromes, the 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease, and the 2018 Cholesterol Clinical Practice Guidelines indicate that the evaluation of CACS may be of some usefulness in specific subpopulations, although this view is not accepted in the US Preventive Services Task Force document. Very recently, the European Society of Cardiology Guidelines on cardiovascular disease prevention in clinical practice stated that CACS estimation may be considered to improve risk classification around treatment decision thresholds. In conclusion, the use of CACS as a diagnostic tool is still controversial. While some evidence exists about is ability to improve stratification of cardiovascular risk in primary prevention, in particular in selected patients who are at intermediate or borderline risk of atherosclerotic cardiovascular disease, there is insufficient evidence to use it as a standard means to assess HMOD.

Effect of Calcium Channel Blockers versus Diuretics for Hypertension

Background

Although calcium channel blockers (CCBs) are recognized as clinical first-line agents for the treatment of hypertension, their use in combination with diuretics in cardiovascular disease caused by hypertension remains controversial.

Methods

We searched the three major databases of the Cochrane Library, EMBASE, and PubMed for the terms “calcium channel blockers,” “thiazide diuretics,” “loop diuretics,” and “hypertension,” “randomized controlled trials” and “meta-analysis trials.” These terms were searched from January 1991 to October 2021.

Results

For the primary outcome, in 5 studies including 35,057 patients, there was no statistically significant difference in all-cause mortality with calcium channel blockers compared with diuretics (RR = 0.98, 95% CI 0.92–1.04, I² = 0). In four studies including 33,643 patients with major cardiovascular events, there was no statistically significant difference in major cardiovascular events with calcium channel blockers compared with diuretics (RR = 1.00, 95% CI 1.04–1.09, I² = 0).

Conclusion

There is no statistically significant difference between calcium channel blockers and diuretics in terms of cardiovascular clinical prognosis in hypertensive patients, but there are positive implications for clinical guidance, which need to be fully validated in new large randomized controlled trials.

Genetic Contributors of Efficacy and Adverse Metabolic Effects of Chlorthalidone in African Americans from the Genetics of Hypertension Associated Treatments (GenHAT) Study

Hypertension is a leading risk factor for cardiovascular disease mortality. African Americans (AAs) have the highest prevalence of hypertension in the United States, and to alleviate the burden of hypertension in this population, better control of blood pressure (BP) is needed. Previous studies have shown considerable interpersonal differences in BP response to antihypertensive treatment, suggesting a genetic component. Utilizing data from 4297 AA participants randomized to chlorthalidone from the Genetics of Hypertension Associated Treatments (GenHAT) study, we aimed to identify variants associated with the efficacy of chlorthalidone. An additional aim was to find variants that contributed to changes in fasting glucose (FG) in these individuals. We performed genome-wide association analyses on the change of systolic and diastolic BP (SBP and DBP) over six months and FG levels over 24 months of treatment. We sought replication in the International Consortia of Pharmacogenomics Studies. We identified eight variants statistically associated with BP response and nine variants associated with FG response. One suggestive LINC02211-CDH9 intergenic variant was marginally replicated with the same direction of effect. Given the impact of hypertension in AAs, this study implies that understanding the genetic background for BP control and glucose changes during chlorthalidone treatment may help prevent adverse cardiovascular events in this population.

Association of Matrix Metalloproteinase-2 (MMP-2) and MMP-9 Promoter Polymorphisms, Their Serum Levels, and Activities with Coronary Artery Calcification (CAC) in an Iranian Population

The serum levels and activity of matrix metalloproteinases (MMPs) are associated with the risk of coronary artery calcification (CAC). We sought to investigate the association between MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs with MMP-2 and MMP-9 serum levels and activity in individuals with CAC. One hundred and fifty-five cases with CAC and 155 healthy individuals as control group from West of Iran were included and frequency of genotypes and alleles of rs243866 and rs3918242 in MMP-2 and MMP-9 genes were determined using PCR-RFLP. We also investigated the serum levels of MMP-2 and MMP-9 and their activity using ELISA and gelatin zymography, respectively. Additionally, serum biochemical parameters including FBS (fasting blood sugar), urea, creatinine, cholesterol, triglyceride, HDL (high-density lipoprotein), LDL (low-density lipoprotein), calcium, and phosphorus as well as blood pressure (systolic blood pressure (SBP) and diastolic blood pressure (DBP)) were measured. Our results showed that both serum levels of MMP-2 and MMP-9 (P < 0.001) and their activity (P < 0.001) were higher in individuals with CAC when compared to the control group. Carrying A and T alleles in MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs, respectively, may predispose the individuals to CAC by acting as the risk factors. Serum levels and activity of MMP-2 and MMP-9 were found to be higher in CAC cases when compared to the healthy controls. Carriers of A allele in rs243866 SNP and T allele in rs3918242 SNP were shown to have higher MMP-2 and MMP-9 serum levels and activity that may result in increased ECM degradation and support the initiation and development of calcification.

Gut Microbiome, Functional Food, Atherosclerosis, and Vascular Calcifications-Is There a Missing Link?

