Population-based assessment of subclinical coronary atherosclerosis using electron-beam computed tomography

Vascular ageing: moving from bench towards bedside

Prevention of cardiovascular disease (CVD) remains one of the largest public health challenges of our time. Identifying individuals at increased cardiovascular risk at an asymptomatic, sub-clinical stage is of paramount importance for minimizing disease progression as well as the substantial health and economic burden associated with overt CVD. Vascular ageing (VA) involves the deterioration in vascular structure and function over time and ultimately leads to damage in the heart, brain, kidney, and other organs. Vascular ageing encompasses the cumulative effect of all cardiovascular risk factors on the arterial wall over the life course and thus may help identify those at elevated cardiovascular risk, early in disease development. Although the concept of VA is gaining interest clinically, it is seldom measured in routine clinical practice due to lack of consensus on how to characterize VA as physiological vs. pathological and various practical issues. In this state-of-the-art review and as a network of scientists, clinicians, engineers, and industry partners with expertise in VA, we address six questions related to VA in an attempt to increase knowledge among the broader medical community and move the routine measurement of VA a little closer from bench towards bedside.

Diagnostic Cardiac CT for the Improvement of Cardiovascular Event Prediction

BACKGROUND

The aim of the long-term Heinz Nixdorf Recall Study (observation period 20 years) was to establish the extent to which computed tomography (CT) improves the predictability of cardiovascular events relative to determination of risk factors alone.

METHODS

In the period 2000-2003, study staff examined 4355 probands (53% of them female) aged 45-75 years with no signs of cardiovascular disease. The Atherosclerotic Cardiovascular Disease (ASCVD) score was calculated on the basis of demographic data and cardiovascular risk factors. Cardiac CT was carried out over the same period and coronary artery calcification (CAC) was graded according to the Agatston score.

RESULTS

The median duration of follow-up was 18.2 years for men and 17.8 years for women. Myocardial infarction or stroke occurred in 458 (11%) of the 4154 participants with complete data. Overall, estimation of risk using a combination of ASCVD score and CAC grade was superior to the ASCVD score alone-even after 10 and 20 years. Classification into established risk categories improved by 12.2% (95% confidence interval: [5.3%; 18.1%]). In the highest ASCVD risk category, we observed occurrence of a cardiovascular event over 20 years for 14% [5.0%; 23.1%] of probands with a CAC score = 0 but for 34.2% [27.5%; 41.4%] of those with a CAC score ≥ 400. In the lowest ASCVD risk category, an event occurred in 2.4% [1.4%; 3.7%] of probands with a CAC score = 0 and in 23.5% [2.3%; 35.8%] of those with a CAC score ≥ 400.

CONCLUSION

Even after 20 years, individual risk prediction is improved by addition of CT-based determination of coronary artery calcification to the ASCVD score. Therefore, assessment of ASCVD risk factors should be complemented more widely by cardiac CT in the primary prevention of cardiovascular disease.

"Global" cardiac atherosclerotic burden assessed by artificial intelligence-based versus manual segmentation in 18F-sodium fluoride PET/CT scans: Head-to-head comparison

BACKGROUND

Artificial intelligence (AI) is known to provide effective means to accelerate and facilitate clinical and research processes. So in this study it was aimed to compare a AI-based method for cardiac segmentation in positron emission tomography/computed tomography (PET/CT) scans with manual segmentation to assess global cardiac atherosclerosis burden.

METHODS

A trained convolutional neural network (CNN) was used for cardiac segmentation in 18F-sodium fluoride PET/CT scans of 29 healthy volunteers and 20 angina pectoris patients and compared with manual segmentation. Parameters for segmented volume (Vol) and mean, maximal, and total standardized uptake values (SUVmean, SUVmax, SUVtotal) were analyzed by Bland-Altman Limits of Agreement. Repeatability with AI-based assessment of the same scans is 100%. Repeatability (same conditions, same operator) and reproducibility (same conditions, two different operators) of manual segmentation was examined by re-segmentation in 25 randomly selected scans.

RESULTS

Mean (± SD) values with manual vs. CNN-based segmentation were Vol 617.65 ± 154.99 mL vs 625.26 ± 153.55 mL (P = .21), SUVmean 0.69 ± 0.15 vs 0.69 ± 0.15 (P = .26), SUVmax 2.68 ± 0.86 vs 2.77 ± 1.05 (P = .34), and SUVtotal 425.51 ± 138.93 vs 427.91 ± 132.68 (P = .62). Limits of agreement were - 89.42 to 74.2, - 0.02 to 0.02, - 1.52 to 1.32, and - 68.02 to 63.21, respectively. Manual segmentation lasted typically 30 minutes vs about one minute with the CNN-based approach. The maximal deviation at manual re-segmentation was for the four parameters 0% to 0.5% with the same and 0% to 1% with different operators.

CONCLUSION

The CNN-based method was faster and provided values for Vol, SUVmean, SUVmax, and SUVtotal comparable to the manually obtained ones. This AI-based segmentation approach appears to offer a more reproducible and much faster substitute for slow and cumbersome manual segmentation of the heart.

Heterogeneity in coronary heart disease risk

There is large inter-individual heterogeneity in risk of coronary heart disease (CHD). Risk factors traditionally used in primary risk assessment only partially explain this heterogeneity. Residual, unobserved heterogeneity leads to age-related attenuation of hazard rates and underestimation of hazard ratios. Its magnitude is unknown. Therefore, we aimed to estimate a lower and an approximate upper bound. Heterogeneity was parametrized by a log-normal distribution with shape parameter σ. Analysis was based on published data. From concordance indices of studies including traditional risk factors and additional diagnostic imaging data, we calculated the part of heterogeneity explained by imaging data. For traditional risk assessment, this part typically remains unexplained, thus constituting a lower bound on unobserved heterogeneity. Next, the potential impact of heterogeneity on CHD hazard rates in several large countries was investigated. CHD rates increase with age but the increase attenuates with age. Presuming this attenuation to be largely caused by heterogeneity, an approximate upper bound on σ was derived. Taking together both bounds, unobserved heterogeneity in studies without imaging information can be described by a shape parameter in the range σ = 1-2. It substantially contributes to observed age-dependences of hazard ratios and may lead to underestimation of hazard ratios by a factor of about two. Therefore, analysis of studies for primary CHD risk assessment should account for unobserved heterogeneity.

Quantification of Coronary Artery Atherosclerotic Burden and Muscle Mass: Exploratory Comparison of Two Freely Available Software Programs

Coronary artery calcification and sarcopenia may have a relevant prognostic impact in oncological and non-oncological patients. The use of freeware software is promising for quantitative evaluation of these parameters after whole-body positron emission tomography (PET)/computed tomography (CT) and might be useful for one-stop shop risk stratification without additional radiation ionizing burden and further charges to health care costs. In this study, we compared two semiautomatic freeware software tools (Horos Medical Image software and LIFEx) for the assessment of coronary artery calcium (CAC) score and muscle mass in 40 patients undergoing whole-body PET/CT. The muscle areas obtained by the two software programs were comparable, showing high correlation with Lin’s concordance coefficient (0.9997; 95% confidence intervals: 0.9995–0.9999) and very good agreement with Bland–Altman analysis (mean difference = 0.41 cm2, lower limit = −1.06 cm2, upper limit = 1.89) was also found. For CAC score, Lin’s concordance correlation coefficient was 0.9976 (95% confidence intervals: 0.9965–0.9984) and in a Bland–Altman analysis an increasing mean difference from 8 to 78 by the mean values (intercept = −0.050; slope = 0.054; p < 0.001) was observed, with a slight overestimation of Horos CAC score as compared to LIFEx, likely due to a different calculation method of the CAC score, with the ROI being equal for the two software programs. Our results demonstrated that off-line analysis performed with freeware software may allow a comprehensive evaluation of the oncological patient, making available the evaluation of parameters, such as muscle mass and calcium score, that may be relevant for the staging and prognostic stratification of these patients, beside standard data obtained by PET/CT imaging. For this purpose, the Horos and LIFEx software seem to be interchangeable.

