Abstract: Background – Ventricular preexcitation (VPE) occurs when atrial electrical impulses prematurely excite the ventricles through aberrant muscle bundles known as accessory pathways (AP). Orthodromic atrioventricular reciprocating tachycardia (OAVRT) is a re-entrant narrow complex tachyarrhythmia maintained by an AP.
Hypothesis/objectives – To describe signalments, clinical signs, electrocardiographic and diagnostic imaging features, treatments, prognostic variables, and outcomes in cats with VPE. We hypothesized that cats with VPE are at risk for developing OAVRT and associated clinical signs. Negative prognostic indicators were hypothesized to include presence of clinical signs and structural heart disease.
Animals – Twenty-three cats diagnosed with VPE between January 2010-August 2022.
Methods – Retrospective, multicenter study. VPE diagnosis was based on ECG evidence of reduced PR interval and delta wave QRS morphology. Median survival time (MST) was estimated by Kaplan-Meier curve.
Results – Fourteen (60.8%) cats with VPE had OAVRT documented on ECG and 4/23 (17.4%) had suspected OAVRT based on associated clinical signs. Common presenting signs included collapse (15/23; 65.2%) and respiratory distress (14/23; 60.8%). Five cats (21.7%) were asymptomatic. ECG during VPE revealed a reduced PR interval (median 40ms; range 20-45ms) and prolonged QRS duration (median 60ms; range 45-90ms). Heart rate during OAVRT ranged from 310-420 bpm (median 375bpm). Treatment included atenolol (10/18), sotalol (5/18), diltiazem (2/18) and amiodarone (1/18). MST from date of diagnosis was 1872 days.
Conclusions and clinical importance – The majority of cats in this study with VPE had clinical OAVRT. The prognosis for cats with VPE is considered fair with MST >5 years.
