Association between the level of serum soluble ST2 and invasively measured aortic pulse pressure in patients undergoing coronary angiography

Despite the well-documented value of ST2 in heart failure and myocardial infarction, the role of ST2 in vascular biology has not yet been well defined. This study was performed to investigate the association between serum soluble ST2 (sST2) and invasively measured aortic pulse pressure (APP). A total of 167 consecutive patients with suspected coronary artery disease (CAD) (65.1 ± 9.8 years; men, 65.9%) referred for invasive coronary angiography was prospectively enrolled. APP was measured at the ascending aorta with a pig-tail catheter, and arterial blood samples for the measurement of sST2 were collected before coronary angiography. Serum sST2 levels were quantified by radioimmunoassay. Most of the patients (73.9%) had significant CAD (stenosis ≥ 50%) on coronary angiography. Patients with higher APP (≥76 mmHg) showed a significantly higher sST2 level compared to those with lower APP (<76 mmHg) (31.7 ± 13.9 ng/mL vs 26.2 ± 10.2 ng/mL, P < .001). In simple correlation analysis, there was a significant positive correlation between sST2 levels and APP (r = 0.413, P < .001). In multiple linear regression analysis, sST2 had an independent association with APP even after controlling for potential confounders (β = 0.331, P < .001). The serum sST2 level may be independently associated with invasively measured APP in patients undergoing coronary angiography. The result of this study gives insight into the role of sST2 in aortic stiffening, and suggests that the sST2 level may be a useful marker of aortic stiffness.

Relationship between brachial-ankle pulse wave velocity and invasively measured aortic pulse pressure

Although brachial-ankle pulse wave velocity (baPWV) has been widely used as an index of arterial stiffness, no consensus exists about whether baPWV can reflect central aortic stiffness. The authors investigated the association between baPWV and invasively measured aortic pulse pressure (APP) in a total of 109 consecutive patients (mean age, 62.3 ± 11.3 years; 67.9% men). Most patients (91%) had obstructive coronary artery disease, and mean baPWV and APP values were 1535 ± 303 cm/s and 66.8 ± 22.5 mm Hg, respectively. In univariate analysis, there was a significant linear correlation between baPWV and APP (r = .635, P < .001). The correlation between baPWV and APP remained significant even after controlling for potential confounders (β = 0.574, P < .001; R²  = .469). Arterial stiffness measured by baPWV showed a strong positive correlation with invasively measured APP, independent of clinical confounders. Therefore, baPWV can be a good marker of central aortic stiffness.

Contribution of backward and forward wave pressures to age-related increases in aortic pressure in a community sample not receiving antihypertensive therapy

Reports on the contribution of aortic forward (Pf) and backward (Pb) wave pressures to age-related increases in central aortic pulse pressure (PPc) have been confounded by the use of participants receiving antihypertensive therapy. We assessed the relative contribution of Pf and Pb to age-related increases in PPc (radial applanation tonometry and SphygmoCor software using an assumed triangular wave for wave separation analysis) in 892 community participants not receiving antihypertensive therapy. We validated our results using aortic flow waves (echocardiography) for wave separation analysis in 254 of these participants. In multivariate regression models in those aged <50 years, adjustments for both Pb and a Pf-independent measure of reflected wave function (RM = Pb/Pf), but not Pf abolished the impact of age on PPc. However, in those aged >50 years, adjustments for Pf (β-coefficient: 0.25 ± 0.06 vs. 0.74 ± 0.08; P < .0001) and Pb (0.04 ± 0.04 vs. 0.74 ± 0.08; P < .0001), but not RM markedly decreased the relationship between age and PPc. On product of coefficient mediation analysis, whether assessed in men or in women, in those participants aged <50 years, independent of several confounders and mean arterial pressure, Pb (P < .005), but not Pf contributed to age-related increases in PPc. In contrast, in those participants aged ≥50 years, independent of several confounders and mean arterial pressure, Pb (P < .005) and Pf (P < .01) contributed to age-related increases in PPc, and Pb effects were markedly diminished by adjustments for Pf (0.26 ± 0.002 vs. 0.52 ± 0.003 mm Hg per year, P < .0001 for comparison). In conclusion, independent of the effects of antihypertensive therapy, aortic backward waves contribute to age-related increases in aortic PPc across the adult lifespan, but at an older age, this effect may be attributed in part to the impact of forward on backward wave pressures.

