Cardiology Specialty Intern University of Illinois Urbana, IL, United States
Abstract:
Background: Myxomatous mitral valve disease (MMVD) is the most commonly acquired heart disease in dogs. Clinical symptoms and signs of cardiac remodeling on echocardiography are surrogates for disease severity. Other findings, such as mitral valve morphology, are not routinely considered, yet may play a crucial role in disease progression. Echocardiographic classification of mitral valve morphology is established in human medicine but has not been evaluated in canine MMVD.
Objectives: To compare the predominant mitral valve morphology (billow, prolapse, prolapse-flail, or isolated flail) and leaflets affected (anterior, posterior, both) in dogs with MMVD ACVIM stages B1, B2, and C. Animals: Dogs (n=1108) with an echocardiographic diagnosis of MMVD ACVIM B1 (595), B2 (314), and C (199) weighing 1-15 kg.
Methods: Echocardiographic studies were retrospectively evaluated. Affected leaflets were identified from the transthoracic right parasternal and left apical four chamber views and Barlow’s 1985 classification was used to determine the predominant morphology.
Results: Single anterior leaflet involvement was more common in stages B1 (79%) and B2 (77%) than C (53%) (P< 0.004). Billow significantly decreases across stages B1 (79%), B2 (17%), and C (5%) (P< 0.0001). Prolapse was significantly more common in stages B2 (47%) and C (32%), than B1 (15%) (P< 0.0001) as was isolated flail B2 (10%), C (8%), B1 (1%) (P< 0.0001). Prolapse-flail significantly increases across stages B1 (6%), B2 (25%), and C (56%) (P< 0.0001). Conclusions and clinical importance: Morphologic features of the MV vary significantly across stages of MMVD. These features may impact progression and treatment recommendations.
