Leik Woie

Serum 25(OH)D Is a 2-Year Predictor of All-Cause Mortality, Cardiac Death and Sudden Cardiac Death in Chest Pain Patients from Northern Argentina

Background Several studies have shown an association between vitamin D deficiency and cardiovascular risk. Vitamin D status is assessed by determination of 25-hydroxyvitamin D [25(OH)D] in serum. Methods We assessed the prognostic utility of 25(OH)D in 982 chest-pain patients with suspected acute coronary syndrome (ACS) from Salta, Northern Argentina. 2-year follow-up data including all-cause mortality, cardiac death and sudden cardiac death were analyzed in quartiles of 25(OH)D, applying univariate and multivariate analysis. Results There were statistically significant changes in seasonal 25(OH)D levels. At follow-up, 119 patients had died. The mean 25(OH)D levels were significantly lower among patients dying than in long-term survivors, both in the total population and in patients with a troponin T (TnT) release (n = 388). When comparing 25(OH)D in the highest quartile to the lowest quartile in a multivariable Cox regression model for all-cause mortality, the hazard ratio (HR) for cardiac death and sudden cardiac death in the total population was 0.37 (95% CI, 0.19–0.73), p = 0.004, 0.23 (95% CI, 0.08–0.67), p = 0.007, and 0.32 (95% CI, 0.11–0.94), p = 0.038, respectively. In patients with TnT release, the respective HR was 0.24 (95% CI, 0.10–0.54), p = 0.001, 0.18 (95% CI, 0.05–0.60), p = 0.006 and 0.25 (95% CI, 0.07–0.89), p = 0.033. 25(OH)D had no prognostic value in patients with no TnT release. Conclusion Vitamin D was shown to be a useful biomarker for prediction of mortality when obtained at admission in chest pain patients with suspected ACS. Trial registration ClinicalTrials.gov NCT01377402

The heart rate of ventricular tachycardia following an old myocardial infarction is inversely related to the size of scarring

AIMS The purpose of the study was to examine the relationship between the initial cycle length (CL) of ventricular tachycardia (VT) and the size of the myocardial scar and its border zone in patients with old myocardial infarction (MI). METHODS AND RESULTS Late gadolinium-enhancement cardiac magnetic resonance was performed prior to implantable cardioverter-defibrillator (ICD) implantation in 24 patients. The size of non-scared myocardium, scar, scar core, and border zone were measured as voxel numbers. The number of core islands, contour-regularity of scar and left-ventricular ejection fraction were also calculated. During the first year after ICD implantation, VT was recorded in 20 patients. With univariate regression analysis, the number of core islands had the highest correlation with the CL of VT (R = 0.614, adjusted R(2) = 0.342, P = 0.004). By multiple regression analyses, the highest correlation was found by the use of scar core and core islands (R = 0.721, adjusted R(2) = 0.464, P = 0.002). CONCLUSION The heart rate of VT (bpm) in patients with old MI is inversely related to the properties of the densest parts of the myocardial scar.

Exploratory data analysis of image texture and statistical features on myocardium and infarction areas in cardiac magnetic resonance images

The cardiac magnetic resonance (CMR) images from a group of patients with myocardial scars and implanted cardioverter-defibrillator (ICD) are divided into a group with low risk of arrhythmias (late incidents) and a group with high risk of arrhythmias (early incidents). Several hundred quantitative features describing sizes, statistics and textures of the segmented and defined areas of the images are computed from manually segmented images in an exploratory analysis. The method used to determine decision regions to discriminate the patients with low risk of arrhythmias from the patient with high risk of arrhythmias is a maximum likelihood estimation based Bayes classifiers described in [1]. The results presented can be interpreted as hypothesis of which features, and combinations of features, that might have discriminative power. A major hypothesis that arises is that there are important textural information in the scarred and non-scarred areas.

