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In patients with aortic stenosis (AS), changes in left ventricular (LV) geometry due to increased LV afterload, preserves LV ejection fraction (EF). However, subclinical myocardial dysfunction may develop despite normal LV EF. In the present study, we aimed to evaluate subclinical LV systolic dysfunction in patients with severe AS, without any cardiovascular disease and with normal LV EF, by using tissue Doppler imaging (TDI), a strain imaging method, “speckle tracking echocardiography” (STE) and its correlation with changes in LV geometry. We also performed a real time three dimensional echocardiography (3 DE) in order to demonstrate LV volumetric analysis.
We studied 25 patients (56% male, 73.9 years) with AS and 20 age and sex-matched controls, without any cardiac disease and with preserved LV EF. Conventional echocardiography, TDI, real time 3 DE and STE- based strain imaging were performed to analyse subclinical LV systolic function. Novel parameters currently used for the assessment of aortic stenosis severity were calculated according to related formulas (energy loss index (ELI), systemic arterial compliance (SAC), valvulo-arterial impedance).
Conventional echocardiographic measurements (LV end diastolic diameter, LV end systolic diameter, LV EF) and LV volumes by 3 DE were similar between the groups. Interventricular septum and posterior wall thickness were increased, compared to controls. (1.27±0.07 cm to 1.1±0.19 cm, p=0.02; 1.25±0.23 cm to 0.9±0.02 cm, p=0.01, respectively). In TDI analysis, we observed marked reduction in LV peak systolic velocity (Sa) (0.06±0.008 m/s to 0.14±0.02 m/s, p=0.0001). LV longitudinal peak systolic strain (9.66±1.29% to 17.60±2.18%, p=0.0001) and strain rate (0.21±0.08 1/s to 1.66±0.56 1/s, p=0.0001) were significantly impaired in patients, compared to controls, demonstrating subclinical ventricular systolic dysfunction. Significant positive correlation was obtained between energy loss index and LV strain/strain rate. (r=0.481, p=0.015; r=0.596, p=0.002 respectively). Aortic valve area was also positively correlated with LV strain (r=0.422, p=0,036).
Patients with AS have evidence of subclinical LV systolic dysfunction, despite preserved EF. Changes in LV geometry are correlated to impairment in LV function. Strain imaging-based novel echocardiographic techniques may provide additional data for detecting early deterioration in systolic function in patients with AS.