Characterization and incidence of inducible monomorphic ventricular tachycardia in a postinfarction rabbit model

Objective: Ventricular tachycardia (VT), occurring late after myocardial infarction, is an important cause of sudden death. Animal models are useful for the investigation of this arrhythmia. The aim of this study is to develop and characterize a model of late postinfarction monomorphic VT in the rabbit. Methods and Results: Myocardial infarction was created by ligation of the left circumflex artery. Cardiac electrophysiologic studies were performed 10 to 17 days postinfarction in 39 rabbits, in 10 sham-operated rabbits, and 6 control rabbits. Ventricular tachycardia was defined as a broad-complex tachycardia with a cycle length of more than 100 milliseconds, a duration of more than 10 seconds, and monomorphic QRS complexes. Using programmed stimulation, we induced VT in 9 rabbits (23%) in the infarct group but in none of the sham or control animals. The mean infarct size was 23% ± 9% (mean ± SD) of the left ventricle. Conclusion: Coronary ligation in the rabbit creates a substrate, which allows the induction of sustained monomorphic VT with programmed stimulation. Monomorphic VT is not inducible in rabbits without myocardial infarction. This model might allow the testing of interventions that reduce the incidence of VT late after myocardial infarction.