Nonparametric percentile curve estimation for a nonnegative marker with excessive zeros

Norm curves for the head circumference, height, and weight of newborns and infants are widely known examples of percentile curves over age, and early accounts date back 50 years. The advent of the Agatston score for coronary calcification based on coronary computed tomography in 1990 heralded the era of a new marker in preventive medicine, in addition to well-known cardiovascular risk factors. A peculiarity of the nonnegative Agatston score in populations that are free of coronary artery disease is the overexpression of zeros. In a case study, we have demonstrated a nonparametric approach for percentile curve estimation using markers such as the Agatston score. This method is based on lowess smoothing of marker-positive scores on age, and the resulting percentile curves are subsequently transposed according to the estimated proportions of zeros. The approach does not involve any parametric assumptions, is robust against outliers, and fulfills the noncrossing property for percentile curves. A simulation study using samples of N=1,000, 2,000, 5,000, and 10,000 subjects illuminates the closeness of the estimated 50^th, 75^th, and 90^th percentile curves to the respective true curves, assuming an exponentially distributed marker and a proportion of zero scores that increase with age.•

The method is applicable to highly skewed data and exemplified here with subgroup data of the referenced procedure.

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The consistency and general performance of the method is shown by means of simulation.

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The method is an explicit, transferable, and reproducible procedure that is applicable to a wide spectrum of markers and scores across various scientific disciplines, far beyond cardiovascular medicine.

Prevalence and extent of coronary artery calcification in the middle-aged and elderly population

AIMS

Coronary artery calcification (CAC) measured on cardiac computed tomography (CT) is an important risk marker for cardiovascular disease (CVD) and has been included in the prevention guidelines. The aim of this study was to describe CAC score reference values in the middle-aged and elderly population and to develop a freely available CAC calculator.

METHODS AND RESULTS

All participants from two population-based cardiac CT screening cohorts (DanRisk and DANCAVAS) were included. The CAC score was measured as a part of a screening session. Positive CAC scores were log-transformed and non-parametrically regressed on age for each gender, and percentile curves were transposed according to proportions of zero CAC scores. Men had higher CAC scores than women, and the prevalence and extend of CAC increased steadily with age. An online CAC calculator was developed, http://flscripts.dk/cacscore. After entering sex, age, and CAC score, the CAC score percentile and the coronary age are depicted including a figure with the specific CAC score and 25%, 50%, 75%, and 90% percentiles. The specific CAC score can be compared to the entire background population or only those without prior CVD.

CONCLUSION

This study provides modern population-based reference values of CAC scores in men and woman and a freely accessible online CAC calculator. Physicians and patients are very familiar with blood pressure and lipids, but unfamiliar with CAC scores. Using the calculator makes it easy to see if a CAC value is low, moderate, or high, when a physician in the future communicate and discusses a CAC score with a patient.

Cardiovascular Risk Factors and Coronary Calcification in a Middle-aged Dutch Population: The ImaLife Study

PURPOSE

To assess the presence of coronary artery calcium (CAC) and its association with cardiovascular risk factors and Systematic COronary Risk Evaluation (SCORE) risk in a middle-aged Dutch population.

METHODS

Classic cardiovascular risk factors and CAC were analyzed in 4083 participants aged 45 to 60 years (57.9% women) from the population-based ImaLife study. CAC scores were quantified on noncontrast cardiac CT scans. Age-specific and sex-specific distribution of CAC categories (0, 1 to 99, 100 to 299, ≥300) and percentiles were determined. SCORE risk categories (<1%, ≥1% to 5%, and ≥5%) were compared with CAC distribution. Population attributable fractions (PAFs) of classic risk factors for CAC were estimated.

RESULTS

CAC was present in 54.5% male and 26.5% female participants. The percentage of individuals with CAC increased with increasing age. Mean SCORE was 2.0% in men and 0.7% in women. In SCORE <1%, 32.7% of men and 17.1% of women had CAC. In men with SCORE ≥5%, 26.9% had no CAC. Only 0.1% of women had SCORE ≥5%. PAF of classic risk factors for CAC was 18.5% in men and 31.4% in women. PAF was highest for hypertension (in men 8.0%, 95% confidence interval, 4.2%-11.8%; in women 13.1%, 95% confidence interval, 7.9%-18.2%) followed by hypercholesterolemia and obesity.

CONCLUSION

In this middle-aged cohort, more than half of the men and a quarter of the women had CAC. One out of 4 men at high risk (SCORE ≥5%) could be placed into a lower risk category owing to absence of CAC. Thus, adding CAC scoring to SCORE could have considerable effect on cardiovascular risk classification. Elimination of exposure to classic risk factors could reduce limited proportion of CAC in a middle-aged population.

Association of progressive thoracic aortic calcification with future cardiovascular events and all-cause mortality: ability to improve risk prediction? Results of the Heinz Nixdorf Recall (HNR) study

AIMS

Thoracic aortic calcification (TAC) is measured by computed tomography (CT). We investigated the association of TAC-progression with incident cardiovascular (CV) events and all-cause mortality in a population-based cohort and to determine its predictive value for these endpoints.

METHODS AND RESULTS

In 3080 participants (45-74 years, 53.6% women), risk factors and TAC via CT were measured at baseline and at a second examination after 5.1 ± 0.3 years. Hard coronary, hard CV events as well as CV events including revascularization and all-cause mortality were recorded during a follow-up time of 7.8 ± 2.2 years after the second CT scan. Cox regression analysis determined the association of TAC-progression with observed endpoints. The predictive value of TAC-progression was assessed using Harrell's C index. We observed 81 hard coronary, 154 hard CV, 231 CV events including revascularization, and 266 deaths. In the crude analysis, event rates increased continuously with the level of TAC-change over 5 years for all endpoints. After adjustment, the significant association of TAC-progression with hard CV events [hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.05-1.57] and all-cause mortality (HR 1.34, 95% CI 1.14-1.58) persisted, per one standard deviation increase in TAC-progression (log(TAC + 1)). Regarding aortic segments separately, HRs were consistently higher for descending thoracic aorta. When adding TAC (baseline and progression) to the model containing classical risk factors and coronary artery calcification (CAC), Harrell's C indices did not increase for any of the observed endpoints.

CONCLUSION

TAC-progression is associated with incident hard CV events and all-cause mortality but fails to improve event prediction over CAC.

Risk prediction for coronary heart disease by a genetic risk score - results from the Heinz Nixdorf Recall study

Background

A Genetic risk score for coronary artery disease (CAD) improves the ability of predicting coronary heart disease (CHD). It is unclear whether i) the use of a CAD genetic risk score is superior to the measurement of coronary artery calcification (CAC) for CHD risk assessment and ii) the CHD risk assessment using a CAD genetic risk score differs between men and women.

Methods

We included 4041 participants (age-range: 45–76 years, 1919 men) of the Heinz Nixdorf Recall study without CHD or stroke at baseline. A standardized weighted CAD genetic risk score was constructed using 70 known genetic variants. The risk score was divided into quintiles (Q1-Q5). We specified low (Q1), intermediate (Q2-Q4) and high (Q5) genetic risk groups. Incident CHD was defined as fatal and non-fatal myocardial infarction, stroke and coronary death. The association between the genetic risk score and genetic risk groups with incident CHD was assessed using Cox models to estimate hazard ratios (HR) and 95%-confidence intervals (CI). The models were adjusted by age and sex (Model1), as well as by established CHD risk factors (RF) and CAC (Model2). The analyses were further stratified by sex and controlled for multiple testing.

Results

During a median follow-up time of 11.6 ± 3.7 years, 343 participants experienced CHD events (219 men). Per-standard deviation (SD) increase in the genetic risk score was associated with 18% increased risk for incident CHD (Model1: p = 0.002) which did not change after full adjustment (Model2: HR = 1.18 per-SD (p = 0.003)). In Model2 we observed a 60% increased CHD risk in the high (p = 0.009) compared to the low genetic risk group. Stratifying by sex, only men showed statistically significantly higher risk for CHD (Model2: HR = 1.23 per-SD (p = 0.004); intermediate: HR = 1.52 (p = 0.04) and high: HR = 1.88 (p = 0.008)) with no statistically significant risk observed in women.

Conclusion

Our results suggest that the CAD genetic risk score could be useful for CHD risk prediction, at least in men belonging to the higher genetic risk group, but it does not outbalance the value of CT-based quantification of CAC which works independently on both men and women and allows better risk stratification in both the genders.

