Biomedical subjects

Khurram Nasir

Publications and source records attributed to Khurram Nasir.

At least 19 recordsLinked to original sources

PubMed2007

Elevated homocysteine is associated with reduced regional left ventricular function: the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: An elevated homocysteine (Hcy) level has been reported to be a risk factor for the development of congestive heart failure in individuals free of myocardial infarction. In this study, we aim to investigate the relationship between Hcy levels and regional left ventricular function in an asymptomatic population. METHOD AND RESULTS: Regional peak systolic midwall circumferential strains were calculated from 1178 tagged magnetic resonance imaging studies in participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Left ventricular regions were defined by coronary territories (left anterior descending, left circumflex, right coronary artery). For the 1178 study participants (66+/-10 years of age, 58% males), the median (interquartile range) of Hcy was 9.1 (9.0 to 9.3). After adjustment for traditional risk factors, race, height, weight, left ventricular end-diastolic mass/volume, serum creatinine, and measures of atherosclerosis, reduced regional myocardial circumferential shortening across sex-specific quartiles of plasma Hcy in the left anterior descending (P=0.038) and left circumflex (P=0.009) regions persisted, which indicated an important association of reduced function with elevated Hcy. Multiple linear regression analyses confirmed that circumferential systolic dysfunction was associated with log transformed Hcy levels in the left anterior descending (P=0.004) and left circumflex (P=0.0002) regions. In the fully adjusted model, the odds ratio for left ventricular strains below the 10th percentile with 1 SD increases in log-transformed Hcy was 1.33 (95% confidence interval, 1.04 to 1.70; P=0.022) for the left anterior descending, 1.28 (95% confidence interval, 1.00 to 1.64; P=0.046) for the left circumflex, and 1.32 (95% confidence interval, 1.03 to 1.69; P=0.025) for the right coronary artery region. CONCLUSIONS: In this asymptomatic population, an elevated Hcy level is associated with reduced regional left ventricular systolic function detected by tagged magnetic resonance imaging.

Aged↗

PubMed2006

Magnetic resonance imaging of arrhythmogenic right ventricular dysplasia: sensitivity, specificity, and observer variability of fat detection versus functional analysis of the right ventricle.

OBJECTIVES: The purpose of this study was to determine interobserver agreement for interpretation of magnetic resonance imaging (MRI) examinations of arrhythmogenic right ventricular dysplasia (ARVD) and to determine sensitivity and specificity of fat detection versus functional parameters measured by MRI. BACKGROUND: The interobserver variability of MRI and the relative importance of different MRI parameters (fat detection, regional and global right ventricular [RV] function) for ARVD diagnosis is unknown. METHODS: Two experienced observers blinded to the clinical history independently analyzed MRI datasets obtained from 40 patients evaluated for ARVD. Twenty normal subjects underwent MRI and served as control subjects. The MRI scans were performed according to a standard protocol on a 1.5-T scanner. The observers reported on fat infiltration, global and regional RV function, myocardial thinning, and chamber dilatation qualitatively. The RV volumes were measured on the cine sequences. RESULTS: Interobserver kappa scores for fat infiltration, global and regional RV function, wall thinning, and RV outflow dilatation were 0.74, 0.94, 0.89, 0.93, and 0.93, respectively. Correlation coefficients between observers for RV end-diastolic volume, end-systolic volume, and ejection fraction were 0.93, 0.94, and 0.95, respectively (p < 0.001). Fifteen patients were diagnosed with ARVD using Task Force criteria. Sensitivity of fat infiltration, RV enlargement, and regional RV dysfunction for diagnosing ARVD was 84%, 68%, and 78%, and specificity was 79%, 96%, and 94%, respectively. CONCLUSIONS: Qualitative assessment of RV structure and function is highly reproducible for experienced observers. Among the qualitative parameters, fat infiltration is less reproducible and lacks specificity compared with RV kinetic abnormalities.

Adipose Tissue↗

PubMed2006

Relation of uric acid levels to presence of coronary artery calcium detected by electron beam tomography in men free of symptomatic myocardial ischemia with versus without the metabolic syndrome.

