Cardiovascular Calcifications in Old Age: Mechanisms and Clinical Implications

Radiographically detectable intra-articular mineralization: Predictor of knee osteoarthritis outcomes or only an indicator of aging? A brief report from the osteoarthritis initiative

Objective

To determine the association between Intra-articular mineralization (IAM) and knee osteoarthritis (OA) outcomes stratified according to participants' age.

Methods

Participants from the Osteoarthritis Initiative (OAI) with baseline radiographic OA (i.e., Kellgren-Lawrence grade ≥2 with Osteoarthritis Research Society International (OARSI) atlas joint space narrowing (JSN)) in either knee were identified. Both knees and dominant hand baseline radiographs were evaluated for the presence of IAM. Whole-grade OARSI-JSN radiographic progression and increased Western Ontario and McMaster universities osteoarthritis index scores of the knees with baseline radiographic OA (assessed annually) were defined as radiographic and symptomatic progression, respectively. Cox proportional-hazards and longitudinal multilevel regression models investigated radiographic and symptomatic progression, respectively.

Results

2010 participants with baseline radiographic OA in either one or both knees (N ​= ​2976) were identified. 178 participants had baseline IAM (hand radiographs ​= ​46, knee radiographs ​= ​166, both ​= ​34). An adjusted logistic regression model suggests an association between age and IAM (Odds Ratio: 1.06, 95% Confidence Interval (CI): 1.04-1.08). Presence of any IAM was not associated with whole-grade OARSI-JSN (Hazard Ratio (HR): 1.00, 95% CI: 0.73-1.37) or symptomatic progression (Estimated difference: 1.24, p-value: 0.13) in all participants. Using stratification analysis, in younger participants <60 years old, presence of any IAM was associated with radiographic progression (HR: 1.90, 95% CI: 1.01-3.60).

Conclusion

Although the presence of any radiographic IAM increases with higher age and does not predict knee OA outcomes across the entire sample of OAI participants, it is associated with knee OA radiographic progression in participants aged <60.

Inorganic Pyrophosphate Plasma Levels Are Decreased in Pseudoxanthoma Elasticum Patients and Heterozygous Carriers but Do Not Correlate with the Genotype or Phenotype

Pseudoxanthoma elasticum (PXE) is a rare ectopic calcification disorder affecting soft connective tissues that is caused by biallelic ABCC6 mutations. While the underlying pathomechanisms are incompletely understood, reduced circulatory levels of inorganic pyrophosphate (PPi)-a potent mineralization inhibitor-have been reported in PXE patients and were suggested to be useful as a disease biomarker. In this study, we explored the relation between PPi, the ABCC6 genotype and the PXE phenotype. For this, we optimized and validated a PPi measurement protocol with internal calibration that can be used in a clinical setting. An analysis of 78 PXE patients, 69 heterozygous carriers and 14 control samples revealed significant differences in the measured PPi levels between all three cohorts, although there was overlap between all groups. PXE patients had a ±50% reduction in PPi levels compared to controls. Similarly, we found a ±28% reduction in carriers. PPi levels were found to correlate with age in PXE patients and carriers, independent of the ABCC6 genotype. No correlations were found between PPi levels and the Phenodex scores. Our results suggest that other factors besides PPi are at play in ectopic mineralization, which limits the use of PPi as a predictive biomarker for severity and disease progression.

Metformin protects against vascular calcification through the selective degradation of Runx2 by the p62 autophagy receptor

