Cardiac rehabilitation and physical activity levels in heart failure

Abstract

Background Maintenance of adequate physical activity (PA) is a key recommendation for people with and without chronic disease, with well-established health benefits. However, there is uncertainty in the level of objectively assessed PA in people with heart failure (HF) and how exercise-based cardiac rehabilitation (CR) interventions can impact upon PA levels (chapter 1). Methods Four linked research studies were undertaken. A systematic review and meta-analysis to determine whether participation in exercise-based CR increases PA levels of patients with coronary heart disease and HF (chapter 2). A laboratory-based calibration study to estimate HF specific accelerometer intensity thresholds for moderate-to-vigorous PA (MVPA) and inactivity (chapter 3). A cross-sectional study to quantify the PA levels of 247 HF patients participating in a randomised controlled trial of a home-based CR intervention (REACH-HF) in HF patients (chapter 4). A pooled analysis study to assess the effects on PA of the REACH-HF intervention in HF patients and explore the patient characteristics associated with a change in PA level (chapter 5). Results The systematic review and meta-analysis identified 40 randomised controlled trials (6480 patients). Moderate evidence was found to support that CR positively impacts PA levels of patients with coronary heart disease and HF compared to control. The calibration study determined HF specific accelerometer values relating to inactivity (right wrist: 18.6mg (95% CI 8.8 to 28.4mg), left wrist: 16.7mg (95% CI 7.8 to 25.6mg), waist: 7.6mg (95% CI -3.1 to 18.4mg)) and moderate intensity PA (right wrist: 45.5mg (95% CI 31.9 to 59.1mg), left wrist: 43.6 (95% CI 38.5 to 56.3mg), waist: 40.6mg (95% CI 24.3 to 57.0)), lower than the non-specific thresholds used in most HF patient studies based on healthy adults. PA levels of 247 HF patients were examined and 45% were found to meet current PA recommendations of 150 minutes per week of MVPA. However, MVPA ranged widely from 0 to 375.2 minutes per week. HF patient age, body composition, employment status, New York Heart Association class, smoking status, NT-proBNP level, and exercise tolerance were associated (P<0.05) with baseline MVPA levels. At final follow-up, there was evidence of an increase in light PA (26.9 mins/day, 95% CI: -0.05 to 53.8, p=0.05) and a decrease in inactivity (-38.31 mins/day, 95% CI: -72.1 to -4.5, p=0.03) during weekdays in HF patients undertaking home-based CR compared to control. Exercise tolerance, HADS anxiety score, presence of diabetes, and living with a parent or child >18 years were associated with a change in PA. Conclusions Objective measurement of PA in HF remains under researched. This thesis discusses methodological, and clinical implications for the future measurement of PA, and exercise-based CR interventions in people with HF (chapter 6).