The importance of Doppler-echocardiographic parameters of left ventricle for risk stratification and early prognosis in aortic stenosis

Risk stratification and decision making are particularly complex in asymptomatic patients with moderate or severe aortic stenosis (AS). When to intervene in these patients is still matter of controversy, and misinterpreting the findings might lead to an unnecessary delay of aortic valve replacement. The risk of sudden death without preceding symptoms remains a concern, as well as the risk of irreversible myocardial damage due to the high global afterload. These factors may also be responsible for an impairment of coronary flow reserve (CFR) and microvascular coronary dysfunction, which has been observed in patients with AS and without obstructive epicardial coronary artery disease. Therefore, valve replacement prior to the onset of symptoms and LV dysfunction may be recommended; however, data in patients with purely asymptomatic AS are lacking. The most frequently used parameters such as mean pressure gradient (Pmean) and maximal jet velocity (Vmax) are necessary in determining the AS severity, but less useful in predicting the outcome and when to intervene in asymptomatic patients. The dobutamine testing (DT) in asymptomatic AS is promising having in mind that most of the Doppler-echocardiographic indices used for evaluation of AS is flow-dependent. The pharmacologic increase of flow could help to correctly assess disease severity, discover the existence of latent symptoms, assess the LV systolic function and, therefore, to guide clinical decisions. The new hemodynamic measurements of severity such as valve resistance (Zva) and the energy-loss index (ELI) have been proposed, however, a common limitation of most of these new indices, as well of the usefulness of DT, is that longitudinal follow-up data from prospective studies are lacking. The aim of this study was to assess which echocardiographic parameter(s) can identify subset of asymptomatic AS patients who are at high risk of short to mid-term cardiac events and to analyze the value of LV systolic and diastolic parameters change during low-dose DT in asymptomatic patients with moderate or severe AS and preserved EF at rest. Moreover, we analyzed different echocardiographic parameters to see which of these contributes the most to impairment of CFR in subgroup of AS patients with nonobstructive coronary arteries. Method: A total of 126 asymptomatic patients with aortic valve area (AVA) _ 1.5cm2 and EF > 50% were enrolled in this prospective study. The follow-up period was 14 months. Clinical data at fol