Evaluation of a Novel Precordial Lead System for the Electrocardiographic Diagnosis of Right Ventricular Enlargement in Dogs

SIMPLE SUMMARY: Echocardiography is the gold-standard method for the assessment of cardiac chamber enlargement. However, precordial leads can play a complementary role in the non-invasive detection of cardiac remodeling. Therefore, the aim of this study was to evaluate the diagnostic accuracy of precordial leads for the detection of right ventricular enlargement in dogs. Healthy dogs and dogs with echocardiographic right ventricular enlargement were enrolled in this prospective observational study. All the electrocardiographic measurements were assessed in both limb and precordial leads, and their diagnostic accuracy for the detection of right ventricular enlargement was evaluated. A total of 84 dogs, 27 with right ventricular enlargement and 57 controls, were enrolled. Q wave amplitude in lead aVR (cutoff > 0.10 mV), R/S ratio in lead V4 (cutoff < 1.15), R/S ratio in lead V5 (cutoff < 1.95) and S wave amplitude in lead V6 (cutoff > 0.70 mV) showed suitable diagnostic accuracy in detecting right ventricular enlargement. Only nine dogs (33%) with right ventricular enlargement presented a right shift of the mean electrical axis. Differently, 19 out of 27 (70%) showed at least one of the identified precordial lead criteria. Adding the reported precordial leads criteria increases the diagnostic accuracy of electrocardiography for the detection of right ventricular enlargement in dogs. ABSTRACT: The purpose of this study was to evaluate the reliability of precordial leads for the detection of right ventricular enlargement (RVE) in dogs. This was a prospective observational study. The RVE was defined by echocardiography. The amplitude (mV) of the Q, R, and S waves, the R/S ratio, and the mean electrical axis (MEA) of the QRS complex were assessed on the 12-lead ECG. The ROC curve and the Youden index yielded the best cutoffs for RVE detection. An area under the curve (AUC) > 0.7 defined suitable diagnostic accuracy. A total of 84 dogs, 27 with RVE and 57 healthy controls, were enrolled. Q wave amplitude in aVR (cutoff > 0.10 mV; AUC = 0.727), R/S ratio in V4 (cutoff < 1.15; AUC = 0.842), R/S ratio in V5 (cutoff < 1.95; AUC = 0.839) and S wave amplitude in V6 (cutoff > 0.70 mV; AUC = 0.703) showed suitable diagnostic accuracy in detecting RVE. Among dogs with RVE, only 9/27 (33%) presented a right shift of MEA. Differently, 19/27 (70%) showed at least one of the identified precordial lead criteria. Assessment of the R/S ratio in V4 and V5 and S wave amplitude in V6 increases the diagnostic accuracy of ECG in distinguishing between dogs with RVE and healthy dogs.