P786The echocardiographic evaluation of left ventricular adaptation to increased afterload and its comparison with parameters of cardiac magnetic resonance

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Objective: To investigate the value of echocardiography (TTE) and cardiac magnetic resonance (CMR) in the assessment of left ventricular (LV) adaptation to an increased afterload and to analyze the effect on the LV systolic function.Background: To maintain an effective LV-arterial coupling, the LV adapts to the increased afterload by changing its geometry resulting in a reduction of the effective systolic myocardial wall stress (SMWS). When the prolonged elevated LV afterload exceeds the limit of LV compensatory mechanisms, an increase in end-systolic volume as well as a decrease in stroke volume and in ejection fraction occurs.Methods: We studied a group of 49 patients: 35 healthy subjects (group I), aged between 19 and 70 years (38±13 years) and 14 patients with aortic valve stenosis (valve area= 0.75 ±0.18 cm2) (group II), aged between 45 and 92 years (77±9 years). We calculated: 1)TTE parameters of wall stress (SMWS 103dyn/cm2), remodeling (h/r), and systolic function (LV ejection fraction by Simpsonapos;s method (2D-EF, %), 2D longitudinal global strain (global-[Latin Small Letter Open E], %)); 2) cardiac magnetic resonance(CMR) end-diastolic mass to volume ratio (LVM/EDV (g/ml)), tridimensional systolic myocardial wall stress (3D SMWS, 103.N/m2) combining LV geometry (3DLVgf) with the downstream arterial load. The statistical analysis was performed by Pearson correlation coefficient and t-test.Results: LVEF was homogeneous in 2 groups (I=64%, II=62%, p=0.69). Significant differences were found between the 2 groups in terms of SMWS, global-[Latin Small Letter Open E] and h/r (p <0.05). Furthermore, while no correlation was found between TTE and CMR parameters in the group I, significant correlations were found in group II for the following comparisons : 1-TTE parameters of systolic function (2D-EF, 2D global-[Latin Small Letter Open E]; r=0.63; p=0.05); 2- TTE parameters of remodeling (h/r) and systolic function (2D global-[Latin Small Letter Open E]) (r=0.53; p=0.05) 3-TTE and CMR parameters of LV remodeling (LVM/ EDV and h/r), (r= 0.87, p=0,0005); 4- TTE 2D global-[Latin Small Letter Open E] and CMR LV geometry factor (3DLVgf) (r= -0.79, p=0,005); 5-TTE 2D global-[Latin Small Letter Open E] and CMR SMWS (r=-0.8, p=0,005); 6–TTE SMWS and CMR SMWS (r= 0.78, p=0,0005).Conclusion: Increased afterload results in LV remodeling with good correlation between TTE and CMR parameters. Its effect on LV contractility was revealed by the good correlation between TTE 2D longitudinal global- [Latin Small Letter Open E] and CMR SMWS, which was found despite the preserved LVEF. Parameters of longitudinal systolic dysfunction may have a clinical interest in management of patients with preserved LVEF as a predictor of heart failure.

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