Vascular calcification is associated with aging, type 2 diabetes, and atherosclerosis, and increases the risk of cardiovascular morbidity and mortality. It is an active, highly regulated process that resembles physiological bone formation. It has previously been established that pharmacological doses of metformin alleviate arterial calcification through adenosine monophosphate-activated protein kinase (AMPK)-activated autophagy, however the specific pathway remains elusive. In the present study we hypothesized that metformin protects against arterial calcification through the direct autophagic degradation of runt-related transcription factor 2 (Runx2). Calcification was blunted in vascular smooth muscle cells (VSMCs) by metformin in a dose-dependent manner (0.5-1.5 mM) compared to control cells (p < 0.01). VSMCs cultured under high-phosphate (Pi) conditions in the presence of metformin (1 mM) showed a significant increase in LC3 puncta following bafilomycin-A1 (Baf-A; 5 nM) treatment compared to control cells (p < 0.001). Furthermore, reduced expression of Runx2 was observed in the nuclei of metformin-treated calcifying VSMCs (p < 0.0001). Evaluation of the functional role of autophagy through Atg3 knockdown in VSMCs showed aggravated Pi-induced calcification (p < 0.0001), failure to induce autophagy (punctate LC3) (p < 0.001) and increased nuclear Runx2 expression (p < 0.0001) in VSMCs cultured under high Pi conditions in the presence of metformin (1 mM). Mechanistic studies employing three-way coimmunoprecipitation with Runx2, p62, and LC3 revealed that p62 binds to both LC3 and Runx2 upon metformin treatment in VSMCs. Furthermore, immunoblotting with LC3 revealed that Runx2 specifically binds with p62 and LC3-II in metformin-treated calcified VSMCs. Lastly, we investigated the importance of the autophagy pathway in vascular calcification in a clinical setting. Ex vivo clinical analyses of calcified diabetic lower limb artery tissues highlighted a negative association between Runx2 and LC3 in the vascular calcification process. These studies suggest that exploitation of metformin and its analogues may represent a novel therapeutic strategy for clinical intervention through the induction of AMPK/Autophagy Related 3 (Atg3)-dependent autophagy and the subsequent p62-mediated autophagic degradation of Runx2.

Menaquinone-7 ameliorates cerebrovascular calcification-associated memory decline in aged mice

Menaquinone (MK)-7 is a vitamin K2 analog that functions as a cofactor of γ-glutamyl carboxylase involved in the activation of vitamin K (VK)-dependent proteins. The present study aimed to evaluate the effect of MK-7 on memory and cognitive function in aged C57BL/6 mice. Eighteen-month-old mice were raised for a further 4 months, fed on a standard or calcium-rich diet (3 % [w/w]), and were orally given MK-7 (40 and 400 μg/day/mouse) five times per week during the same period. The Morris water maze (MWM) test was performed at 19 and 22 months. The aged mice showed noticeable memory declines in the MWM test at all time points compared with 6-week-old mice, and this memory loss was significantly restored by the daily administration of high-dose MK-7 for 4 months. MK-7 administration also improved micro-computed tomography-based cerebrovascular calcification and aging-associated declines in growth arrest-specific 6, total and carboxylated matrix Gla proteins, and ganglioside levels in the brain of aged mice. It serologically reduced phosphorous levels in the blood, but not the urea, cholesterol, and calcium. Taken together, the long-term administration of MK-7 significantly improved age-related memory and cognitive impairments, possibly through inhibition of cerebrovascular calcification in aged mice, indicating that it can be used to develop new drugs for improving memory and cognitive function in older adults.

Sex Differences in Culprit Plaque Characteristics Among Different Age Groups in Patients With Acute Coronary Syndromes

BACKGROUND

Despite the significant decline in cardiovascular mortality in women over the past several decades, sex differences in the underlying pathology of acute coronary syndromes remain poorly understood. Previous postmortem studies have demonstrated sex differences in coronary plaque morphology with a higher prevalence of plaque erosion in young women and more plaque rupture in older women after menopause, whereas men showed no increase in prevalence of plaque rupture with age. However, in vivo data are limited.

METHODS

This study included patients who presented with acute coronary syndrome and underwent preintervention optical coherence tomography imaging of the culprit lesion. The culprit plaque was categorized as plaque rupture, plaque erosion or culprit plaque with calcification, and stratified by age. Features of plaque vulnerability at culprit lesion were also analyzed.

RESULTS

In 1368 patients (women=286), women and men had a similar distribution of culprit plaque morphology (plaque rupture versus plaque erosion). However, significant sex differences were found in the underlying mechanisms of acute coronary syndrome among different age groups: women showed a significant ascending trend with age in plaque rupture (P<0.001) and the features of plaque vulnerability such as lipid plaque (P<0.001), thin-cap fibroatheroma (P=0.005), and microstructures including macrophages, cholesterol crystals, and calcification (P=0.026). No trend was observed in men.

