الفهرس 
Introduction and RationaleOnly 14 pages are availabe for public view
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Abstract
Exertional dyspnea is a prevalent symptom impacting millions of people. (Karnani N. G. et al., 2005) The presence of normal EF does not exclude a cardiac etiology for dyspnea, as approximately 50% of patients with HF have only mildly reduced EF or preserved EF (heart failure with preserved ejection fraction [HFpEF]) (Owan T. E. et al., 2006a). Diagnosis of the cardiac cause of dyspnea is challenging and relies on identifying evidence of elevated left ventricular (LV) filling pressures at rest or during exercise. (Borlaug B. A., 2013) Diastolic stress echocardiography refers to the use of exercise Doppler echocardiography to detect impaired LV diastolic functional reserve and the resulting increase in LV filling pressure during exercise (by assessing E/e` ratio) (Burgess M. I. et al., 2006) The left atrium plays a critical role in maintaining LV filling by functioning as a reservoir for pulmonary venous flow during LV systole; a conduit for blood flow into the LV during early diastole; and as a booster pump during late diastole. Dysfunction of these normal left atrial mechanics impairs LV filling (Vieira M. J. et al., 2014) More recently, the assessment of left atrial deformation via strain and strain rate has allowed for accurate and reproducible analysis of left atrial function using speckle tracking echocardiography.(Saraiva R. M. et al., 2010) (Singh A. et al., 2017)
This study is a cross sectional descriptive study. In our study, we investigated 80 patient with unexplained exertional dyspnea with normal resting LV filling pressure at rest. Some of these patients may show elevated LV filling pressure with exercise. The current guidelines recommend to do diastolic stress echocardiography for those patients.
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In our study, we aim to study resting left atrial function, namely left atrium strain using speckle tracking and its relation to the results of diastolic stress echocardiography.
All patients underwent complete resting echocardiography including assessment of diastolic dysfunction using the recommended 2016 guidelines and resting left atrium strain using speckle tracking at rest.
Then we did diastolic stress echocardiography for all participants and the result of diastolic stress echocardiography was compared with the resting left atrium strain results.
Our results showed that Left atrium volume indexed was seen to be higher in patients with positive diastolic stress echocardiography. But in logistic regression analysis LA volume indexed failed to have a statistical significance as an independent predictor of positive diastolic stress echocardiography (P value 0.852)
The results showed that Patients with positive diastolic stress echocardiography had a mean LA strain of 18.4%, patients with indeterminate diastolic stress echocardiography had a mean LA strain of 29.5 and patients with negative diastolic stress echocardiography had a mean LA strain of 40. We did logistic regression analysis and it was found that LA strain was an independent predictor of a positive result on DSE testing (P value :0.008)
Conclusion:
Patients with positive diastolic stress echocardiography were associated with