Why the study?
Does oral flecainide cause pro-arrhythmic effects in a dog with dilated cardiomyopathy?
Does oral flecainide cause pro-arrhythmic effects in a dog with dilated cardiomyopathy?
Flecainide may have pro-arrhythmic effects in dogs with dilated cardiomyopathy, and short-term in-hospital monitoring is insufficient to accurately determine arrhythmia burden compared to Holter monitoring.
Flecainide may be proarrhythmic in dogs with DCM; hypothesis-generating and challenges adequacy of short-term in-hospital monitoring.
A 10‐year‐old, female, spayed Pitbull mix presented for evaluation of an arrhythmia. Echocardiography revealed enlargement of all cardiac chambers and decreased left ventricular systolic function. Electrocardiography demonstrated isolated, ventricular premature complexes. The dog was diagnosed with dilated cardiomyopathy and started on oral pimobendan. Forty‐eight‐hour Holter monitor at this time demonstrated a 2% total ventricular arrhythmia burden, with ventricular couplets and triplets but without ventricular tachycardia. Evidence of complex ventricular ectopy (triplets and couplets) prompted the start of oral flecainide. Recheck in‐hospital echocardiography 6 weeks later demonstrated a normal sinus rhythm. However, recheck Holter demonstrated increased ventricular arrhythmia complexity with runs of ventricular tachycardia. Flecainide was discontinued, and oral sotalol was started. Recheck Holter 4 weeks later revealed a reduction in ventricular arrhythmia burden and no episodes of ventricular tachycardia. This report demonstrates the possible pro‐arrhythmic potential of flecainide and the inaccuracy of in‐hospital, short‐term echocardiographies to determine arrhythmia burden in dogs.
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Mitchell et al. (2026) studied this question.
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