Left ventricular wall thickness in cats: agreement between echocardiographic views

Various echocardiographic views are used to assess left ventricular wall thickness (LVWT), but whether these measurements are interchangeable remains unclear.

To assess agreement of LVWT measurements between different echocardiographic views and techniques in cats.

Four hundred eight cats: 292 with maximal LVWT (MaxLVWTd) < 6 mm and 116 with MaxLVWTd ≥6 mm.

Cross-sectional study. Echocardiograms performed and measured by a single observer. Septal and free wall LVWT were measured using 2-dimensional (2D) right parasternal long-axis (RPLA) 4- and 5-chamber views, 2D short-axis (RPSA), and M-mode RPSA views. Bland-Altman analysis assessed agreement between views.

Septal thickness (4.6 mm [range, 2.9-9.5] vs 4.2 mm [range, 2.8-9.2], P < .0001) and free wall thickness (4.6 mm [range, 3.0-11.1] vs. 4.1 mm [range, 2.4-12.3]; P < .0001) were significantly greater in 2D RPLA than 2D RPSA. Agreement between 2D RPLA and 2D RPSA showed wide limits of agreement (LoA) and heteroscedasticity for septal and free wall measurements. Between 2D RPSA and M-mode RPSA, a small bias was noted for septal thickness (-0.04 mm, 95%, -0.12 to 0.04 mm), but LoA remained wide (-1.1 to 1.1 mm). Agreement between 4- and 5-chamber 2D RPLA showed small biases (septum: -0.09 mm, 95% CI -0.14 to -0.04 mm; free wall: -0.03 mm, 95% CI -0.09 to 0.02), with wide LoA (septum: -0.8 to 0.7 mm; free wall: -0.9 to 0.8 mm).

LVWT measurements vary significantly across echocardiographic views and are not interchangeable. Standardized measurement protocols are needed to improve consistency in cardiac phenotyping.