Prognostic value of left atrial stiffness estimated using echocardiography in dogs with myxomatous mitral valve disease.

INTRODUCTION: No studies have investigated the prognostic value of left atrial stiffness (LASt) estimated using echocardiography in dogs with myxomatous mitral valve disease (MMVD).

ANIMALS: 72 dogs had MMVD and 46 dogs were healthy dogs.

MATERIALS AND METHODS: Clinical retrospective cohort study. The survival information of MMVD dogs that underwent echocardiographic examination was obtained. The peak velocities of early diastolic transmitral flow (E) and mitral annular motion as determined by pulsed wave Doppler (E') were determined. The left atrial reservoir strain (εS ) was determined by two-dimensional speckle tracking echocardiography of the left atrium. The LASt was estimated by the formula: E/E'/εS . The 95% prediction interval of LASt was computed from the data of the healthy dogs.

RESULTS: 17 dogs having MMVD died of cardiac-related causes with 55 MMVD dogs censored. The MMVD dogs with LASt > its 95% upper prediction limit (LASt > 0.56; n = 26; median survival time, 484 days; 95% confidence interval, 283 days-indeterminable) had shorter survival times (P<0.001) than those with LASt ≤ its 95% upper prediction limit (LASt ≤ 0.56; n = 46; median survival time, >1112 days; 95% confidence interval, indeterminable). Multivariable Cox's proportional hazard analysis demonstrated that the ratio of the left atrial dimension to the aortic annulus dimension and LASt were independent predictors of cardiac-related death among conventional echocardiographic indices, εS and LASt in MMVD dogs.

CONCLUSIONS: In dogs with MMVD, increased LASt estimated using echocardiography is an independent predictor of cardiac-related death, and LASt can be more useful for prognostication than εS .