부산대학교 도서관

Purpose: To evaluate the role of left ventricular (LV) global afterload and various echocardiographic parameters of systolic function in a prospective cohort of 52 asymptomatic patients (pts) with severe aortic stenosis (indexed aortic valve area: 0.4±0.1 cm2/m2) and normal LV ejection fraction (EF=61±5%).Methods: By 2D Speckle Tracking Echocardiography, myocardial strain, rotations and twist were evaluated. The valvulo-arterial impedance (Zva) was calculated, as a measure of LV global afterload. Predefined end-points were the occurrence of symptoms (dyspnea, angina, syncope), aortic valve replacement or death.Results: At study entry, all pts had decreased longitudinal strain (LS=-15±4%) and increased circumferential strain (CS=-22±5%), twist (24±7°) and Zva (5.8±2 mmHg/mL/m2). Increased Zva was closely associated with CS increase (r=0.59, p=0.02) and LS decrease (r=-0.56, p=0.016). Whereas no relationship was found between myocardial function and trans-aortic gradients. During follow-up (11±7.5 months, range 1- 23 months), in univariable Cox regression analysis, predictors of events were: LVEF (p=0.02), mass index (p=0.01), LS (p<0.0001), radial strain (0.04) and Zva (p=0.0002). In multivariable Cox regression analysis, only global LS (HR 95% CI 1.41 (1.01 to 1.95, p=0.03) and Zva (HR 95% CI 2.78 (1.09 to 7.08, p=0.03) were independently associated with the combined end-point. Using receiver-operator characteristic curve analysis, a LS ≤ -18% (sensitivity=96%, specificity=73%) and a Zva ≥4.7 mmHg/ml/m2 (sensitivity=100%, specificity=91%) were identified as the best cut-off values to be associated with events.Conclusions: Prognosis of pts with aortic stenosis may depend not only on valvular load but also on arterial load imposed on the ventricle and its consequences on longitudinal function.