Ejection fraction velocity ratio as an indicator of aortic stenosis severity

Heterotopic ossification in mice overexpressing Bmp2 in Tie2+ lineages

Bone morphogenetic protein (Bmp) signaling is critical for organismal development and homeostasis. To elucidate Bmp2 function in the vascular/hematopoietic lineages we generated a new transgenic mouse line in which ectopic Bmp2 expression is controlled by the Tie2 promoter. Tie2CRE/+;Bmp2tg/tg mice develop aortic valve dysfunction postnatally, accompanied by pre-calcific lesion formation in valve leaflets. Remarkably, Tie2CRE/+;Bmp2tg/tg mice develop extensive soft tissue bone formation typical of acquired forms of heterotopic ossification (HO) and genetic bone disorders, such as Fibrodysplasia Ossificans Progressiva (FOP). Ectopic ossification in Tie2CRE/+;Bmp2tg/tg transgenic animals is accompanied by increased bone marrow hematopoietic, fibroblast and osteoblast precursors and circulating pro-inflammatory cells. Transplanting wild-type bone marrow hematopoietic stem cells into lethally irradiated Tie2CRE/+;Bmp2tg/tg mice significantly delays HO onset but does not prevent it. Moreover, transplanting Bmp2-transgenic bone marrow into wild-type recipients does not result in HO, but hematopoietic progenitors contribute to inflammation and ectopic bone marrow colonization rather than to endochondral ossification. Conversely, aberrant Bmp2 signaling activity is associated with fibroblast accumulation, skeletal muscle fiber damage, and expansion of a Tie2+ fibro-adipogenic precursor cell population, suggesting that ectopic bone derives from a skeletal muscle resident osteoprogenitor cell origin. Thus, Tie2CRE/+;Bmp2tg/tg mice recapitulate HO pathophysiology, and might represent a useful model to investigate therapies seeking to mitigate disorders associated with aberrant extra-skeletal bone formation.

Supravalvular Aortic Stenosis and the Risk of Premature Death Among Patients With Homozygous Familial Hypercholesterolemia

Patients with homozygous familial hypercholesterolemia (HoFH) have a high risk for premature death. Supravalvular aortic stenosis (SVAS) is a common and the feature lesion of the aortic root in HoFH. The relation between SVAS and the risk of premature death in patients with HoFH has not been fully investigated. The present study analysis included 97 HoFH patients with mean age of 14.7 (years) from the Genetic and Imaging of Familial Hypercholesterolemia in Han Nationality Study. During the median (±SD) follow-up 4.0 (±4.0) years, 40 (41.2%) participants had SVAS and 17 (17.5%) participants experienced death. The proportion of premature death in the non-SVAS and SVAS group was 7.0% and 32.5%, respectively. Compared with the non-SVAS group, SVAS group cumulative survival was lower in the HoFH (log-rank test, p <0.001). This result was further confirmed in the multivariable Cox regression models. After adjusting for age, sex, low density lipoprotein cholesterol (LDL_C)-year-score, lipid-lowering drugs, cardiovascular disease, and carotid artery plaque, SVAS was an independent risk factor of premature death in HoFH on the multivariate analysis (hazard ratio 4.45; 95% confidence interval, 1.10 to 18.12; p = 0.037). In conclusion, a significantly increased risk of premature death was observed in HoFH patients with SVAS. Our study emphasized the importance of careful and aggressive management in these patients when appropriate.

Value of ejection fraction/velocity ratio in the prognostic stratification of patients with asymptomatic aortic valve stenosis

BACKGROUND

The ejection fraction/velocity ratio (EFVR) is a simple function-corrected index of aortic stenosis severity with a good correlation with aortic valve area measured using the Gorlin formula at cardiac catheterization. It is calculated by dividing left ventricular ejection fraction (LVEF) to 4 × (peak jet velocity)² .

OBJECTIVE

Our aim was to evaluate the value of EFVR in predicting adverse events in patients with asymptomatic aortic stenosis.

METHODS

We analyzed the clinical and echocardiographic data of 216 asymptomatic patients with at least moderate aortic stenosis (AVA ≤ 1.5 cm² ). The primary end-point was cardiovascular death or aortic valve replacement.

RESULTS

There were 119 (55%) men and mean age was 68 ± 10 years. The mean follow-up time was 4.2 ± 1.6 years (median 4.3 years). During follow-up, the composite end-point of death or aortic valve replacement was reached in 105 patients (49%). Using multivariate Cox regression analysis, EFVR and valvulo-arterial impedance emerged as independent variables associated with outcome (P < 0.001 and P = 0.001, respectively). In the subgroup of patients with severe aortic stenosis (AVA < 1 cm² ), EFVR ≤ 0.9 was associated with an increased hazard ratio for the composite end-point of mortality and aortic valve replacement (HR 2.14, 95% CI: 1.15-4.0, P = 0.017), even after adjusting for aortic valve area.