The gut microbiome is represented by the genome of all microorganisms (symbiotic, potential pathogens, or pathogens) residing in the intestine. These ecological communities are involved in almost all metabolic diseases and cardiovascular diseases are not excluded. Atherosclerosis, with a continuously increasing incidence in recent years, is the leading cause of coronary heart disease and stroke by plaque rupture and intraplaque hemorrhage. Vascular calcification, a process very much alike with osteogenesis, is considered to be a marker of advanced atherosclerosis. New evidence, suggesting the role of dietary intake influence on the diversity of the gut microbiome in the development of vascular calcifications, is highly debated. Gut microbiota can metabolize choline, phosphatidylcholine, and L-carnitine and produce vasculotoxic metabolites, such as trimethylamine-N-oxide (TMAO), a proatherogenic metabolite. This review article aims to discuss the latest research about how probiotics and the correction of diet is impacting the gut microbiota and its metabolites in the atherosclerotic process and vascular calcification. Further studies could create the premises for interventions in the microbiome as future primary tools in the prevention of atherosclerotic plaque and vascular calcifications.

Circulatory microRNA expression profile for coronary artery calcification in chronic kidney disease patients

BACKGROUND & AIM

Coronary artery disease (CAD) is the primary cause of mortality in patients with end stage renal disease (ESRD). MicroRNA profiling is proven as a powerful tool in the diagnosis of any disease at the molecular level. Hence, the present study aimed to profile the microRNA expression for CAD especially coronary artery calcification in CKD patients.

MATERIALS AND METHODS

Two hundread patients with CKD stages 3 to 5 without dialysis and healthy controls were included in this study. All two hundred patients underwent 1024 multi sliceardiac computed tomography (CT) scan for calcium scoring. The calcium scoring more than 100 have been included in the study. We performed miRNA microarray analysis from serum samples of seven high calcium scored with CKD patients and one control patients.

RESULTS

Seven patients have observed circulating miRNAs has significantly upregulated and downregulated when compared with control patients. mir21, mir 67, mir 390, mir 56, mir 250, mir 65 and mir 13 were up regulated and mir235, mir256, mir226, mir207, mir255, mir193 were downregulated. There was no significant difference in left ventricle function.

CONCLUSION

13 microRNAs play a potential role in coronary artery calcification in CKD patients.

Mitochondrial Dysfunction: Cause or Consequence of Vascular Calcification?

Mitochondria are crucial bioenergetics powerhouses and biosynthetic hubs within cells, which can generate and sequester toxic reactive oxygen species (ROS) in response to oxidative stress. Oxidative stress-stimulated ROS production results in ATP depletion and the opening of mitochondrial permeability transition pores, leading to mitochondria dysfunction and cellular apoptosis. Mitochondrial loss of function is also a key driver in the acquisition of a senescence-associated secretory phenotype that drives senescent cells into a pro-inflammatory state. Maintaining mitochondrial homeostasis is crucial for retaining the contractile phenotype of the vascular smooth muscle cells (VSMCs), the most prominent cells of the vasculature. Loss of this contractile phenotype is associated with the loss of mitochondrial function and a metabolic shift to glycolysis. Emerging evidence suggests that mitochondrial dysfunction may play a direct role in vascular calcification and the underlying pathologies including (1) impairment of mitochondrial function by mineral dysregulation i.e., calcium and phosphate overload in patients with end-stage renal disease and (2) presence of increased ROS in patients with calcific aortic valve disease, atherosclerosis, type-II diabetes and chronic kidney disease. In this review, we discuss the cause and consequence of mitochondrial dysfunction in vascular calcification and underlying pathologies; the role of autophagy and mitophagy pathways in preventing mitochondrial dysfunction during vascular calcification and finally we discuss mitochondrial ROS, DRP1, and HIF-1 as potential novel markers and therapeutic targets for maintaining mitochondrial homeostasis in vascular calcification.

Role of Inflammation in Arterial Calcification

Arterial calcification, characterized by calcium phosphate deposition in the arteries, can be divided into intimal calcification and medial calcification. The former is the predominant form of calcification in coronary artery plaques; the latter mostly affects peripheral arteries and aortas. Both forms of arterial calcification have strong correlations with adverse cardiovascular events. Intimal microcalcification is associated with increased risk of plaque disruption while the degree of burden of coronary calcification, measured by coronary calcium score, is a marker of overall plaque burden. Continuous research on vascular calcification has been performed during the past few decades, and several cellular and molecular mechanisms and therapeutic targets were identified. However, despite clinical trials to evaluate the efficacy of drug therapies to treat vascular calcification, none have been shown to have efficacy until the present. Therefore, more extensive research is necessary to develop appropriate therapeutic strategies based on a thorough understanding of vascular calcification. In this review, we mainly focus on intimal calcification, namely the pathobiology of arterial calcification, and its clinical implications.

Abdominal aortic calcification: from ancient friend to modern foe

Background

Abdominal aortic calcifications were already ubiquitous in ancient populations from all continents. Although nowadays generally considered as an innocent end stage of stabilised atherosclerotic plaques, increasing evidence suggests that arterial calcifications contribute to cardiovascular risk. In this review we address abdominal aortic calcification from an evolutionary perspective and review the literature on histology, prevalence, risk factors, clinical outcomes and pharmacological interventions of abdominal aortic calcification.

Design

The design of this study was based on a literature review.

Methods

Pubmed and Embase were systematically searched for articles on abdominal aortic calcification and its synonyms without language restrictions. Articles with data on histology, prevalence, risk factors clinical outcomes and/or pharmacological interventions were selected.

Results

Abdominal aortic calcification is highly prevalent in the general population and prevalence and extent increase with age. Prevalence and risk factors differ between males and females and different ethnicities. Risk factors include traditional cardiovascular risk factors and decreased bone mineral density. Abdominal aortic calcification is shown to contribute to arterial stiffness and is a strong predictor of cardiovascular events and mortality. Several therapies to inhibit arterial calcification have been developed and investigated in small clinical trials.

