This study was performed at the Cornell University Hospital for Animals, Department of Clinical Sciences, Cornell University, Ithaca, NY. Preliminary data were presented at the ECVIM-CA Congress, Barcelona, Spain, 2004.
Combination Therapy with Digoxin and Diltiazem Controls Ventricular Rate in Chronic Atrial Fibrillation in Dogs Better than Digoxin or Diltiazem Monotherapy: A Randomized Crossover Study in 18 Dogs
Article first published online: 13 APR 2009
Copyright © 2009 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 23, Issue 3, pages 499–508, May/June 2009
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How to Cite
Gelzer, A.R.M., Kraus, M.S., Rishniw, M., Moïse, N.S., Pariaut, R., Jesty, S.A. and Hemsley, S.A. (2009), Combination Therapy with Digoxin and Diltiazem Controls Ventricular Rate in Chronic Atrial Fibrillation in Dogs Better than Digoxin or Diltiazem Monotherapy: A Randomized Crossover Study in 18 Dogs. Journal of Veterinary Internal Medicine, 23: 499–508. doi: 10.1111/j.1939-1676.2009.0301.x
- Issue published online: 19 MAY 2009
- Article first published online: 13 APR 2009
- Submitted December 1, 2008; Revised February 11, 2009; Accepted February 11, 2009.
- Heart failure;
- 24 hours Holter antiarrhythmic;
- Rate control
Background: Atrial fibrillation (AF) with excessively high ventricular rates (VR) occurs in dogs with advanced heart disease. Rate control improves clinical signs in these patients. Optimal drug therapy and target VR remain poorly defined.
Hypothesis: Digoxin-diltiazem combination therapy reduces VR more than either drug alone in dogs with high VR AF.
Animals: Eighteen client-owned dogs (>15 kg) with advanced heart disease, AF, and average VR on 24-hour Holter > 140 beats per minute (bpm).
Methods: After baseline Holter recording, dogs were randomized to digoxin or diltiazem monotherapy, or combination therapy. Repeat Holter evaluation was obtained after 2 weeks; dogs were then crossed over to the other arm (monotherapy or combination therapy) for 2 weeks and a third Holter was acquired. Twenty-four hour average VR, absolute and relative VR changes from baseline, and percent time spent within prespecified VR ranges (>140, 100–140, and <100 bpm) were compared. Correlations between serum drug concentrations and VR were examined.
Results: Digoxin (median, 164 bpm) and diltiazem (median, 158 bpm) decreased VR from baseline (median, 194 bpm) less than the digoxin-diltiazem combination (median, 126 bpm) (P < .008 for each comparison). With digoxin-diltiazem, VR remained <140 bpm for 85% of the recording period, but remained >140 bpm for 88% of the recording period with either monotherapy. Serum drug concentrations did not correlate with VR.
Conclusions and Clinical Importance: At the dosages used in this study, digoxin-diltiazem combination therapy provided a greater rate control than either drug alone in dogs with AF.