Unblinded, randomized, multicenter. Patients were randomized to either the Thermo Cardiosystems, Inc. (TCI) vented electric (VE) LVAD or optimal medical therapy (OMM) and followed for at least two years. If randomized to LVAD therapy, patients received a LVAD implantation within 12 hours of randomization. If randomized to medical therapy, patients received optimal medical management including the use of digoxin, diuretics, and ACE (Angiotensin Converting Enzyme) inhibitors in maximally tolerated doses. The primary endpoint was all-cause mortality. Secondary endpoints included cardiovascular mortality, exercise capacity (six-minute walk test) and health-related quality of life, adverse effects, and the relative cost-effectiveness of LVADs versus medical management. Recruitment ended in June, 2001.