Comparison of dual-source and electron-beam CT for the assessment of coronary artery calcium scoring

Epidemiology and Prognostic Implications of Coronary Artery Calcium in Asymptomatic Individuals With Prediabetes: A Multicohort Study

OBJECTIVE

To describe the epidemiology and prognostic value of coronary artery calcium (CAC) in individuals with prediabetes.

RESEARCH DESIGN AND METHODS

We pooled participants free of clinical atherosclerotic cardiovascular disease (ASCVD) from four prospective cohorts: the Multi-Ethnic Study of Atherosclerosis, Heinz Nixdorf Recall Study, Framingham Heart Study, and Jackson Heart Study. Two definitions were used for prediabetes: inclusive (fasting plasma glucose [FPG] ≥100 to <126 mg/dL and hemoglobin A1c [HbA1c] ≥5.7% to <6.5%, if available, and no glucose-lowering medications) and restrictive (FPG ≥110 to <126 mg/dL and HbA1c ≥5.7% to <6.5%, if available, among participants not taking glucose-lowering medications).

RESULTS

The study included 13,376 participants (mean age 58 years; 54% women; 57% White; 27% Black). The proportions with CAC ≥100 were 17%, 22%, and 37% in those with euglycemia, prediabetes, and diabetes, respectively. Over a median (25th-75th percentile) follow-up time of 14.6 (interquartile range 7.8-16.4) years, individuals with prediabetes and CAC ≥100 had a higher unadjusted 10-year incidence of ASCVD (13.4%) than the overall group of those with diabetes (10.6%). In adjusted analyses, using the inclusive definition of prediabetes, compared with euglycemia, the hazard ratios (HRs) for ASCVD were 0.79 (95% CI 0.62, 1.01) for prediabetes and CAC 0, 0.70 (0.54, 0.89) for prediabetes and CAC 1-99, 1.54 (1.27, 1.88) for prediabetes and CAC ≥100, and 1.64 (1.39, 1.93) for diabetes. Using the restrictive definition, the HR for ASCVD was 1.63 (1.29, 2.06) for prediabetes and CAC ≥100.

CONCLUSIONS

CAC ≥100 is frequent among individuals with prediabetes and identifies a high ASCVD risk subgroup in which the adjusted ASCVD risk is similar to that in individuals with diabetes.

Coronary Artery Calcium Scoring in Asymptomatic Patients

Coronary artery calcium (CAC) scoring is an important prognostic tool for personalized cardiovascular preventive care and has recently been incorporated into American College of Cardiology/American Heart Association guidelines. CAC provides direct visualization and quantification of CAC burden for risk stratification and primary prevention of cardiovascular events in an asymptomatic population. CAC scoring is recommended for individuals with intermediate 10-year atherosclerotic cardiovascular disease (ASCVD) risk and selective populations with borderline ASCVD risk. In this review, we outline the interpretation of CAC scores for predicting the risk of cardiovascular events, and we highlight the guidelines for starting statin and potentially starting aspirin therapy. A CAC score of 0 is the strongest negative predictive factor for cardiovascular disease (CVD), and a 0 score can successfully de-risk a patient. On the contrary, higher CAC scores correlate with worse cardiovascular prognostic outcomes. The CAC scan is a widely available and reproducible means for an early look at the atherosclerotic burden, and it can help strategize early interventions. The CAC interpretation and the decision to start treatment need to be personalized based on individual risk factors. We believe the emerging literature supports our contention that the CAC score can be used more broadly to improve the prophylaxis and treatment of a wider range of apparently healthy patients.

Current and Emerging Markers and Tools Used in the Diagnosis and Management of Chronic Kidney Disease-Mineral and Bone Disorder in Non-Dialysis Adult Patients

Chronic kidney disease (CKD) is a significant public health concern associated with significant morbidity and has become one of the foremost global causes of death in recent years. A frequent comorbidity of CKD is secondary hyperparathyroidism (SHPT), exemplified by high serum parathyroid hormone (PTH) levels. The mineral metabolism disturbances resulting from CKD and progression to SHPT are currently considered part of the definition of chronic kidney disease-mineral and bone disorder (CKD-MBD). However, CKD-MBD does not only include abnormalities in laboratory-measured parameters; it is a complex condition characterized by dysregulation of bone turnover, mineralization, growth and strength, accompanied by vascular or another soft-tissue calcification. Together, this increases the risk of bone fractures, cardiovascular disease, and overall mortality in CKD-MBD patients. Monitoring serum markers is essential in diagnosing SHPT and CKD-MBD, and there are several recognized indicators for prognosis, optimal clinical management and treatment response in late-stage kidney disease patients receiving dialysis. However, far fewer markers have been established for patients with non-dialysis CKD. This review provides an overview of current and emerging markers and tools used in the diagnosis and management of CKD-MBD in non-dialysis adult patients.

