Etanercept Induces Low QRS Voltage and Autonomic Dysfunction in Mice with Experimental Chagas Disease

Background

Chagas disease is a tropical parasitic disease caused by the flagellate protozoanTrypanosoma cruzi. Chagasic cardiomyopathy is characterized by disorders ofautonomic regulation and action potential conduction in the acute and chronicphases of infection. Although tumor necrosis factor alpha (TNF-α) has been linkedto cardiomyopathy in experimental models and in patients with Chagas disease,other reports suggest that TNF-α may exert anti-parasitic actions during the acutephase of infection.

Objectives

This study aimed to determine the effects of a soluble TNF-α blocker, etanercept,on electrocardiographic parameters in the acute phase of experimental infectionwith Trypanosoma cruzi.

Methods

Electrocardiograms were obtained from untreated infected mice and infected micewho were treated with etanercept 7 days after infection. ECG wave and heart ratevariability parameters were determined using Chart for Windows.

Results

Etanercept treatment resulted in a low QRS voltage and decreased heart ratevariability compared with no treatment. However, the treated mice exhibited adelay in the fall of the survival curve during the acute phase.

Conclusion

The results of this study suggest that although etanercept treatment promotessurvival in mice infected with a virulent T. cruzi strain, TNF-α blockadegenerates a low voltage complex and autonomic dysfunction during the acute phaseof infection. These findings indicate that mortality during the acute phase can beattributed to a systemic inflammatory response rather than cardiacdysfunction.