The objective of this study was to evaluate whether uric acid (UA) levels were associated with coronary artery calcium (CAC) in white men asymptomatic for coronary heart disease. We also evaluated whether this relation was dependent or not on the presence of the metabolic syndrome (MS). The study population consisted of 371 asymptomatic Brazilian men (48 +/- 7 years of age) who underwent a routine evaluation. The average 10-year total risk of coronary heart disease calculated by Framingham risk score was 10.8 +/- 7.8%. The age-adjusted prevalence of CAC in patients with a high UA level (fourth quartile > or =7.1 mg/dl, n = 91) was significantly higher than that in those with a normal UA level (58% vs 44%, p = 0.02). With respect to age, smoking, physical activity, and components of MS-adjusted analyses, a high UA level was independently associated with the presence of CAC (p = 0.043) and with increasing levels of CAC (p = 0.028). Prevalence of MS showed a graded increase according to serum UA values. In patients with the MS, after adjusting for age, smoking, physical activity, and white blood cell count, high levels of UA were strongly associated with the presence of any CAC (odds ratio 3.47, 95% confidence interval 1.26 to 9.53, p = 0.01) and with increasing levels of CAC (odds ratio 2.74, 95% confidence interval 1.15 to 6.50, p = 0.02). Conversely, there was no significant association of high UA levels in patients without the MS. However, the interaction between high UA level and the MS did not achieve statistical significance for the presence of CAC (p = 0.11) or higher levels of CAC (p = 0.16). In conclusion, our study suggests that, among asymptomatic moderate-risk men, high UA levels were independently associated with CAC in subjects with the MS.

Brazil↗

PubMed2006

Normal reference values for the adult right ventricle by magnetic resonance imaging.

The purpose of this study was to establish reference ranges for magnetic resonance imaging (MRI) measurements of the adult right ventricle stratified by gender. Cardiovascular MRI is increasingly used for evaluating the right ventricle in congenital and acquired heart disease, but gender-specific normative values are currently unavailable. Study participants included 500 subjects free of clinical cardiovascular disease who were participants in the Multi-Ethnic Study of Atherosclerosis (MESA). All subjects underwent MRI according to a standard protocol. The endocardial margins of the right ventricle were manually contoured on short-axis images, and right ventricular (RV) volumes were calculated using a summation-of-disks method. RV dimensions were measured on 4-chamber gradient-echo images and in the short-axis plane. Except for the ejection fraction, all unadjusted RV parameters were significantly greater in men than in women (p <0.001). In the entire study population, RV volumes and linear dimensions each correlated significantly with height (r = 0.38 to 0.64, p = 0.001 for all) and body surface area (r = 0.41 to 0.64, p = 0.001 for all). Gender differences persisted after adjustment for subject height. After adjustment for body surface area, volumetric variables remained significantly greater (p = 0.001) in men than in women. Even after adjusting for body surface area and height, Chinese participants had significantly lower RV volumes compared with Caucasians. In conclusion, gender-specific normal values for the adult right ventricle by MRI are presented. Cardiovascular MRI measures of RV volumes and linear dimensions differ significantly according to gender and body size. These values will be useful to differentiate RV health from diseases that result in abnormal RV structure and function.

Adult↗

PubMed2006

Coronary calcium progression rates with a zero initial score by electron beam tomography.

BACKGROUND: A review of existing literature shows that for individuals with initial coronary calcium scores (CCS) of zero it would be reasonable to consider follow-up scanning no sooner than 3 years from the initial evaluation, however the data is very limited. In this study, we sought to determine the rate of new calcifications in patients initially presenting with a zero initial score on electron beam tomography (EBT). METHODS AND RESULTS: We evaluated 710 physician-referred participants (253 women and 448 men, mean age=56+/-9 years [range=29 to 93]) with no coronary artery calcium (CAC) at baseline electron beam tomography (EBT) scan. The participants underwent a follow-up scan at least 12 months apart. In our study, 248 (35%) were followed for 1-3 years, 256 (36%) for 3-5 years and 204 (29%) for >5 years, respectively. Overall, more than half of the individuals (62%) did not develop any CAC (score remained zero) in the interim period, whereas only 2% had CAC progression >50 during the follow-up. The overall median (interquartile range) and mean+/-S.D. change/year in these individuals was 0 (0-0.8) and 1+/-3, respectively. Only 11 (2%) had CAC progression/year of 11-50, whereas 3 (1%) had CAC change/year >50. It is interesting to note that even among individuals with long-term follow-up (>5 years), very few individuals (2%) had CAC progression >50. Individuals with follow-up 3-5 years did not have a significantly higher odds ratio for CAC change >10 (p=0.17) as compared to the reference group (follow-up of 1-3 years). All the other individuals who had a longer follow-up (>5 years) had a significantly higher likelihood of CAC progression >10 (OR=6.6, 95% CI=2.6-16.9, p<0.0001) compared to the reference group. CONCLUSION: In individuals with no detectable coronary calcium on an initial EBT scan, a repeat scan can be recommended no sooner than 5 years.

