Patients randomized to have an LV lead will have a long coronary sinus sheath inserted which will be used to perform an occlusive venogram of the coronary sinus to determine if there are veins suitable for left ventricular lead placement. Those in the left ventricular pacing arm will instead have a left ventricular epicardial pacing lead placed as apically as possible in a large calibre left ventricular branch of the coronary sinus.