Diagnostic accuracy of the electrocardiogram for detection of atrial and ventricular overloads in dogs

ABSTRACT

Background: Analysis of the electrocardiogram may suggest atrial and ventricular overloads. However, it has a lowsensitivity and specificity for diagnosis of cardiac chamber overload. The accuracy of electrocardiographic interpretation can be improve using new cut-offs for the duration and amplitude of the electrocardiographic waves. Ourobjective was to evaluate the use of the electrocardiogram in the diagnosis of atrial and ventricular overload, usingechocardiography as the gold standard test for the diagnosis of atrioventricular overload. We aimed to define newcut-off values that would increase the sensitivity and specificity of the electrocardiogram for diagnosis of chamberoverload in dogs.Materials, Methods & Results: Eletrocardiogram records were obtained in 81 dogs divided into 3 groups Group1A (healthy dogs ≤ 10 kg); Group 1B (dogs ≤ 10 kg with mitral or tricuspid valve disease); Group 2 (dogs weighingbetween 10.1 and 20 kg) and Group 3 (dogs > 20.1 kg). Duration in milliseconds (ms) and amplitude in millivolts(mV) of P waves and QRS complexes, PR and QT segment, T wave amplitude and ST segment were evaluated in leadDII. Using leads I and III, the mean cardiac electrical axis in the frontal plane, expressed in degrees, was determinedas the mean of three consecutive measurements. Values considered normal in Group 1A and 1B for the durantion ofP wave was ≤ 45 ms and QRS duration ≤ 55 ms. In Group 2 the duration of P wave was ≤ 47 ms and QRS duration ≤61 ms. In Group 3 the duration of P wave was ≤ 50 ms and duration QRS ≤ 64 ms. These values (duration of P waveand QRS duration) were compared with echocardiographic measurements of the left atrium, considering the referencevalue AE/Ao ≤ 1.4 and measurements of the left ventricle in M-mode according to the body weight, respectively. AP wave amplitude ≤ 0.4 mV suggested that the right atrium size was normal and this was...