Adult↗

PubMed2006

Lower myocardial perfusion reserve is associated with decreased regional left ventricular function in asymptomatic participants of the multi-ethnic study of atherosclerosis.

BACKGROUND: Myocardial ischemia is an important determinant of regional left ventricular systolic function. Myocardial blood flow reserve may be impaired by cardiovascular disease before alterations of myocardial perfusion at rest become manifest. Nevertheless, the relation between flow reserve and regional myocardial function has not been studied in individuals without a history of clinical heart disease. METHODS AND RESULTS: Seventy-four participants (66+/-9 years, mean+/-SD) of the Multi-Ethnic Study of Atherosclerosis (MESA) underwent myocardial magnetic resonance tagging and contrast-enhanced perfusion studies. Regional myocardial function was evaluated as peak systolic circumferential strain (Ecc) in the three main coronary territories (left anterior descending [LAD], left circumflex, and right coronary artery [RCA]). Myocardial blood flow at rest and during adenosine-induced hyperemia was quantified by contrast-enhanced magnetic resonance imaging, to study the relation between regional flow and function after multivariable adjustment for age, gender, body mass index, left ventricular mass, and traditional risk factors. Lower regional myocardial blood flow during hyperemia was associated with reduced regional left ventricular function expressed as lower Ecc in the RCA (P<0.01) and left circumflex regions (P<0.05) measured in the subendocardium, mid-wall, and subepicardium. In contrast, no significant association was seen in the LAD territory (P=0.16). In addition, segmental function in LAD and RCA regions was reduced when individuals in the lowest 10th percentile for regional myocardial flow reserve were compared with the other participants. Absolute decreases in mid-wall Ecc LAD and RCA and global Ecc were 3.0%, 3.4%, and 2.8%, respectively (P<0.05 for all regions). CONCLUSIONS: Lower myocardial flow reserve is related to reduced regional function in asymptomatic individuals.

Aged↗

PubMed2006

Subclinical atherosclerosis and incipient regional myocardial dysfunction in asymptomatic individuals: the Multi-Ethnic Study of Atherosclerosis (MESA).

OBJECTIVES: This study sought to determine whether increased carotid intima-media thickness (IMT) is related to reduced regional myocardial function in participants of the Multi-Ethnic Study of Atherosclerosis (MESA). BACKGROUND: Carotid artery IMT is an established index of subclinical atherosclerosis, and tagged magnetic resonance imaging (MRI) can detect incipient alterations of segmental function that precede overt myocardial failure. METHODS: The MESA study is a prospective observational study including four ethnic groups free from clinical cardiovascular disease. Peak midwall systolic circumferential strain (ECC) and regional strain rates were calculated by harmonic phase from tagged MRI data of 500 participants. Systolic ECC and diastolic strain rate were regressed on IMT of the common carotid artery defined by ultrasound, with adjustments for body mass index, blood pressure, cholesterol, diabetes, smoking, left ventricular hypertrophy, C-reactive protein, age, and gender. RESULTS: The mean participant age was 66 +/- 10 years (mean +/- SD). Among the 58 participants, 4% were male and the interquartile (25th to 75th percentile) range for IMT was 0.25 mm. Multiple linear regression analyses showed that increased IMT was related to reduced systolic regional function (less shortening ECC) in all myocardial regions (p < 0.05), except in the inferior wall. The analyses also showed that greater IMT was associated with a lower diastolic strain rate (diastolic reduced function) in all regions (p < 0.01), except in the anterior wall. CONCLUSIONS: Greater carotid IMT is associated with alterations of myocardial strain parameters reflecting reduced systolic and diastolic myocardial function. These observations indicate a relationship between subclinical atherosclerosis and incipient myocardial dysfunction in a population free of clinical heart disease.

