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

Abstract

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 (CT_Dilt+Digox), diltiazem monotherapy (MT_Dilt), digoxin monotherapy (MT_Digox), or amiodarone monotherapy (MT_Amiod) 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 CT_Dilt+Digox and 26 receiving monotherapies (MT_Digox = 16; MT_Dilt = 5; MT_Amiod = 5). The efficacy rate documented in dogs treated with CT_Dilt+Digox was significantly higher than that observed in dogs from the composite monotherapy group (i.e., MT_Dilt+MT_Digox+MT_Amiod) (P=0.048). The rate of TRSEs documented in dogs treated with CT_Dilt+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 CT_Dilt+Digox was significantly longer than that observed in dogs of the MT_Digox group (P=0.01).

Discussion: In dogs with secondary AF we included, CT_Dilt+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 CT_Dilt+Digox as a first-line antiarrhythmic treatment in dogs with secondary AF.

Keywords: Amiodarone; Cardiac arrhythmia; Digoxin; Diltiazem; Holter monitoring.