CONCLUSIONS

Age related sex differences in culprit plaque morphology and vulnerability were identified in patients with acute coronary syndrome: prevalence of plaque rupture and vulnerability increased with age in women but not in men.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01110538 and NCT03479723.

Pro-Calcific Environment Impairs Ischaemia-Driven Angiogenesis

Peripheral arterial disease (PAD) is characterised by accelerated arterial calcification and impairment in angiogenesis. Studies implicate vascular calcification as a contributor to PAD, but the mechanisms remain unclear. We aimed to determine the effect of calcification on ischaemia-driven angiogenesis. Human coronary artery endothelial cells (ECs) were treated with calcification medium (CM: CaCl₂ 2.7 mM, Na₂PO₄ 2.0 mM) for 24 h and exposed to normoxia (5% CO₂) or hypoxia (1.2% O₂; 5% CO₂ balanced with N₂). In normoxia, CM significantly inhibited tubule formation and migration and upregulated calcification markers of ALP, BMP2, and Runx2. CM elevated levels of calcification-protective gene OPG, demonstrating a compensatory mechanism by ECs. CM failed to induce pro-angiogenic regulators VEGFA and HIF-1α in hypoxia and further suppressed the phosphorylation of endothelial nitric oxide synthase (eNOS) that is essential for vascular function. In vivo, osteoprotegerin-deficient mice (OPG^−/−), a calcification model, were subjected to hind-limb ischaemia (HLI) surgery. OPG^−/− mice displayed elevated serum alkaline phosphatase (ALP) activity compared to wild-type controls. OPG^−/− mice experienced striking reductions in blood-flow reperfusion in both 8-week-old and 6-month-old mice post-HLI. This coincided with significant impairment in tissue ischaemia and reduced limb function as assessed by clinical scoring (Tarlov). This study demonstrated for the first time that a pro-calcific environment is detrimental to ischaemia-driven angiogenesis. The degree of calcification in patients with PAD can often be a limiting factor with the use of standard therapies. These highly novel findings require further studies for full elucidation of the mechanisms involved and have implications for the development of therapies to suppress calcification in PAD.

Abdominal aortic calcification and cognitive function among older adults: Cross-sectional analysis of National Health and Nutrition Examination Survey, 2013-2014

OBJECTIVES

Subclinical atherosclerotic disease is an emerging risk factor for cognitive function among older adults, though less is known about the association between abdominal aortic calcification (AAC) and cognitive function. This study aimed to examine the cross-sectional association of AAC with cognitive function in a nationally representative sample of population in the U.S.

METHODS

A total of 1,209 older adults (60 years or older) in the 2013-2014 National Health and Nutrition Examination Survey were included. AAC was obtained with dual-energy X-ray absorptiometry. Cognitive function was examined using the CERAD Word Learning subtest (memory), Digit Symbol Substitution Test (executive function/processing speed), and Animal Fluency Test (language). Test-specific and global cognition z-scores were created based on means and standard deviations of cognitive tests. Multivariable linear regression models were used to examine the associations of presence of AAC and severity of AAC with cognition z-scores.

RESULTS

Adjusted for covariates, presence of AAC was associated with poorer global cognition (beta (β) = -0.17, 95% confidence interval (CI): -0.28, -0.06), memory (β = -0.20, 95% CI: -0.31, -0.09), and language ability (β = -0.15, 95% CI: -0.29, -0.01). More severe AAC was associated with poorer cognitive function. The associations were significant among participants <75 years.

DISCUSSION

The presence of AAC and greater severity of AAC, were associated with poorer cognitive function, particularly among older adults <75 years. Future research is expected to assess whether lowering global vascular risk can slow cognitive decline.