Aged↗

PubMed2006

Clinical course and long-term follow-up of patients receiving implantable cardioverter-defibrillators.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are increasingly used for primary and secondary prevention of sudden cardiac death. Defibrillators were introduced into clinical practice in 1980. Since that time, factors affecting long-term survival and the natural history of defibrillator patients have not been described. OBJECTIVES: The purpose of this study was to identify clinical predictors of long-term survival in patients receiving ICDs. METHODS: The prognostic value of several clinical variables on the likelihood of survival or appropriate ICD therapy in 1,382 consecutive patients receiving ICDs from 1980 to 2003 were evaluated. Data were collected at the time of device implantation, and follow-up was completed through March 2005. RESULTS: In 70 +/- 51 months of follow-up (range 0-282 months), 792 patients died and 421 patients received appropriate ICD therapy at least once. Age, left ventricular ejection fraction, New York Heart Association (NYHA) functional class, Charlson comorbidity index, and antiarrhythmic drug use correlated with mortality. beta-Blocker and angiotensin-converting enzyme inhibitor use was associated with improved survival. Only NYHA functional class correlated with ICD therapy. Patients free of shocks for the first 5 years after ICD implantation had continued risk of arrhythmia recurrence. CONCLUSION: The heart failure characteristics of patients predicted ICD shock probability and survival better than the arrhythmia characteristics or the underlying heart disease. Antiarrhythmic drug use was associated with increased mortality. Beta-blocker and angiotensin-converting enzyme inhibitor use was associated with improved survival. A measurable arrhythmic risk even after prolonged shock-free intervals indicates the need for continued ICD therapy in all patients with appropriate ICD indications.

Adolescent↗

PubMed2006

Relationship of subclinical coronary atherosclerosis and National Cholesterol Education Panel guidelines in asymptomatic Brazilian men.

BACKGROUND AND OBJECTIVE: Coronary heart disease (CHD) is the leading cause of death worldwide including Brazil. Improved precision in detecting early coronary disease may aid in more targeted preventive therapy. The National Cholesterol Education Program (NCEP) provides guidelines for determining the aggressiveness of primary prevention strategies including lipid lowering based on Framingham risk equation. Identification of subclinical atherosclerosis and coronary plaque burden is a step towards identifying high-risk individuals. This investigation was designed to determine how the updated NCEP guidelines classify asymptomatic individuals with presence of any as well as advanced CACS (coronary artery calcium score), a powerful intermediary for CHD events, in asymptomatic Brazilian men. METHODS AND RESULTS: Five hundred forty-six asymptomatic Brazilian men (mean age: 46+/-7 years) presented to a single electron beam tomography (EBT) facility in Sao Paulo. The study population was categorized into low risk (0-1 risk factors, n=166, 30%), intermediate risk (> or = 2 risk factors but < 10% risk of CHD over 10 years, n=150, 27%), moderately high risk (2 risk factors and 10-20% risk of hard CHD events in 10 years, n=147, 28%) and high-risk (> or = 2 risk factors and > 20% risk of hard CHD events in 10 years, n=83, 15%), respectively. In our study population, overall no CACS, mild CACS (1-99.9), moderate-severe CACS (> or = 100) were observed in 317 (58%), 160 (29%) and 69 (13%) men, respectively. Advanced calcification (CACS > or = 75th percentile for age) was present in 19% (n=104) men. Based on the LDL-C cutoffs recommended by the NCEP guidelines for initiation of lipid lowering, overall only 55% with CACS > or = 100 and 42% men with CACS > or = 75th percentile qualified for pharmacotherapy. As a result nearly half of individuals with CACS > or = 100 (45%) and CACS > or = 75th percentile (48%) missed eligibility for drug therapy. CONCLUSION: Our findings reveal the potential limitation of NCEP guidelines in identifying asymptomatic Brazilian men with significant coronary atherosclerosis who are potential candidates for aggressive primary prevention. Assessment of CACS may provide incremental value to global risk assessment in high-risk Brazilian men.

