Left atrial volume and function in dogs with naturally occurring myxomatous mitral valve disease.
OBJECTIVE
Myxomatous mitral valve disease (MMVD) induces progressive left atrial (LA) enlargement. The LA modulates left ventricular filling and performance through its reservoir, conduit, and contractile function. Assessment of LA size and function may provide valuable information on the level of cardiac compensation. Left atrial function in dogs with naturally occurring MMVD remains largely unexplored. The objective of this study was to evaluate LA volume and function in dogs with naturally occurring MMVD.


METHODS
This prospective study included 205 client-owned dogs of different breeds, 114 healthy dogs, and 91 dogs with MMVD of different disease severities.


METHODS
Using two-dimensional echocardiography, the biplane area-length method was applied to assess LA volume and calculate volumetric indices of LA reservoir, conduit, and contractile function.


RESULTS
Left atrial volume and LA stroke volume increased, whereas LA reservoir and contractile function decreased with increasing disease severity. A maximal LA volume <2.25mL/kg was the optimal cut off identified for excluding congestive heart failure in dogs with chronic MMVD with a sensitivity of 96% and a specificity of 100%. An active LA emptying fraction <24% and/or a LA expansion index <126% were suggestive of congestive heart failure in dogs with chronic MMVD with a sensitivity of 77% and a specificity of 89% and a sensitivity of 82% and a specificity of 82%, respectively.


CONCLUSIONS
Dogs with MMVD appear to have larger LA volumes with poorer LA function. Deteriorating LA function, characterized by a decreasing reservoir and active contractile function, was evident in dogs with MMVD with increasing disease severity.
Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark. Electronic address: miriam@veterinarkliniken.se.
M
M
Höllmer
Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
J L
JL
Willesen
Department of Mathematics and Statistics, Faculty of Sciences, University of Copenhagen, Copenhagen, Denmark.
A
A
Tolver
Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
J
J
Koch
D000818:Animals; D016279:Atrial Function, Left; D002306:Cardiac Volume; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D005260:Female; D006349:Heart Valve Diseases / Q000503:physiopathology / Q000662:veterinary*; D017379:Hypertrophy, Left Ventricular / Q000662:veterinary; D008297:Male; D008943:Mitral Valve; D011446:Prospective Studies
Active left atrial emptying fraction; Biplane area-length method; Congestive heart failure; Left atrial size; Volumetric function