Rapid and Potent Antiarrhythmic Effect of Cardiac Resynchronization Therapy in a Patient with Advanced Dilated Cardiomyopathy and a Large Ventricular Arrhythmia Burden

Fig. 1. Electrocardiographic findings before and after initiation of cardiac resynchronization therapy. (A) Initial electrocardiogram exhibits the sinus rhythm and notched broad QRS complexes with left bundle branch block configuration. The QRS complex duration was 200 ms, and the corrected QT interval calculated by Bazett's formula was 550 ms. (B) Follow-up electrocardiogram acquired during biventricular pacing exhibits shortening of the QRS complex duration from 200 to 160 ms and of the corrected QT interval from 550 to 500 ms. aVR: augmented voltage right arm, aVL: augmented voltage left arm, aVF: augmented voltage left foot.

Fig. 2. Radiographic findings. (A) Initial chest X-ray displays cardiomegaly with a cardiac-thoracic ratio of 0.7 and minor fissural effusion. (B) Follow-up chest X-ray acquired 3 days after the initiation of cardiac resynchronization therapy displays a slight decrease in the cardiacthoracic ratio compared to the initial image.

Fig. 3. Ventricular arrhythmia burden before and after initiation of cardiac resynchronization therapy. (A) The bar graph displays the daily or average (asterisk) burdens of ventricular arrhythmias, which were recorded by 24-hour or 72-hour ambulatory electrocardiographic monitoring according to the hospital admission days. (B) Data from 24-hour ambulatory electrocardiographic monitoring acquired 5 days after admission demonstrate the occurrence of polymorphic ventricular tachycardia, which persisted for 27 seconds and terminated spontaneously. (C) Analysis of the follow-up 24-hour ambulatory electrocardiographic monitoring data acquired one day before the initiation of cardiac resynchronization therapy displays a large burden of VPCs with multiple episodes of non-sustained monomorphic VT. Although optimal medical therapy was performed for over 4 weeks, the daily burden of ventricular arrhythmias was still 19% of the total daily beats. (D) Analysis of the follow-up 24-hour ambulatory electrocardiographic monitoring data acquired 3 days after the initiation of cardiac resynchronization therapy displays near complete disappearance of VPCs and VTs. The ventricular arrhythmia burden was…