Adult↗

PubMed2006

Hypertension and smoking are associated with reduced regional left ventricular function in asymptomatic: individuals the Multi-Ethnic Study of Atherosclerosis.

OBJECTIVES: This study sought to test the hypothesis that reduced regional left ventricular (LV) function is associated with traditional risk factors including hypertension, hypercholesterolemia, and smoking in asymptomatic individuals. BACKGROUND: Coronary artery disease is the main etiology of congestive heart failure in the U.S. and Europe. However, the relationship between risk factors for coronary artery disease and decreased myocardial function has not been studied systematically in asymptomatic individuals. METHODS: The Multi-Ethnic Study of Atherosclerosis (MESA) is a cohort study designed to investigate the nature of atherosclerosis in asymptomatic individuals. A total of 1,184 participants (45 to 84 years old) underwent tagged cardiac magnetic resonance imaging. Regional LV function was quantified by analyzing peak systolic circumferential strain (Ecc) in regions corresponding to the left anterior descending (LAD), circumflex (LCX), and right coronary (RCA) territories. The association between risk factors and strains was studied using multiple linear regression. RESULTS: Higher diastolic blood pressure (DBP) was associated with lower Ecc (p < or = 0.002). The Ecc's in the LAD territory of participants with DBP <80, 80 to 84, 85 to 89, and > or =90 mm Hg were -15.6%, -14.8%, -14.2%, and -13.7%, respectively (p < 0.001). Similar results were documented in other territories and after multivariable analysis. Smokers had lower Ecc in the LAD and RCA regions compared with nonsmokers. Furthermore, dose response relationship between cigarette consumption measured in pack-years and regional LV dysfunction by Ecc was noted (p < or = 0.01 in LAD and RCA territories). Finally, combined diastolic hypertension and smoking was associated with a greater reduction of regional LV function. CONCLUSIONS: Higher diastolic blood pressure and smoking are associated with decreased regional LV function in asymptomatic individuals.

Aged↗

PubMed2006

Association of body mass index, metabolic syndrome, and leukocyte count.

Obesity and metabolic syndrome (MS), which often co-exist, are associated with an increased cardiovascular risk. An increased leukocyte count is also associated with an increased cardiovascular risk. However, the role of obesity, independent of MS, has been debated. We sought to assess the influence of MS on the association of obesity and leukocyte count in asymptomatic patients. The data from 431 asymptomatic Brazilian men (mean age 46 +/- 7 years), who presented for cardiovascular risk assessment, were analyzed. MS was defined as the presence of > or =3 of the following risk factors: hypertension (> or =130/85 mm Hg), truncal obesity (> or =102 cm or 40 in), hypertriglyceridemia (> or =150 mg/dl), high-density lipoprotein cholesterol (< or =40 mg/dl), and hyperglycemia (glucose > or =110 mg/dl). Obesity was defined as a body mass index of > or =30 kg/m(2). Confounding variables (age, smoking, lipid-lowering therapy, and physical activity) and leukocyte count (10(9)/L) were recorded. The patients were divided into 4 groups: group1, no obesity and no MS; group 2, obesity but no MS; group 3, no obesity but MS; and group 4, obesity and MS. The mean leukocyte count increased from groups 1 to 4 (6.10 +/- 0.09, 6.42 +/- 0.28, 6.71 +/- 0.21, and 6.96 +/- 0.22 x 10(9)/L, p < 0.001 for trend). Multivariate regression analysis demonstrated that the leukocyte count was significantly higher in groups 3 (coefficient 0.61, p = 0.007) and 4 (coefficient 0.86, p < 0.001) compared with group 1. However, no significant difference was found in the leukocyte count between groups 1 and 2 (coefficient 0.29, p = 0.42) and groups 3 and 4 (coefficient 0.25, p = 0.41). The association between obesity and leukocyte count was highly dependent on the presence of MS.

Body Mass Index↗

PubMed2006

Zero filled partial fourier phase contrast MR imaging: in vitro and in vivo assessment.

