 Using a previously established minimum clinically important difference MCID of 1.08 hours per day for improvement in daily activity effect size1.54 as measured by Medtronic ICDsCRTs, a total of 8 subjects per group would be needed to achieve a statistical power 1-β of 0.80 two-tailed, α0.05 for a between-groups comparison utilizing two groups. Therefore, depending on the observed effect size in the proposed study, utilizing 3 groups with approximately 10 subjects in each group should provide adequate statistical power for a between-groups comparison with 3 groups. 