CONCLUSIONS

In patients with asymptomatic moderate to severe aortic stenosis, EFVR is useful for risk stratification. Our results suggest that incorporating EFVR in the evaluation of patients with asymptomatic aortic stenosis might help identify those who are most likely to benefit from early elective aortic replacement.

Analysis of coronary flow haemodynamics in homozygous familial hypercholesterolaemic adolescents with aortic supravalvular stenosis

OBJECTIVE

To study coronary artery haemodynamics in adolescents with homozygous familial hypercholesterolaemia and aortic supravalvular stenosis.

METHODS

Patients diagnosed with familial hypercholesterolaemia who were younger than 16 years and who had undergone transthoracic echocardiography from 2007 to 2010 were included in this study. We included patients with homozygous familial hypercholesterolaemia and aortic supravalvular stenosis and those with heterozygous familial hypercholesterolaemia. All patients underwent stress echocardiography, and left anterior descending coronary artery flow was successfully detected. Coronary flow velocity reserve was calculated as the ratio of hyperaemic mean diastolic flow velocity after injection of adenosine to basal mean diastolic flow velocity. Changes in coronary haemodynamics and the relationship between lipid concentrations were determined.

RESULTS

A total of 11 patients with homozygous familial hypercholesterolaemia were enrolled in this study. Lipid concentrations were measured, and the mean coronary flow velocity reserve was 1.97 plus or minus 0.51. Seven children were included in the group of patients with heterozygous familial hypercholesterolaemia. In these children, the mean coronary flow velocity reserve was 3.08 plus or minus 0.84.

CONCLUSION

The coronary flow velocity reserve of homozygous familial hypercholesterolaemic patients is lower than that of heterozygous familial hypercholesterolaemic patients, and it is associated with a high concentration of low-density lipoprotein cholesterol. Aortic stenosis and plaques compromised the ostia of the coronary artery and caused increased basal mean diastolic coronary velocity with blunted increase in peak velocity, which decreased the coronary flow velocity reserve.

Diet-induced aortic valve disease in mice haploinsufficient for the Notch pathway effector RBPJK/CSL

OBJECTIVE

Calcific aortic valve disease is similar to atherosclerosis in that both diseases result from chronic inflammation and endothelial dysfunction. Heterozygous NOTCH1 mutations have been associated to calcific aortic disease and a bicuspid aortic valve. We investigated whether mice with genetic inactivation of the Notch signaling pathway are prone to develop valve disease when exposed to a predisposing diet.

METHODS AND RESULTS

Using Doppler echocardiography, histology, immunohistochemistry, quantitative gene expression analysis, and cell culture assays, we examined the effect of a hypercholesterolemic diet supplemented with vitamin D on mice heterozygous for null mutations in the Notch1 receptor or the effector transcription factor gene RBPJk. After 16 weeks on the hyperlipidemic diet, calcific aortic disease was detected in heterozygous RBPJk mice. Analysis of valve leaflets revealed macrophage infiltration, enhanced collagen deposition, proosteogenic protein expression, and calcification. Heterozygous null Notch1 mice displayed milder histopathologic changes and did not develop any significant hemodynamic disturbance. Valvular disease correlated with reduced expression of the Notch target gene Hey1 in valves of RBPJk heterozygous mice fed the hyperlipidemic diet. Consistent with the in vivo data, Notch signaling inhibition in porcine valve interstitial cells led to downregulation of HEY1 transcription, activation of osteogenic markers, and increased calcified nodule formation.

CONCLUSIONS

We show that Notch signaling disruption via RBPJk heterozygous inactivation results in aortic valve disease. Notch1 heterozygous mice do not show functional impairment, suggesting that additional Notch receptors may be involved in aortic valve homeostasis and disease. Our data establish a genetic mouse model of calcific aortic valve disease and may help to identify a patient population with reduced valvular NOTCH signaling at risk for developing this disease.

Ejection fraction/velocity ratio identifies prosthesis-patient mismatches in patients with aortic bioprosthetic valves and left ventricular dysfunction

OBJECTIVES

Recently, a new echocardiographic nonflow corrected index (ejection fraction/velocity ratio [EFVR] = percent left ventricular ejection fraction [EF]/maximum aortic gradient) has been introduced and has shown excellent accuracy in quantifying the effective orifice area (EOA) in native aortic valves and bio-prostheses. The objective of this study was to assess the utility of the EFVR to quantify the indexed EOA in patients with an aortic bioprosthesis and left ventricular dysfunction considering an indexed EOA value of 0.85 cm(2)/m(2) or less to be indicative of a prosthesis-patient mismatch (PPM), defined as an EOA of the inserted prosthetic valve of less than that of the normal human valve.

