Left ventricular outflow tract planimetry by 3D echocardiography predicts obstruction and heart failure symptoms in hypertrophic cardiomyopathy

Purpose: Three-dimensional echocardiography (3DE) enables a fast and reliable measurement of left ventricular outflow tract area [LVOT(A)] inpatientswith hypertrophic cardiomyopathy (HCM). Whether 3DLVOT(A) at rest could predict symptomatic status inHCMis currently uncertain. Methods: In 31HCMpatients (pts) with LVejection fraction.50%,3D LV full-volume datasets (38+6 vps) were obtained by transthoracic 3DE. A comprehensive LV analysis by 3DE was done (including volumes and mass) and the smallest 3DLVOT(A) during systole was planimetered on 3D LV rendered images using EchoPac BT12 (GE Vingmed, N). LVOT maximal gradient was assessed by continuous Doppler, and Valsalva maneuver was performed if no significant LVOTobstruction at rest (gradient , 30 mmHg) was present. Symptomatic status was defined by NYHA class (II-IV). Results: Pts with obstructive HCM (n=11) had smaller LVOT(A) than those with nonobstructive forms(n=20): 1.98+0.51vs 3.45+0.67cm2 (p,0.001).Significant correlation between 3DLVOT(A) planimetry at rest and maximal provocable LVOT gradient was identified (r=0.70, p,0.0001).3DLVOT(A) inHCM(AUC=0.87), aswell asmaximal gradient and 3D LV mass/end-diastolic volume ratio (AUC 0.86 and 0.84, respectively, p,0.001) were closely related with symptomatic status (Figure). A cut-off value of 3DLVOT(A) ,2.6 cm2 had 82% sensitivity and 86% specificity to predict heart failure symptoms (NYHA II-IV). Conclusion: LVOT area planimetry by transthoracic 3D echocardiography at rest emerged as a clinical predictor of heart failure symptoms in HCM patients