Abstract 19084: Electrocardiographic and Echocardiographic Determinants of Increased Left Ventricular Mechanical Dispersion in Severe Aortic Stenosis
Introduction: Left ventricular (LV) mechanical dispersion by strain echocardiography has been associated with presence of myocardial fibrosis on late gadolinium contrast enhanced cardiac magnetic resonance in hypertrophic cardiomyopathy patients. In patients with severe aortic stenosis (AS), LV hypertrophy may also cause prolongation of electrical conduction and LV mechanical dispersion. We investigated the underlying determinants of prolonged mechanical dispersion in patients with severe AS.
Methods: 408 patients (36.3 % women, 69±12 years) with severe AS underwent clinically indicated transthoracic echocardiography. LV ejection fraction (LVEF) was calculated by using end-diastolic and end-systolic volumes. The LV mass (in gram) was calculated from the 2D LV linear measurements obtained on the parasternal LV long-axis view and indexed to body surface area. Mechanical dispersion (in msec) was calculated as standard deviation of time from onset Q/onset R-wave on ECG to maximal myocardial shortening in 16 LV segments. ECG data collected included assessment of QRS morphology [narrow, left bundle branch block (LBBB), right bundle branch block (RBBB) and non-specific intraventricular conduction disorders (IVCD)]
Results: Narrow QRS morphology demonstrated the lowest mechanical dispersion (55±16 ms), whereas LBBB morphology demonstrated the highest mechanical dispersion (74±24msec, p<0.001), in comparison with IVCD morphology (71±19 msec, p<0.001) and RBBB morphology (57±20 ms, p=1). There was a significant negative correlation between LVEF and mechanical dispersion (r= -0.29, p<0.0001) and significant positive correlation between LV Mass Index and mechanical dispersion (r=0.34, p<0.0001)(Figure).
Conclusions: Patients with severe AS and LBBB morphology demonstrated the worst mechanical dispersion. Higher mechanical dispersion is associated with worse LVEF and higher LV mass index, thus reflecting a worse hemodynamic impact of the AS.
Author Disclosures: E.A. Prihadi: None. M. Leung: None. E.M. Vollema: None. A. Ng: None. N. Ajmone Marsan: None. J.J. Bax: None. V. Delgado: Speakers Bureau; Modest; Abbott Vascular.
- © 2016 by American Heart Association, Inc.