Alternative sites for right ventricular pacing in Chagas disease: a comparative study of the mid-septum and inflow tract.

Background: The right ventricular mid-septum and inflow tract are alternative pacing sites that are potentially less harmful to cardiac function.

Objective: This study aimed to analyze the influence of these two alternative pacing sites on the clinical course of patients with chronic Chagas disease, who underwent definitive pacemaker implantation.

Methods: A total of 80 patients with Chagas disease and classical indications for definitive pacemaker implantation were randomized into two groups between October 2008 and August 2010: 40 received inflow tract implantation and 40 patients received mid-septum implantation. The analyzed parameters included: (1) progression stage of chronic chagasic cardiomyopathy (CCC), (2) electrocardiographic analysis, (3) left ventricular remodeling, and (4) electromechanical dyssynchrony. The assessment was performed 24-48 hours after implantation and a follow-up period of 18 months.

Results: Compared with inflow tract implantation, mid-septum implantation was associated with slower CCC progression and the generation of narrower QRS complexes (131.8 ± 8.4 milliseconds vs 150.5 ± 10.5 milliseconds; P < 0.01). No left ventricular remodeling was detected. Intraventricular dyssynchrony was more frequent in the inflow tract group than in the mid-septum group (85% vs 32.5%, respectively; odds ratio [OR], 9.15; P = 0.02) as was interventricular dyssynchrony (37.5% vs 17.5%, respectively; OR, 2.83; P < 0.01).

Conclusions: Mid-septum implantation was associated with slower CCC progression, generation of narrower QRS complexes, and lower electromechanical dyssynchrony, suggesting that this pacing site could be less harmful to cardiac function than the inflow tract site in patients with CCC.