Pre-operative left atrial size and functions are predictors of left atrial reverse remodelling after mitral valvuloplasty for myxomatous mitral valve disease in dogs

Objectives: The objective of this study was to determine alterations in left atrial size, function, and determinants of left atrial reverse remodelling (LARR) after mitral valvuloplasty (MVP) in dogs with myxomatous mitral valve disease. Animals: Thirty-seven dogs undergoing MVP were included in this study. Materials and Methods: Echocardiographic parameters, including left atrial (LA) strain, were evaluated at baseline, during the early postoperative period (within two weeks), and at one and three months postoperatively. Patients were divided into two groups based on the attainment of LARR, defined as a left atrial-to-aortic root ratio (LA:Ao) < 1.6 at three months. The predictors of LARR were analysed using univariate logistic regression analysis. Results: Left atrial-to-aortic root ratio significantly decreased in the early postoperative period (median: 1.68; lower and upper quartiles: 1.54-1.92) compared to that in baseline (2.41; 2.00-2.80), with a further significant reduction observed at three months (1.46; 1.34-1.63). Left atrial reverse remodelling was achieved in 27 (73%) patients. Baseline left atrial-to-aortic root ratio was higher, and peak atrial longitudinal strain and peak atrial contraction strain (PACS) were lower in the non-LARR group than in the LARR group. Among the baseline parameters, PACS was the strongest predictor of LARR (area under the curve: 0.837). Conclusions: Following MVP, the LA size decreased in the early postoperative period and continued to decrease over three months of follow-up. A low PACS score was the most reliable predictor of inadequate LARR. Further studies are necessary to determine the relationship between LARR, prognosis, and the optimal timing for surgical intervention.