Assessment of Left Atrial Deformation and Function by 2‐Dimensional Speckle Tracking Echocardiography in Healthy Dogs and Dogs With Myxomatous Mitral Valve Disease

Abstract

BackgroundThe assessment of left atrial (LA) function by 2‐dimensional speckle tracking echocardiography (STE) holds important clinical implications in human medicine. Few similar data are available in dogs.ObjectivesTo assess LA function by STE in dogs with and without myxomatous mitral valve disease (MMVD), analyzing LA areas, systolic function, and strain.AnimalsOne hundred and fifty dogs were divided according to the American College of Veterinary Internal Medicine classification of heart failure: 23 dogs in class A, 52 in class B1, 36 in class B2, and 39 in class C + D.MethodsProspective observational study. Conventional morphologic and Doppler variables, LA areas, and STE‐based LA strain analysis were performed in all dogs and results were compared among groups. Correlation analysis was carried out between LA STE variables and other echocardiographic variables.ResultsVariability study showed good reproducibility for all the tested variables (coefficient of variation <16%). Left atrial areas, fractional area change, peak atrial longitudinal strain (PALS), peak atrial contraction strain, and contraction strain index (CSI) differed significantly between groups B2 and C + D and all the other groups (overall P < .001), whereas only PALS differed between groups B1 and A (P = .01). Left atrial areas increased with progression of the disease, whereas LA functional parameters decreased. Only CSI increased nonsignificantly from group A to group B1 and then progressively decreased. Thirty‐one significant correlations (P < .001, r > .3) were found between conventional left heart echocardiographic variables and LA areas and strain variables.Conclusions and Clinical ImportanceLeft atrial STE analysis provides useful information on atrial function in the dog, highlighting a progressive decline in atrial function with worsening of MMVD.

Prognostic value of echocardiographic indices of left atrial morphology and function in dogs with myxomatous mitral valve disease

“…Dogs had been examined during a previous study evaluating LA deformation and function using STE in a larger group of dogs, and only those with MMVD and follow‐up available were enrolled in the present study . Dogs were presented to the cardiology unit of the Veterinary Teaching Hospital of the University of Bologna for cardiac evaluation on the basis of cardiac murmur clarification, clinical signs referable to heart disease (eg, dyspnea, cough, syncope), for breed screening, or for preanesthetic evaluation.…”

“…Left atrial maximal area (LAAmax) and minimal area (LAAmin) expressed in cm 2 were automatically calculated by the software and then indexed to the AoArea. Left atrial fractional area change then was calculated using the formula: FAC = ([LAAmax – LAAmin]/LAAmax) × 100, and expressed as a percentage . Left atrial maximal (LAVmax) and minimal (LAVmin) volume was calculated using the monoplane area‐length method using the formula: LAV = (0.85 × A 1 × A 1)/ L , where A 1 is the LAA and L is LA length .…”

“…The same cine‐loops and beats used to measure LA areas and volumes were successively employed for the STE analysis using dedicated software (QLAB quantification software version 9.1, Philips Healthcare, Monza, Italy.) as previously described . Briefly, the operator selected 3 points on the LA (2 on the MV annulus and 1 on the LA roof) and the software automatically drew a region of interest on the entire LA wall dividing it into 7 regions (from the basilar segments to the roof of the LA), and manual editing was done if necessary.…”

“…Finally, the contraction strain index (CSI) was calculated using the formula: CSI = ([PALS/PACS] × 100; Figure ). This last variable represents the contribution of LA contraction to LV filling . The entire image analysis was performed by a single operator (MBT).…”

“…Until now, survival studies have considered only LA diameter and its ratio to aortic root diameter (Ao; [LA/Ao]) as predictors of survival . Canine and feline LA function has been non‐invasively estimated with echocardiography using several approaches, such as measuring LA fractional shortening, LA fractional area change (FAC), and LA ejection fraction (EF) . Assessment of atrial deformation profiles obtained using tissue Doppler imaging (TDI) and its derived variables, strain and strain rate, recently has been proposed as an alternative method of exploring LA mechanics both in humans and dogs .…”