Progression of coronary artery calcification seems to be inevitable, but predictable - results of the Heinz Nixdorf Recall (HNR) study

Aim

Coronary artery calcification (CAC), as a sign of atherosclerosis, can be detected and progression quantified using computed tomography (CT). We develop a tool for predicting CAC progression.

Methods and results

In 3481 participants (45–74 years, 53.1% women) CAC percentiles at baseline (CAC_b) and after five years (CAC_5y) were evaluated, demonstrating progression along gender-specific percentiles, which showed exponentially shaped age-dependence. Using quantile regression on the log-scale (log(CAC_b+1)) we developed a tool to individually predict CAC_5y, and compared to observed CAC_5y. The difference between observed and predicted CAC_5y (log-scale, mean±SD) was 0.08±1.11 and 0.06±1.29 in men and women. Agreement reached a kappa-value of 0.746 (95% confidence interval: 0.732–0.760) and concordance correlation (log-scale) of 0.886 (0.879–0.893). Explained variance of observed by predicted log(CAC_5y+1) was 80.1% and 72.0% in men and women, and 81.0 and 73.6% including baseline risk factors. Evaluating the tool in 1940 individuals with CAC_b>0 and CAC_b<400 at baseline, of whom 242 (12.5%) developed CAC_5y>400, yielded a sensitivity of 59.5%, specificity 96.1%, (+) and (−) predictive values of 68.3% and 94.3%. A pre-defined acceptance range around predicted CAC_5y contained 68.1% of observed CAC_5y; only 20% were expected by chance. Age, blood pressure, lipid-lowering medication, diabetes, and smoking contributed to progression above the acceptance range in men and, excepting age, in women.

Conclusion

CAC nearly inevitably progresses with limited influence of cardiovascular risk factors. This allowed the development of a mathematical tool for prediction of individual CAC progression, enabling anticipation of the age when CAC thresholds of high risk are reached.

Fully automatic model-based calcium segmentation and scoring in coronary CT angiography

PURPOSE

The paper presents new methods for automatic coronary calcium detection, segmentation and scoring in coronary CT angiography (cCTA) studies.

METHODS

Calcium detection and segmentation are performed by modeling image intensity profiles of coronary arteries. The scoring algorithm is based on a simulated unenhanced calcium score (CS) CT image, constructed by virtually removing the contrast media from cCTA. The methods are implemented as part of a fully automatic system for CS assessment from cCTA.

RESULTS

The system was tested in two independent clinical trials on 263 studies and demonstrated 0.95/0.91 correlation between the CS computed from cCTA and the standard Agatston score derived from unenhanced CS CT. The mean absolute percent difference (MAPD) of 36/39 % between the two scores lies within the error range of the standard CS CT (15-65 %).

CONCLUSIONS

High diagnostic performance, combined with the benefits of the fully automatic solution, suggests that the proposed technique can be used to eliminate the need in a separate CS CT scan as part of the cCTA examination, thus reducing the radiation exposure and simplifying the procedure.

Catalysis in abiotic structured media: an approach to selective synthesis of biopolymers

Micro- and nanoenvironments formed by amphiphile self-assembled structures, water-ice lattices and minerals have well-defined, repeating, chemical and physical properties that can be used for selective synthesis of biopolymers, such as RNAs and proteins. The advances made in the development of polymerization supported by these micro- and nanosystems are reviewed here. In particular, it is shown that these systems promote non-enzymatic biopolymerization, yielding long polymers whose sequence composition is determined by the interactions between monomers and the supporting environment. When used to compartmentalize enzymatic biopolymerization, micro- and nanostructures allow the implementation of molecular selection and evolution schemes, which are difficult in homogeneous medium, yielding very active molecules. Thus, micro- and nanoenvironment approaches to the synthesis and selection of biopolymers could be developed into a new biotechnological tool for the production of biopolymers with novel functions.