Determinants of left ventricular mass in a French male population

Impaired endothelial responses in apparently healthy young people associated with subclinical variation in blood pressure and cardiovascular phenotype

BACKGROUND

A phenomenon of endothelial impairment, independent of classical cardiovascular risk factors, has been observed in young people. We identified subjects with persistently reduced, or declining, endothelial function during adolescence and early adulthood, without apparent cardiovascular risk, and investigated the clinical relevance of this finding.

METHODS

Endothelial vasomotor responses were assessed by brachial artery flow-mediated dilatation (FMD) at age 15 years in 47 subjects (22 males) who returned for a repeated measurement at age 25. Subjects underwent quantification of left ventricular mass (LVM) and function by cardiovascular magnetic resonance, central arterial stiffness by applanation tonometry, and common carotid artery intima-media thickness using ultrasound on their visit at age 25.

RESULTS

Individuals with low average FMD over 10-year period, although normotensive, had 5 mm Hg higher systolic blood pressure and, significantly greater LVM (73.48 ± 7.73 vs. 56.25 ± 9.54 g/m(2), P = 0.0001), carotid intima-media thickness (cIMT) (0.53 ± 0.06 vs. 0.47 ± 0.04 mm, P = 0.03), and pulse wave velocity (5.97 ± 0.63 vs. 5.29 ± 0.59 m/s, P = 0.02) than those with higher endothelial responses. Subjects with the greatest decline in FMD over 10 years had a significant increase in mean arterial pressure but similar cardiovascular phenotype.

CONCLUSION

Persistently reduced, or declining, endothelial function during adolescence, in the absence of overt cardiovascular disease, is a sensitive early marker associated with subclinical changes in blood pressure (BP) and an adverse cardiovascular phenotype. The findings highlight the potential importance of endothelial responses during adolescence in primary prevention strategies for hypertension.

Prevalence and determinants of left ventricular hypertrophy and remodelling patterns in hypertensive patients: the St. Petersburg study

OBJECTIVE

The primary aim of the present study was to determine the prevalence of left ventricular hypertrophy (LVH) in hypertensive patients with the use of different threshold values and also to assess the distribution of left ventricular (LV) geometry patterns verified by two different methods of relative wall thickness (RWT) calculation. The secondary aim was to evaluate the impact of different demographic determinants into prevalence of LVH and remodelling patterns.

PATIENTS AND METHODS

A cross-sectional study in a population-based sample of 734 essential hypertensives from the primary care clinic was undertaken. Echocardiography was performed and analysed by trained observers. The LV posterior wall thickness (PWd), interventricular septum (IVSd) and LV mass index (LVMI) were measured. The following criteria for LVH definition were used: LVMI >125 g/m2 and 134/110 g/m2, and >131/110 and 116/104 g/m2 in males/females, respectively. The RWT was calculated as a 2PWd/LVDD or PWd + IVSd/LVDD, where LVDD is the LV internal dimension at the end of diastole. The values exceeding 0.45 were considered evidence for concentric remodelling.

RESULTS

Prevalence of LVH ranged from 52.2 to 72.2% by the use of different threshold for LVH definition. It was shown that the LVH estimation without sex-specific criteria underestimates the prevalence of LVH in women and overestimates it in men. The prevalence of concentric LVH and concentric remodelling was higher when the IVSd was included in the RWT calculation. Only one-quarter of patients were free from morphological alterations and eccentric LVH was as frequently observed as concentric LVH. Sex, obesity stage and type as well as hypertension level and duration contributed to LVH level and remodelling pattern.

CONCLUSIONS

The use of different threshold values can significantly influence the assessment of prevalence of LVH in hypertension. The "mild" criteria, to our opinion, can overestimate the prevalence of structural LV remodelling, while implementation of sex-specific criteria for the definition of LVH increases the sensitivity of the method. In any way, eccentric LVH is as common for hypertension as a concentric LVH, the proportion of the latter increasing with age and more frequently observed in males. Concomitant obesity, in particular abdominal, significantly increases LVH prevalence.

Determinants of left ventricular mass and presence of metabolic risk factors in normotensive individuals

BACKGROUND

Insulin resistance and obesity are recognized as left ventricular (LV) mass determinants independent of blood pressure (BP). Prevalence of LV hypertrophy (LVH) and the relationship between LV mass to body composition and metabolic variables were evaluated in normotensive individuals as participants of a population-based study.

METHODS

LV mass was measured using the second harmonic image by M-mode 2D guided echocardiography in 326 normotensive subjects (mean 47+/-9.4 years). Fasting serum lipids and glucose, BP, body composition and waist circumference (WC) were recorded during a clinic visit.

