THE DIAGNOSTIC ACCURACY OF RADIOGRAPHIC CARDIAC INDICES IN THE ASSESSMENT OF CARDIOMEGALY AND LEFT ATRIAL ENLARGEMENT IN RATS WITH DILATED CARDIOMYOPATHY: AN EXPERIMENTAL STUDY

Abstract

The purpose of this study was to determine the diagnostic value of the ver-tebral heart score (VHS), radiographic left atrial dimension (RLAD), and vertebral left atrial size (VLAS) in the radiographic evaluation of doxorubicin-induced dilated cardio-myopathy (DCM) in rats. The animals were allocated into two experimental groups, a DCM group (n=100), which received weekly injections of doxorubicin (2 mg/kg per dose intraperitoneally [ip]) over nine weeks, and a control group (n=18) receiving an appropri-ate volume of 0.9% saline ip. Radiographic cardiac indices (VHS, RLAD, VLAS) were measured two weeks after the final injection, and cardiac morphological parameters (heart weight [HW], heart weight:body weight ratio [HBW], and heart weight:tibial length ratio [HTL]) were determined after sacrifice in all surviving rats (17 control and 54 DCM). Correlations were calculated between the indices and parameters, as well as their sen-sitivity and specificity in detecting cardiomegaly and left atrial enlargement (LAE) with the three classifiers (HW≤0.96 g, HBW≤235, and HTL≤201). A powerful negative correla-tion was observed between the indices and parameters (rs≥-0.711, P<0.001). Area under the curve values were 0.989 for RL-VHS, 0.992 for DV-VHS, 0.971 for RLAD, and 0.948 for VLAS. The sensitivity and specificity of these indices in detecting cardiomegaly and LAE at the optimal cut-off values were 94.4% and 100%, respectively, at 8.8 vertebrae (v) for RL-VHS and DV-VHS, 96.3% and 94.1% at 1.4v for RLAD, and 94.4% and 88.2% at 2.1v for VLAS. Radiographic cardiac indices offer an accurate and repeatable method for predicting cardiomegaly and LAE in rats with DCM. Natančnost diagnostike radiografskih kazalcev srca pri ocenjevanju kardiomegalije in povečanja levega preddvora pri podganah z dilatativno kardiomiopatijo: Eksperimentalna študija Izvleček: Namen te študije je bil določiti diagnostično vrednost vertebralne srčne ocene (VHS), radiografske dimenzije levega atrija (RLAD) in vertebralne velikosti levega atrija (VLAS) pri radiografski oceni z doksorubicinom povzročene dilatativne kardiomiopatije (DCM) pri podganah. Živali so bile razdeljene v dve eksperimentalni skupini: skupino z DCM (n=100), ki je devet tednov prejemala tedenske injekcije doksorubicina (2 mg/kg na odmerek intraperitonealno [ip]), in kontrolno skupino (n=18), ki je prejemala ustrezno količino 0,9 % fiziološke raztopine ip. Radiografske kazalnike srca (VHS, RLAD, VLAS) smo izmerili dva tedna po zadnji injekciji, morfološke parametre srca (teža srca [HW], razmerje med težo srca in telesno težo [HBW] ter razmerje med težo srca in dolžino goleni [HTL]) pa smo določili po žrtvovanju vseh preživelih podgan (17 kontrolnih in 54 DCM). Izračunane so bile korelacije med kazalniki in parametri ter njihova občutljivost in specifičnost pri odkrivanju kardiomegalije in povečanja levega atrija (LAE) s tremi klasifikatorji (HW≤0,96 g, HBW≤235 in HTL≤201). Med kazalniki in parametri je bila ugotovljena močna negativna korelacija (rs≥-0,711, P<0,001). Vrednosti površine pod krivuljo so bile 0,989 za RL-VHS, 0,992 za DV-VHS, 0,971 za RLAD in 0,948 za VLAS. Občutljivost in specifičnost teh kazalnikov pri odkrivanju kardiomegalije in LAE pri optimalnih mejnih vrednostih sta bili 94,4 % oziro-ma 100 % pri 8,8 vretencu (v) za RL-VHS in DV-VHS, 96,3 % oziroma 94,1 % pri 1,4 v za RLAD ter 94,4 % oziroma 88,2 % pri 2,1 v za VLAS. Radiografski kazalniki srca omogočajo natančno in ponovljivo metodo za napovedovanje kardiomegalije in LAE pri podganah z DCM. Ključne besede: dilatativna kardiomiopatija; doksorubicin; VHS; RLAD; VLAS; podgana