Functional electrical stimulation for chronic heart failure: A meta-analysis

Introduction: We conducted a meta-analysis of randomized, controlled trials of combined electrical stimulation versus conventional exercise training or placebo control in heart failure patients. Methods: A systematic search was conducted of Medline (Ovid) (1950-September 2011), Embase.com (1974-September 2011), Cochrane Central Register of Controlled Trials and CINAHL (1981-September 2011). The search strategy included a mix of MeSH and free text terms for the key concepts heart failure, exercise training and functional electrical stimulation (FES). Results: FES produced inferior improvements in peak VO₂ when compared to cycle training: mean difference (MD) -0.32 ml.kg⁻¹.min⁻¹ (95% C.I.-0.63 to -0.02 ml.kg⁻¹.min⁻¹, p=0.04), however FES elicited superior improvements in peak VO₂: MD 2.30ml.kg⁻¹.min⁻¹ (95% C.I. 1.98 to 2.62 ml.kg⁻¹.min⁻¹, pb0.00001); and six minute walk distance to sedentary care or sham FES; MD 46.9 m (95% C.I. 22.5 to 71.3m, p=0.0002). There was no difference in change in quality of life between cycling and FES, but FES elicited significantly larger improvements in Minnesota Living with Heart Failure score than placebo or sham treatment; MD 1.15 (95% C.I. 0.69 to 1.61, pb0.00001). Moreover, the total FES intervention hours were strongly correlated with change in peak VO₂, (r=0.80, p=0.02). Conclusions: Passive or active exercise is beneficial for patients with moderate to severe heart failure, but active cycling, or other aerobic/resistance activity is preferred in patients with heart failure who are able to exercise, and FES is the preferred modality in those unable to actively exercise. The benefits of FES may however, be smaller than those observed in conventional exercise training. Aggregate hours of electrical stimulation therapy were associated with larger improvements in cardio-respiratory fitness.