Concentric Hypertrophy is Overestimated by 2D as Compared to 3D Echocardiography in Patients with HFpEF: Long Term Implications for Treatment

Abstract

Background Accurate left ventricular (LV) mass calculation yields important prognostic information relating to structural heart disease. Two-dimensional (2D) echocardiography-based calculation is based on LV geometric assumptions of symmetry while three-dimensional (3D) echocardiography could overcome these limitations. The study aims to compare the performance of 2D compared to 3D LV mass calculation. Methods Prospective review of echocardiography at University of Louisville, Kentucky. Normal ejection fraction (EF) was defined as >=52% in males and >=54% in females. The following calculations were made: Relative wall thickness (RWT) = 2x posterior wall thickness/LV internal diastolic dimension (LVIDd) and 2D LV mass = 0.8{1.04([LVIDd + IVSd +PWd]3 - LVIDd3)} + 0.6. Concentric hypertrophy was RWT > 0.42 and LV mass >95kg/m2 in females or >115kg/m2 in males. Same cutoffs were used for 2D and 3D echocardiography. Results Total 154 patients in the study. There was a weak positive correlation between 2D and 3D LV mass index (R= 0.534, r2= 0.286, p= 0.001) (figure 1). Seventy patients had 3D EF >=45% with clinical heart failure (HFpEF). Among HFpEF patients, LV hypertrophy (LVH) was present in 74% patients by 2D and 30% by 3D echocardiography (McNemar test p= 0.001). Using 3D echocardiography as the reference, 68% of the normal patients were misdiagnosed as LV hypertrophy by 2D (table 1). Two-third of the concentric remodeling patients by 3D were misclassified as concentric hypertrophy by 2D echocardiography (p=0.001). Conclusion Using necropsy proven LV mass index cutoffs, 2D over-diagnosed LV hypertrophy through overestimation of the mass, compared to 3D echocardiography. The majority of HFpEF patients show no structural hypertrophy of LV by 3D. This suggest that the majority of HFpEF patients may be more amenable to pharmacological prevention of progressing to LV remodeling or LVH.