Endurance exercise training volume is not associated with progression of coronary artery calcification

BACKGROUND

Recent cross-sectional studies have suggested a dose-dependent relationship between lifelong exposure to physical activity and the burden of calcified coronary artery disease (CAD). No longitudinal studies have addressed this concern.

HYPOTHESIS

Exercise volume is associated with progression of coronary artery calcium (CAC), defined as ≥10 units increase in CAC score.

METHODS

Sixty-one recreational athletes who were assessed by coronary computed tomography angiography (CCTA) as part of the NEEDED 2013/14 study were re-assessed 4-5 years later, in 2018.

RESULTS

Subjects were 45.9 ± 9.6 years old at inclusion, and 46 (74%) were male. Between 2013 and 2018, the participants reported median 5 (range: 0-20, 25th-75th percentile: 4-6) hours of high-intensity exercise per week. None of the included subjects smoked during follow-up. At inclusion, 21 (33%) participants had coronary artery calcifications. On follow-up CCTA in 2018, 15 (25%) subjects had progressive coronary calcification (≥10 Agatston units increase in CAC). These subjects were older (53 ± 9 vs 44 ± 9 years old, P = .002) and had higher levels of low-density lipoprotein at baseline (3.5 (2.9-4.3) vs 2.9 (2.3-3.5) mmol/L, P = .031) as compared to subjects with stable condition. No relationship was found between hours of endurance training per week and progression of coronary artery calcification. In multiple regression analysis, age and baseline CAC were the only significant predictors of progressive CAC.

CONCLUSION

No relationship between exercise training volume and the progression of coronary artery calcification was found in this longitudinal study of middle-aged recreational athletes.

Male-pattern baldness and incident coronary heart disease and risk factors in the Heinz Nixdorf Recall Study

Male-pattern baldness (MPB) is characterized by a progressive hair loss from the frontal and vertex scalp that affects about 80% of men at the age of 80 years. Epidemiological studies show positive associations between MPB and coronary heart disease (CHD) and CHD related risk factors such as blood pressure (BP), diabetes mellitus (DM) or elevated blood lipid levels. The results however vary with regard to the pattern of hair loss (i.e. moderate, severe, frontal or vertex). Further, no study has investigated for a shared genetic determinant between MPB and CHD as well as CHD related risk factors. Using the longitudinal data from the population-based Heinz Nixdorf Recall study we aimed to systematically investigate the association between MPB and incident CHD and CHD risk factors on (i) an epidemiological (N = 1,673 males) and (ii) a genetic (N = 1,357 males) level. The prevalence of any baldness in our study population was 88% (mean age ± SD: 64±7.5 years). Compared to men with ‘no baldness’, in men with any kind of baldness a slightly increased risk for CHD (Hazard ratio [95% confidence interval (95%CI)] = 1.2 [0.8; 1.9]), a slightly higher extend of coronary artery calcification (CAC) (Beta [95%CI] = 0.2 [-0.1; 0.6]), a moderately increased risk for DM (prevalence ratio [95%CI] = 1.4 [0.9; 2.0]) and higher body mass index (BMI) (Beta [95%CI] = 0.6 [0.00003; 1.2]) seem to be indicated in the adjusted model. In contrast, the MPB genetic risk score did not show any association with CHD or CHD risk factors. Taken together, the results of our study suggest a weak association between MPB and a few CHD risk factors (CAC, DM and BMI) but do not point to MPB as a strong surrogate measure for CHD and CHD risk factors in general.

Association of Coronary Artery Calcium Score vs Age With Cardiovascular Risk in Older Adults: An Analysis of Pooled Population-Based Studies

Importance

Besides age, other discriminators of atherosclerotic cardiovascular disease (ASCVD) risk are needed in older adults.

Objectives

To examine the predictive ability of coronary artery calcium (CAC) score vs age for incident ASCVD and how risk prediction changes by adding CAC score and removing only age from prediction models.

Design, Setting, and Participants

We conducted an analysis of pooled US population-based studies, including the Framingham Heart Study, the Multi-Ethnic Study of Atherosclerosis, and the Cardiovascular Health Study. Results were compared with 2 European cohorts, the Rotterdam Study and the Heinz Nixdorf Recall Study. Participants underwent CAC scoring between 1998 and 2006 using cardiac computed tomography. The participants included adults older than 60 years without known ASCVD at baseline.

Exposures

Coronary artery calcium scores.

Main Outcomes and Measures

Incident ASCVD events including coronary heart disease (CHD) and stroke.

Results

The study included 4778 participants from 3 US cohorts, with a mean age of 70.1 years; 2582 (54.0%) were women, and 2431 (50.9%) were nonwhite. Over 11 years of follow-up (44 152 person-years), 405 CHD and 228 stroke events occurred. Coronary artery calcium score (vs age) had a greater association with incident CHD (C statistic, 0.733 vs 0.690; C statistics difference, 0.043; 95% CI of difference, 0.009-0.075) and modestly improved prediction of incident stroke (C statistic, 0.695 vs 0.670; C statistics difference, 0.025; 95% CI of difference, -0.015 to 0.064). Adding CAC score to models including traditional cardiovascular risk factors, with only age being removed, provided improved discrimination for incident CHD (C statistic, 0.735 vs 0.703; C statistics difference, 0.032; 95% CI of difference, 0.002-0.062) but not for stroke. Coronary artery calcium score was more likely than age to provide higher category-free net reclassification improvement among participants who experienced an ASCVD event (0.390; 95% CI, 0.312-0.467 vs 0.08; 95% CI -0.001 to 0.181) and to result in more accurate reclassification of risk for ASCVD events among these individuals. The findings were similar in the 2 European cohorts (n = 4990).

Conclusions and Relevance

Coronary artery calcium may be an alternative marker besides age to better discriminate between lower and higher CHD risk in older adults. Whether CAC score can assist in guiding the decision to initiate statin treatment for primary prevention in older adults requires further investigation.

Early imaging biomarkers of lung cancer, COPD and coronary artery disease in the general population: rationale and design of the ImaLife (Imaging in Lifelines) Study

Lung cancer, chronic obstructive pulmonary disease (COPD), and coronary artery disease (CAD) are expected to cause most deaths by 2050. State-of-the-art computed tomography (CT) allows early detection of lung cancer and simultaneous evaluation of imaging biomarkers for the early stages of COPD, based on pulmonary density and bronchial wall thickness, and of CAD, based on the coronary artery calcium score (CACS), at low radiation dose. To determine cut-off values for positive tests for elevated risk and presence of disease is one of the major tasks before considering implementation of CT screening in a general population. The ImaLife (Imaging in Lifelines) study, embedded in the Lifelines study, is designed to establish the reference values of the imaging biomarkers for the big three diseases in a well-defined general population aged 45 years and older. In total, 12,000 participants will undergo CACS and chest acquisitions with latest CT technology. The estimated percentage of individuals with lung nodules needing further workup is around 1–2%. Given the around 10% prevalence of COPD and CAD in the general population, the expected number of COPD and CAD is around 1000 each. So far, nearly 4000 participants have been included. The ImaLife study will allow differentiation between normal aging of the pulmonary and cardiovascular system and early stages of the big three diseases based on low-dose CT imaging. This information can be finally integrated into personalized precision health strategies in the general population.

Normative data from linear and nonlinear quantile regression in CANTAB: Cognition in mid-to-late life in an epidemiological sample

Introduction

Normative cognitive data can help to distinguish pathological decline from normal aging. This study presents normative data from the Cambridge Neuropsychological Test Automated Battery, using linear regression and nonlinear quantile regression approaches.

Methods

Heinz Nixdorf Recall study participants completed Cambridge Neuropsychological Test Automated Battery tests: paired-associate learning, spatial working memory, and reaction time. Data were available for 1349-1529 healthy adults aged 57-84 years. Linear and nonlinear quantile regression analyses examined age-related changes, adjusting for sex and education. Quantile regression differentiated seven performance bands (percentiles: 97.7, 93.3, 84.1, 50, 15.9, 6.7, and 2.3).

Results

Normative data show age-related cognitive decline across all tests, but with quantile regression revealing heterogeneous trajectories of cognitive aging, particularly for the test of episodic memory function (paired-associate learning).

