Abstract 18392: Latent Myopathy is More Pronounced in Low Flow Versus Normal Flow Aortic Stenosis Pre- and Post-aortic Valve Replacement in Patients with Normal Left Ventricular Ejection Fraction

Abstract

Background: Strain assessment using speckle tracking echocardiography (STE) is more sensitive than 2D echocardiography to detect subtle changes in left ventricular (LV) function. Mid cavity fibrosis on MRI and low indexed stroke volume are independent predictors of mortality in severe AS with preserved LV ejection fraction (LVEF). The role of 2D STE to identify latent myopathy (fibrosis) in AVR and normal LVEF is limited.

Methods: Demographic, 2D echocardiographic, and STE data were analyzed in patients with severe AS and preserved LVEF who underwent tissue AVR. Velocity vector imaging (VVI) 2D STE was used to assess global and regional peak systolic longitudinal strain and strain rate in both pre- and post-AVR echocardiograms. Basal and mid segment averages were compared to normal reference values. Low flow (LF) was defined as an indexed LV stroke volume <35ml/m2.

Results: Between July 2009 to May 2012, 47 patients (76 ± 10 yrs, 42% male) who underwent tissue AVR had both a pre- and post-AVR echo within 6.3 ± 6.7 months of surgery. Compared with pre-AVR values, global longitudinal strain (-6.6 ± 4.9% vs. -10.3 ± 3.7%; p=0.002) and strain rate (-0.8 ± 0.3 1/s vs. -0.9 ± 0.3 1/s; p=0.03) improved within 3.2 ± 2.3 months post-AVR. Pre-AVR mid segments showed a worse myopathy than basal segments, with a decrement of -10.1 ± 1.6% vs. -8.8 ± 1.6% (p=0.0009) from reference values. Although, improvement was seen in both mid (-8.6 ± 5.6 % vs. -10.6 ± 4.3%; p= 0.04) and basal (-8.2 ± 5.5% vs. -10.8 ± 5.0%; p=0.02) segments post-AVR, the myopathy remained more pronounced in the mid segments. Overall, 21 (46%) patients were classified as LF with significant improvement in pre- vs. post-AVR strain (-5.3 ± 4.6% vs. -9.4 ± 4.1%; p=0.003). However, compared with normal flow (-8.6 ± 5.7%) LF had lower pre-AVR (-5.3 ± 4.6%; p=0.05) and post-AVR (-12.4 ± 3.4% vs. -9.4 ± 4.1%; p=0.02) longitudinal strain.

Conclusions: STE VVI can identify both global and regional latent myopathy in patients with severe AS and preserved LVEF undergoing AVR. The myopathy is more pronounced in low indexed stroke volume pre and post-AVR. Furthermore, the myopathy in normal flow and low flow patients is more pronounced in the mid segments both pre- and post-AVR.