Conclusions

Abdominal aortic calcification is from all eras and increasingly acknowledged as an independent contributor to cardiovascular disease. Large studies with long follow-up must be carried out to show whether inhibition of abdominal aortic calcification will further reduce cardiovascular risk.

Pharmacological and Nutritional Modulation of Vascular Calcification

Vascular calcification is an independent predictor of cardiovascular disease, and therefore, inhibition or regression of this processes is of clinical importance. The standard care regarding prevention and treatment of cardiovascular disease at this moment mainly depends on drug therapy. In animal and preclinical studies, various forms of cardiovascular drug therapy seem to have a positive effect on vascular calcification. In particular, calcium channel blockers and inhibitors of the renin-angiotensin-aldosteron system slowed down arterial calcification in experimental animals. In humans, the results of trials with these drugs are far less pronounced and often contradictory. There is limited evidence that the development of new atherosclerotic lesions may be retarded in patients with coronary artery disease, but existing lesions can hardly be influenced. Although statin therapy has a proven role in the prevention and treatment of cardiovascular morbidity and mortality, it is associated with both regression and acceleration of the vascular calcification process. Recently, nutritional supplements have been recognized as a potential tool to reduce calcification. This is particularly true for vitamin K, which acts as an inhibitor of vascular calcification. In addition to vitamin K, other dietary supplements may also modulate vascular function. In this narrative review, we discuss the current state of knowledge regarding the pharmacological and nutritional possibilities to prevent the development and progression of vascular calcification.

Calcium Signaling and Tissue Calcification

Calcification is a regulated physiological process occurring in bones and teeth. However, calcification is commonly found in soft tissues in association with aging and in a variety of diseases. Over the last two decades, it has emerged that calcification occurring in diseased arteries is not simply an inevitable build-up of insoluble precipitates of calcium phosphate. In some cases, it is an active process in which transcription factors drive conversion of vascular cells to an osteoblast or chondrocyte-like phenotype, with the subsequent production of mineralizing "matrix vesicles." Early studies of bone and cartilage calcification suggested roles for cellular calcium signaling in several of the processes involved in the regulation of bone calcification. Similarly, calcium signaling has recently been highlighted as an important component in the mechanisms regulating pathological calcification. The emerging hypothesis is that ectopic/pathological calcification occurs in tissues in which there is an imbalance in the regulatory mechanisms that actively prevent calcification. This review highlights the various ways that calcium signaling regulates tissue calcification, with a particular focus on pathological vascular calcification.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Granzyme B deficiency promotes osteoblastic differentiation and calcification of vascular smooth muscle cells in hypoxic pulmonary hypertension

Calcification is a major risk factor for vascular integrity. This pathological symptom and the underlying mechanisms in hypoxic pulmonary artery hypertension remain elusive. Here we report that pulmonary vascular medial calcification is elevated in pulmonary artery hypertension models as a result of an osteoblastic phenotype change of pulmonary arterial smooth muscle cells induced by hypoxia. Notably, inhibiting store-operated calcium channels significantly decreased osteoblastic differentiation and calcification of pulmonary arterial smooth muscle cells under hypoxia. We identified granzyme B, a major constituent of cytotoxic T lymphocytes/natural killer cell granules involved in apoptosis, as the main regulator of pulmonary arterial calcification. Overexpression of granzyme B blocked the mineralization through its effect on store-operated calcium channels in cultured pulmonary arterial smooth muscle cells under hypoxic conditions. Mice with overexpression of granzyme B exposed to hypoxia for 3 weeks showed attenuated vascular calcification and pathological progression of hypoxic pulmonary arterial hypertension. Our findings emphasize the central function of granzyme B in coordinating vascular calcification in hypoxic pulmonary arterial hypertension.

Left Ventricular Hypertrophy Predicts Cardiovascular Events in Hypertensive Patients With Coronary Artery Calcifications

BACKGROUND

Coronary artery calcification (CAC) is associated with increased cardiovascular (CV) risk. Left ventricular hypertrophy (LVH) is an independent risk factor for CV events. Our aim was to estimate the relative CV risk of LVH in the presence of CAC.

METHODS

We included asymptomatic hypertensive patients who were enrolled in the calcification arm of the INSIGHT (International Nifedipine Study Intervention as Goal for Hypertension Therapy). Patients had baseline echocardiography and computed tomography to assess CAC. The primary end-point was the first CV event.

RESULTS

Two hundred and fifty-two subjects (mean age 64.7 ± 5.5 years, 54% men) were followed for a mean of 13.3 ± 2.6 years. 72 patients (28.5%) had LVH and 159 patients (63%) had CAC. During follow up, 89 patients had a first CV event. The rate of CV events was higher in those with than in those without CAC (43.4% vs. 21.5%, P < 0.01) and in those with than in those without LVH (44% vs. 31.6%, P < 0.01). However, LVH had no effect on CV events in the absence of CAC, whereas LVH almost doubled the rate of CV events (61.4% vs. 36.5%, P < 0.01) in the presence of CAC. In comparison to patients without CAC and without LVH the hazard ratio for CV event in those with LVH was 1.46 (95% confidence interval [CI], 0.50-4.21) in those without CAC and 4.4 (95% CI, 2.02-9.56) in those with CAC.

CONCLUSIONS

LVH and CAC independently predict CV events in asymptomatic hypertensive patients. However, the risk of LVH is mainly observed in those with CAC.