RESULTS

Applying a normalization criterion not related to body weight (g/height raised to the power 2.7) and the cut-off points of 47.7 (men) and 46.6 g/m(2.7) (women), LVH was found in 7.9% of the sample. Univariate analysis showed LV mass (g/m(2.7)) related to age, body mass index (BMI), WC, fat and lean body mass, systolic and diastolic BP, and metabolic variables (cholesterol, HDL-c, triglycerides and glucose). In multivariate analysis only BMI and age-adjusted systolic BP remained as independent predictors of LV mass, explaining 31% and 5% of its variability. Removing BMI from the model, WC, age-adjusted systolic BP and lean mass remained independent predictors, explaining 25.0%, 4.0% and 1.5% of LV mass variability, respectively. After sex stratification, LV mass predictors were WC (8%) and systolic BP (5%) in men and WC (36%) and systolic BP (3%) in women.

CONCLUSION

BMI in general and particularly increased abdominal adiposity (WC as surrogate) seems to account for most of LV mass increase in normotensive individuals, mainly in women.

Traditional cardiovascular risk factors in relation to left ventricular mass, volume, and systolic function by cardiac magnetic resonance imaging: the Multiethnic Study of Atherosclerosis

OBJECTIVES

The goal of this study was to examine the cross-sectional associations of cardiovascular risk factors with left ventricular (LV) geometry and systolic function measured by cardiac magnetic resonance imaging (MRI) in the Multiethnic Study of Atherosclerosis (MESA).

BACKGROUND

Cardiovascular risk factors including hypertension, smoking, and obesity are known to be associated with increased LV mass, but less is known about the association of risk factors with LV systolic function, particularly in populations without clinical cardiovascular disease.

METHODS

Participants were from 4 racial/ethnic groups and were free of clinical cardiovascular disease. Blood pressure, health habits, body mass index, lipid levels, and glucose abnormalities were assessed and MRI exams performed at baseline (n = 4,869). Multivariable linear regression was used to model the association of risk factors with LV mass, end-diastolic volume, stroke volume, ejection fraction, and cardiac output.

RESULTS

The mean age was 62 years, and 52% of the participants were women. After adjustment for sociodemographic variables and height, higher systolic blood pressure and body mass index were associated with larger LV mass and volumes. Current smoking and diabetes were associated with greater LV mass (+7.7 g, 95% confidence interval [CI] +5.5 to +9.9 and +3.5 g, 95% CI +1.2 to +5.8, respectively), and with lower stroke volume (-1.9 ml, 95% CI -3.3 to -0.5 and -4.5 ml, 95% CI -6.0 to -3.0, respectively) and lower ejection fraction (-1.6%, 95% CI -2.1 to -1.0 and -0.8%, 95% CI -1.5 to -0.2, respectively).

CONCLUSIONS

In this cohort free of clinical cardiovascular disease, modifiable risk factors were associated with subclinical alterations in LV size and systolic function as detected by cardiac MRI.

Cardiovascular Mortality in Overweight Subjects

The role of obesity and overweight as independent risk factors for cardiovascular disease is still debated. The aim of this study was to evaluate the impact of overweight on cardiovascular mortality according to the presence or absence of associated risk factors. This study included 139,562 men and 104,236 women, aged 18 to 95 years, who had a standard health checkup at the IPC Center between 1972 and 1988. The follow-up period for mortality ended in December 1997. In both genders, the prevalence of hypertension, diabetes, and hypercholesterolemia increased with body mass index (P<0.001). When compared with subjects with a body mass index <25 kg/m2 without associated risk factors, overweight subjects without associated risk factors did not have an increased risk of cardiovascular mortality. Risk of cardiovascular death increased significantly when overweight was associated with hypertension alone [hazard ratio: 2.05 (1.71 to 2.46) in men; 2.15 (1.48 to 3.11) in women]. In both genders, the association of overweight with diabetes alone or hypercholesterolemia alone did not increase the risk. By contrast, in the presence of hypertension, cardiovascular mortality dramatically increased in overweight subjects with hypercholesterolemia [hazard ratio: 2.65 (2.20 to 3.19) in men, 2.57 (1.80 to 3.68) in women] or diabetes [hazard ratio: 3.01 (2.29 to 3.95) in men; 4.50 (2.67 to 7.58) in women]. The data suggest that the presence of high blood pressure in overweight subjects is the key factor leading to a significant increase in cardiovascular mortality. Because overweight significantly increases the prevalence of associated risk factors, especially hypertension, it should be considered as a major cardiovascular risk determinant.

Metabolic syndrome and echocardiographic left ventricular mass in blacks: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

The metabolic syndrome has been associated with cardiovascular disease, but few studies have examined its relationship with subclinical measures such as echocardiographic left ventricular (LV) mass. This relationship is likely to be of particular importance in blacks, in whom both the metabolic syndrome and LV hypertrophy are common.