Contributions of aortic pulse wave velocity and backward wave pressure to variations in left ventricular mass are independent of each other

Aortic pulse wave velocity (PWV) and backward waves, as determined from wave separation analysis, predict cardiovascular events beyond brachial blood pressure. However, the extent to which these aortic hemodynamic variables contribute independent of each other is uncertain. In 749 randomly selected participants of African ancestry, we therefore assessed the extent to which relationships between aortic PWV or backward wave pressures (Pb) (and hence central aortic pulse pressure [PPc]) and left ventricular mass index (LVMI) occur independent of each other. Aortic PWV, PPc, forward wave pressure (Pf), and Pb were determined using radial applanation tonometry and SphygmoCor software and LVMI using echocardiography; 44.5% of participants had an increased left ventricular mass indexed to height^1.7. With adjustments for age, brachial systolic blood pressure or PP, and additional confounders, PPc and Pb, but not Pf, were independently related to LVMI and left ventricular hypertrophy (LVH) in both men and women. However, PWV was independently associated with LVMI in women (partial r = 0.16, P < .001), but not in men (partial r = 0.03), and PWV was independently associated with LVH in women (P < .05), but not in men (P = .07). With PWV and Pb included in the same multivariate regression models, PWV (partial r = 0.14, P < .005) and Pb (partial r = 0.10, P < .05) contributed to a similar extent to variations in LVMI in women. In addition, with PWV and Pb included in the same multivariate regression models, PWV (P < .05) and Pb (P < .02) contributed to LVH in women. In conclusion, aortic PWV and Pb (and hence pulse pressure) although both associated with LVMI and LVH produce effects which are independent of each other.

Brachial Pressure Control Fails to Account for Most Distending Pressure-Independent, Age-Related Aortic Hemodynamic Changes in Adults

BACKGROUND

Although several characteristics of aortic function, which are largely determined by age, predict outcomes beyond brachial blood pressure (BP), the extent to which brachial BP control accounts for age-related variations in aortic function is uncertain. We aimed to determine the extent to which brachial BP control in the general population (systolic/diastolic BP < 140/90 mm Hg) accounts for age-related aortic hemodynamic changes across the adult lifespan.

METHODS

Central aortic pulse pressure (PPc), backward wave pressure (Pb), pulse wave velocity (PWV), and PP amplification (PPamp) (applanation tonometry and SphygmoCor software) were determined in 1,185 participants from a community sample (age >16 years; 36.4% uncontrolled BP).

RESULTS

With adjustments for distending pressure (mean arterial pressure, MAP), no increases in PPc, Pb, or PWV and decreases in PPamp were noted in those with an uncontrolled brachial BP younger than 50 years. In those older than 50 years with an uncontrolled brachial BP, MAP-adjusted aortic hemodynamic variables were only modestly different to those with a controlled brachial BP (PPc, 46±14 vs. 42±15 mm Hg, P < 0.02, Pb, 23±8 vs. 21±8 mm Hg, PWV, 8.42±3.21 vs. 8.19±3.37 m/second, PPamp, 1.21±0.17 vs. 1.21±0.14). Nonetheless, with adjustments for MAP, marked age-related increases in PPc, Pb, and PWV and decreases in PPamp were noted in those with uncontrolled and controlled brachial BP across the adult lifespan (P < 0.0001).

CONCLUSION

Brachial BP control in the general population fails to account for most distending pressure-independent, age-related changes in aortic hemodynamics across the adult lifespan.

Indexes of aortic pressure augmentation markedly underestimate the contribution of reflected waves toward variations in aortic pressure and left ventricular mass

Although indexes of wave reflection enhance risk prediction, the extent to which measures of aortic systolic pressure augmentation (augmented pressures [Pa] or augmentation index) underestimate the effects of reflected waves on cardiovascular risk is uncertain. In participants from a community sample (age >16), we compared the relative contribution of reflected (backward wave pressures and the reflected wave index [RI]) versus augmented (Pa and augmentation index) pressure wave indexes to variations in central aortic pulse pressure (PPc; n=1185), and left ventricular mass index (LVMI; n=793). Aortic hemodynamics and LVMI were determined using radial applanation tonometry (SphygmoCor) and echocardiography. Independent of confounders, RI and backward wave pressures contributed more than forward wave pressures, whereas Pa and augmentation index contributed less than incident wave pressure to variations in PPc (P<0.0001 for comparison of partial r values). In those <50 years of age, while backward wave pressures (partial r=0.28, P<0.0001) contributed more than forward wave pressures (partial r=0.15, P<0.001; P<0.05 for comparison of r values), Pa (partial r=0.13, P<0.005) contributed to a similar extent as incident wave pressure (partial r=0.22, P<0.0001) to variations in LVMI. Furthermore, in those ≥50 years of age, backward wave pressures (partial r=0.21, P<0.0001), but not forward wave pressures (P=0.98), while incident wave pressure (partial r=0.23, P<0.0001), but not Pa (P=0.80) were associated with LVMI. Pa and augmentation index underestimated the effect of wave reflection on PPc and LVMI in both men and women. Thus, as compared with relations between indexes of aortic pressure augmentation and PPc or LVMI, strikingly better relations are noted between aortic wave reflection and PPc or LVMI.