424 Underestimation of Left Ventricular (LV) Dilatation by Linear Dimensions in Comparison to Volumetric Assessment in Chronic Severe Aortic Regurgitation (AR) – Time to Update the Management Guidelines?

Abstract

Chronic severe AR (CSAR) results in compensatory LV dilatation to maintain forward stroke volume. “Severe” dilatation (LV end-diastolic dimension (LVEDD)) ≥80mm is associated with sudden cardiac death and poorer postoperative outcomes. European Society of Cardiology guidelines recommend valve surgery (Class IIa) in asymptomatic patients with LVEDD>70mm and LV ejection fraction (LVEF)>50%. LVEDD underestimates LV dilatation due to geometrical limitations in comparison to volumetric measurements (Indexed LV end-diastolic volume (iLVEDV)), however thresholds for intervention remain unchanged. To determine the prevalence of undiagnosed LV dilatation by LVEDD in CSAR when referenced to iLVEDV. A retrospective review of all transthoracic echocardiograms performed in a tertiary laboratory with CSAR was undertaken. Studies with an aortic prosthesis, ≥moderate mitral regurgitation/aortic stenosis, LVEF<50%, or inadequate images for Simpson’s biplane volume assessment were excluded. 54 patients with primary CSAR were included. 18 cases (33%; Males (M)=11, Females (F)=7) had normal LVEDD (M=53±4mm; F=49±2mm) but were dilated by iLVEDV criteria. Of these patients with discrepant measurements, 22% were reclassified as mildly dilated (M=2, 83±4ml/m2; F=2, 66±3ml/m2), 11% moderate (M=1, 92ml/m2; F=1, 72ml/m2), and 75% severe (M=8, 117±13ml/m2; F=4, 95±5ml/m2). Conversely, severe dilatation by LVEDD demonstrated agreement with iLVEDV in all cases. LVEDD appears sensitive for severe LV dilatation in CSAR. However, a considerable proportion of patients will have normal LVEDD values with evidence of significant dilatation by volumetric assessment. Given the prognostic implications of LV dilatation, chamber sizing by iLVEDV may be more appropriate to guide timing of intervention in volume-loading valvular lesions.