Retrospective evaluation of notched QRS complexes in dogs: 85 cases

Notched QRS complexes on electrocardiography (ECG) have been described in veterinary and human reports, but little is known about this finding in veterinary patients. Therefore, the objectives of this study were to describe the signalment and cardiac disease diagnosis in dogs with notched QRS complexes, as well as to describe the specific leads and number of leads with notched QRS complexes on ECG.

Eighty-five dogs with notched QRS complexes of normal duration in at least one ECG lead.

Retrospective review of digitally stored ECGs and associated medical records of dogs with a recorded ECG as part of routine clinical evaluation.

Age at time of ECG recording was 9.15 ± 3.38 years for the 85 dogs with notched QRS complexes in at least one ECG lead. The number of ECG leads with notched QRS complexes did not increase with age. Most dogs (69.4%) with notched QRS complexes had cardiac disease. The odds ratio of a dog having cardiac disease if more than one lead was identified with notched QRS complexes was 3.97. The most common cardiac disease identified was chronic atrioventricular valvular degeneration, and the majority of these dogs (80%) had two or less leads with notched QRS complexes.

Dogs with and without cardiac disease can have notched QRS complexes. The likelihood of a dog having cardiac disease that has more than one ECG lead with notched QRS complexes is significant, and this should warrant diagnostic evaluation.