Impact of valvuloarterial impedance on left ventricular longitudinal deformation in patients with aortic valve stenosis and preserved ejection fraction.

ABSTRACT

BACKGROUND: Left ventricular (LV) longitudinal deformation is a good marker of intrinsic myocardial dysfunction in pressure overload cardiomyopathies. AIM: To assess the effect of valvuloarterial haemodynamic load on LV longitudinal deformation in patients with aortic valve stenosis (AVS) and preserved LV ejection fraction (LVEF). METHODS: Global LV longitudinal strain (GLS) was measured using speckle tracking imaging in a series of 82 consecutive patients with AVS (mean age 75+/-10 years; 50% men). The global (valvular+arterial) haemodynamic load imposed on the LV was estimated by the valvuloarterial impedance (Z(va)), and was calculated using either arm-cuff systolic peripheral blood pressure or systolic central aortic blood pressure estimated by SphygmoCor. RESULTS: Among this series of 82 patients with preserved LVEF, 79% had reduced LV GLS (<-18%). LV GLS correlated weakly with AVS severity, systemic vascular resistance and systemic arterial compliance. However, there was a good inverse correlation between increase in Z(va) and impairment of LV GLS (r=0.41 p<0.0001). On multivariable analysis, impaired GLS was associated with increased Z(va) (p<0.0001), increased E/Ea ratio (p=0.001) and increased LV end-diastolic volume index (p=0.021), while indices of valvular load were not. Utilization of estimated central aortic blood pressure in place of brachial pressure did not improve the performance of Z(va) to predict GLS. CONCLUSION: The magnitude of the global haemodynamic load as reflected by Z(va) is a powerful determinant of altered LV longitudinal deformation in AVS patients with preserved LVEF. The calculation of Z(va) may be useful to identify the patients who are potentially at higher risk for the development of myocardial dysfunction. Use of estimated central aortic pressure in the calculation of Z(va) does not appear to provide any incremental predictive value over that calculated with the simple measurement of brachial pressure.