The Role of Cardiac Resynchronization Therapy for Arterial Switch Operations Complicated by Complete Heart Block

Abstract

As mortality in patients with D-loop transposition of the great arteries (D-TGA) has decreased after the arterial switch operation (ASO), the focus has shifted to higher risk groups and outcomes that impact long-term morbidity and mortality, such as left ventricular (LV) dysfunction. We sought to examine the perioperative factors associated with LV dysfunction in patients with D-TGA and ventricular septal defects (VSD) after ASO. A retrospective study was made of all patients with D-TGA/VSD who underwent ASO/VSD closure from 2001 to 2011. Patients with prematurity, L-looped ventricles, and straddling atrioventricular valves were excluded. The primary endpoint was moderate or severe LV dysfunction measured by echocardiogram 2 months or more after surgery. A total of 112 patients underwent ASO/VSD closure at a median age of 5 days. Median time of follow-up was 6.5 months, with no mortality noted. Six patients (8%) were noted to have at least moderate LV dysfunction. Risk factors were heart block requiring pacemaker placement (p<0.001) and length of intensive care unit admission (p=0.04). All 6 patients with heart block had an epicardial lead on the right ventricular free wall; 4 had moderate or severe LV dysfunction and underwent upgrade to cardiac resynchronization therapy (CRT); median time from initial pacemaker to CRT was 5 months. With a median follow-up of 5 months after CRT, LV function improved to normal (2 patients) or mild dysfunction (2 patients). Left ventricular dysfunction after surgical repair for D-TGA/VSD is low, with heart block and pacemaker insertion playing a significant role. The LV function improved after patients were upgraded to a CRT device.