PURPOSE: To validate partial Fourier phase contrast magnetic resonance (PC MR) with full number of excitation (NEX) PC MR measurements in vitro and in vivo. MATERIALS AND METHODS: MR flow measurements were performed using a partial Fourier and a full NEX PC MR sequence in a flow phantom and in 10 popliteal and renal arteries of 10 different healthy volunteers. Average velocity, peak velocity, and flow results were calculated and compared with regression analysis. RESULTS: Excellent correlations in average velocities (r = 0.99, P < 0.001), peak velocities (r = 0.99, P < 0.001), and flow rates (r = 0.98, P < 0.001) were demonstrated in vitro between the two different acquisitions. For the popliteal arteries there was excellent correlation between peak velocities for both acquisitions (r = 0.98, P < 0.0001); the correlation of average velocity measurements when using all data points in the cardiac cycle for all volunteers was 0.96 (P < 0.001). For the renal arteries the same comparison resulted in a good correlation for average velocity (0.93, P < 0.001) and peak velocity measurements (r = 0.91, P = 0.002), although the correlation coefficient for flow rates was 0.88 (P = 0.004). Blurring of the vessel margins was consistently observed on magnitude images acquired with the partial Fourier method, causing overestimation of the vessel area and some error in the flow measurements. CONCLUSION: Partial Fourier PC MR is able to provide comparable average and peak velocity values when using 1 NEX PC MRI as a reference.

Adult↗

PubMed2006

Subclinical coronary atherosclerosis: racial profiling is necessary!

OBJECTIVES: We aim to review the studies comparing coronary calcification across different ethnic groups. BACKGROUND: There is still uncertainty regarding ethnic differences in the prevalence, progression, and risk of coronary artery disease. Clues to possible racial differences in rates of coronary heart disease (CHD) may be found by identifying subclinical disease. Coronary artery calcification (CAC) can be used to predict risk of CHD in both symptomatic and asymptomatic subjects. METHODS: Online databases were searched for studies assessing racial differences in CAC. RESULTS: Most of the published studies have shown that racial differences exist in the prevalence and severity of CAC. Whites have a higher prevalence of CAC as compared to African Americans and other ethnic groups even after adjustment for risk factors. These differences in CAC are even more pronounced in men and in the elderly. Data regarding the distribution of CAC in ethnic groups outside the United States are limited. Emerging evidence indicates that while several ethnic groups outside the United States tend to have a greater prevalence of CHD risk factors, their prevalence of CAC is lower, as compared with Americans. Thus, the data obtained in the United States may not be able to be fully extrapolated to populations outside the United States for assessment of CHD risk. CONCLUSIONS: The presence and extent of CAC varies among different racial groups within and outside the United States. The relationship between calcification and the incidence of CHD in these ethnic groups needs further exploration. Thus, it is important to develop ethnic specific CAC nomograms to more accurately determine the underlying CHD risk associated with CAC in these individuals. It will also be imperative to obtain outcome data and relate it to baseline levels of CAC to help us put in perspective the significance of racial differences in CAC and how they impact on cardiac risk prediction.

Adult↗

PubMed2006

Association of increased cardiorespiratory fitness with low risk for clustering of metabolic syndrome components in asymptomatic men.