Dietary potassium regulates vascular calcification and arterial stiffness

Vascular calcification is a risk factor that predicts adverse cardiovascular complications of several diseases including atherosclerosis. Reduced dietary potassium intake has been linked to cardiovascular diseases such as hypertension and incidental stroke, although the underlying molecular mechanisms remain largely unknown. Using the ApoE-deficient mouse model, we demonstrated for the first time to our knowledge that reduced dietary potassium (0.3%) promoted atherosclerotic vascular calcification and increased aortic stiffness, compared with normal (0.7%) potassium-fed mice. In contrast, increased dietary potassium (2.1%) attenuated vascular calcification and aortic stiffness. Mechanistically, reduction in the potassium concentration to the lower limit of the physiological range increased intracellular calcium, which activated a cAMP response element-binding protein (CREB) signal that subsequently enhanced autophagy and promoted vascular smooth muscle cell (VSMC) calcification. Inhibition of calcium signals and knockdown of either CREB or ATG7, an autophagy regulator, attenuated VSMC calcification induced by low potassium. Consistently, elevated autophagy and CREB signaling were demonstrated in the calcified arteries from low potassium diet-fed mice as well as aortic arteries exposed to low potassium ex vivo. These studies established a potentially novel causative role of dietary potassium intake in regulating atherosclerotic vascular calcification and stiffness, and uncovered mechanisms that offer opportunities to develop therapeutic strategies to control vascular disease.

Clinical roles of calcium channel blockers in ischemic heart diseases

Calcium (Ca) channel blockers (CCBs) inhibit Ca²⁺ channels in the myocardium or vascular smooth muscle cells, inhibit myocardium contraction, inhibit the impulse conduction system (anti-arrhythmias) and cause vasodilation. New classifications based on subtypes of Ca channels and α1 subunits have been proposed. Moreover, CCBs have pleiotropic effects on coronary spastic angina (CSA), including variant angina, myocardial infarction (MI) and stent thrombosis (ST). Although the roles of CCBs in clinical situations remain unknown, further studies in this field are expected to broaden our understanding. In this article, we explain the clinical roles of CCBs in ischemic heart diseases, such as CSA, MI and ST, based on previous knowledge and as demonstrated in representative clinical trials.

Foot Gangrene in Patients with End-Stage Renal Disease: A Case Control Study

The prevalence of peripheral arterial disease (PAD) in patients with end-stage renal disease (ESRD) is high, with an annual risk of amputation estimated at 13%, and indications for limb revascularization in patients combining ESRD with stage IV PAD (foot gangrene) are still controversial. This case-controlled study compared survival, limb salvage, and quality of life in a group of patients hospitalized for foot gangrene according to their renal status (ESRD versus no renal insufficiency). All patients with ESRD hospitalized for foot gangrene (n=16) from 1996 to 2002 were compared with a control group with normal creatininemia (n=24) hospitalized for foot gangrene due to peripheral atherosclerotic arterial disease. The 2 groups were matched for age, sex ratio, and number with diabetes mellitus. After a mean follow-up of 467 ±410 days, patients with ESRD had a more severe prognosis as regards mortality (68.7% vs 12.5%, p=0.0005) and major amputation (31% versus 8%, p=0.09). The ESRD group was characterized by more frequent extensive arterial calcifications (16/16 vs 13/24, p=0.002), owing to a higher level of the calcium phosphorus product (3.54 ±1.2 vs 2.4 ±0.6, p=0.0023), and by impaired microcirculatory perfusion, as indicated by a lower oxygen pressure (TcPO2) (15.6 ±12 mm Hg vs 26 ±16, p=0.07). ESRD implies a poor prognosis in patients with stage IV peripheral arterial disease.

Clinical imaging of vascular disease in chronic kidney disease

Arterial wall calcification, once considered an incidental finding, is now known to be a consistent and strong predictor of cardiovascular events in patients with chronic renal insufficiency. It is also commonly encountered in radiologic examinations as an incidental finding. Forthcoming bench, translational, and clinical data seek to establish this and pre-calcification changes as surrogate imaging biomarkers for noninvasive prognostication and treatment follow-up. Emerging paradigms seek to establish vascular calcification as a surrogate marker of disease. Imaging of pre-calcification and decalcification events may prove more important than imaging of the calcification itself. Data-driven approaches to screening will be necessary to limit radiation exposure and prevent over-utilization of expensive imaging techniques.

Current understanding of coronary artery calcification

Coronary artery calcification (CAC) is highly prevalent in patients with coronary heart disease (CHD) and is associated with major adverse cardiovascular events. There are two recognized type of CAC—intimal and medial calcification, and each of them have specific risk factors. Several theories about the mechanism of vascular calcification have been put forward, and we currently believe that vascular calcification is an active, regulated process. CAC can usually be found in patients with severe CHD, and this asymptomatic phenomenon make early diagnosis of CAC important. Coronary computed tomographic angiography is the main noninvasive tool to detect calcified lesions. Measurement of coronary artery calcification by scoring is a reasonable metric for cardiovascular risk assessment in asymptomatic adults at intermediate risk. To date, effective medical treatment of CAC has not been identified. Several strategies of percutaneous coronary intervention have been applied to CHD patients with CAC, but with unsatisfactory results. Prognosis of CAC is still a major problem of CHD patients. Thus, more details about the mechanisms of CAC need to be elucidated in order to improve the understanding and treatment of CAC.