Probability mapping of scarred myocardium using texture and intensity features in CMR images

BackgroundThe myocardium exhibits heterogeneous nature due to scarring after Myocardial Infarction (MI). In Cardiac Magnetic Resonance (CMR) imaging, Late Gadolinium (LG) contrast agent enhances the intensity of scarred area in the myocardium.MethodsIn this paper, we propose a probability mapping technique using Texture and Intensity features to describe heterogeneous nature of the scarred myocardium in Cardiac Magnetic Resonance (CMR) images after Myocardial Infarction (MI). Scarred tissue and non-scarred tissue are represented with high and low probabilities, respectively. Intermediate values possibly indicate areas where the scarred and healthy tissues are interwoven. The probability map of scarred myocardium is calculated by using a probability function based on Bayes rule. Any set of features can be used in the probability function.ResultsIn the present study, we demonstrate the use of two different types of features. One is based on the mean intensity of pixel and the other on underlying texture information of the scarred and non-scarred myocardium. Examples of probability maps computed using the mean intensity of pixel and the underlying texture information are presented. We hypothesize that the probability mapping of myocardium offers alternate visualization, possibly showing the details with physiological significance difficult to detect visually in the original CMR image.ConclusionThe probability mapping obtained from the two features provides a way to define different cardiac segments which offer a way to identify areas in the myocardium of diagnostic importance (like core and border areas in scarred myocardium).

B-type natriuretic peptide and high sensitive C-reactive protein predict 2-year all cause mortality in chest pain patients: a prospective observational study from Salta, Argentina

BackgroundSeveral mechanisms are involved in the pathophysiology of the Acute Coronary Syndrome (ACS). We have addressed whether B-type natriuretic peptide (BNP) and high-sensitive C-reactive protein (hsCRP) in admission samples may improve risk stratification in chest pain patients with suspected ACS.MethodsWe included 982 patients consecutively admitted with chest pain and suspected ACS at nine hospitals in Salta, Northern Argentina. Total and cardiac mortality were recorded during a 2-year follow up period. Patients were divided into quartiles according to BNP and hsCRP levels, respectively, and inter quartile differences in mortality were statistically evaluated applying univariate and multivariate analyses.Results119 patients died, and the BNP and hsCRP levels were significantly higher among these patients than in survivors. In a multivariable Cox regression model for total death and cardiac death in all patients, the hazard ratio (HR) in the highest quartile (Q4) as compared to the lowest quartile (Q1) of BNP was 2.32 (95% confidence interval (CI), 1.24-4.35), p = 0.009 and 3.34 (95% CI, 1.26-8.85), p = 0.015, respectively. In the TnT positive patients (TnT > 0.01 ng/mL), the HR for total death and cardiac death in Q4 as compared to Q1 was 2.12 (95% CI, 1.07-4.18), p = 0.031 and 3.42 (95% CI, 1.13-10.32), p = 0.029, respectively.The HR for total death for hsCRP in Q4 as compared to Q1 was 1.97 (95% CI, 1.17-3.32), p = 0.011, but this biomarker did not predict cardiac death (p = 0.21). No prognostic impact of these two biomarkers was found in the TnT negative patients.ConclusionBNP and hsCRP may act as clinically useful biomarkers when obtained at admission in a population with suspected ACS.Trial RegistrationClinicalTrials.gov Identifier: NCT01377402.

Vitamin D Predicts All-Cause and Cardiac Mortality in Females with Suspected Acute Coronary Syndrome: A Comparison with Brain Natriuretic Peptide and High-Sensitivity C-Reactive Protein

Vitamin D may not only reflect disease but may also serve as a prognostic indicator. Our aim was to assess the gender-specific utility of vitamin D measured as 25-hydroxy-vitamin D [25(OH)D] to predict all-cause and cardiac death in patients with suspected acute coronary syndrome (ACS) and to compare its prognostic utility to brain natriuretic peptide (BNP) and high-sensitivity C-reactive protein (hsCRP). Blood samples were harvested on admission in 982 patients. Forty percent were women (65.9 ± 12.6 years). Mortality was evaluated in quartiles of 25(OH)D, BNP, and hsCRP, respectively, during a 5-year follow-up, applying univariate and multivariate analyses. One hundred and seventy-three patients died; 78 were women. In 92 patients (37 women), death was defined as cardiac. In women, the univariate hazard ratio (HR) for total death of 25(OH)D in Quartile (Q) 2 versus Q1, Q3 versus Q1, and Q4 versus Q1 was 0.55 (95% CI 0.33–0.93), 0.29 (95% CI 0.15–0.55), and 0.13 (95% CI 0.06–0.32), respectively. In females, it was an independent predictor of total and cardiac death, whereas BNP and hsCRP were less gender-specific. No gender differences in 25(OH)D were noted in a reference material. Accordingly, vitamin D independently predicts mortality in females with suspected ACS.