Discussion

This study presents normative data from Cambridge Neuropsychological Test Automated Battery in mid-to-late life. Quantile regression can model heterogeneity in age-related cognitive trajectories as seen in the paired-associate learning episodic memory measure.

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The study presents normative cognitive data from the Cambridge Neuropsychological Test Automated Battery in mid-to-late life.

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Most tasks showed similar decline across performance bands with increasing age.

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Quantile regression is sensitive for evaluating diverging trajectories with age.

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Episodic memory showed accelerated decline in the average performance range.

External validity of a cardiovascular screening including a coronary artery calcium examination in middle-aged individuals from the general population

Background

Coronary artery calcium is important in cardiovascular risk stratification, but this knowledge is based on studies with a significant selection bias. This study aims to evaluate the external validity of a screening programme including coronary artery calcium examination, and the association between coronary artery calcium and cardiovascular events.

Design

Multi-centre population based study.

Methods

Randomly selected middle-aged men and women ( N = 1751) free of cardiovascular disease were invited to the examination during 2009–2010. Participation rate in the examination was 70%. Participants ( n = 1227) and non-participants ( n = 524) were compared regarding: cardiovascular medical treatment, Charlson comorbidity index and socioeconomic status (evaluated by cohabitation, gross income and education). Study endpoints were cardiovascular events and mortality.

Results

Non-participants had a significant higher comorbidity ( p = 0.003) and a lower socioeconomic status ( p < 0.0001), while cardiovascular medical treatment was alike. Over a median follow-up time of 6.5 years the cardiovascular event and mortality rates were equal (6.7% vs. 6.4%, p = 0.80 and 0.4% vs. 0.5%, p = 0.76, respectively). Adjusted hazard ratio was 0.90 (95% confidence interval (CI) 0.63–1.37). Among participants, the extent of coronary artery calcium was significantly associated with increased risk of cardiovascular events (hazard ratio 1.92, 95% CI 1.03–3.54, hazard ratio 3.66, 95% CI 1.82–7.32, hazard ratio 6.51, 95% CI 3.17–13.36 for coronary artery calcium scores 1–99, 100–399, ≥400 AU, respectively).

Conclusions

Non-participants had a higher comorbidity index and a lower socioeconomic status, but the cardiovascular event and mortality rates were equal to those of participants. Thus, a screening programme including a coronary artery calcium examination had a high external validity regarding cardiovascular risk, but also a significant social imbalance.

Cardiac computed tomography in patients with symptomatic new-onset atrial fibrillation, rule-out acute coronary syndrome, but with intermediate pretest probability for coronary artery disease admitted to a chest pain unit

Background

Atrial fibrillation (AF) and coronary artery disease (CAD) may be encountered coincidently in a large portion of patients. However, data on coronary artery calcium burden in such patients are lacking. Thus, we sought to determine the value of cardiac computed tomography (CCT) in patients presenting with new-onset AF associated with an intermediate pretest probability for CAD admitted to a chest pain unit (CPU).

Methods

Calcium scores (CS) of 73 new-onset, symptomatic AF subjects without typical clinical, electrocardiographic, or laboratory signs of acute coronary syndrome (ACS) admitted to our CPU were analyzed. In addition, results from computed tomography angiography (CTA) were related to coronary angiography findings whenever available.

Results

Calcium scores of zero were found in 25%. Median Agatston score was 77 (interquartile range: 1–270) with gender- and territory-specific dispersal. CS scores above average were present in about 50%, high (> 400)-to-very high (> 1000) CS scores were found in 22%. Overall percentile ranking showed a relative accordance to the reference percentile distribution. Additional CTA was performed in 47%, revealing stenoses in 12%. Coronary angiography was performed in 22% and resulted in coronary intervention or surgical revascularization in 7%. On univariate analysis, CS > 50th percentile failed to serve as an independent determinant of significant stenosis during catheterization.

Conclusions

Within a CPU setting, relevant CAD was excluded or confirmed in almost 50%, the latter with a high proportion of coronary angiographies and subsequent coronary interventions, underlining the diagnostic value of CCT in symptomatic, non-ACS, new-onset AF patients when admitted to a CPU.

Value of Progression of Coronary Artery Calcification for Risk Prediction of Coronary and Cardiovascular Events: Result of the HNR Study (Heinz Nixdorf Recall)

Supplemental Digital Content is available in the text.

Background:

Computed tomography (CT) allows estimation of coronary artery calcium (CAC) progression. We evaluated several progression algorithms in our unselected, population-based cohort for risk prediction of coronary and cardiovascular events.

Methods:

In 3281 participants (45–74 years of age), free from cardiovascular disease until the second visit, risk factors, and CTs at baseline (b) and after a mean of 5.1 years (5y) were measured. Hard coronary and cardiovascular events, and total cardiovascular events including revascularization, as well, were recorded during a follow-up time of 7.8±2.2 years after the second CT. The added predictive value of 10 CAC progression algorithms on top of risk factors including baseline CAC was evaluated by using survival analysis, C-statistics, net reclassification improvement, and integrated discrimination index. A subgroup analysis of risk in CAC categories was performed.

Results:

We observed 85 (2.6%) hard coronary, 161 (4.9%) hard cardiovascular, and 241 (7.3%) total cardiovascular events. Absolute CAC progression was higher with versus without subsequent coronary events (median, 115 [Q1–Q3, 23–360] versus 8 [0–83], P<0.0001; similar for hard/total cardiovascular events). Some progression algorithms added to the predictive value of baseline CT and risk assessment in terms of C-statistic or integrated discrimination index, especially for total cardiovascular events. However, CAC progression did not improve models including CAC_5y and 5-year risk factors. An excellent prognosis was found for 921 participants with double-zero CAC_b=CAC_5y=0 (10-year coronary and hard/total cardiovascular risk: 1.4%, 2.0%, and 2.8%), which was for participants with incident CAC 1.8%, 3.8%, and 6.6%, respectively. When CAC_b progressed from 1 to 399 to CAC_5y≥400, coronary and total cardiovascular risk were nearly 2-fold in comparison with subjects who remained below CAC_5y=400. Participants with CAC_b≥400 had high rates of hard coronary and hard/total cardiovascular events (10-year risk: 12.0%, 13.5%, and 30.9%, respectively).

Conclusions:

CAC progression is associated with coronary and cardiovascular event rates, but adds only weakly to risk prediction. What counts is the most recent CAC value and risk factor assessment. Therefore, a repeat scan >5 years after the first scan may be of additional value, except when a double-zero CT scan is present or when the subjects are already at high risk.

In vitro evaluation of a new iterative reconstruction algorithm for dose reduction in coronary artery calcium scoring

Background

Coronary artery calcium (CAC) scoring is a widespread tool for cardiac risk assessment in asymptomatic patients and accompanying possible adverse effects, i.e. radiation exposure, should be as low as reasonably achievable.

Purpose

To evaluate a new iterative reconstruction (IR) algorithm for dose reduction of in vitro coronary artery calcium scoring at different tube currents.

Material and Methods

An anthropomorphic calcium scoring phantom was scanned in different configurations simulating slim, average-sized, and large patients. A standard calcium scoring protocol was performed on a third-generation dual-source CT at 120 kVp tube voltage. Reference tube current was 80 mAs as standard and stepwise reduced to 60, 40, 20, and 10 mAs. Images were reconstructed with weighted filtered back projection (wFBP) and a new version of an established IR kernel at different strength levels. Calcifications were quantified calculating Agatston and volume scores. Subjective image quality was visualized with scans of an ex vivo human heart.

Results

In general, Agatston and volume scores remained relatively stable between 80 and 40 mAs and increased at lower tube currents, particularly in the medium and large phantom. IR reduced this effect, as both Agatston and volume scores decreased with increasing levels of IR compared to wFBP (P < 0.001). Depending on selected parameters, radiation dose could be lowered by up to 86% in the large size phantom when selecting a reference tube current of 10 mAs with resulting Agatston levels close to the reference settings.

Conclusion

New iterative reconstruction kernels may allow for reduction in tube current for established Agatston scoring protocols and consequently for substantial reduction in radiation exposure.

