Evaluation of myocardial protective effects of enalapril maleate against experimental supraventricular tachyarrhythmia in dogs by measuring cardiac troponin I levels

The development of ventricular systolic dysfunction in animals with supraventricular tachyarrhythmia (SVTA) has been reported to be largely due to myocardial injury, resulting from activation of the renin-angiotensin-aldosterone system. The objectives of this study were to demonstrate that the development of myocardial injury and the myocardial protective effect of enalapril maleate could be evaluated in a dog model of SVTA by measuring blood cardiac troponin I (cTnI) concentrations. Rapid atrial pacing (RAP) model dogs were divided into a Control group (no medication, n = 7) and an Enalapril group (enalapril maleate at 0.5 mg/kg once per day, n = 7). After 1, 2, and 3 weeks of RAP, significantly lower concentrations of cTnI were observed in the Enalapril group than in the Control group (P < 0.01). Upon histopathological examination of heart tissues, the control group showed more severe necrotic changes in myocardiocytes than the Enalapril group. In conclusion, this study demonstrated that both the development of myocardial injury and the myocardial protective effect of enalapril maleate could be assessed by measuring blood cTnI concentrations in SVTA model dogs. The results indicate that such measurements could comprise a useful method to diagnose myocardial injury and determine the therapeutic effect of a drug not only in human medicine but also in the veterinary field.