Interventions to Improve Daily Activity in Heart Failure

Few studies have been able to demonstrate intervention efficacy for improving daily activity in heart failure (HF). Exercise alone is ineffective, though psychosocial-based interventions including health coaching and daily activity feedback appear to be promising. Therefore, the primary purpose of the present proposed study is to investigate the effect of two different intervention approaches (1. daily activity feedback with associated encouragement, and 2. health coaching with an associated individualized home exercise program) on daily activity, exercise tolerance, HF-related health status, and lower extremity functional strength. A secondary purpose is to compare daily activity as recorded by Medtronic® implanted cardioverter defibrillator (ICDs) and cardiac resynchronization therapy (CRT) devices to daily activity recorded by a well-established triaxial accelerometer.

This will be a single-blinded randomized trial, with subject randomization stratified by age and baseline activity level. Subjects will be randomized to one of three groups: 1) A control group receiving usual care, 2) a group receiving only feedback with associated encouragement about their daily activity, and 3) an intervention group that will receive health coaching with an associated individualized home exercise program.

The study will consist of a 3 month intervention period and a 6 month follow-up/ retention period (total study enrollment period of 9 months). The primary study endpoint is Medtronic device-measured daily activity. All study endpoints will be assessed at baseline, 3 months, and 9 months. The investigators who are conducting study measurements will be blinded to group assignment.

Using a previously established minimum clinically important difference (MCID) of 1.08 hours per day for improvement in daily activity (effect size=1.54) as measured by Medtronic ICDs/CRTs, a total of 8 subjects per group would be needed to achieve a statistical power (1-β) of 0.80 (two-tailed, α=0.05) 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.

Statistical analyses will be conducted to meet the planned study objectives. With regard to intervention effects, one way analysis of variance with planned contrasts will be used to examine between-group differences for each of the continuous variables [Patient Activity, Kansas City Cardiomyopathy Questionnaire (KCCQ), Patient Health Questionnaire (PHQ-9), six-minute walk test (6MWT), 30 second timed chair rise (30-s TCR), heart rate variability, Optivol Fluid Index]. If the data do not meet the requisite assumptions, the Kruskal-Wallis analysis of variance by ranks will be used. Baseline to 3 months data will be used to assess immediate intervention effects and to 9 month follow-up will be used to assess retention effects.

With regard to concurrent validity of the Medtronic Patient Activity measurement, the Pearson correlation coefficient will be calculated between the daily Patient Activity (minutes per day) and two Actigraph parameters: daily activity count and steps per day. Correlation coefficients will be calculated for the baseline, 3-month, and 9-month monitoring periods to provide a greater number of sampling days. Correlation coefficients will also be calculated for changes in daily activity measurements between baseline and 3 months and baseline and 9 months to determine concurrent validity of change in daily activity measurements.