METHODS

We studied 100 patients (62 men and 38 women; mean age +/- SD, 71 +/- 8.6 years) with an aortic bioprosthesis and left ventricular dysfunction (EF < or =49%), and we evaluated the indexed EOA by both the continuity equation (CE) and EFVR.

RESULTS

We found a significant linear correlation between the CE and EFVR (r = 0.85; P < .0001) and good agreement between the two methods in identifying patients with an indexed EOA of 0.85 cm(2)/m(2) or less; the correlation began to become nonlinear for patients with an indexed EOA of greater than 1.2 cm(2)/m(2), which was not clinically relevant. Notably, all 11 patients with a discrepancy between the indexed EOA and EFVR (ie, EFVR < or =1.0 and indexed EOA >0.85 cm(2)/m(2)) also showed an indexed EOA of greater than 0.85 but less than or equal to 1.0 cm(2)/m(2) (meaning the presence of a mild PPM).

CONCLUSIONS

The EFVR can be considered a reliable echocardiographic alternative to the CE, especially in conditions in which that is technically difficult, allowing identification of a PPM (indexed EOA < or =0.85 cm(2)/m(2)) with excellent sensitivity and specificity.

Ejection fraction-velocity ratio for the assessment of aortic bioprosthetic valves in patients with systolic dysfunction

BACKGROUND

The continuity equation (CE) represents the 'gold standard' for the evaluation of aortic valve area in patients with aortic stenosis, but it is time-consuming and subject to error, and can be technically demanding. Recently, a new echocardiographic nonflow corrected index was introduced and demonstrated excellent accuracy in quantifying the effective orifice area (EOA) in native aortic valves and bioprostheses. This new index, the ejection fraction (EF)-velocity ratio (EFVR), is obtained by dividing the percentage left ventricular EF by the maximum aortic gradient.

OBJECTIVE

To assess the usefulness of this echocardiographic index for quantifying the EOA in patients with aortic bioprosthesis and left ventricular dysfunction.

METHODS

A total of 70 patients (25 women and 45 men) with aortic bioprosthesis and left ventricular dysfunction (EF of 49% or less) were studied. The mean (+/- SD) age of the study population was 71.4+/-9 years. The EOA was evaluated, both by the CE and by the EFVR.

RESULTS

A significant linear correlation between the CE and the EFVR was found (r=0.80; P<0.0001). The receiver operating characteristic curve analysis showed good agreement between the CE and the EFVR. An EFVR value of 1.15 or less was found to have a good sensitivity (89%) and good specificity (91%) in identifying patients with an EOA of 1.0 cm2 or smaller, with positive and negative predictive values of 79% and 95%, respectively.

CONCLUSIONS

The EFVR, a simple index that is less time-consuming than the CE, allows the identification of patients with aortic bioprosthesis stenosis with excellent sensitivity and specificity. It may be taken into consideration in clinical practice for the evaluation of patients with aortic bioprosthesis stenosis and left ventricular dysfunction.

Use of the Ejection Fraction-Velocity Ratio in the Hemodynamic Assessment of Aortic Bioprosthetic Valves

BACKGROUND

A new echocardiographic severity index of aortic valve stenosis has been recently introduced: the ejection fraction-velocity ratio (EFVR), which is a simple ratio ejection fraction/4Vmax2. This nonflow corrected index demonstrated an excellent accuracy in quantifying the effective orifice area (EOA) in native aortic valves. There is no information about the reliability of EFVR in assessing aortic EOA in patients with bioprostheses.

METHODS

In 141 consecutive patients with aortic bioprostheses (85 males, mean age 74 +/- 9 years), EOA was calculated by both continuity equation (CE) and EFVR.

RESULTS

The correlation between CE and EFVR was highly significant (r = 0.88; P < 0.0001). The area under the receiver operating characteristic (ROC) curve was 0.97 (considering a positive case CE < 1.0 cm2, best cutoff of EFVR was <1.06). Using CE as gold standard and a cutoff of 1.0 for both indexes, EFVR showed good sensitivity (80%) and specificity (98%). Also in a subgroup of 46 patients with moderate or severe mitral regurgitation, the EFVR had a good diagnostic accuracy (sensitivity 89%, specificity 97%). In 91 patients with ejection fraction < or = 50%, the EFVR confirmed good sensitivity (79%) and specificity (97%).

CONCLUSIONS

The EFVR, a simple and not time-consuming index, demonstrated a good diagnostic accuracy in assessing EOA also in patients with aortic bioprostheses. The presence of moderate to severe mitral regurgitation or left ventricular dysfunction does not reduce significantly the reliability of this new index. The EFVR can be taken into consideration in the clinical practice, at least when CE measurements are technically difficult.