Evolution of clinical variables with biventricular pacing
| Variable | Before implantation | After implantation | p Value |
| QRS (ms) | 185 (26) | 158 (19) | < 0.001 |
| QRS axis | −19 (61)° | 48 (78)° | < 0.001 |
| NYHA class | 3.3 (0.5) | 2.0 (0.6) | < 0.001 |
| V˙o 2 max (ml/kg/min) | 12.3 (4.7) | 16.3 (4.3) | < 0.001 |
| LVEF (%) | 22 (6) | 26 (8) | < 0.001 |
LVEF, left ventricular ejection fraction; NYHA, New York Heart Association functional class; V˙o 2 max, maximum oxygen consumption.