الفهرس 
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Abstract
AS has been demonstrated to increase the risk of coronary artery disease and myocardial ischemia is a major complication in the course of AS., Also sudden death may occur among patients with AS. This may be caused by primary ventricular arrhythmias among patients with left ventricular hypertrophy and ventricular dysfunction or by arrhythmias due to myocardial ischemia.
So, this study aimed at early detection of Subclinical left ventricular (LV) dysfunction in AS patients and its relation with the degree of severity of AS which may be identified by a reduction in longitudinal function, assessed using 2D speckle tracking echocardiography (STE).
The current study included (65) patients (35 males & 30 females) divided into four groups, group I (control): included (15) normal subjects their ranged from 54-71, group (2) : included 21 patients with mild AS their age ranged from 50-70 years old. group (3) : included 11 patients with moderate AS their age ranged from 53-71 years old. group (4) : included 18 patients with severe AS their age ranged from 61-75 years old. They were assessed for baseline characteristics, ECG, echocardiography (M mode, dopplar, and 2D speckle tracking).
There was no statistically significant difference between the four groups as regard demographic ,laboratory &some of 2DE parameters (LVEDD,LVESD,ESV,EDV,FS&EF) , the current study found statistically significant difference between the four groups as regard NYHA class, ECG changes ,some of 2DE parameters (IVS,PWT,LAD,LVMI,AVA,PV&MPG) &STE parameters(GLVS) .
Measurement of LVEF was the main indication of echocardiography& was the main indicator of LV function, But we found that LVEF is not a sensitive method to asses LV function as subclinical changes may alter LV function in spite of normal LVEF.
In this study, we demonstrated a significant relationship between GLVS assessed by 2D-STI and AS severity in patients with normal EF, As the AS severity progresses, GLS was reduced, whereas EF was unchanged. Our study adds some interesting findings to the current knowledge on LV function in AS patients.
Previous studies reported a reduction in longitudinal strain measured by both tissue doppler imaging (TDI) and STI in severe AS patients with preserved EF. It is thought that longitudinal contraction is a particular marker of subendocardial function, which may be disproportionately involved in subclinical disease, including myocardial ischemia.
In the present study, the peak longitudinal systolic strain showed statistically significant difference between the four groups (mean 18.9±1.4, 18.8±1.3, 15.35±1.6 &12.42±1.4) in control ,mild ,moderate &severe AS groups respectively So, our study demonstrated that GLS gradually decreased from an earlier to later stage of AS with unchanged EF.This indicated that subtle change in longitudinal shortening that does not alter EF progresses gradually from mild to severe AS.
Also the present study showed that severity of AS was the independent predictor for the reduction in GLS. This highlights the relationship between severity of AS and the impairment of GLS. So we thought that Global longitudinal strain measurement by 2DS was superior to EF for the prediction of outcome and may become the optimal method for assessment of global LV systolic function.
The detection of subclinical cardiovascular complications in AS patients may provide an approach for identifying high risk individuals who may benefit from earlier and more active intervention to prevent clinical complications. So it is suggested that all patients with AS should be routinely and repeatedly subjected to 2D speckle tracking echocardiographic assessment of cardiac functions during long term management of those patients.