Dataset Information

Left ventricular shape variation in asymptomatic populations: the Multi-Ethnic Study of Atherosclerosis.

ABSTRACT: Although left ventricular cardiac geometric indices such as size and sphericity characterize adverse remodeling and have prognostic value in symptomatic patients, little is known of shape distributions in subclinical populations. We sought to quantify shape variation across a large number of asymptomatic volunteers, and examine differences among sub-cohorts.An atlas was constructed comprising 1,991 cardiovascular magnetic resonance (CMR) cases contributed from the Multi-Ethnic Study of Atherosclerosis baseline examination. A mathematical model describing regional wall motion and shape was used to establish a coordinate map registered to the cardiac anatomy. The model was automatically customized to left ventricular contours and anatomical landmarks, corrected for breath-hold mis-registration between image slices. Mathematical techniques were used to characterize global shape distributions, after removal of translations, rotations, and scale due to height. Differences were quantified among ethnicity, sex, smoking, hypertension and diabetes sub-cohorts.The atlas construction process yielded accurate representations of global shape (errors between manual and automatic surface points in 244 validation cases were less than the image pixel size). After correction for height, the dominant shape component was associated with heart size, explaining 32% of the total shape variance at end-diastole and 29% at end-systole. After size, the second dominant shape component was sphericity at end-diastole (13%), and concentricity at end-systole (10%). The resulting shape components distinguished differences due to ethnicity and risk factors with greater statistical power than traditional mass and volume indices.We have quantified the dominant components of global shape variation in the adult asymptomatic population. The data and results are available at cardiacatlas.org. Shape distributions were principally explained by size, sphericity and concentricity, which are known correlates of adverse outcomes. Atlas-based global shape analysis provides a powerful method for quantifying left ventricular shape differences in asymptomatic populations.ClinicalTrials.gov NCT00005487.

SUBMITTER: Medrano-Gracia P

PROVIDER: S-EPMC4145340 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Left ventricular shape variation in asymptomatic populations: the Multi-Ethnic Study of Atherosclerosis.

Medrano-Gracia Pau P Cowan Brett R BR Ambale-Venkatesh Bharath B Bluemke David A DA Eng John J Finn John Paul JP Fonseca Carissa G CG Lima Joao A C JA Suinesiaputra Avan A Young Alistair A AA

Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance 20140730

<h4>Background</h4>Although left ventricular cardiac geometric indices such as size and sphericity characterize adverse remodeling and have prognostic value in symptomatic patients, little is known of shape distributions in subclinical populations. We sought to quantify shape variation across a large number of asymptomatic volunteers, and examine differences among sub-cohorts.<h4>Methods</h4>An atlas was constructed comprising 1,991 cardiovascular magnetic resonance (CMR) cases contributed from ...[more]

PMID: 25160814

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Project description:BACKGROUND:Elevated left ventricular mass (LVM) is a strong predictor of negative cardiovascular outcomes, including heart failure, stroke, and sudden cardiac death. A relationship between close (< 50 m compared with > 150 m) residential proximity to major roadways and higher LVM has previously been described, but the mechanistic pathways that are involved in this relationship are not known. Understanding genetic factors that influence susceptibility to these effects may provide insight into relevant mechanistic pathways. OBJECTIVE:We set out to determine whether genetic polymorphisms in genes affecting vascular and autonomic function, blood pressure, or inflammation influence the relationship between traffic proximity and LVM. METHODS:This was a cross-sectional study of 1,376 genotyped participants in the Multi-Ethnic Study of Atherosclerosis, with cardiac magnetic resonance imaging performed between 2000 and 2002. The impact of tagged single-nucleotide polymorphisms (tagSNPs) and inferred haplotypes in 12 candidate genes (ACE, ADRB2, AGT, AGTR1, ALOX15, EDN1, GRK4, PTGS1, PTGS2, TLR4, VEGFA, and VEGFB) on the relationship between residential proximity to major roadways and LVM was analyzed using multiple linear regression, adjusting for multiple potential confounders. RESULTS:After accounting for multiple testing and comparing homozygotes, tagSNPs in the type 1 angiotensin II receptor (AGTR1, rs6801836) and arachidonate 15-lipoxygenase (ALOX15, rs2664593) genes were each significantly (q < 0.2) associated with a 9-10% difference in the association between residential proximity to major roadways and LVM. Participants with suboptimal blood pressure control demonstrated stronger interactions between AGTR1 and traffic proximity. CONCLUSIONS:Common polymorphisms in genes responsible for vascular function, inflammation, and oxidative stress appear to modify associations between proximity to major roadways and LVM. Further understanding of how genes modify effects of air pollution on CVD may help guide research efforts into specific mechanistic pathways.

Project description:BACKGROUND:Although diabetes mellitus (DM) and insulin resistance associate with adverse cardiac events, the associations of left ventricular (LV) remodeling and function with compromised glucose metabolism have not been fully evaluated in a general population. We used cardiovascular magnetic resonance (CMR) to evaluate how CMR indices are associated with DM or insulin resistance among participants before developing cardiac events. METHODS:We studied 1476 participants who were free of clinical cardiovascular disease and who underwent tagged CMR in the Multi-Ethnic Study of Atherosclerosis (MESA). LV shape and longitudinal myocardial shortening and torsion were assessed by CMR. A higher sphericity index represents a more spherical LV shape. Multivariable linear regression was used to evaluate the associations of DM or homeostasis model assessment-estimated insulin resistance (HOMA-IR) with CMR indices. RESULTS:In multiple linear regression, longitudinal shortening was lower in impaired fasting glucose than normal fasting glucose (NFG) (0.36% lower vs. NFG, p?<?0.05); torsion was greater in treated DM (0.24 °/cm greater vs. NFG, p?<?0.05) after full adjustments. Among participants without DM, greater log-HOMA-IR was correlated with greater LV mass (3.92 g/index, p?<?0.05) and LV mass-to-volume ratio (0.05 /index, p?<?0.01), and lower sphericity index (-?1.26/index, p?<?0.01). Greater log-HOMA IR was associated with lower longitudinal shortening (-?0.26%/index, p?<?0.05) and circumferential shortening (-?0.30%/index, p?<?0.05). Torsion was positively correlated with log-HOMA-IR until 1.5 of log-HOMA-IR (0.16 °/cm/index, p?=?0.030).), and tended to fall once above 1.5 of log-HOMA-IR (-?0.50 °/cm/index, p?=?0.203). The sphericity index was associated negatively with LV mass-to-volume ratio (-?0.02/%, p?<?0.001) and torsion (-?0.03°/cm/%, p?<?0.001). CONCLUSIONS:Glucose metabolism disorders are associated with LV concentric remodeling, less spherical shape, and reduced systolic myocardial shortening in the general population. Although torsion is higher in participants who are treated for DM and impaired insulin resistance, myocardial shortening was progressively decreased with higher HOMA-IR and torsion was increased only with less severe insulin resistance. CLINICAL TRIAL REGISTRATION:Multi-Ethnic Study of Atherosclerosis (MESA): A full list of participating MESA investigators and institutions can be found at http://www.mesa-nhlbi.org/ . Study Start Date: January 1999 ( NCT00005487 ).

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Dataset Information

Left ventricular shape variation in asymptomatic populations: the Multi-Ethnic Study of Atherosclerosis.

Publications

Left ventricular shape variation in asymptomatic populations: the Multi-Ethnic Study of Atherosclerosis.

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