C03 - Comparison of Electrocardiographic Findings in Dogs with Dilated Cardiomyopathy Eating High- or Low-pulse Diets

Abstract: Background – Dilated cardiomyopathy (DCM) can occur in dogs eating high-pulse diets (HPD), leading to life-threatening complications including arrhythmias. Detailed ECG findings in dogs with DCM eating HPD versus low-pulse diets (LPD) have not been reported. Hypothesis/Objectives – To compare ECG measurements and heart rate (HR) in dogs with DCM eating HPD versus LPD, with the hypothesis of slower HR and longer corrected QT interval (QTc; Van de Water) in dogs eating HPD. Animals – Dogs with DCM eating HPD (n = 42) or LPD (n = 7).  Methods – Retrospective study of ECG findings from dogs with DCM previously enrolled in a prospective study and with a multi-lead ECG available. ECG measurements, HR (during physical examination, echocardiogram, and multi-lead ECG), and medication history were compared between HPD and LPD groups.  Results – Echocardiographic measurements and frequency of atrial fibrillation were not different between groups. Dogs eating HPD had a lower median HR compared to the LPD group on physical examination [130 (80-245) vs. 160 (125-230) bpm; P = 0.007], during echocardiography [140 (50-230) vs. 170 (150-220) bpm; P = 0.01], and ECG [average HR: 138 (40-253) vs. 174 (150-215) bpm; P = 0.01 and instantaneous HR: 140 (40-250) vs. 180 (150-240) bpm; P = 0.02]. Overall, 54% of dogs had prolonged QTc but there was no difference between groups. Conclusions and Clinical Importance – Dogs with DCM eating HPD had a lower HR compared to those eating LPD. This may provide insight into the underlying cause for diet-associated DCM.