Valve area and the risk of overestimating aortic stenosis

The Flow Rate in Patients With Low-Gradient Aortic Stenosis

PURPOSE

 The decision to assess the severity and determine the ideal timing of intervention for low-gradient aortic stenosis poses a greater challenge. Recently, a novel method for determining the flow status of patients with aortic stenosis has been introduced, utilizing flow rate measurements. In this study, we investigated whether the flow status of patients with low-gradient aortic stenosis is linked to mortality within a three-year timeframe.

METHODS

Twenty-nine patients diagnosed with low-gradient aortic stenosis and valve area ≤ 1 cm were identified during 2010-2015. Each patient's flow rate across the aortic valve was computed, and the study scrutinized echocardiographic parameters to ascertain their correlation with mortality over a three-year timeframe.

RESULTS

 We observed that among patients with low-gradient aortic stenosis and a valve area of ≤1 cm, a decreased flow rate across the aortic valve emerged as an independent predictor of mortality. A flow rate < 210 ml/s was linked with a three-year mortality rate of 66.7%, whereas a low stroke volume index < 35 ml/m² did not show an association with three-year mortality. This observation might be attributed to the smaller body sizes prevalent among these older patients, particularly females, which could influence the calculation of the stroke volume index.

CONCLUSION

 In older patients with low-gradient aortic stenosis, the flow rate can better reflect flow status than the stroke volume index, and it also suggests a prognostic significance in predicting mortality. Additional studies are warranted to validate these findings across broader patient populations and to assess the potential efficacy of early intervention strategies in this particular patient cohort.

Grading of Aortic Stenosis: Is it More Complicated in Women?

Aortic stenosis (AS) is the most common valvular heart disease and the main indication for valvular replacement in older women. Correct AS grading is mandatory for an adequate selection of patients for both surgical and transcatheter aortic valve replacement. Women and men have different AS severity grades at the same level of aortic valve calcification. Moreover, besides having smaller cardiac volumes, left ventricular outflow tract and aortic size, women have a specific pattern of left ventricular structural and functional remodelling in response to the AS-related chronic pressure overload. Here, the sex-specific cardiac changes in AS that make AS grading more challenging in women, with consequences for the management and outcome of this group of patients, are reviewed.

New Evidence About Aortic Valve Stenosis and Cardiovascular Hemodynamics

Aortic stenosis (AS) is the most common degenerative valvular disease in western word. In patients with severe AS, small changes in aortic valve area can lead to large changes in hemodynamics. The correct understanding of cardiac hemodynamics and its interaction with vascular function is of paramount importance for correct identification of severe AS and to plan effective strategies for its treatment. In the current review with highlight the importance of pressure recovery phenomenon and valvular arterial impedance as novel tools in the evaluation of patients with aortic stenosis.

Evaluation of mechanical prosthetic valves: the role of three dimensional echocardiography in calculating effective orifice area in obese vs non-obese individuals

Calculation of effective orifice area (EOA) is crucial for the evaluation of prosthetic valve (PV) function and there is lack of data on the best method, particularly in obese patients, in whom two-dimensional (2D) transthoracic echocardiography (TTE) is cumbersome. We sought to compare two methods of calculating EOA through Continuity equation; one using standard 2D-TTE and other three-dimensional (3D) stoke volume (SV), in patients with bileaflet mechanical PV stratified by body mass index (BMI). On conventional TTE, SV mas measured using standard 2D derived data and 3D derived SV in 38 aortic and 62 mitral PV patients who were referred for further evaluation for mild/moderate symptoms of dyspnea. Patients were categorized with regard to transprosthetic flow into 'normal-flow' and 'high-flow' groups and several echocardiographic data including 2D and 3D EOA were compared. Rates of obesity (BMI ≥ 30) were similar within high and normal flow groups of mitral and aortic PV patients. Correlation and agreement of 2D and 3D EOA was sought in patients with and without obesity. After identifying patients with possible severe obstruction, ROC analysis was carried out to identify whether 2D and 3D derived EOA could discriminate those with obstruction. There was good correlation and agreement between two methods in patients without obesity in both mitral and aortic PV. In obese individuals, however, there was no correlation between 2D and 3D EOA; in whom echocardiographic criteria showing severe obstruction revealed that 3D EOA measurements were more accurate. ROC analysis supported that 3D EOA performs better to identify patients with obstructive characteristics. In patients with bileaflet PV, measurement of EAO by 3D derived SV yields more accurate results irrespective of BMI.