Greater preclinical atherosclerosis in treated monogenic familial hypercholesterolemia vs. polygenic hypercholesterolemia

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is a common inherited disorder of low density lipoprotein-cholesterol (LDL-C) metabolism. It is associated with higher risk of premature coronary heart disease. Around 60% of patients with a clinical diagnosis of FH do not have a detectable mutation in the genes causing FH and are most likely to have a polygenic cause for their raised LDL-C. We assessed the degree of preclinical atherosclerosis in treated patients with monogenic FH versus polygenic hypercholesterolemia.

METHODS

FH mutation testing and genotypes of six LDL-C-associated single nucleotide polymorphisms (SNPs) were determined using routine methods. Those with a detected mutation (monogenic) and mutation-negative patients with LDL-C SNP score in the top two quartiles (polygenic) were recruited. Carotid intima media thickness (IMT) was measured by B-mode ultrasound and the coronary artery calcium (CAC) score was performed in three lipid clinics in the UK and the Netherlands.

RESULTS

86 patients (56 monogenic FH, 30 polygenic) with carotid IMT measurement, and 166 patients (124 monogenic, 42 polygenic) with CAC score measurement were examined. After adjustment for age and gender, the mean of all the carotid IMT measurements and CAC scores were significantly greater in the monogenic than the polygenic patients [carotid IMT mean (95% CI): 0.74 mm (0.7-0.79) vs. 0.66 mm (0.61-0.72), p = 0.038 and CAC score mean (95%): 24.5 (14.4-41.8) vs. 2.65 (0.94-7.44), p = 0.0004].

CONCLUSIONS

In patients with a diagnosis of FH, those with a monogenic cause have a higher severity of carotid and coronary preclinical atherosclerosis than those with a polygenic aetiology.

Socioeconomic Status Interacts with the Genetic Effect of a Chromosome 9p21.3 Common Variant to Influence Coronary Artery Calcification and Incident Coronary Events in the Heinz Nixdorf Recall Study (Risk Factors, Evaluation of Coronary Calcium, and Lifestyle)

Background—

Genetic variants of a locus within the chromosome 9p21.3 region are consistently associated with coronary artery disease and coronary artery calcification (CAC). The aim of this study was to examine whether a 9p21.3 common variant interacts with socioeconomic status (SES) to influence CAC and incident coronary events in a population-based cohort.

Methods and Results—

9p21.3 single nucleotide polymorphism rs2891168 was genotyped in 4116 participants of the Heinz Nixdorf Recall study. SES indicators (education and income) and CAC were assessed at baseline. Incident coronary events were ascertained over a median follow-up of 9.3 years. Multiple regression models were fitted to estimate genetic effects on log e (CAC+1) and incident coronary events. Genetic effects were highest in the lower income tertile with a 53.1% (95% confidence interval, 30.6%–79.6%; P =1.8×10 – 7 ) increase in CAC and a hazard ratio of 1.44 (95% confidence interval, 1.01–2.07; P =0.049) for incident coronary events per additional risk allele. After including genotype×SES interaction terms in the regression models, genotype×income interactions were observed for CAC (exp[β g×income ]=0.85 [95% confidence interval, 0.74–0.98; P g×income =0.02] per 1000€/mo increase and additional risk allele) and for incident coronary events (hazard ratio g×income =0.69 [95% confidence interval, 0.48–0.98; P g×income =0.04] per 1000€/mo increase and additional risk allele). No interaction was observed using education as SES indicator.

Conclusions—

A 9p21.3 common variant seems to interact with SES to influence CAC and incident coronary events in a population-based cohort. This supports the hypothesis that better material, psychosocial, and lifestyle conditions enable higher SES groups to reduce the expression of their genetic susceptibility to coronary artery disease.

[Prevalence and extent of coronary artery calcification in an asymptomatic cardiovascular Mexican population: Genetics of Atherosclerotic Disease study]

OBJECTIVE

The prevalence of coronary artery calcification (CAC), a specific marker of atherosclerosis, is unknown in Mexico. Our aim was to investigate the prevalence and quantity of CAC and their association with cardiovascular risk factors in a Mexican population.

METHODS

CAC was measured by multidetector computed tomography in asymptomatic subjects who participated in the Genetics of Atherosclerotic Disease study. Cardiovascular risk factors and medication were recorded.

RESULTS

The sample included 1,423 individuals (49.5% men), aged 53.7±8.4 years. Those with CAC showed a higher prevalence of dyslipidaemia, diabetes, hypertension, and other risk factors. The prevalence of CAC>0 Agatston units was significantly higher among men (40%) than among women (13%). Mean values of CAC score increased consistently with increasing age and were higher in men than women in each age group. Age and high low density lipoprotein cholesterol were independently associated with prevalence of CAC>0 in men and women, while increasing systolic blood pressure in women and age in both genders showed an independent association with CAC extension.

CONCLUSIONS

In the Mexican population the prevalence and extent of CAC were much higher in men than in women, and strongly increased with age. Independent predictors of CAC prevalence were age and low density lipoprotein cholesterol (LDL-C).

Left ventricular function at two-year follow-up in treatment-naive rheumatoid arthritis patients is associated with anti-cyclic citrullinated peptide antibody status: a cohort study

OBJECTIVES

In rheumatoid arthritis (RA), the role of autoimmunity, especially anti-cyclic citrullinated peptide antibody (anti-CCP) level, and the time-course of left ventricular (LV) function is unknown. The objective was to assess LV function and the amount of coronary calcium in relation to anti-CCP levels in a cohort of treatment-naive RA patients, and to assess changes in these parameters during a 2 year follow-up period.

METHOD

Sixty-six steroid- and disease-modifying anti-rheumatic drug-naive RA patients were treated with methotrexate according to the Danish national guidelines. We assessed LV function by conventional echocardiography and speckle-tracking echocardiography. We estimated the amount and progression of coronary calcium by coronary computed tomography. Patients were examined at the time of diagnosis and after 2 years.

RESULTS

Patients with elevated anti-CCP at baseline and after 2 years, compared to those with non-persistently elevated anti-CCP, had significantly less improvement in S´ (1 ± 1.4 cm/s vs 0.2 ± 0.9 cm/s; p = 0.04) and a worsening in global longitudinal systolic strain (GLS) (0.6 ± 1.8% vs -1 ± 2.8%; p = 0.04). There was a significant correlation between ΔGLS over 2 years and anti-CCP at 2 year follow-up (r = 0.36; p = 0.006). We observed a small progression of coronary calcium score during the 2 year follow-up period. No differences in progression were found between patients with high anti-CCP titres at baseline and 2 year follow-up (n = 12) and patients with normal/low anti-CCP titres (n = 32) (23.8 ± 40.3 vs 22.6 ± 68.9; p = 0.96).

CONCLUSIONS

Deformation analysis by speckle-tracking echocardiography is a valuable tool to detect early development of myocardial dysfunction despite normal ejection fraction in RA.

Coronary Artery Calcium as an Independent Surrogate Marker in the Risk Assessment of Patients With Atrial Fibrillation and an Intermediate Pretest Likelihood for Coronary Artery Disease Admitted to a German Chest Pain Unit

BACKGROUND

About 10% of patients admitted to a chest pain unit (CPU) exhibit atrial fibrillation (AF).

HYPOTHESIS

To determine whether calcium scores (CS) are superior over common risk scores for coronary artery disease (CAD) in patients presenting with atypical chest pain, newly diagnosed AF, and intermediate pretest probability for CAD within the CPU.

METHODS

In 73 subjects, CS was related to the following risk scores: Global Registry of Acute Coronary Events (GRACE) score, including a new model of a frequency-normalized approach; Thrombolysis In Myocardial Infarction score; European Society of Cardiology Systematic Coronary Risk Evaluation (SCORE); Framingham risk score; and Prospective Cardiovascular Münster Study score. Revascularization rates during index stay were assessed.

RESULTS

Median CS was 77 (interquartile range, 1-270), with higher values in men and the left anterior descending artery. Only the modified GRACE (ρ = 0.27; P = 0.02) and the SCORE (ρ = 0.39; P < 0.005) were significantly correlated with CS, whereas the GRACE (τ = 0.21; P = 0.04) and modified GRACE (τ = 0.23; P = 0.02) scores were significantly correlated with percentile groups. Only the CS significantly discriminated between those with and without stenosis (P < 0.01).

CONCLUSIONS

Apart from modified GRACE score, overall correlations between risk scores and calcium burden, as well as revascularization rates during index stay, were low. By contrast, the determination of CS may be used as an additional surrogate marker in risk stratification in AF patients with intermediate pretest likelihood for CAD admitted to a CPU.

