Insulin resistance and plasma triglyceride level are differently related to cardiac hypertrophy and arterial stiffening in hypertensive subjects

Longitudinal Change in Myocardial Function and Clinical Parameters in Middle-Aged Subjects: A 3-Year Follow-up Study

BACKGROUND

Metabolic syndrome (MetS) is closely associated with the aging process. However, changes in metabolic conditions and cardiac function that occur in middle aged population remain unclear. We evaluated longitudinal changes in metabolic parameters and cardiac function during a 3-year period in subjects with suspected MetS.

METHODS

We studied 191 participants with suspected MetS at baseline and after 3 years. Anthropometric parameters, including waist circumference (WC), and metabolic parameters, including fasting blood glucose and lipid profile were measured. Conventional echocardiography with two-dimensional speckle tracking was performed.

RESULTS

Mean age was 56.2±4.4 years, and there were 97 women (50.8%). Men had increased WC and triglycerides (TG) (WC 91.2±6.8 cm vs. 84.0±8.0 cm, P<0.001; TG 184.4±116.3 mg/dL vs. 128.2±53.6 mg/dL, P<0.001), and reduced global longitudinal strain (GLS) (-15.4%±2.1% vs. -17.1%±2.0%, P<0.001) compared to women. After 3.4 years, values of WC and TG did not change in men but increased in women (all P<0.05). The absolute value of left ventricular (LV) GLS did not change in men but was reduced in women (P=0.011). Change in TG was independently associated with worsening of LV GLS only in women (standardized β, -0.309; 95% confidence interval, -0.130 to -0.009; P=0.025).

CONCLUSION

In middle aged population, a vulnerable period for metabolic disturbance, cardiac remodeling tended to progress, which was prominent in women. Progression of adiposity and dyslipidemia after menopause may accelerate subclinical cardiac remodeling in middle-aged women. Lifestyle modification and medical interventions may help prevent further cardiac dysfunction in these subjects.

Triglycerides are related to left ventricular mass in hypertensive patients independently of other cardiometabolic risk factors: the effect of gender

Given the inconsistent results on the prognostic significance of triglycerides (TGs), the purpose of the present study was to investigate the association of plasma TGs with left ventricular mass (LVM) in hypertensive patients. We studied 760 never treated, non diabetic, hypertensive patients. Τransthoracic echocardiography was performed and LVMI was calculated according to the Devereux formula, adjusted to body surface area. Triglycerides were associated with LVMI after adjustment for age, gender, systolic blood pressure (SBP), smoking and fasting glucose (b = 0.08, p = 0.009). This relationship remained significant even after adjustment for BMI, LDL-C and ApoB/ApoA1 ratio (b = 0.07, p = 0.04). Gender-stratified analysis indicated that TGs were related to LVMI in men (p = 0.001) but not in women (p = NS). In addition, TGs were related with LV hypertrophy (LVH) in men, increasing the odds by 7% to present LVMI over 115 g/m² (OR = 1.07 per 10 mg/dl increase in TGs, p = 0.01). In conclusion, TGs are associated with LVMI in hypertensive patients, independently of other risk factors, including LDL-C. Given the prognostic significance of LVH, it might be suggested that TGs may serve as a useful marker for indentifying hypertensive patients at high risk. The gender discrepancy may suggest a possible gender-specific modulatory effect of TGs on LV structure.

Triglyceride to HDL-C ratio and increased arterial stiffness in children, adolescents, and young adults

BACKGROUND AND OBJECTIVE

Lipid levels are linked to early atherosclerosis. Risk stratification may be improved by using triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C), which relates to arterial stiffness in adults. We tested whether TG/HDL-C was an independent predictor of arterial stiffness in youth.

METHODS

Subjects 10 to 26 years old (mean 18.9 years, 39% male, 56% non-Caucasian, n = 893) had laboratory, anthropometric, blood pressure, and arterial stiffness data collected (brachial distensibility, augmentation index, carotid-femoral pulse-wave velocity). Subjects were stratified into tertiles of TG/HDL-C (low, n = 227; mid, n = 288; high, n = 379).

RESULTS

There was a progressive rise in cardiovascular (CV) risk factors and arterial stiffness across TG/HDL-C ratio. The high TG/HDL-C ratio group had the stiffest vessels (all P < .03 by analysis of variance). TG/HDL-C as a continuous variable was an independent determinant of brachial distensibility in CV risk factor adjusted model and for carotid-femoral pulse-wave velocity in obese subjects, with trend for higher augmentation index.

CONCLUSIONS

TG/HDL-C, an estimate of small, dense low-density lipoprotein cholesterol, is an independent determinant of arterial stiffness in adolescents and young adults, especially in obese youth. These data suggest that use of TG/HDL-C may be helpful in identifying young adults requiring aggressive intervention to prevent atherosclerotic CV diseases.

