This is the case of a 48-year-old patient with Chagas disease admitted to the ICU with heart failure and 35 bpm bradycardia due to complete AV block with QRS complex of 147 ms and right bundle branch block (Fig. 1). A transient pacemaker was implanted and an echocardiogram was performed (video 1) with left ventricular ejection fraction (LVEF) of 33% due to global hypokinesis and severely depressed global longitudinal strain (GLS) (−9.9%) with elevated mechanical dispersion of 91 ms (Fig. 1). For all this and due to the cardiac magntic resonance imaging findings that confirmed the presence of biventricular dilatation with LVEF of 33%, and areas of late gadolinium enhancement (Fig. 2), it was decided to implant a cardiac resynchronization therapy device associated with a defibrillator (video 2). Fifteen (15) days after implantation, the patient showed significant functional improvement, ECG with left ventricular pacing with QRS complex of 127 ms (Fig. 3), and an increased LVEF of 48% (video 3) and GLS up to −14% on the echocardiogram with mechanical dispersion reduction of 28.4 msg (Fig. 3).

Figure 1

Figure 2

Figure 3