New mechanisms of antiplatelet activity of nifedipine, an L-type calcium channel blocker

Platelet hyperactivity often occursd in hypertensive patients and is a key factor in the development of cardiovascular diseases including thrombosis and atherosclerosis. Nifedipine, an L-type calcium channel blocker, is widely used for hypertension and coronary heart disease therapy. In addition, nifedipine is known to exhibit an antiplatelet activity, but the underlying mechanisms involved remain unclear. Several transcription factors such as peroxisome proliferator-activated receptors (PPARs) and nuclear factor kappa B (NF-κB) exist in platelets and have an ability to regulate platelet aggregation through a non-genomic mechanism. The present article focuses on describing the mechanisms of the antiplatelet activity of nifedipine via PPAR activation. It has been demonstrated that nifedipine treatment increases the activity and intracellular amount of PPAR-β/-γ in activated platelets. Moreover, the antiplatelet activity of nifedipine is mediated by PPAR-β/-γ-dependent upon the up-regulation of the PI3K/AKT/NO/cyclic GMP/PKG pathway, and inhibition of protein kinase Cα (PKCα) activity via an interaction between PPAR-β/-γ and PKCα. Furthermore, suppressing NF-κB activation by nifedipine through enhanced association of PPAR-β/-γ with NF-κB has also been observed in collagen-stimulated platelets. Blocking PPAR-β/-γ activity or increasing NF-κB activation greatly reverses the antiplatelet activity and inhibition of intracellular Ca²⁺ mobilization, PKCα activity, and surface glycoprotein IIb/IIIa expression caused by nifedipine. Thus, PPAR-β/-γ- dependent suppression of NF-κB activation also contributes to the antiplatelet activity of nifedipine. Consistently, administration of nifedipine markedly reduces fluorescein sodium-induced vessel thrombus formation in mice, which is considerably inhibited when the PPAR-β/-γ antagonists are administrated simultaneously. Collectively, these results provide important information regarding the mechanism by which nifedipine inhibits platelet aggregation and thrombus formation through activation of PPAR-β/-γ- mediated signaling pathways. These findings highlight that PPARs are novel therapeutic targets for preventing and treating platelet-hyperactivity-related vascular diseases.

Can antihypertensive medication interfere with the vicious cycle between hypertension and vascular calcification?

Vascular calcification is a phenomenon of disturbed calcium deposition, as part of the calcium that is supposed to be deposited to our bones, is lodged to our vessels. There are two forms of vascular calcification, each with a distinct anatomical distribution and clinical relevance, namely the intimal and medial calcification. Studies have demonstrated that hypertension may cause vascular calcification but also that both types of calcification, especially medial, promote arterial rigidity and hence hypertension. Implications of this two-way road are largely unknown as there is no consensus yet on their exact clinical value. However, several antihypertensive medications seem to be able to interfere with the cycle of high blood pressure and vascular calcium deposits. The present review summarizes the up-to-date data regarding the effect of antihypertensive medication on vascular calcification.

Serum Gamma-glutamyltransferase Levels Predict the Progression of Coronary Artery Calcification in Adults With Type 2 Diabetes Mellitus

Progression of coronary artery calcification (CAC) may be more predictive of future coronary heart disease events than a baseline CAC score. We determined whether serum gamma-glutamyltransferase (GGT) activity can independently predict the progression of CAC in adults with type 2 diabetes mellitus (T2DM). Patients (n = 326) without symptomatic cardiovascular (CV) disease were evaluated by CAC imaging. The CAC scores were assessed at baseline and after 20 ± 4 months. Serum GGT activities were significantly higher in progressors compared with nonprogressors (39 ± 16 vs 27 ± 11 U/L, P < .001). Multivariable analyses demonstrated that GGT activity retained a strong association with CAC progression after adjustment for CV risk factors. Additionally, there was a graded association between GGT activity quartile and annualized CAC progression. In asymptomatic patients with T2DM, we prospectively found that serum GGT activity may be an independent predictor of CAC progression but not a predictor of CAC incidence.

Thiazolidinedione-independent activation of peroxisome proliferator-activated receptor γ is a potential target for diabetic macrovascular complications

Macrovascular complications are responsible for the high morbidity and mortality in patients with diabetes. Peroxisome proliferator‐activated receptor γ (PPARγ) plays a central role in the process of adipocyte differentiation and insulin sensitization, and also possesses anti‐atherogenic effects. Recently, some statins, angiotensin II type 1 receptor blockers and calcium channel blockers have been reported to activate PPARγ. However, the impact of PPARγ activation on diabetic macrovascular complications is not fully understood. It has been reported that the activation of PPARγ by thiazolidinediones induces anti‐atherogenic effects in vascular cells, including monocytes/macrophages, endothelial cells and smooth muscle cells, in atherosclerotic animal models and in clinical studies. We have reported that hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), which are used for treatment of hypercholesterolemia, activate PPARγ and mediate anti‐atherogenic effects through PPARγ activation in macrophages. Also, telmisartan, an angiotensin type I receptor blocker, has been reported to have anti‐atherogenic effects through PPARγ activation. Furthermore, we have reported that nifedipine, a dihydropyridine calcium channel blocker, can activate PPARγ, thereby mediating anti‐atherogenic effects in macrophages. Therefore, statin therapy and part of anti‐hypertensive therapy might produce beneficial effects through PPARγ activation in hypercholesterolemic and/or hypertensive patients with diabetes, and PPARγ might be a therapeutic target for diabetic macrovascular complications. In the present review, we focus on the anti‐atherogenic effects of PPARγ and suggest potential therapeutic approaches to prevent diabetic macrovascular complications. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00182.x, 2012)

