The diagnostic role of acceleration time measurement in patients with classical low flow low gradient aortic stenosis with reduced left ventricular ejection fraction
Authors: Memic Sancar K , Babur Guler G , Tanboga H A , Turkvatan Cansever A , Demir A R , Guler A , Tekin M , Uygur B , Birant A , Avci Y , Guler E , Erturk M 
Published: June 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Low-flow, low-gradient (LF-LG) AS can occur with a reduced or preserved left ventricular ejection fraction (LVEF) and is difficult to diagnose in either case(1). The main challenge is to distinguish between true severe and pseudo-severe stenosis. Dobutamine stress echocardiography (DSE) is recommended for the distinction of stenosis severity and LV flow reserve in classical LF-LG AS(2). Individual dissimilarities can be seen in the DSE results depending on the severity of the AS and LV afterload mismatch and/or on the existence of accompanying cardiomyopathy(3). One-third of the classical LF- LG AS with reduced LVEF patients do not have LV flow reserve (an increase of less than 20% in SV during DSE)(2). This patient group with an indeterminate DSE result has high surgical risk, and additional examinations are always required(4).

Purpose
The aim of our study was to evaluate the role of Acceleration time (AT), Ejection time (ET), and AT/ET ratio in predicting DSE outcome in classical LF-LG AS patients with reduced EF, and to distinguish between true and pseudo AS to determine the cut-off for AT which can be a useful evalu- ation method in clinical practice.

Methods
Sixty-seven classical LF-LG AS with reduced LVEF patients who underwent dobutamine stress echocardiography (DSE) were included in the study. Patients with ventricular arrhythmia and pace rhythm, moderate and severe mitral stenosis, severe aortic insufficiency, and paradoxical LF-LG AS patients were excluded. According to DSE results, all patients were divided into two groups; true AS and pseudo-severe AS. Aortic valve calcium score was measured in patients with inconclusive DSE results. AT and other ejection dynamics (ET and AT/ET) were calculated by taking baseline echocardiographic records into account for all patients(1,5). The predictive power of AT and other ejection dynamics were evaluated to estimate true and pseudo-severe AS.

Results
According to DSE results, out of 67 patients, 44 (65.7%) was diagnosed as true severe AS. There was a statistically significant relation between baseline AT and true AS [adjusted OR 4.47 (95% CI 1.93–10.4), p = 0.001]. The best cutoff value of AT was measured as 100 msec according to the Youden index. This value had a sensitivity value of 77%, specificity value of 87%, positive predictive value of 92%, and a negative predictive value of 67%.

Conclusion
In conclusion, the biggest difference of our study from the other studies in the literature is that we only included LF-LG AS patients with reduced EF in our study. Additionally, the study assesses the predictive strengths of ejection dynamics, one by one, regarding DSE results, and therefore, assesses role of ejection dynamics role to distinguish true and pseudo severe AS. As a result of our analysis, AT has a diagnos- tic role in the determination of true severe AS. Large-scale studies are needed to be carried out regarding true severe AS among LF LG AS patients with reduced LVEF.