Dilated cardiomyopathy following right ventricular pacing for AV block in young patients: resolution after upgrading to biventricular pacing systems.

INTRODUCTION: Cardiac resynchronization therapy (CRT) has been demonstrated to result in clinical improvement in older adult patients with dilated cardiomyopathy (DCM), specifically those with left bundle branch block and prolonged QRS duration. We sought to demonstrate the benefits of CRT on improvement in cardiac function and clinical outcome in young patients that developed congestive heart failure (CHF) and DCM following cardiac pacing for AV block.

METHODS AND RESULTS: We reviewed the charts of six patients who developed CHF or low cardiac output symptoms and DCM following implantation of right ventricular (RV)-based pacing systems for AV block, and subsequently underwent CRT. Patients ranged in age from 6 months to 23.7 years (mean: 11.3 +/- 3.6 years). AV block was congenital (3), post-surgery (2), and acquired (1). Pacing had been performed for 0.1-14.5 (7.6 +/- 2.4) years prior to development of DCM. Two patients required listing for cardiac transplantation. Following CRT: (1) QRS duration shortened from 204 +/- 15 to 138 +/- 10 msec, P = 0.002, (2) left ventricular ejection fraction improved from 34 +/- 6 to 60 +/- 2%, P = 0.003, and (3) left ventricular end diastolic dimension shortened from 5.5 +/- 0.8 to 4.3 +/- 0.5 cm, P = 0.03. All patients demonstrated clinical improvement and have been weaned from CHF medications and listing for cardiac transplantation.

CONCLUSIONS: CRT can benefit young patients that develop CHF and DCM following RV pacing for AV block. Upgrading to biventricular pacing systems should be considered early in the management of these patients prior to listing for cardiac transplantation.