No Change in Arrhythmic Horses after Human Heart Medication

In an attempt to quiet the fluttering of horses' hearts caused by atrial fibrillation, researchers in Belgium found that a human medication does not restore a normal cardiac rhythm, despite reaching therapeutic levels.

Propafenone, an antiarrhythmic drug used with some success in human patients, does not appear to be a viable treatment option for horses with atrial fibrillation, report researchers from Ghent University in Belgium.

Atrial fibrillation, defined as an abnormal and irregular heart beat caused by the rapid and chaotic quivering of the atria of the heart, is the most common cardiac disorder in horses.

Affected horses commonly have:

  • A history of exercise intolerance;
  • Epistaxis (bleeding from the nose);
  • Respiratory tract disease;
  • Weakness, and/or;
  • Syncope (fainting).

Current treatment modalities for horses include oral administration of quinidine sulfate, an antiarrhythmic drug, and electrical cardioconversion performed under general anesthesia; however, major concerns surrounding safety and efficacy exist with both approaches.

In an attempt to identify a new therapy that's both safe and effective, the research team led by Dominique De Clercq, DVM, PhD, evaluated the intravenous administration of propafenone in two horses with naturally occurring atrial fibrillation and four horses with experimentally induced atrial fibrillation.

Despite the fact that the propafenone did reach therapeutic blood levels, none of the horses converted to a regular heart rhythm (a sinus rhythm) post-administration. All horses did respond to standard oral doses of quinidine sulfate.

The study, "Use of propafenone for conversion of chronic atrial fibrillation in horses," was published in the February 2009 edition of the American Journal of Veterinary Research.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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