Use of nifedipine in the treatment of hypertension

Hypertension is an important modifiable risk factor for cardiovascular disease; its prevention and treatment currently represent major health concerns around the world, especially in western countries. Effective, well-tolerated drugs such as dihydropyridine calcium channel blockers, to be used either alone or in combination treatments, play a key role in reducing cardiovascular morbidity and mortality. The extended-release formulation of nifedipine given once daily provides a relatively constant concentration profile and has proved to be effective in reducing blood pressure values. In the International Nifedipine gastrointestinal therapeutic system Study: Intervention as a Goal in Hypertension Treatment (INSIGHT) study, it was demonstrated that nifedipine confers cardiovascular protection as effectively as diuretics in high-risk patients, with a smaller incidence of adverse metabolic consequences. Furthermore, two INSIGHT substudies demonstrated that nifedipine prevents the progression of carotid atherosclerosis and reduces the worsening of coronary calcifications, supporting the use of calcium channel blockers in hypertensive patients--especially those at high cardiovascular risk. This review discusses the existing clinical evidence supporting the use of nifedipine in the treatment of hypertension.

Nifedipine gastrointestinal therapeutic system (GITS) in the treatment of coronary heart disease and hypertension

Since the 1960s, calcium antagonists have been available for the treatment of angina pectoris and hypertension. The first of this class, nifedipine, was introduced and readily accepted as the third treatment option for angina, alongside beta-blockers and nitrates. However, the short-acting formulations of nifedipine had pharmacokinetic properties that were far from ideal and in 1995, several studies involving various dosing regimens reported possible dangerous effects in secondary prevention. Since then, large-scale, randomized controlled trials with new controlled-released formulations of nifedipine have demonstrated the effectiveness and safety of this drug. As a consequence of these results, guidelines for both hypertension and angina pectoris have been recently reconsidered, and have put the modern formulations of calcium channel blockers in a pole position. Within this group of therapeutics, nifedipine gastrointestinal therapeutic system has a unique position and it cannot be replaced by other controlled-release formulations of nifedipine, the pharmaceutical properties of which have yet to be tested in large-scale outcome trials.

Hypertension in Chronic Kidney Disease - Role of Arterial Calcification and Impact on Treatment

Hypertension contributes to the progression of kidney diseases as well as to the occurrence of cardiovascular events such as myocardial infarction, heart failure and stroke. The prevalence of hypertension is elevated in patients with kidney disease, and increases progressively as glomerular filtration rate falls. A better understanding of the mechanisms leading to hypertension in renal diseases has been gained in recent years; in this article we will review the pathogenesis of hypertension in chronic kidney disease (CKD) with a special focus on vascular calcification because calcification is associated with an increased incidence of cardiovascular morbidity in CKD patients. Although calcification of large arteries and blood pressure increase with age, few studies have specifically investigated a possible connection between these two factors as determinants of the severity of hypertension in CKD. Finally, we will review the trends in hypertension treatment in CKD patients. Expanded understanding of the role of CKD as both a cause and a target of hypertension highlights key points of pathophysiology of hypertension and may contribute to the identification of new strategies for its prevention and treatment.

Mechanistic insights into vascular calcification in CKD

Cardiovascular disease begins early in the course of renal decline and is a life-limiting problem in patients with CKD. The increased burden of cardiovascular disease is due, at least in part, to calcification of the vessel wall. The uremic milieu provides a perfect storm of risk factors for accelerated calcification, but elevated calcium and phosphate levels remain key to the initiation and progression of vascular smooth muscle cell calcification in CKD. Vascular calcification is a highly regulated process that involves a complex interplay between promoters and inhibitors of calcification and has many similarities to bone ossification. Here, we discuss current understanding of the process of vascular calcification, focusing specifically on the discrete and synergistic effects of calcium and phosphate in mediating vascular smooth muscle cell apoptosis, osteochondrocytic differentiation, vesicle release, calcification inhibitor expression, senescence, and death. Using our model of intact human vessels, factors initiating vascular calcification in vivo and the role of calcium and phosphate in driving accelerated calcification ex vivo are described. This work allows us to link clinical and basic research into a working theoretical model to explain the pathway of development of vascular calcification in CKD.

Potential use of coronary artery calcium progression to guide the management of patients at risk for coronary artery disease events

OPINION STATEMENT

Subclinical coronary artery disease (CAD) is widespread and under-diagnosed. Preventive efforts are required to reduce the burden of this disease and its complications. Imaging of coronary artery calcium (CAC) with cardiac computed tomography is highly specific for the diagnosis of subclinical CAD and can also facilitate treatment decisions in preventive cardiology. Indeed, CAC testing has been recommended by the American Heart Association for asymptomatic patients at intermediate risk for future cardiac events (as defined by clinical risk factors) to refine existing risk estimates. However, the optimal follow-up of those patients who have already undergone CAC testing remains unclear, particularly with regards to repeat CAC testing. The existing literature points to two major considerations for the use of CAC progression in the management of subclinical CAD. On one hand, CAC progression has been used as a surrogate marker to test the efficacy of cardiac preventive medications in halting or regressing CAD. To date, study results have been mostly disappointing and CAC progression appears resistant to medications such as statins. On the other hand, however, CAC progression has potential as a clinical indicator of underlying CAD activity. This may facilitate optimization or up-titration of preventive medications by using CAC progression as a marker of subclinical disease activity. We believe that the data, thus far, argues against the use of a CAC progression as a clinical surrogate marker of preventive therapy efficacy. Further studies with non-statin medications and with concomitant outcome data are needed. However, CAC progression has potential for monitoring subclinical CAD in some patients and may facilitate treatment decisions. In this review we will provide recommendations for repeat CAC testing and discuss when repeat CAC testing may be helpful to assess coronary artery disease progression.