Frailty in Acute and Chronic Coronary Syndrome Patients Entering Cardiac Rehabilitation

Worldwide population ageing is partly due to advanced standard of care, leading to increased incidence and prevalence of geriatric syndromes such as frailty and disability. Hence, the age at the onset of acute coronary syndromes (ACS) keeps growing as well. Moreover, ageing is a risk factor for both frailty and cardiovascular disease (CVD). Frailty and CVD in the elderly share pathophysiological mechanisms and associated conditions, such as malnutrition, sarcopenia, anemia, polypharmacy and both increased bleeding/thrombotic risk, leading to a negative impact on outcomes. In geriatric populations ACS is associated with an increased frailty degree that has a negative effect on re-hospitalization and mortality outcomes. Frail elderly patients are increasingly referred to cardiac rehabilitation (CR) programs after ACS; however, plans of care must be tailored on individual's clinical complexity in terms of functional capacity, nutritional status and comorbidities, cognitive status, socio-economic support. Completing rehabilitative intervention with a reduced frailty degree, disability prevention, improvement in functional state and quality of life and reduction of re-hospitalization are the goals of CR program. Tools for detecting frailty and guidelines for management of frail elderly patients post-ACS are still debated. This review focused on the need of an early identification of frail patients in elderly with ACS and at elaborating personalized plans of care and secondary prevention in CR setting.

Age-Related Differences in the Noninvasive Evaluation for Possible Coronary Artery Disease: Insights From the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) Trial

Importance

Although cardiovascular (CV) disease represents the leading cause of morbidity and mortality that increases with age, the best noninvasive test to identify older patients at risk for CV events remains unknown.

Objective

To determine whether the prognostic utility of anatomic vs functional testing varies based on patient age.

Design, Setting, and Participants

Prespecified analysis of the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) study, which used a pragmatic comparative effectiveness design. Participants were enrolled from 193 sites across North America and comprised outpatients without known coronary artery disease (CAD) but with symptoms suggestive of CAD. Data were analyzed between October 2018 and April 2019.

Interventions

Randomization to noninvasive testing with coronary computed tomographic angiography or functional testing.

Main Outcomes and Measures

The composite of CV death/myocardial infarction (MI) over a median follow-up of 25 months.

Results

Among 10 003 PROMISE patients, we included the 8966 who received the noninvasive test to which they were randomized and had interpretable results; 6378 (71.1%) were younger than 65 years, 2062 (23.0%) were between ages 65 and 74 years, and 526 (5.9%) were 75 years and older. More than half of participants were women (4720 of 8966 [52.6%]). Only a minority of patients were of nonwhite race/ethnicity, a proportion that was lower among the older age groups (1071 of 6378 [16.8%] for <65 years; 258 of 2062 [12.5%] for age 65-74 years; 41 of 526 [7.8%] for ≥75 years). Compared with patients younger than 65 years, older patients were more likely to have a positive test result (age 65-74 years: odds ratio, 1.65; 95% CI, 1.42-1.91; age ≥75 years: odds ratio, 2.32; 95% CI, 1.83-2.95), regardless of noninvasive test completed. A positive functional test result was not associated with CV death/MI in patients younger than 65 years (hazard ratio [HR], 1.09; 95% CI, 0.43-2.82) but it was among older patients (age 65-74 years: HR, 3.18; 95% CI, 1.44-7.01; age ≥75 years: HR, 6.55; 95% CI, 1.46-29.35). Conversely, a positive anatomic test result was associated with CV death/MI among patients younger than 65 years (HR, 3.04; 95% CI, 1.46-6.34) but not among older patients (age, 65-74 years: HR, 0.67; 95% CI, 0.15-2.94; age ≥75 years: HR, 1.07; 95% CI, 0.22-5.34; P for interaction = .01). An elevated coronary artery calcium score was predictive of events in patients younger than 65 years (HR, 2.73; 95% CI, 1.31-5.69) but not for older patients (age 65-74 years: HR, 0.44; 95% CI, 0.14-1.42; age ≥75 years: HR, 1.31; 95% CI, 0.25-6.88).

Conclusions and Relevance

Older patients with stable symptoms suggestive of CAD are more likely to have a positive noninvasive test result and more coronary artery calcium. However, only a positive functional test result was associated with risk of CV death/MI. Age-specific approaches to noninvasive evaluation of CAD should be further examined.