Subclinical coronary atherosclerosis is more pronounced in men and women with lower socio-economic status: associations in a population-based study Coronary atherosclerosis and social status

Background

Social inequalities of manifest coronary heart diseases are well documented in modern societies. Less evidence is available on subclinical atherosclerotic disease despite the opportunity to investigate processes underlying this association. Therefore, we examined the relationship between coronary artery calcification as a sign of subclinical coronary atherosclerosis, socio-economic status and established cardiovascular risk factors in a healthy population.

Design

Cross-sectional.

Methods

In a population-based sample of 4487 men and women coronary artery calcification was assessed by electron beam computed tomography quantified by the Agatston score. Socio-economic status was assessed by two indicators, education and income. First, we investigated associations between the social measures and calcification. Second, we assessed the influence of cardiovascular risk factors on this association.

Results

After adjustment for age, men with 10 and less years of formal education had a 70% increase in calcification score compared with men with high education. The respective increase for women was 80%. For income the association was weaker (among men 20% higher for the lowest compared with the highest quartile; and among women 50% higher, respectively). Consecutive adjustment for cardiovascular risk factors significantly attenuated the observed association of socio-economic status with calcification.

Conclusions

Social inequalities in coronary heart diseases seem to influence signs of subclinical coronary atherosclerosis as measured by coronary artery calcification. Importantly, cumulation of major cardiovascular risk factors in lower socio-economic groups accounted for a substantial part of this association.

Ankle-Brachial Index but Neither Intima Media Thickness Nor Coronary Artery Calcification is Associated With Mild Cognitive Impairment

BACKGROUND

Several studies have reported an association of atherosclerosis with mild cognitive impairment (MCI) and dementia independent of cardiovascular risk factors.

OBJECTIVE

To compare the cross-sectional association of the ankle-brachial index (ABI), intima media thickness (IMT), and coronary artery calcification (CAC) with MCI and its subtypes, amnestic MCI (aMCI) and non-amnestic MCI (naMCI) in the population-based Heinz Nixdorf Recall cohort study.

METHODS

4,086 participants performed a validated brief cognitive assessment at the first follow-up examination (2006-2008). MCI was diagnosed according to previously published criteria. Prevalence ratio (PR) regression models adjusted for age, gender, education, cardiovascular risk factors, and APOE genotype were used to compare the association of the ABI, the CAC-Agatston score and the IMT with MCI and its subtypes.

RESULTS

We identified 490 participants with MCI (mean age 66.1 ± 7.8, 46.9 % male, aMCI n = 249, naMCI n = 241) and 1,242 cognitively normal participants. A decreasing ABI (per 0.1) was significantly associated with a higher MCI prevalence in fully adjusted models (PR 1.06; 95% confidence interval (CI) 1.01-1.11), whereas an increasing CAC (log(CAC+1)) or IMT (per 0.1 mm) were not associated after adjustment. A decreasing ABI was also significantly associated with naMCI in fully adjusted models (PR 1.12; CI 1.03-1.21) but not with aMCI.

CONCLUSIONS

Our data show that the degree of generalized atherosclerosis as measured by the ABI is associated with MCI and with naMCI in a population-based cohort.

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Association between coronary artery calcification and left ventricular diastolic dysfunction in elderly people

Coronary artery calcification (CAC) is associated with the incidence of congestive heart failure. We evaluated the association between CAC and left ventricular diastolic dysfunction (LVDD) in elderly patients without coronary artery disease. Coronary computed tomography was performed in 1,021 consecutive patients >55 years of age who were suspected of having coronary artery disease. A total of 530 patients (age, 70 ± 8 years; 56 % men) with a LV ejection fraction >50 % and without obstructive coronary artery disease and a history of coronary artery disease were included in the analysis. LVDD was defined according to a standard algorithm by echocardiography (septal e' <8, lateral e' <10, and left atrial volume index ≥34 mL/m(2)). A total of 224 of 530 patients had LVDD. CAC scores in patients with LVDD were higher than those in patients without LVDD (p < 0.01). The prevalence of LVDD in patients with CAC scores ≥400 was greater than that in patients with CAC scores of 0-9 (58 vs. 34 %, p < 0.01). After adjustment for confounding factors, the CAC score was associated with LVDD, with an odds ratio of 1.96 (95 % confidence interval: 1.11-3.43, p = 0.02) for a CAC score ≥400 compared with a CAC score of 0-9. A CAC score ≥400 was associated with LVDD in elderly patients without CAD in this population. Further prospective studies are needed to evaluate the clinical relevance of CAC as a risk of heart failure with preserved ejection fraction.

Thoracic aortic calcification is associated with incident stroke in the general population in addition to established risk factors

AIMS

The aorta is a major source of cerebral thromboembolism, but its role in stroke pathogenesis is not well understood due to its poor accessibility for non-invasive imaging. We examined whether thoracic aortic calcification (TAC), a marker of aortic plaque load, is associated with stroke in addition to established risk factors.

METHODS AND RESULTS

A total of 3930 subjects from the population-based Heinz Nixdorf Recall study (45-75 years; 47.1% men) without previous stroke, coronary heart disease, or myocardial infarction were evaluated for incident stroke events over 109.0 ± 23.3 months. Cox proportional hazards regressions were used to examine associations with stroke of TAC in addition to established risk factors (age, sex, systolic blood pressure, LDL, HDL, diabetes, and smoking) and coronary artery calcification (CAC). 101 incident strokes occurred during the follow-up period. Subjects suffering a stroke had significantly higher TAC values at baseline than the remaining subjects (median = 83.1 [Q1;Q3 = 4.7;472.9] vs. 15.7 [0.0;117.1]; P < 0.001). In a multivariable Cox proportional hazards regression, log(TAC + 1) (hazards ratio [HR] = 1.09 [95% confidence interval = 1.00-1.19]; P = 0.044) was associated with stroke in addition to established risk factors. Further analyses revealed that log(DTAC + 1), i.e. calcification of the descending aorta (1.11 [1.02-1.20]; P = 0.016), but not log(ATAC + 1), i.e. calcification of the ascending aorta (1.02 [0.93-1.11]; P = 0.713), was associated with stroke. The HR for log(TAC + 1) decreased to 1.06 (0.97-1.16; P = 0.202), when log(CAC + 1) was also inserted into multivariable analyses.

CONCLUSION

Calcification of the thoracic aorta, more specifically its descending segment, is associated with incident stroke in addition to established risk factors. CAC outperforms aortic calcification as a stroke predictor.

Development of a new diabetes risk prediction tool for incident coronary heart disease events: the Multi-Ethnic Study of Atherosclerosis and the Heinz Nixdorf Recall Study

OBJECTIVE

We develop a new diabetes CHD risk estimator using traditional risk factors plus coronary artery calcium (CAC), ankle-brachial index (ABI), high sensitivity C-reactive protein, family history of CHD, and carotid intima-media thickness and compared it with United Kingdom Prospective Diabetes study (UKPDS), Framingham risk and the NCEP/ATP III risk scores in type 2 diabetes mellitus (T2DM).

METHODS AND RESULTS

We combined data from T2DM without clinical CVD in the Multi-Ethnic Study of Atherosclerosis (MESA) and the Heinz Nixdorf Recall Study (N = 1343). After a mean follow-up of 8.5 years, 85 (6.3%) participants had incident CHD. Among the novel risk markers, CAC best predicted CHD independent of the FRS [hazard ratio: HR (95% CI): log (CAC +25):1.69 (1.45-1.97), p < 0.0001; CAC categories: CAC ≤ 25 as reference, >25 and ≤125:2.29 (0.87-5.95), >125 and ≤400: 3.87 (1.57-9.57), >400: 5.97 (2.57-13.84), respectively). The MESA-HNR diabetes CHD risk score has better accuracy for the main outcome versus the FRS or UKPDS [area under curve (AUC) of 0.76 vs. 0.70 and 0.69, respectively; all p < 0.05]. The MESA-HNR risk score improved risk classification versus the FRS (net reclassification improvement (NRI) = 0.19 and integrated discrimination improvement (IDI) = 0.046, p < 0.05) and UKPDS (NRI = 0.215 and IDI = 0.046, p < 0.05). Compared with the ATP III guidelines, the MESA-HNR score has an NRI of 0.74 for the main outcome.

