RESUMO
BACKGROUND: Strain and strain rate are sensitive markers of left ventricular (LV) myocardial function. The aim of this study was to assess reference ranges and regional patterns of LV strain and strain rate using two-dimensional speckle-tracking echocardiography in a large population of black and white subjects. METHODS: This study involved a retrospective review of prospectively collected images in 557 participants in the Coronary Artery Risk Development in Young Adults study who remained healthy at the year 25 examination. LV deformation parameters were measured in apical four-chamber, apical two-chamber, and parasternal short-axis views in 509, 391, and 521 subjects, respectively. RESULTS: Patients' mean age was 49.6 ± 3.6 years, 61.6% were women, and 69.5% were white. White women showed the highest LV systolic and diastolic deformation values, reflected by a more negative reference range for apical four-chamber longitudinal strain (-16.4%; 95% prediction interval [PI], -20.8% to -12.0%) and a higher positive reference range for early diastolic strain rate (0.93 1/sec; 95% PI, 0.41 to 1.46 1/sec), respectively. The lowest LV systolic and diastolic deformation values were found in black men, with apical four-chamber longitudinal strain (14.7%; 95% PI, -19.1% to -10.3%) and early diastolic strain rate (0.79 1/sec; 95% PI, 0.42 to 1.16 1/sec). Absolute strain increased from the epicardium toward the endocardium. A base-to-apex gradient of longitudinal strain toward the apex was exhibited in inferior and inferoseptal regions and, in contrast, in the opposite direction in anterior and anterolateral walls. Sex had the strongest influence on LV deformation variability. CONCLUSIONS: Strain and strain rate reference values were sex and race related. White women showed the highest reference ranges for LV deformation, while the lowest values were found in black men. Significant layer- and level-specific patterns in regional LV deformation were identified.
Assuntos
Negro ou Afro-Americano , Ecocardiografia/métodos , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/etnologia , Disfunção Ventricular Esquerda/fisiopatologia , Função Ventricular Esquerda/fisiologia , População Branca , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Valores de Referência , Estudos Retrospectivos , Fatores SexuaisRESUMO
OBJECTIVE: Prolonged sedentary time (ST) might be contributing to the diabetes epidemic, but most studies have been cross-sectional and few have objectively measured ST. The purpose of this study was to evaluate cross-sectional and 5-year longitudinal relationships between ST and metabolic parameters and outcomes. RESEARCH DESIGN AND METHODS: This was an analysis of 2,027 Coronary Artery Risk Development in Young Adults (CARDIA) study participants (aged 38-50 years, 57% female, and mean BMI of 29.0 ± 7.0 kg/m(2)) with accelerometry data (≥4 days with ≥10 h/day) measured at the year 20 follow-up exam (2005-2006). Metabolic variables (fasting glucose, fasting insulin, 2-h postchallenge glucose, HOMA of insulin resistance [HOMA-IR], and HbA1c) and outcomes (impaired fasting glucose [IFG], impaired glucose tolerance [IGT], prediabetes by HbA1c, and diabetes) were assessed concurrently and 5 years later. RESULTS: Average ST was 8.1 ± 1.7 h/day or 55 ± 10% of wear time. Each additional hour per day of ST was cross-sectionally associated with a 3% higher fasting insulin and HOMA-IR (both P < 0.01) but not 5-year changes in metabolic parameters. Having ≥10 h/day vs. <6 h/day of ST was associated with an odds ratio (OR) = 2.74 (95% CI 1.13, 6.62) for IGT and an OR = 3.80 (95% CI 1.39, 10.35) for diabetes. ST was not associated with prevalent IFG, prevalent prediabetes by HbA1c, or 5-year incidence of any metabolic outcomes (all P > 0.05). CONCLUSIONS: ST was independently related to insulin, HOMA-IR, and prevalent diabetes and IGT but did not predict 5-year changes in metabolic parameters or incidence of metabolic outcomes. These results suggest that higher ST may not be a risk factor for future metabolic outcomes, but more research with repeated ST measurement and longer follow-up is needed.