2017 ACVIM Forum Research Abstract Program

Echocardiographic LA size was evaluated objectively by the left atrial-to-aortic ratio (LA:Ao) and LA volume via the monoplane modified Simpson's method of discs (MOD). LA volumes (LAV) were indexed to body weight as mL/kg. Objective measures of LA size were stratified into categories of normal (LA:Ao < 1.5; LAV < 1.3), mild (1.5 ≤ LA:Ao < 1.7; 1.3 ≤ LAV < 2.35), moderate (1.7 ≤ LA:Ao < 2; 2.35 ≤ LAV < 3.4), or severely enlarged (LA: Ao ³ 2; LAV ³ 3.4). Interreader agreement of radiographic LAE evaluation was assessed by linearly weighted kappa (k) and intraclass correlation (ICC). Sensitivity (Se) and specificity (Sp) of identifying varying degrees of echocardiographic LAE on radiographs was assessed using both LA:Ao and LAV. 101 dogs were included with a median weight of 8.6 kg (range 1-65 kg) and a median age of 8 years old (range 0.2-15 years). Echocardiographic diagnoses included normal (n = 13), chronic degenerative valve disease (n = 43), dilated cardiomyopathy (n = 12), pulmonic stenosis (n = 13), left-to-right patent ductus arteriosus (n = 11), subaortic stenosis (n = 4), and single cases of other cardiac diseases. Agreement for the presence or absence of radiographic LAE was excellent between all readers (ICC = 0.7828) The interreader agreement for the degree of radiographic LAE ranged from moderate to substantial (k = 0.493-0.701) dependent on the combination of readers. For the 7 distinct subjective LAE criteria, the interreader agreement ranged from fair to good (ICC = 0.264-0.586) with the strongest interreader agreement for increased height of the caudodorsal heart margin, splaying of the mainstem bronchi, and enlargement of the left auricle. Agreement between specialists was higher than agreement between all readers for each individual criterion, with the exception of elevation of the left caudal mainstem bronchus.