# Arrhythmia Inducibility in the CAVB Dog Model, A Critical Analysis on Underlying Factors

## TL;DR

This study examines why some dogs with heart block are resistant to a specific arrhythmia, finding body weight and certain heart parameters are linked to the condition.

## Contribution

The study identifies body weight and baseline cardiac parameters as predictors of arrhythmia inducibility in CAVB dogs.

## Key findings

- Body weight, not sex or age, is associated with TdP inducibility in CAVB dogs.
- Longer ventricular repolarization and increased contractility predict TdP arrhythmias.
- Cardiac parameter differences disappear after dofetilide infusion.

## Abstract

The dog with chronic atrioventricular block (CAVB) combines a number of risk factors associated with Torsade de Pointes (TdP) arrhythmias. Nevertheless, approximately 33% of the animals are resistant to dofetilide-induced TdP arrhythmia. Of a group of 78 experimentally identical CAVB dogs, we compared TdP inducible vs. non-inducible animals for a set of basic, and cardiac electrical and mechanical parameters. Body weight, but not sex or age, is associated with TdP inducibility. Of the cardiac parameters, longer ventricular repolarization duration and increased contractility at baseline are associated with dofetilide-induced TdP arrhythmias. Differences in cardiac parameters disappeared upon dofetilide infusion. We discuss that prolonged repolarization and increased contractility may be early indications of calcium-mediated early after depolarization that may develop into TdP arrhythmias.