BACKGROUND: From a preventive aspect, it is especially important to investigate the lifestyle risk factors associated with cardiovascular disease (CVD). The purpose of this study was to determine the relationship of increasing metabolic syndrome (MS) components across increasing levels of estimated cardiorespiratory fitness (CRF) in asymptomatic young to middle-aged men. METHODS: We studied 449 consecutive asymptomatic men (47 +/- 7 years) who underwent a maximal treadmill exercise test according to the Bruce protocol. Cardiorespiratory fitness (CRF) was divided into tertiles based on metabolic equivalents (METs). The following MS components were studied: 1) waist circumference > 102 cm; 2) serum triglycerides > or = 150 mg/dL; 3) HDL cholesterol levels of < 40 mg/dL; 4) fasting blood glucose (FBG) > or = 110 mg/dL or 5) blood pressure > or = 130/85 mmHg or treated hypertension. Multinomial logistic regression was used to investigate the relationship between clustering of MS components and CRF as determined by metabolic equivalents (METs). We used polytomous logistic regression to determine the likelihood of clustering of increasing components of metabolic syndrome with intermediate (2nd tertile) and low (1st tertile) levels of CRF as compared to those with highest levels of CRF (3rd tertile). RESULTS: Overall in the study population, zero, 1, 2 and > or = 3 (i.e., metabolic syndrome) risk factors for MS were observed in 29% (n = 129), 26% (n = 118), 22% (n = 98) and 23% (n = 104) men, respectively. The mean METS achieved in the study population was 10 +/- 2 (range 4-20). Nearly half (49%) of individuals with the highest levels of CRF had no MS risk factors whereas only 18% of those with low CRF (METS < 9) had no MS risk factors. On the other end of the spectrum, the prevalence of MS (> or = 3 MS risk factors) increased significantly across decreasing levels of CRF (6, 22, 33% p < 0.0001 for trend). Multivariable polytomous logistic regression (adjusting for age, smoking, cholesterol-lowering therapy) demonstrated that individuals with low CRF (1st tertile of METS) compared to those with highest CRF had 3.1- (p = 0.001) and 11.8- (p < 0.0001) fold higher risk of having 2 and > or = 3 MS components, respectively. Similar results were observed when the analyses was repeated adjusting for Framingham risk score. CONCLUSIONS: Asymptomatic men with low levels of CRF have a greater likelihood for clustering of MS components and thus are at higher CVD risk. Further studies are needed to define the risk of cardiovascular disease in patients with intermediate levels of CRF and address which treatment strategies are most important given an individual's risk profile.

Adult↗

PubMed2006

Framingham risk equation underestimates subclinical atherosclerosis risk in asymptomatic women.

BACKGROUND: Coronary heart disease (CHD) is the leading cause of death among American women. Currently, global risk assessment derived by Framingham risk equation (FRE) is used to identify women at increased risk for CHD. Electron-beam computed tomography (EBCT) derived coronary artery calcium (CAC) scores are validated markers for future CHD events among asymptomatic individuals. However, the adequacy of FRE for identifying asymptomatic women with CAC is unknown. METHODS AND RESULTS: We studied 2447 consecutive non-diabetic asymptomatic females (55 +/- 10 years). Based upon FRE, 90% were classified as low-risk (FRE < or = 9% 10-year risk of hard CHD events), 10% intermediate-risk (10-20%), and none were considered as high-risk (> 20%). Coronary artery calcium was present in 33%, whereas CAC > or = 100 and CAC > or = 400 were seen in 10 and 3% of women, respectively. Overall, 20% of women had age-gender derived > or = 75th percentile CAC. According to FRE, the majority (84%) of women with significant CAC > or = 75th percentile were classified as low-risk. Approximately half (45%) of low-risk women with > or = 2 CHD risk factors and a family history of premature CHD had significant CAC. CONCLUSION: Framingham risk equation frequently classifies women as being low-risk, even in the presence of significant CAC. Determination of CAC may provide incremental value to FRE in identifying asymptomatic women who will benefit from targeted preventative measures.

Atherosclerosis↗

PubMed2005

Arrhythmogenic right ventricular dysplasia: a United States experience.

BACKGROUND: Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by right ventricular dysfunction and ventricular arrhythmias. The purpose of our study was to describe the presentation, clinical features, survival, and natural history of ARVD in a large cohort of patients from the United States. METHODS AND RESULTS: The patient population included 100 ARVD patients (51 male; median age at presentation, 26 [interquartile range {IQR}, 18 to 38; range, 2 to 70] years). A familial pattern was observed in 32 patients. The most common presenting symptoms were palpitations, syncope, and sudden cardiac death (SCD) in 27%, 26%, and 23% of patients, respectively. Among those who were diagnosed while living (n=69), the median time between first presentation and diagnosis was 1 (range, 0 to 37) year. During a median follow-up of 6 (IQR, 2 to 13; range, 0 to 37) years, implantable cardioverter/defibrillators (ICD) were implanted in 47 patients, 29 of whom received an appropriate ICD discharge, including 3 patients who received the ICD for primary prevention. At follow-up, 66 patients were alive, of whom 44 had an ICD in place, 5 developed signs of heart failure, 2 had a heart transplant, and 18 were on drug therapy. Thirty-four patients died either at presentation (n=23: 21 SCD, 2 noncardiac deaths) or during follow-up (n=11: 10 SCD, 1 of biventricular heart failure), of whom only 3 were diagnosed while living and 1 had an ICD implanted. On Kaplan-Meier analysis, the median survival in the entire population was 60 years. CONCLUSIONS: ARVD patients present between the second and fifth decades of life either with symptoms of palpitations and syncope associated with ventricular tachycardia or with SCD. Diagnosis is often delayed. Once diagnosed and treated with an ICD, mortality is low. There is a wide variation in presentation and course of ARVD patients, which can likely be explained by the genetic heterogeneity of the disease.

