Background: Myocardial contractility and cardiac output are strongly dependent on afterload. In patients with severe aortic stenosis (AS) and normal left ventricular ejection fraction (LVEF), a relatively low cardiac output is associated with poor prognosis. The aim of the study was to evaluate the relationship between valvular resistance and stroke volume (SV) and to assess SV adequacy to afterload in patients with severe aortic stenosis and normal LVEF.
Methods: We assessed clinical characteristics and echocardiographic parameters in 44 patients with isolated severe AS and preserved LVEF. Left ventricular end and mean diastolic pressure (LVEDP and LVMDP) were measured by cardiac catheterization. SV values were plotted in relation to valvular resistance. Patients were divided into two groups with SV that was higher (group 1) or lower (group 2) than SV calculated by regression equation using valvular resistance as the dependent variable.
Results: At the same degree of valvular stenosis, patients in group 1 exhibited better contractility as assessed by global longitudinal strain (p<0.05), higher peak (p<0.01) and mean gradient (p<0.05), indexed SV (p<0.001) and transvalvular flow (p=0.01) than patient in group 2, who had higher heart rate (HR, p<0.05), shorter ejection time (ET, p<0.05), more elevated LVEDP (p<0.05) and LVMDP (p<0.05).
Conclusion: The presence of inappropriately decreased SV relatively to afterload in patients with severe AS and normal LVEF was associated with lower contractility, higher HR, shorter ET and elevated LV diastolic pressure suggesting failed hemodynamic adaptation to afterload.
