Preoperative age, STS score, and aortic valve area did not differ (age: 81 vs. 84 years; STS score 12 vs. 12; AVA 0.61 vs. 0.61cm2, no LVH versus severe LVH groups respectively). Peak gradient (PG) was higher in severe LVH group (PG 79 vs. 84mmHg, p<0.0001) but mean gradient (MG) did not differ (MG: 47 vs. 49mmHG, p=NS). The severe LVH group had a higher LV ejection fraction(p<0.001), higher preoperative pulmonary artery pressures(p<0.001), worse mitral and tricuspid regurgitation(p<0.01). There was no difference in peri-procedural mortality (6.8% vs. 7.8%, p=0.5). There were not differences in ventilation time, inotrope use or overall length of stay between groups. At 1 year follow up, mortality rates did not differ (29 vs. 25%, p=0.3). PG and MG did not differ (PG: 23 vs. 24mmH, MG: 12 vs. 12mmHg). LV mass regression did not differ between groups. The severe LVH group continued to have a higher ejection fraction (59 vs. 67%, p<0.001).