Abstract 229: Increased Relative Wall Thickness is Associated With Increased Left Ventricular Twist in Patients With Severe Aortic Stenosis
Background: Ventricular twist is increased in patients with aortic stenosis (AS) compared to normal controls. In patients with AS, subendocardial myofiber shortening is reduced relative to subepicardial myofiber shortening and this is associated with increased LV twist. The cause for the reduction in subendocardial myofiber shortening and associated increase in twist has not been clearly defined. Increased wall thickness exacerbates subendocardial ischemia and may help explain these observations.
Hypothesis: Hypertrophic remodeling of the LV is associated with increased ventricular twist.
Methods: Forty-one patients with severe symptomatic AS [mean age 84 years, 51% female, ejection fraction (EF) 53%, aortic valve area (AVA) 0.57 cm2, and mean gradient 41 mmHg] had transthoracic echo images obtained on GE Vivid 7 machines. Apical and basal rotation were measured on GE EchoPac™ analysis software utilizing 2D speckle tracking of the parasternal short-axis views at the apex (beyond the papillary muscles) and base (mitral valve in view). LV twist was calculated as the peak absolute difference between apical and basal rotation. Relative wall thickness (RWT) = (2 × posterior wall thickness)/LV end-diastolic dimension. LV mass was calculated by the area-length method.
Results: Mean LV twist (± SD) progressively increased as RWT increased: LV twist by RWT quartiles from lowest to highest was 9.2°±4.6°, 14.0°±4.0°, 16.8°±6.9°, and 22.8°±9.1° (p for trend <0.0001). After adjusting for EF, AVA and LV mass, increased RWT was significantly associated with increased LV twist (â = 25.1; p = 0.01; r2 = 0.50). There was no evidence of a differential effect of RWT on LV twist in patients with varying EFs (EF*RWT interaction p = 0.49). While related in univariable analysis (p = 0.002), LV mass was not associated with LV twist in a multivariable model (p = 0.38).
Conclusions: Increased ventricular twist in patients with severe symptomatic AS is associated with increased RWT. Since increased RWT has been associated with a poor prognosis further studies are needed to determine the impact of LV twist on clinical outcomes in patients with severe aortic stenosis.