Effect of exercise training on biologic vascular age in healthy seniors

Arteriosclerosis with aging leads to central arterial stiffening in humans, which could be a prime cause for increased cardiac afterload in the elderly. The purpose of the present study was to assess the effects of 1 yr of progressive exercise training on central aortic compliance and left ventricular afterload in sedentary healthy elderly volunteers. Ten healthy sedentary seniors and 11 Masters athletes (>65 yr) were recruited. The sedentary seniors underwent 1 yr of progressive exercise training so that at the end of the year, they were exercising ∼200 min/wk. Central aortic compliance was assessed by the Modelflow aortic age, which reflects the intrinsic structural components of aortic compliance. Cardiac afterload was assessed by effective arterial elastance (Ea) with its contributors of peripheral vascular resistance (PVR) and systemic arterial compliance (SAC). After exercise training, Ea, PVR, and SAC were improved in sedentary seniors and became comparable with those of Masters athletes although the Modelflow aortic age was not changed. Moreover, after exercise training, when stroke volume was restored with lower body negative pressure back to pretraining levels, the exercise training-induced improvements in Ea, PVR, and SAC were eliminated. Aortic stiffening with aging was not improved even after 1 yr of progressive endurance exercise training in the previously sedentary elderly, while left ventricular afterload was reduced. This reduced afterload after exercise training appeared to be attributable to cardiovascular functional modulation to an increase in stroke volume rather than to intrinsic structural changes in the arterial wall.

Congestive heart failure with preserved ejection fraction is associated with severely impaired dynamic Starling mechanism

Sedentary aging leads to increased cardiovascular stiffening, which can be ameliorated by sufficient amounts of lifelong exercise training. An even more extreme form of cardiovascular stiffening can be seen in heart failure with preserved ejection fraction (HFpEF), which comprises ~40~50% of elderly patients diagnosed with congestive heart failure. There are two major interrelated hypotheses proposed to explain heart failure in these patients: 1) increased left ventricular (LV) diastolic stiffness and 2) increased arterial stiffening. The beat-to-beat dynamic Starling mechanism, which is impaired with healthy human aging, reflects the interaction between ventricular and arterial stiffness and thus may provide a link between these two mechanisms underlying HFpEF. Spectral transfer function analysis was applied between beat-to-beat changes in LV end-diastolic pressure (LVEDP; estimated from pulmonary artery diastolic pressure with a right heart catheter) and stroke volume (SV) index. The dynamic Starling mechanism (transfer function gain between LVEDP and the SV index) was impaired in HFpEF patients (n = 10) compared with healthy age-matched controls (n = 12) (HFpEF: 0.23 ± 0.10 ml·m⁻²·mmHg⁻¹ and control: 0.37 ± 0.11 ml·m⁻²·mmHg⁻¹, means ± SD, P = 0.008). There was also a markedly increased (3-fold) fluctuation of LV filling pressures (power spectral density of LVEDP) in HFpEF patients, which may predispose to pulmonary edema due to intermittent exposure to higher pulmonary capillary pressure (HFpEF: 12.2 ± 10.4 mmHg² and control: 3.8 ± 2.9 mmHg², P = 0.014). An impaired dynamic Starling mechanism, even more extreme than that observed with healthy aging, is associated with marked breath-by-breath LVEDP variability and may reflect advanced ventricular and arterial stiffness in HFpEF, possibly contributing to reduced forward output and pulmonary congestion.

'Dynamic' Starling mechanism: effects of ageing and physical fitness on ventricular-arterial coupling

Cardiovascular diseases increase with advancing age, associated with left ventricular and arterial stiffening in humans. In contrast, daily exercise training prevents and/or improves both ventricular and arterial stiffening with ageing. We propose a new approach to quantify the dynamics of the Starling mechanism, namely the beat-to-beat modulation of stroke volume (SV) caused by beat-to-beat alterations in left ventricular filling, which we propose reflects the complex interaction between ventricular and arterial stiffness. We hypothesized that the dynamic Starling mechanism would be impaired with ageing, and that this impairment would be prevented and restored by daily exercise training. Two different approaches were employed: (1) a cross-sectional study to assess the effects of ageing and life-long exercise training; and (2) a longitudinal study to assess the effects of one-year endurance training in the elderly. Spectral transfer function gain between beat-to-beat changes in left ventricular end-diastolic pressure and SV was used as an index of the dynamic Starling mechanism. Gain was significantly lower in the sedentary elderly (70 +/- 3 years) than in both young individuals (27 +/- 6 years) and Masters athletes (68 +/- 3 years), and it was significantly lower in Masters athletes than in young controls (elderly: 0.37 +/- 0.11; Masters athletes: 0.96 +/- 0.55; young: 1.52 +/- 0.42 ml m(-2) mmHg(-1), mean +/- s.d.). Gain increased by 65% after one-year exercise training in the elderly, although the response was quite variable (P = 0.108). These findings suggest that the dynamic Starling mechanism is impaired with human ageing possibly due to ventricular-arterial stiffening. Life-long daily exercise training may minimize this impairment, although the effect may be limited particularly when started later in life.