**4. Strain imaging and ejection fraction in aortic stenosis**

Measuring LV ejection fraction is crucial in the management of patients with asymptomatic severe aortic stenosis (AS). According to the current American Heart Association/American College of Cardiology and European Society of Cardiology guidelines there is a Class I indication (Level of Evidence: B) to perform aortic valve intervention in asymptomatic patients with severe AS when the LVEF becomes <50% [7, 8]. Predictors of poor outcome in aortic stenosis include advanced age, significant leaflet calcification, rapid disease progression and decreased left ventricular (LV) ejection fraction (EF). Patients can develop impaired LVEF due to afterload mismatch or from true depression of myocardial contractility due to myocardial fibrosis. Myocardial fibrosis occurs early in the natural history of aortic stenosis, affecting diastolic and systolic function and offering a substrate for ventricular arrhythmias, playing a role in the progression to heart failure and sudden cardiac death. These observations indicate that current echocardiographic assessment of LV function by measuring only the LVEF is insufficient and that new parameters detecting subtle myocardial impairment are needed to improve risk stratification and predict outcomes in patients with AS.

Several studies have defined the added value of global longitudinal strain over LVEF to characterize and prognosticate the clinical evolution of patients with aortic stenosis:

• There is growing evidence suggesting the prognostic role of global longitudinal strain (GLS), in asymptomatic patients with AS. The American Society of

Echocardiography (ASE) on cardiac chamber quantification acknowledged the incremental value of LV GLS over traditional LVEF measurements, and recommended its clinical use in patients [9].

