A rare form of trifascicular block with intermittent complete atrioventricular block in a patient with Chagas disease.

Trifascicular block, which consists of impaired conduction in the three main fascicles of the ventricular conduction system, may progress to high-grade or complete atrioventricular block. Exceptionally, it is possible to register in the same patient paroxysmal alternating atrioventricular block and bilateral bundle branch block. This is the electrocardiogram of a male, 60 year-old patient coming from an endemic area, with positive serology for Chagas disease, with the exclusively dromotropic form (there are no signs of cardiac muscle involvement), manifest by repetitive pre-syncope and syncope episodes.