Supraventricular tachycardia in dogs: 65 cases (1990-2007)

Objective - To characterize the signalment, clinical findings, and prognosis of dogs with supraventricular tachycardia (SVT). Design - Retrospective study. Setting - North Carolina State University Veterinary Teaching Hospital. Animals, Intervention, and Measurements - Case selection included all patients at the veterinary teaching hospital with SVT during years 1990-2007. Medical records from dogs with at least 1 recorded episode of SVT were extracted. The signalment, history, electrocardiographic, radiographic, and echocardiographic findings, therapy, and response to therapy were reviewed and summarized. Follow-up was conducted to determine the date and cause of death. Kaplan-Meier survival curves were constructed and analyzed. The relationships between patient characteristics and responses to therapy and prognosis were evaluated. Main Results - Sixty-five records documented a diagnosis of SVT. Sixty-two percent were males. Labrador Retrievers and Boxers were overrepresented compared with the general hospital population. Median age at presentation was 9 years (range 0.5-15.5 y). The median heart rate during SVT was 270/minute (range 187-375/min). The most common presenting complaint was syncope (30%), 23% were asymptomatic at the time of diagnosis. Most dogs had structural heart disease (65%). Median survival was 472 days (< 1-2007 d). Identification of sustained SVT (> 30 s) did not affect survival (P=0.50), nor did the presence of congestive heart failure (P=0.70). Conclusions - The majority of dogs with SVT had structural heart disease or a severe concurrent illness at the time of SVT diagnosis. SVT, though often a persistent and occasionally sustained arrhythmia, does not appear to be a primary factor in mortality.