Transthoracic two-dimensional and three-dimensional echocardiography for the measurement of mitral valve area planimetry in English Bull Terriers with and without heart disease

Introduction: Mitral valve area (MVA) planimetry is used to diagnose and classify mitral stenosis (MS) in humans using two-dimensional and three-dimensional echocardiography (MVA(2D )and MVA(3D)). This study aimed to evaluate agreement, feasibility, and observer variability between MVA(2D) and MVA(3D) in English Bull Terriers (BT). Our hypotheses were (1) that the MVA of BT is generally smaller than that of breeds with similar body weight and (2) that these techniques could be used to diagnose MS in BTs. Animals: Twenty healthy BTs, 15 healthy Boxers, and 49 BTs with heart disease. Materials and methods: A prospective diagnostic agreement study was conducted. All dogs underwent a thorough clinical examination, conventional transthoracic echocardiography, and three-dimensional echocardiography. Results: Bland-Altman plots (limits of agreement: 0.12-1.5) showed consistent bias and poor agreement between MVA(2D) and MVA(3D). For the 69 BTs, MVA(3D) (2.1 +/- 0.50 cm(2)) measurements were significantly lower than MVA(2D) measurements (2.9 +/- 0.60 cm(2)), and healthy BTs had significantly lower MVA parameters than healthy Boxers (p < 0.001). Intraobserver and interobserver variability were excellent for both MVA(2D) and MVA(3D) (intraclass correlation coefficient >0.9). Six BTs were diagnosed with MS, with MVA(3D) less than 1.8 cm(2) and a mean transmitral gradient (MTG) of more than 5 mmHg. Conclusions: Both MVA(2D) and MVA(3D) are feasible, have low observer variability and can be used to diagnose MS in BTs. For assessing the narrowest orifice area, the preferred method is MVA(3D). The smaller MVA in BTs compared to Boxers may indicate some degree of MS. (C) 2021 Elsevier B.V. All rights reserved.