MicroRNAs that target Ca(2+) transporters are involved in vascular smooth muscle cell calcification

The role of microRNAs (miRNAs) in vascular calcification is currently unclear. To examine how miRNAs are involved in vascular smooth muscle cell (VSMC) calcification, we explored the alteration of miRNAs in VSMC calcification in vitro and in vivo. Klotho homozygous mutant mice (kl/kl) display vascular calcification and have perturbations of calcium handling. We therefore hypothesized that the calcium perturbations in VSMCs could be mediated by miRNAs. Using an miRNA array analysis, we demonstrated that miRNAs are aberrantly expressed in the aortic media of 3-week-old kl/kl mice compared with wild-type (WT) mice. The expression levels of miR-135a(*), miR-762, miR-714, and miR-712(*) in the aortic media of kl/kl mice were significantly higher than in WT mice. We used quantitative real-time reverse transcriptase polymerase chain reaction to further confirm that these miRNAs were increased in the aortic media of kl/kl mice and in cultured VSMCs treated with high phosphate and calcium. A search of the miRNA database indicated that the Ca(2+) efflux proteins NCX1, PMCA1, and NCKX4 frequently appeared as potential targets of these miRNAs. The transfection of miRNA mimics into cultured VSMCs reduced the protein levels of each potential target. Conversely, miRNA inhibitors reduced phosphate and calcium-induced VSMC calcification. Furthermore, these inhibitors decreased the intracellular Ca(2+) concentration in cultured VSMCs after treatment with phosphate and calcium. Our results suggest that increased expression of miR-135a(*), miR-762, miR-714, and miR-712(*) in VSMCs may be involved in VSMC calcification by disrupting Ca(2+) efflux proteins.

Metabolic effects of manidipine

The calcium channel antagonists (CCAs) were originally introduced as vasodilators for the treatment of coronary heart disease, but are now also noted for their clinical efficacy in the management of hypertension. Data from large clinical studies have shown that CCAs are not associated with the undesirable metabolic effects (e.g. worsening of dyslipidemia and reduction of insulin sensitivity) seen with older agents such as thiazide diuretics and beta-adrenoceptor antagonists (beta-blockers) that are used to treat hypertension. Indeed, reductions in cardiovascular risk and rates of onset of new cases of diabetes mellitus have been reported in trials in patients with hypertension treated with CCAs. These beneficial effects extend beyond those expected to accompany reductions in BP. Until recently, the biochemical effects underlying these metabolic changes were only poorly understood, but pharmacologic studies have now started to shed more light on these issues. Of particular interest are studies with manidipine, some of which suggest that this agent may be associated with greater improvements in insulin sensitivity and may have better renal protective properties than other CCAs. Confirmation of potential differences among CCAs in terms of the relative magnitude of any beneficial metabolic effects requires further study. Ongoing research is expected to clarify further the action of these agents at the cellular level and to assist with the optimization of antihypertensive therapy, particularly in patients with elevated cardiovascular risk profiles.

Hydrochlorothiazide: is it a wise choice?

INTRODUCTION

Hydrochlorothiazide (HCTZ) has not been shown to reduce mortality or cardiovascular events when given as a single agent. In fact, HCTZ increased cardiovascular death and coronary artery disease (CAD) compared to placebo and usual care in 2 randomized trials, yet it is the most prescribed diuretic in the United States (U.S.). The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure does not recommend one thiazide diuretic over another. However, there are more clinical data for chlorthalidone and indapamide than HCTZ.

AREAS COVERED

This review summarizes the differences between HCTZ, chlorthalidone and indapamide for pharmacological profile, surrogate marker data and clinical trial data.

EXPERT OPINION

The use of the term 'thiazide diuretic' should be replaced with 'non-thiazide sulfonamide diuretic' for chlorthalidone and indapamide. Furthermore, chlorthalidone and indapamide, rather than HCTZ, should be recommended due to the lack of evidence and potential harm of the latter.

Relation of coronary artery calcium to cardiovascular risk in patients with combined diabetes mellitus and systemic hypertension

Certain patients with type 2 diabetes mellitus (DM) do not have increased cardiovascular (CV) risk. The aim of the present study was to stratify hypertensive adults with DM into those with low or high CV risk according to the absence or presence of coronary artery calcium (CAC). The study group included 423 patients, a subgroup of the 544 participants in the calcification side arm of the International Nifedipine Study: Intervention as Goal for Hypertension Therapy. All underwent a baseline computed tomography scan with an unenhanced dual-detector spiral computed tomography scan for CAC measurements. All were free of CV disease and completed 3 years (short-term) of follow-up. A total of 268 patients were included in the 15-year (long-term) follow-up period. The study group was divided into 4 subgroups according to the presence or absence of DM and CAC and was analyzed for a first CV event. Of the 423 patients, 164 (39%) had DM. Cardiovascular events occurred in 41 patients during the first 3 years and in 111 of 268 patients during the long-term follow-up. The rate of CV events was greater in the patients with DM with CAC than in those without (15% vs 7% after 3 years and 52% vs 32% after 15 years). Compared to those without DM without CAC, the short-term adjusted hazard ratio for CV event in those with DM with and without CAC was 6.6 (95% confidence interval 1.4 to 30.5) and 3.9 (95% confidence interval 0.7 to 22.6), respectively. A similar trend was seen in the long-term follow-up study. In conclusion, patients with hypertension and DM can be stratified into a lower CV risk in the absence of CAC.