Adolescent↗

PubMed2005

Comprehensive coronary risk determination in primary prevention: an imaging and clinical based definition combining computed tomographic coronary artery calcium score and national cholesterol education program risk score.

Cardiovascular disease (CVD) is the leading cause of mortality and a major cause of morbidity. Coronary heart disease (CHD) accounts for nearly half of all CVD deaths. Currently estimation of risk in primary prevention is based on the Framingham risk equations, which inputs traditional risk factors and is helpful in predicting the development of CHD in asymptomatic individuals. However many individuals suffer events in the absence of established risk factors for atherosclerosis and broad based population risk estimations may have little precision when applied to a given individual. To meet the challenge of CHD risk assessment, several tools have been developed to identify atherosclerotic disease in its preclinical stages. This paper aims to incorporate information from coronary artery calcification (CAC) scoring from a computed tomographic "heartscan" (using Electron Beam Tomography (EBT) as the validated prototype) along with current Framingham risk profiling in order to refine risk on an absolute scale by combining imaging and clinical data to affect a more comprehensive calculation of absolute risk in a given individual. For CAC scores above the 75th percentile but <90th percentile, 10 years is added to chronological age, and for CAC scores above the 90th percentile, 20 years is added to current chronological age. Among those in whom a positive CAC score is the norm such as older individuals (men> or =55 years, women> or =65 years) a CAC = 0 will result in an age point score corresponding to the age-group whose median CAC score is zero i.e., 40-44 years for men and 55-59 years for women. The utilization of CAC scores allows the inclusion of sub-clinical disease definition into the context of modifiable risk factors as well as identifies high-risk individuals requiring aggressive treatment.

Aged↗

PubMed2005

Increased level of cardiorespiratory fitness blunts the inflammatory response in metabolic syndrome.

OBJECTIVE: The presence of metabolic syndrome is associated with a higher degree of inflammation. We sought to assess whether the higher levels of cardiorespiratory fitness attenuate the levels of inflammation in people with metabolic syndrome. RESEARCH DESIGN AND METHODS: We studied 449 consecutive asymptomatic men (47+/-7 years) who underwent a maximal treadmill exercise test according to the Bruce protocol. Cardiorespiratory fitness was divided into tertiles based on metabolic equivalents (METs). White blood cells (WBC) (x10(9) cells/L) count was used as marker of inflammation. RESULTS: In our study population, 23% of the participants had the metabolic syndrome. The WBC count increased (p < 0.0001 for trend) with increasing number of risk factors for metabolic syndrome; however there was an inverse relationship (p < 0.0001 for trend) with increasing tertiles of fitness (6.47 cells x 10(9) cells/L for lowest tertile and 5.7 x 10(9) cells/L for highest tertile). Multiple linear regression analyses demonstrated that as compared to individuals with no MS risk factor, the WBC count remained significantly higher in men with metabolic syndrome in first tertile (regression coefficient: 1.2, 95% CI 0.4-2.0, p = 0.003) and second tertile (regression coefficient: 0.61, 95% CI 0.4-2.0, p = 0.02) of cardiorespiratory fitness, respectively. However, in the highest tertile of fitness no increase in level of WBC count was observed with increasing metabolic syndrome risk factors. CONCLUSION: Our findings suggest that in people with metabolic syndrome an increased level of physical fitness might exert its beneficial effect via attenuating inflammation.

Adult↗