Baseline patient characteristics
| Characteristic | |
| Male gender (n, %) | 53 (50) |
| History of supraventricular arrhythmia (n, %) | 55 (52) |
| Prior CCF admission (n, %) | 8 (8) |
| Ventricular morphology (n, %) | |
| Systemic LV | 40 (38) |
| Systemic RV | 40 (38) |
| Single ventricle | 26 (25) |
| Systemic ventricle impairment (n, %) | |
| Normal | 67 (63) |
| Mild | 32 (30) |
| Moderate | 7 (7) |
| Subpulmonary ventricle impairment (n, %) | |
| Normal | 71 (67) |
| Mild | 8 (8) |
| Moderate | 1 (1) |
| N/A | 26 (25) |
| Moderate–severe systemic AVV regurgitation (n, %) | 6 (6) |
| QRS width (ms, mean±SD) | 123±28 |
| QRS morphology (n, %) | |
| RBBB | 36 (34) |
| LBBB | 4 (4) |
| IVCD | 19 (18) |
| Ventricular lead route (n, %)* | |
| Endocardial | 53 (51) |
| Epicardial | 51 (49) |
*Two patients had atrial leads only.
AVV, atrioventricular valve; CCF, congestive cardiac failure; IVCD, interventricular conduction delay; LBBB, left bundle branch block; LV, left ventricle; N/A, not available; RBBB, right bundle branch block; RV, right ventricle.