Omega-3 index and prognosis in acute coronary chest pain patients with a low dietary intake of omega-3

Abstract Background. The omega-3 index (eicosapentaenoic acid + docosahexaenoic acid) content in red blood cell membranes has been suggested as a novel risk marker for cardiac death. Objective. To assess the ability of the omega-3 index to predict all-cause mortality, cardiac death and sudden cardiac death following hospitalization with an acute coronary syndrome (ACS), and to include arachidonic acid (AA) in risk assessment. Material and methods. The omega-3 index was measured in 572 consecutive patients (median 63 years and 59% males) admitted with chest pain and suspected ACS in an inland Northern Argentinean city with a dietary habit that was essentially based on red meat and a low intake of fish. Clinical endpoints were collected during a 5-year follow-up period, median 3.6 years, range 1 day to 5.5 years. Stepwise Cox regression analysis was employed to compare the rate of new events in the quartiles of the omega-3 index measured at inclusion. Multivariable analysis was performed. Results. No statistical significant differences in baseline characteristics were noted between quartiles of the omega-3 index. The median of the adjusted omega-3 index was 3.6%. During the follow-up period, 100 (17.5%) patients died. Event rates were similar in all quartiles of the omega-3 index, with no statistical significant differences. AA added no prognostic information. Conclusion. In a population with a low intake of fish and fish oils, the adjusted omega-3 index did not predict fatal events following hospitalization in patients with acute chest pain and suspected ACS.

Segmentation of scarred and non-scarred myocardium in LG enhanced CMR images using intensity-based textural analysis

The Late Gadolinium (LG) enhancement in Cardiac Magnetic Resonance (CMR) imaging is used to increase the intensity of scarred area in myocardium for thorough examination. Automatic segmentation of scar is important because scar size is largely responsible in changing the size, shape and functioning of left ventricle and it is a preliminary step required in exploring the information present in scar. We have proposed a new technique to segment scar (infarct region) from non-scarred myocardium using intensity-based texture analysis. Our new technique uses dictionary-based texture features and dc-values to segment scarred and non-scarred myocardium using Maximum Likelihood Estimator (MLE) based Bayes classification. Texture analysis aided with intensity values gives better segmentation of scar from myocardium with high sensitivity and specificity values in comparison to manual segmentation by expert cardiologists.

Segmentation of Scarred Myocardium in Cardiac Magnetic Resonance Images

The segmentation of scarred and nonscarred myocardium in Cardiac Magnetic Resonance (CMR) is obtained using different features and feature combinations in a Bayes classifier. The used features are found as a local average of intensity values and the underlying texture information in scarred and nonscarred myocardium. The segmentation classifier was trained and tested with different experimental setups and parameter combinations and was cross validated due to limited data. The experimental results show that the intensity variations are indeed an important feature for good segmentation, and the average area under the Receiver Operating Characteristic (ROC) curve, that is, the AUC, is 91.58 ± 3.2%. The segmentation using texture features also gives good segmentation with average AUC values at 85.89 ± 5.8%, that is, lower than the direct current (DC) feature. However, the texture feature gives robust performance compared to a local mean (DC) feature in a test set simulated from the original CMR data. The segmentation of scarred myocardium is comparable to manual segmentation in all the cross validation cases.

Texture classification of scarred and non-scarred myocardium in cardiac MRI using learned dictionaries

The late gadolinium enhancement in Cardiac Magnetic Resonance (CMR) imaging is used to increase the intensity of scar area in myocardium for thorough examination. The results in our previous work [1] arises the hypothesis that there are textural differences between the non-scarred myocardium and the scarred areas. This paper presents our work of testing the hypothesis further by applying dictionary learning techniques and sparse representation on CMR images (manually segmented by cardiologists) in order to find textural differences in the myocardium and to classify texture in the non-scarred myocardium and the scarred areas. After my-ocardial infarction, cardiac patients considered to have high risk of ventricular arrhythmia are implanted with Implantable Cardioverter-Defibrillator (ICD). Our ultimate goal is to accurately identify the patients with highest risk of arrhythmia, who are to be implanted with ICD by exploring the textural properties in the scarred region of late gadolinium enhanced CMR images.