Efficacy and safety of different antiarrhythmic protocols used for rate control in dogs with secondary atrial fibrillation.

INTRODUCTION/

OBJECTIVES

Studies comparing the effects of antiarrhythmic protocols used for rate control in dogs with secondary atrial fibrillation (AF) are currently limited; therefore, this study aimed to report detailed data on the efficacy and therapy-related side-effects (TRSEs) of different antiarrhythmic protocols in dogs with secondary AF.

ANIMALS, MATERIALS, AND

METHODS

Dogs with secondary AF treated with combination therapy with diltiazem and digoxin (CTDilt+Digox), diltiazem monotherapy (MTDilt), digoxin monotherapy (MTDigox), or amiodarone monotherapy (MTAmiod) were retrospectively evaluated. Signalment, clinical, diagnostic, therapeutic, and outcome data were retrieved. Electrocardiographically, antiarrhythmic efficacy was defined by a reduction in the mean heart rate on Holter monitoring ≤125 beats/minutes. Statistical analysis was performed to compare selected data, including the rate of efficacy and TRSEs as well as the median survival time, between dogs treated with different antiarrhythmic protocols.

RESULTS

Fifty-four dogs were included, with 28 receiving the CTDilt+Digox and 26 receiving monotherapies (MTDigox = 16; MTDilt = 5; MTAmiod = 5). The efficacy rate documented in dogs treated with CTDilt+Digox was significantly higher than that observed in dogs from the composite monotherapy group (i.e., MTDilt+MTDigox+MTAmiod) (P=0.048). The rate of TRSEs documented in dogs treated with CTDilt+Digox was similar to that observed in dogs from the composed monotherapy group (P=0.129). The median survival time documented in dogs treated with CTDilt+Digox was significantly longer than that observed in dogs of the MTDigox group (P=0.01).

DISCUSSION: In dogs with secondary AF we included, CTDilt+Digox was well tolerated and provided clinically relevant benefits compared to the use of a single antiarrhythmic drug.

LIMITATIONS: Retrospective design; heterogeneous sample size of categories analyzed; clinicopathological data available for many, but not all, dogs.

CONCLUSIONS

Our findings support the indication to generally consider CTDilt+Digox as a first-line antiarrhythmic treatment in dogs with secondary AF.