Arterial calcification in chronic kidney disease: key roles for calcium and phosphate

Vascular calcification contributes to the high risk of cardiovascular mortality in chronic kidney disease (CKD) patients. Dysregulation of calcium (Ca) and phosphate (P) metabolism is common in CKD patients and drives vascular calcification. In this article, we review the physiological regulatory mechanisms for Ca and P homeostasis and the basis for their dysregulation in CKD. In addition, we highlight recent findings indicating that elevated Ca and P have direct effects on vascular smooth muscle cells (VSMCs) that promote vascular calcification, including stimulation of osteogenic/chondrogenic differentiation, vesicle release, apoptosis, loss of inhibitors, and extracellular matrix degradation. These studies suggest a major role for elevated P in promoting osteogenic/chondrogenic differentiation of VSMC, whereas elevated Ca has a predominant role in promoting VSMC apoptosis and vesicle release. Furthermore, the effects of elevated Ca and P are synergistic, providing a major stimulus for vascular calcification in CKD. Unraveling the complex regulatory pathways that mediate the effects of both Ca and P on VSMCs will ultimately provide novel targets and therapies to limit the destructive effects of vascular calcification in CKD patients.

Coronary artery calcification predicts long-term mortality in hypertensive adults

BACKGROUND

Coronary artery calcification (CAC) predicts mortality in normotensive individuals. We hypothesized that CAC has an impact on long-term mortality in hypertensive patients.

METHODS

We followed 423 participants of the INSIGHT (International Nifedipine Study Intervention as Goal for Hypertension Therapy) calcification substudy, for the incidence of mortality as a function of CAC. All patients were hypertensive (mean age 64 ± 6 years, 48% male), without coronary artery or peripheral vascular disease, aged >55 years and with at least one more major cardiovascular (CV) risk factor. All underwent a baseline computed tomography (CT) (Dual slice) to determine the calcification score and were followed for a mean period of 14 ± 0.5 years. Mortality and the cause of death were derived from the registry of the Ministry-of-Interior Affairs.

RESULTS

During the follow-up, 94 patients died; 27 from CV causes, 54 from non-CV causes and 13 of undefined causes. The prevalence of calcification at baseline was 59% (195/329) among the survivors compared to 82% (77/94) in participants who died and 96.7% (26/27) among those who died of CV causes. The incidence of CV death was 14 times higher among those with than those without CAC (9.6% (26/272) vs. 0.7% (1/151); P < 0.01). After adjusting for age, gender, left ventricular hypertrophy, proteinuria, duration of hypertension, and renal function the presence of calcification predicted all cause mortality with a hazard ratio (HR) of 1.8 (95% confidence interval (CI) 1.04-3.07).

CONCLUSIONS

CAC is associated with long-term mortality in asymptomatic hypertensive adults.

Arterial calcifications

Arterial calcifications as found with various imaging techniques, like plain X-ray, computed tomography or ultrasound are associated with increased cardiovascular risk. The prevalence of arterial calcification increases with age and is stimulated by several common cardiovascular risk factors. In this review, the clinical importance of arterial calcification and the currently known proteins involved are discussed. Arterial calcification is the result of a complex interplay between stimulating (bone morphogenetic protein type 2 [BMP-2], RANKL) and inhibitory (matrix Gla protein, BMP-7, osteoprotegerin, fetuin-A, osteopontin) proteins. Vascular calcification is especially prevalent and related to adverse outcome in patients with renal insufficiency and diabetes mellitus. We address the special circumstances and mechanisms in these patient groups. Treatment and prevention of arterial calcification is possible by the use of specific drugs. However, it remains to be proven that reduction of vascular calcification in itself leads to a reduced cardiovascular risk.

Chronic mineral dysregulation promotes vascular smooth muscle cell adaptation and extracellular matrix calcification

In chronic kidney disease (CKD) vascular calcification occurs in response to deranged calcium and phosphate metabolism and is characterized by vascular smooth muscle cell (VSMC) damage and attrition. To gain mechanistic insights into how calcium and phosphate mediate calcification, we used an ex vivo model of human vessel culture. Vessel rings from healthy control subjects did not accumulate calcium with long-term exposure to elevated calcium and/or phosphate. In contrast, vessel rings from patients with CKD accumulated calcium; calcium induced calcification more potently than phosphate (at equivalent calcium-phosphate product). Elevated phosphate increased alkaline phosphatase activity in CKD vessels, but inhibition of alkaline phosphatase with levamisole did not block calcification. Instead, calcification in CKD vessels most strongly associated with VSMC death resulting from calcium- and phosphate-induced apoptosis; treatment with a pan-caspase inhibitor ZVAD ameliorated calcification. Calcification in CKD vessels was also associated with increased deposition of VSMC-derived vesicles. Electron microscopy confirmed increased deposition of vesicles containing crystalline calcium and phosphate in the extracellular matrix of dialysis vessel rings. In contrast, vesicle deposition and calcification did not occur in normal vessel rings, but we observed extensive intracellular mitochondrial damage. Taken together, these data provide evidence that VSMCs undergo adaptive changes, including vesicle release, in response to dysregulated mineral metabolism. These adaptations may initially promote survival but ultimately culminate in VSMC apoptosis and overt calcification, especially with continued exposure to elevated calcium.