CONCLUSIONS

This new CHD risk estimator has better discriminative ability for incident CHD than the FRS, UKPDS, and the ATP III/NCEP recommendations in a multi-ethnic cohort with T2DM.

Coronary artery calcification, intima-media thickness, and ankle-brachial index are complementary stroke predictors

BACKGROUND AND PURPOSE

Coronary artery calcification (CAC), a marker of coronary atherosclerosis, predicts stroke in addition to established risk factors. Whether CAC's predictive value can be improved by peripheral atherosclerosis markers, namely carotid intima-media thickness (CIMT) and ankle-brachial index (ABI), was unknown.

METHODS

A total of 3289 participants of the population-based Heinz Nixdorf Recall study (45-75 years; 48.8% men) without previous stroke or coronary heart disease were evaluated for incident stroke for 9.0±1.9 years. CAC, CIMT, and ABI were examined as stroke predictors.

RESULTS

Eighty-four strokes occurred during follow-up. In multivariable Cox proportional hazard regressions, CAC (hazard ratio, 1.45 [95% confidence interval, 1.11-1.88] per SD increase in ln(CAC+1); SD, 2.40), CIMT (1.34 [1.08-1.66] per SD increase; SD, 0.127 mm), and ABI (1.55 [1.32-1.82] per SD decrease; SD, 0.148) were associated with stroke in addition to established risk factors. When combined with each other, ln(CAC+1)'s hazard ratio remained similar when CIMT (1.41 [1.09-1.83]) was inserted into the multivariable model, but slightly decreased when ABI (1.31 [1.01-1.72]) or CIMT and ABI (1.29 [0.99-1.68]) were included. Although CAC alone did not significantly elevate the area under the curve in Harrell's c-statistics (by 0.009; P=0.379) in addition to established risk factors, the combination of CAC and ABI increased area under the curve (by 0.029; P=0.047), as did ABI (by 0.025; P=0.038) but not CIMT (by 0.002; P=0.795) alone. The combination of CAC and ABI also resulted in significant category-free net reclassification and integrated discrimination improvement.

CONCLUSIONS

CAC, CIMT, and ABI provide complementary information about stroke risk. ABI, which is distinctive in a small subpopulation, had the highest and CIMT, which is distributed across a larger range of values, had the lowest predictive value.

Age and sex based reference values for incidental coronary artery and thoracic aorta calcifications on routine clinical chest CT: a powerful tool to appreciate available imaging findings

OBJECTIVE

To establish age and gender specific reference values for incidental coronary artery and thoracic aorta calcification scores on routine diagnostic CT scans. These reference values can aid in structured reporting and interpretation of readily available imaging data by chest CT readers in routine practice.

METHODS

A random sample of 1572 (57% male, median age 61 years) was taken from a study population of 12,063 subjects who underwent diagnostic chest CT for non-cardiovascular indications between January 2002 and December 2005. Coronary artery and thoracic aorta calcifications were graded using a validated ordinal score. The 25th, 50th and 75th percentile cut points were calculated for the coronary artery and thoracic aorta calcification scores within each age/gender stratum.

RESULTS

The 75th percentile cut points for coronary artery calcification scores were higher for men than for women across all age groups, with the exception of the lowest age group. The 75th percentile cut points for thoracic aorta calcifications scores were comparable for both genders across all age groups. Based on the obtained age and gender reference values a calculation tool is provided, that allows one to enter an individual's age, gender and calcification scores to obtain the corresponding estimated percentiles.

CONCLUSIONS

The calculation tool as provided in this study can be used in daily practice by CT readers to examine whether a subject has high calcifications scores relative to others with the same age and gender.

Effect of smoking and other traditional risk factors on the onset of coronary artery calcification: results of the Heinz Nixdorf recall study

BACKGROUND

Coronary artery calcium (CAC) indicates coronary atherosclerosis and can be present in very early stages of the disease. The conversion from no CAC to any CAC reflects an important step of the disease process as cardiovascular risk is increased in persons even with mildly elevated CAC. We sought to identify risk factors that determined incident CAC>0 in men and women from an unselected general population with a special focus on the role of smoking.

METHODS

All 4814 persons that were initially studied in the Heinz Nixdorf Recall Study were invited to participate in the follow-up examination after 5.1 ± 0.3 years. All traditional Framingham risk factors were quantified using standard techniques. Smokers were categorized in never, former and present smokers. The CAC scores were measured from EBCT using the Agatston method.

RESULTS

Overall, out of 342 men and 919 women with zero CAC at baseline, 107 (31.3%) men and 210 (22.9%) women had CAC>0 at second examination. In multivariable analysis, age (OR estimate per 5 years: 1.34 (95%CI: 1.21-1.47)), LDL cholesterol (per 10 mg/dL: 1.05 (95%CI: 1.01-1.10)), systolic blood pressure (per 10 mmHg: 1.19 (95%CI: 1.11-1.28)) and current smoking (1.49 (95%CI: 1.04-2.15)) were independent predictors of CAC onset. The probability of CAC onset steadily increased with age from 23.3% (men) and 15.3% (women) at age 45-49 years to 66.7% (men) and 42.9% (women) at age 70-74 years. The difference in age-dependent conversion rates was quantified by years between reaching a given level of CAC onset probability. We found a consistent pattern with respect to smoking status: presently (formerly) smoking middle-aged men convert to positive CAC 10 (5) years earlier than never smokers, for women (middle-aged to elderly) this time span is 8 (5) years.

CONCLUSION

Several traditional CVD risk factors are associated with CAC onset during 5 years follow-up. CAC onset is accelerated by approximately 10 (5) years for present (former) compared to never smokers.

B-type natriuretic peptide: distribution in the general population and the association with major cardiovascular and coronary events--the Heinz Nixdorf Recall Study

BACKGROUND

A B-type natriuretic peptide (BNP) threshold of 100 pg/ml is used in practice for identification of heart failure, but data about the "normal" distribution of BNP in a large population in primary prevention are rare. We aimed to characterize the BNP distribution in a healthy subset of a population-based cohort and to evaluate the association of elevated BNP levels with major events.

METHODS

In a first step, we determined gender-specific distribution and 90th percentiles of BNP in participants who were at baseline free from known determinants of increased BNP, i.e. cardiovascular disease, hypertension or chronic kidney disease. Consecutively, the association of BNP levels above these 90th percentiles with subsequent cardiovascular and coronary events was assessed in the entire cohort.

RESULTS

In the BNP-normal sub-sample (n = 1,639), we defined gender-specific 90th percentile of BNP (31.3 pg/ml for men, 45.5 pg/ml for women). From overall 3,697 subjects (mean age 59.4, 52.4 % female), 194 subjects developed a major cardiovascular event and 122 myocardial infarction during a mean follow-up period of 8.0 ± 1.5 years. The 90th percentiles derived from the normal subset as threshold showed strong associations with major events in the entire cohort even after adjusting for traditional risk factors: hazard ratio (95% CI): 1.86 (1.37; 2.53), p < 0.0001 for cardiovascular, and 1.77 (1.19; 2.62), p = 0.005 for coronary events.

CONCLUSION

The gender-specific 90th percentile of BNP (31 pg/ml for males and 45 pg/ml for females) obtained from a BNP-normal sub-sample is associated with incident major cardiovascular and coronary events, suggesting that even BNP values lower than 100 pg/ml could imply prognostic information in the general population.

Association of obstructive sleep apnoea with subclinical coronary atherosclerosis

BACKGROUND

Accumulating evidence suggests a role of obstructive sleep apnoea (OSA) as a risk factor for coronary atherosclerosis. This study aimed i) to assess the prevalence of OSA in the general population and ii) to analyse the association of this disorder with traditional cardiovascular disease risk factors and subclinical coronary atherosclerosis.

METHODS

In a cross-sectional analysis of the Heinz Nixdorf Recall study a subgroup of 1604 subjects (791 men, age 50-80 years) underwent OSA screening. Furthermore, coronary artery calcium (CAC) was measured. OSA was defined as apnoea-hypopnoea index (AHI) ≥ 15/h.

