Reversal of Wolff-Parkinson-White Syndrome induced dilated cardiomyopathy via resynchronization and subsequent accessory pathway ablation

Recurrent or incessant tachycardia is frequently found in symptomatic Wolff-Parkinson-White (WPW) syndrome, leading to ventricular dysfunction, dilated cardiomyopathy (DCM) and heart failure in infants and children. Recently, Winter, et al. report that WPW syndrome could provoke many kinds of cardiac dysfunction, leading to remodeling and progressive ventricular dilatation through pre-excitation-related dyssynchrony, even without arrhythmia. Asymptomatic WPW syndrome-induced DCM has rarely been reported, with incidence rates higher in pediatric patients than in adults. However, the pathogenesis of asymptomatic WPW syndrome-induced DCM remains unclear. Here, we present a case of an adult patient with DCM associated with asymptomatic free wall accessory pathway (AP), who received cardiac function improvement both after pacemaker implantation and radiofrequency ablation.  A 35-year-old man was referred to hospital with a chief complaint of progressive chest congestion and short breath for 3 months, but no paroxysmal palpitations. He had an unremarkable medical history. Cardiac examination showed a grade 2/6 systolic murmur at the cardiac apex, moist rales bilaterally in the lower lobes, and slight peripheral edema in the lower limbs/pedal edema. The initial surface ECG showed typical delta waves [leads I, aVL (+); lead II (±)], and the duration of the QRS complex was 202 ms with a left bundle branch block (LBBB)-like sentence, which indicates a right free wall accessory pathway (AP)(Figure 1A). The N-terminal pro-brain natriuretic peptide (NT-proBNP) level was 2326 pg/mL, and a chest X-ray showed cardiomegaly (Figure 2A). Doppler echocardiography demonstrated impaired left