167 Is Global Left Ventricular Afterload has an Impact on Left Atrial Function in Patients with Aortic Stenosis?

Abstract

In aortic stenosis (AS), global left ventricular (LV) afterload is evaluated using valvulo-arterial impedance (Zva) and has been recently associated with LV dysfunction and patient outcome. Left atrial (LA) enlargement is a surrogate marker of diastolic burden and a predictor of outcome. Whether LA function might be affected by elevated global LV afterload has never been examined. The aim of this study was thus undertaken to investigate the impact of Zva on LA volume and function in severe AS. Tissue Doppler imaging and 2D transthoracic echocardiography including measurements of LV and LA function and AS assessment was performed in 39 consecutive patients (63% of male, 70±13 years) with an aortic valve area < 1cm 2 . Zva was calculated by dividing the estimated LV systolic pressure (systolic arterial pressure + aortic mean transvalvular gradient) by the LV stroke volume index. Patients were studied in 2 groups according to Zva (median = 4.7ml/mmHg/m 2 ). Although patients with Zva ≥ 4.7 had higher LV mass (178±47 vs. 143±33 g/m 2 , p=0.03), there was no significant difference between the 2 groups regarding LV volume and function. By contrast, patients with a Zva ≥ 4.7 had lower LA ejection fraction (42±13 vs. 53±10%, p=0.02), LA passive function (18±8 vs. 26±10%, p=0.03) and LA conduit volume (19±21 vs. 47±24ml, p=0.0012) compared to those with a low Zva. Late annular diastolic velocity (Aa) was significantly lower in patients with a Zva ≥ 4.7 (7.1±3 vs. 9.2±3 cm/s, p=0.04), suggesting impaired LA active function. There are significant correlations between Zva and Aa (r=−0.62, p=0.0002), LA ejection fraction (r=−0.41, p=0.018), LA passive (r=−0.39, p=0.03) and LA conduit volume (r=−0.71, p<0.0001). In patients with severe AS, global LV afterload had significant impact on LA ejection fraction and on LA active, passive and conduit functions. Further studies are needed to evaluate the prognostic impact of LA dysfunction in AS.