Trial Registration

ClinicalTrials.gov identifier: NCT01174550.

Age-associated arterial calcification: the current pursuit of aggravating and mitigating factors

PURPOSE OF REVIEW

The incidence of arterial calcification increases with age, can occur independently of atherosclerosis and hyperlipidemia, contributes to vessel stiffening, and is associated with adverse cardiovascular outcomes. Here, we provide an up-to-date review of how aging leads to arterial calcification and discuss potential therapies.

RECENT FINDINGS

Recent research suggests that mitochondrial dysfunction (impaired efficiency of the respiratory chain, increased reactive oxygen species production, and a high mutation rate of mitochondrial DNA), cellular senescence, ectonucleotidases, and extrinsic factors such as hyperglycemia promote age-determined calcification. We discuss the future potential impact of antilipidemics, senolytics, and poly(ADP-ribose)polymerases inhibitors on age-associated arterial calcification.

SUMMARY

Understanding how mechanisms of aging lead to arterial calcification will allow us to pinpoint prospective strategies to mitigate arterial calcification, even after the effects of aging have already begun to occur.

Discovery of os cordis in the cardiac skeleton of chimpanzees (Pan troglodytes)

Cardiovascular diseases, especially idiopathic myocardial fibrosis, is one of the most significant causes of morbidity and mortality in captive great apes. This study compared the structure and morphology of 16 hearts from chimpanzees (Pan troglodytes) which were either healthy or affected by myocardial fibrosis using X-ray microtomography. In four hearts, a single, hyperdense structure was detected within the right fibrous trigone of the cardiac skeleton. High resolution scans and histopathology revealed trabecular bones in two cases, hyaline cartilage in another case and a focus of mineralised fibro-cartilaginous metaplasia with endochondral ossification in the last case. Four other animals presented with multiple foci of ectopic calcification within the walls of the great vessels. All hearts affected by marked myocardial fibrosis presented with bone or cartilage formation, and increased collagen levels in tissues adjacent to the bone/cartilage, while unaffected hearts did not present with os cordis or cartilago cordis. The presence of an os cordis has been described in some ruminants, camelids, and otters, but never in great apes. This novel research indicates that an os cordis and cartilago cordis is present in some chimpanzees, particularly those affected by myocardial fibrosis, and could influence the risk of cardiac arrhythmias and sudden death.

Role of bone mineral density in the inverse relationship between body size and aortic calcification: results from the Baltimore Longitudinal Study of Aging

OBJECTIVE

There is a J-shaped relationship between body mass index (BMI) and cardiovascular outcomes in elderly patients (obesity paradox). Whether low BMI correlates with aortic calcification (AC) and whether this association is accounted for by bone demineralization is uncertain.

METHODS

Presence of AC was evaluated in 687 community-dwelling individuals (49% male, mean age 67 ± 13 years) using CT images of the thoracic, upper and lower abdominal aorta, and scored from 0 to 3 according to number of sites that showed any calcification. Whole-body bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry. Predictors of AC were assessed by logistic regression, and the role of BMD using mediation analysis.

RESULTS

Age and cardiovascular risk factors were positively associated while both BMI (r = -0.11, p < 0.01) and BMD (r = -0.17, p < 0.0001) were negatively associated with AC severity. In multivariate models, lower BMI (OR 0.96, 95%CI 0.92-0.99, p = 0.01), older age, higher systolic blood pressure, use of lipid-lowering drugs and smoking were independent predictors of AC. A nonlinear relationship between BMI and AC was noticed (p = 0.03), with decreased AC severity among overweight participants. After adjusting for BMD, the coefficient relating BMI to AC was reduced by 14% and was no longer significant, whereas BMD remained negatively associated with AC (OR 0.82, 95%CI 0.069-0.96, p = 0.01), with a trend for a stronger relationship in older participants.

CONCLUSION

Low BMI is associated with increased AC, possibly through calcium mobilization from bone, resulting in low BMD. Prevention of weight loss and bone demineralization with aging may help reducing AC.