METHODS AND RESULTS

Echocardiography, performed at 1 of 4 sites in the Atherosclerosis Risk in Communities (ARIC) Study, was used to assess LV dimensions in 1572 black women and men aged 49 to 75 years in 1993-1996. Participants were categorized by number of metabolic syndrome characteristics (hypertension, dyslipidemia [low HDL cholesterol or high triglycerides], and glucose intolerance). Age-adjusted mean LV mass indexed by height (g/m) increased in a stepwise gradient with increasing number of metabolic syndrome disorders (none, any 1, any 2, all 3) in both women and men (125.1, 143.9, 153.7, 169.3 and 130.5, 148.7, 160.8, 170.2, respectively; P<0.001, tests for trend). Associations were diminished slightly by adjustment for smoking, alcohol intake, and education; additional adjustment for waist circumference resulted in some attenuation, but associations remained statistically significant. Analyses focusing on components of LV mass revealed that posterior wall and interventricular septal thickness, but not LV chamber size, were significantly and independently associated in general with the number of metabolic syndrome disorders. Consistent with these findings, relative wall thickness was also associated with number of disorders. Associations were similar across age and central adiposity. Hypertension had a strong influence on LV mass with additional contributions from dyslipidemia and glucose intolerance; strong synergistic effects of the syndrome beyond its individual components were not observed.

CONCLUSIONS

In this cross-sectional population-based study of black women and men, the degree of metabolic syndrome clustering was strongly related to LV mass and its wall thickness components. These associations are consistent with a possible influence of underlying factors such as insulin resistance or other vascular processes on myocardial thickening and not on chamber size.

Optimal threshold value for left ventricular hypertrophy in blacks: the Atherosclerosis Risk in Communities study

The distribution of echocardiographic left ventricular (LV) mass differs among ethnicities. Because ethnic-specific echocardiographic criteria for LV hypertrophy (LVH) are not established, we determined whether threshold values derived from overwhelmingly white populations are appropriate for blacks, a subgroup having more LVH. Between 1992 and 1994, LV mass was measured echocardiographically in the Jackson, Mississippi, black cohort of the Atherosclerosis Risk in Communities study. Participants free of prevalent cardiovascular disease (CVD) (n=1616; mean+/-SD, age 59+/-5.7; 65% women and 57% with hypertension) were included. The optimal LVH threshold value was selected from the continuum of LV mass index (LVMI=LV mass/height(2.7)) using 3 methods: (1) the best operating point from the area under the resulting receiver-operating characteristic (ROC) curve predicting incident CVD; (2) the value with the smallest probability value associated with incident CVD; and (3) visual inspection of functions of LVMI and CVD in the general additive model (GAM) plot. At a median follow-up of 6.8 years, there were 192 events (coronary heart disease=87, stroke=62, and congestive heart failure=43; incidence=17.6/1000 person-years). The best operating point from the resulting ROC analysis was 51.2 g/m(2.7) for sensitivity (53.4%) and specificity (61.5%). The Cox and GAM models adjusted for age, gender, systolic blood pressure, hypertension, diabetes, smoking, total cholesterol-to-high-density lipoprotein ratio, LVH by ECG criterion, and socioeconomic status found 50 to 51 g/m(2.7) as the optimal threshold for LVH in middle-aged blacks, corresponding to a minimum probability value and to a log-hazard ratio of zero, respectively. Because these values are close to the 51 g/m(2.7) established from predominantly white populations, this cutpoint is appropriate for both groups.

Influence of excess fat on cardiac morphology and function: study in uncomplicated obesity

OBJECTIVE

To evaluate whether or not "uncomplicated" obesity (without associated comorbidities) is really associated with cardiac abnormalities.

RESEARCH METHODS AND PROCEDURES

We evaluated cardiac parameters in obese subjects with long-term obesity, normal glucose tolerance, normal blood pressure, and regular plasma lipids. We selected 75 obese patients [body mass index (BMI) >30 kg/m(2)], who included 58 women and 17 men (mean age, 33.7 +/- 11.9 years; BMI, 37.8 +/- 5.5 kg/m(2)) with a > or =10-year history of excess fat, and 60 age-matched normal-weight controls, who included 47 women and 13 men (mean age, 32.7 +/- 10.4 years; BMI, 23.1 +/- 1.4 kg/m(2)). Each subject underwent an oral glucose tolerance test to exclude impaired glucose tolerance or diabetes mellitus, bioelectrical impedance analysis to calculate fat mass and fat-free mass, and echocardiography.

RESULTS

Obese patients presented diastolic function impairment, hyperkinetic systole, and greater aortic root and left atrium compared with normal subjects. No statistically significant differences between obese subjects and normal subjects were found in indexed left ventricular mass (LVM/body surface area, LVM/height(2.7), and LVM/fat-free mass(kg)), and no changes in left ventricular geometry were observed. No statistically significant differences in cardiac parameters between extreme (BMI > 40 kg/m(2)) and mild obesity (BMI < 35 kg/m(2)) were observed.

DISCUSSION

In conclusion, our data showed that obesity, in the absence of glucose intolerance, hypertension, and dyslipidemia, seems to be associated only with an impairment of diastolic function and hyperkinetic systole, and not with left ventricular hypertrophy.