RESULTS

OSA was observed in 29.1% of men and 15.6% of women. In a multiple linear regression analysis adjusted for risk factors AHI was associated with CAC in men aged ≤65 years (estimated log-transformed increase of CAC = 0.25, 95% confidence interval (CI) = -0.001-0.50, p = 0.051) and in women of any age (estimated log-transformed increase = 0.23, 95% CI = 0.04-0.41, p = 0.02). Doubling of the AHI was associated with a 19% increase of CAC in men aged ≤65 years and with a 17% increase in women of any age.

CONCLUSIONS

In the general population aged ≥50 years OSA is associated with subclinical atherosclerosis in men aged ≤65 years and in women of any age, independent of traditional cardiovascular risk factors.

Comparison of factors associated with carotid intima-media thickness in the Multi-ethnic Study of Atherosclerosis (MESA) and the Heinz Nixdorf Recall Study (HNR)

BACKGROUND

The measurement of carotid intima-media thickness (CIMT) is a valid method to quantify levels of atherosclerosis. The present study was conducted to compare the strengths of associations between CIMT and cardiovascular risk factors in two different populations.

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) and the Heinz Nixdorf Recall Study (HNR) are two population-based prospective cohort studies of subclinical cardiovascular disease. All Caucasian subjects aged 45 to 75 years from these cohorts who were free of baseline cardiovascular disease (n = 2,820 in HNR, n = 2,270 in MESA) were combined. CIMT images were obtained using B-mode sonography at the right and left common carotid artery and measured 1 cm starting from the bulb.

RESULTS

In both studies, age, male sex, and systolic blood pressure showed the strongest association (P < .0001 for each) for a higher CIMT. The mean of mean far wall CIMT was slightly higher in MESA participants (0.71 vs 0.67 mm). Almost all significant variables were consistent between the two cohorts in both magnitude of association with CIMT and statistical significance, including age, sex, smoking, diabetes, cholesterol levels, and blood pressure. For example, the association with systolic blood pressure was (ΔSD = 0.011; 95% confidence interval, 0.0009 to 0.014) per mm Hg in MESA and (ΔSD = 0.010; 95% confidence interval, 0.005 to 0.021) per mm Hg in HNR. This consistency persisted throughout the traditional (Framingham) risk factors.

CONCLUSIONS

A comparison of the associations between traditional cardiovascular risk factors and CIMT across two culturally diverse populations showed remarkable consistency.

Predicting risk of coronary events and all-cause mortality: role of B-type natriuretic peptide above traditional risk factors and coronary artery calcium scoring in the general population: the Heinz Nixdorf Recall Study

AIMS

Several biomarkers including B-type natriuretic peptide (BNP) have been suggested to improve prediction of coronary events and all-cause mortality. Moreover, coronary artery calcium (CAC) as marker of subclinical atherosclerosis is a strong predictor for cardiovascular mortality and morbidity. We aimed to evaluate the predictive ability of BNP and CAC for all-cause mortality and coronary events above traditional cardiovascular risk factors (TRF) in the general population.

METHODS

We followed 3782 participants of the population-based Heinz Nixdorf Recall cohort study without coronary artery disease at baseline for 7.3 ± 1.3 years. Associations of BNP and CAC with incident coronary events and all-cause mortality were assessed using Cox regression, Harrell's c, and time-dependent integrated discrimination improvement (IDI(t), increase in explained variance).

RESULTS

Subjects with high BNP levels had increased frequency of coronary events and death (coronary events/mortality: 14.1/28.2% for BNP ≥100 pg/ml vs. 2.7/5.5% for BNP < 100 pg/ml, respectively). Subjects with a BNP ≥100 pg/ml had increased incidence of hard endpoints sustaining adjustment for CAC and TRF (for coronary events: hazard ratio (HR) (95% confidence interval (CI)) 3.41(1.78-6.53); for all-cause mortality: HR 3.35(2.15-5.23)). Adding BNP to TRF and CAC increased measures of predictive ability: coronary events (Harrell's c, for coronary events, 0.775-0.784, p = 0.09; for all-cause mortality 0.733-0.740, p = 0.04; and IDI(t) (95% CI), for coronary events: 2.79% (0.33-5.65%) and for all-cause mortality 1.78% (0.73-3.10%).

CONCLUSIONS

Elevated levels of BNP are associated with excess incident coronary events and all-cause mortality rates, with BNP and CAC significantly and complementary improving prediction of risk in the general population above TRF.

Coronary artery calcification is an independent stroke predictor in the general population

BACKGROUND AND PURPOSE

Coronary artery calcification (CAC) is a noninvasive marker of plaque load that predicts myocardial infarcts in the general population. Herein, we investigated whether CAC predicts stroke events in addition to established risk factors that are part of the Framingham risk score.

METHODS

A total of 4180 subjects from the population-based Heinz Nixdorf Recall study (45-75 years of age; 47.1% men) without previous stroke, coronary heart disease, or myocardial infarction were evaluated for stroke events over 94.9 ± 19.4 months. Cox proportional hazards regressions were used to examine CAC as stroke predictor in addition to established vascular risk factors (age, sex, systolic blood pressure, low-density lipoprotein, high-density lipoprotein, diabetes mellitus, smoking, and atrial fibrillation).

RESULTS

Ninety-two incident strokes occurred (82 ischemic, 10 hemorrhagic). Subjects suffering a stroke had significantly higher CAC values at baseline than the remaining subjects (median, 104.8[Q1;Q3, 14.0;482.2] vs 11.2[0;106.2]; P<0.001). In a multivariable Cox regression, log10(CAC+1) was an independent stroke predictor (hazards ratio, 1.52 [95% confidence interval, 1.19-1.92]; P=0.001) in addition to age (1.35 per 5 years [1.15-1.59]; P<0.001), systolic blood pressure (1.25 per 10 mm Hg [1.14-1.37]; P<0.001), and smoking (1.75 [1.07-2.87]; P=0.025). CAC predicted stroke in men and women, particularly in subjects <65 years of age and independent of atrial fibrillation. CAC discriminated stroke risk specifically in participants belonging to the low (<10%) and intermediate (10%-20%) Framingham risk score categories.

CONCLUSIONS

CAC is an independent stroke predictor in addition to classical risk factors in subjects at low or intermediate vascular risk.

[The Heinz Nixdorf Recall study]

The Heinz Nixdorf Recall Study is a population-based study that aims to improve the prediction of cardiovascular events by integrating new imaging and non-imaging modalities in risk assessment. One focus of the study is the evaluation of the quantification of subclinical coronary artery calcifications (coronary artery calcification, CAC) as a prognostic factor in predicting cardiac events. Primary endpoints are myocardial infarction and sudden cardiac death. The study was initiated in the late 1990s and enrolled a total of 4,814 participants aged 45-75 years between December 2000 and August 2003. A 5-year follow-up examination took place between 2006 and 2008. Currently, the 10-year follow-up is under way and is estimated to be finished in July 2013. Extending the original aims of the study, serial CAC measurements will allow the characterization of the natural history of CAC dynamics, the identification of its determinants and an understanding of the impact of CAC progression on the primary endpoints. The Heinz Nixdorf Recall Study will significantly extend our knowledge about new modalities in the prediction of cardiac events.

Coronary artery calcium distributions in older persons in the AGES-Reykjavik study

Coronary Artery Calcium (CAC) is a sign of advanced atherosclerosis and an independent risk factor for cardiac events. Here, we describe CAC-distributions in an unselected aged population and compare modelling methods to characterize CAC-distribution. CAC is difficult to model because it has a skewed and zero inflated distribution with over-dispersion. Data are from the AGES-Reykjavik sample, a large population based study [2002-2006] in Iceland of 5,764 persons aged 66-96 years. Linear regressions using logarithmic- and Box-Cox transformations on CAC+1, quantile regression and a Zero-Inflated Negative Binomial model (ZINB) were applied. Methods were compared visually and with the PRESS-statistic, R(2) and number of detected associations with concurrently measured variables. There were pronounced differences in CAC according to sex, age, history of coronary events and presence of plaque in the carotid artery. Associations with conventional coronary artery disease (CAD) risk factors varied between the sexes. The ZINB model provided the best results with respect to the PRESS-statistic, R(2), and predicted proportion of zero scores. The ZINB model detected similar numbers of associations as the linear regression on ln(CAC+1) and usually with the same risk factors.