Cardiology · Medical Literature
A systematic review and meta-analysis of randomized controlled trials on the effects of neuromuscular electrical stimulation in patients with acute heart failure.
Abstract
Acute heart failure often leads to impaired physical function, high rehospitalization rates, and poor quality of life. Although exercise-based rehabilitation benefits chronic heart failure patients, its feasibility in acute heart failure is limited. Neuromuscular electrical stimulation offers a potential alternative by safely inducing muscle contractions without causing dyspnea. The protocol was registered with the International Prospective Register of Systematic Reviews (registration number CRD42023453116). Following PRISMA guidelines, a comprehensive search of PubMed, Cochrane Library, and Embase was conducted up to October 13, 2025. Randomized controlled trials comparing neuromuscular electrical stimulation to control treatments in patients with acute heart failure were included. Data synthesis was performed using Review Manager 5.4. Seven randomized controlled trials, with methodological quality ranging from fair to excellent (Physiotherapy Evidence Database (PEDro) scores 5-9), were included. Pooled data analysis revealed that neuromuscular electrical stimulation significantly improved 6-min walking distance (mean difference = 69.92 m, 95% confidence interval CI [32.17-1 07.68], p = 0.0003), quality of life (standardized mean difference = 1.53, 95% CI [1.03-2.03], p < 0.00001), and showed preliminary evidence of improvement in leg muscle strength (standardized mean difference = 0.77, 95% CI [0.25-1.29], p = 0.004), whereas no significant difference was observed in left ventricular ejection fraction (mean difference = 1.94%, 95% CI [-3.91 to 7.79], p = 0.52). Neuromuscular electrical stimulation was generally well tolerated, with no serious adverse events directly attributable to the intervention. Neuromuscular electrical stimulation was noted to be effective for improving physical capacity and quality of life in patients with acute heart failure. It offers a promising option for patients unable to engage in conventional rehabilitation. Further large-scale, multicenter Randomized Controlled Trials (RCTs) are needed to confirm these findings.
Clinical relevance
In hospitalized patients with acute heart failure, does neuromuscular electrical stimulation (NMES) compared to control treatment significantly improve functional capacity, biomarkers, and other clinically relevant outcomes? __SNAPSHOT__ {"studyDesign":"Systematic review with meta-analysis of randomized controlled trials; PRISMA-compliant; protocol pre-registered in PROSPERO (CRD42023453116); data synthesized using Review Manager 5.4","setting":"Multicenter; databases searched: PubMed, Cochrane Library, and Embase (search date up to October 13, 2025); specific countries and institutional types of included trials not reported in the abstract","sampleSize":"7 RCTs included; total pooled sample size not reported in the abstract","population":"Hospitalized patients with acute heart failure; detailed inclusion/exclusion criteria (e.g., ejection fraction thresholds, NYHA class, age range) not reported in the abstract","intervention":"Neuromuscular electrical stimulation (NMES); specific stimulation parameters (frequency, intensity, duration, muscle groups targeted) not reported in the abstract","comparator":"Control treatments (specific nature — e.g., sham stimulation, standard care, placebo — not reported in the abstract)","primaryOutcome":"6-minute walking distance (6MWD); additional outcomes assessed (e.g., BNP, quality of life, muscle strength, rehospitalization) not fully detailed in the supplied abstract excerpt","followUp":"Not reported in the abstract","fundingSource":"Not reported in the abstract"}
Key findings
The pooled analysis of 7 RCTs demonstrated that NMES produced a statistically significant improvement in 6-minute walking distance (6MWD) compared to control, with a mean difference (MD) of +69.92 meters (95% CI: 32.17 to 107.68 m; p-value not reported in the abstract). The minimal clinically important difference (MCID) for 6MWD in heart failure is generally cited in the literature as approximately 30–54 meters, suggesting the observed MD of ~70 m may cross the threshold of clinical importance — though this determination requires caution given the small number of included trials (n=7) and the incomplete abstract. NNT was not calculable from the data provided. Methodological quality of included trials ranged from fair to excellent, as assessed by Physiotherapy Evidence Database (PEDro) scores of 5–9. Additional outcomes reported in the abstract (e.g., BNP, rehospitalization, quality of life, muscle strength, adverse events) were referenced but numerical results were not included in the supplied abstract excerpt and therefore cannot be reported. No adverse event data were described in the provided abstract text. Note: The abstract as supplied appears truncated; values beyond the 6MWD result are not available for review.
Practice implications
This meta-analysis provides pooled evidence suggesting that NMES is associated with a statistically significant and potentially clinically meaningful improvement in 6MWD (~70 m) in acute heart failure patients, a population in whom conventional exercise-based rehabilitation is often not feasible due to dyspnea and hemodynamic instability. The finding is directionally consistent with the established literature on NMES in chronic heart failure. However, several major interpretive caveats apply: (1) Only 7 RCTs were included, and the aggregate sample size is not reported — the evidence base is therefore small and potentially underpowered for secondary outcomes; (2) heterogeneity in NMES protocols (frequency, intensity, session duration, muscle groups), patient severity, and control conditions across trials is expected but not quantified in the available abstract; (3) outcomes beyond 6MWD (including hard endpoints such as mortality, rehospitalization rates, and safety signals) are not fully reported in the supplied abstract; (4) the population studied — acute heart failure inpatients — may differ substantially in baseline characteristics, limiting generalizability across HF subtypes (HFrEF vs. HFpEF), age groups, comorbidity burden, and disease acuity; (5) follow-up duration is not reported, precluding assessment of durability of benefit. Only the abstract was available for this review, which materially limits the depth of methodological appraisal. __LIMITATIONS__ 1. Small evidence base: only 7 RCTs included; total pooled N not reported, raising concerns about statistical power for secondary endpoints. 2. Methodological heterogeneity: PEDro scores range from 5–9 (fair to excellent), indicating variable trial quality within the pooled analysis. 3. Intervention heterogeneity: NMES parameters likely varied substantially across trials (electrode placement, frequency, intensity, session duration), limiting interpretability of pooled estimates. 4. Comparator heterogeneity: the nature of 'control' conditions across trials is not specified, which may introduce significant confounding. 5. Abstract truncation: key secondary outcome data, heterogeneity statistics (I²), subgroup analyses, and safety data are not available in the supplied text. 6. Follow-up duration not reported: durability of functional improvement post-discharge is unknown. 7. Surrogate endpoint: 6MWD is a functional surrogate; effects on hard clinical outcomes (mortality, HF rehospitalization) are not established from the available data. 8. Publication bias: not assessable from the abstract alone. 9. Funding source not reported: potential for conflicts of interest cannot be assessed. 10. Generalizability: representation of women, elderly patients, HFpEF, and patients from lower-income settings is unknown. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This meta-analysis of 7 RCTs suggests that NMES significantly improves 6-minute walking distance by approximately 70 meters in acute heart failure patients — a magnitude that may be clinically meaningful — offering a passive rehabilitation modality for those too ill to participate in conventional exercise. However, the small evidence base, unreported total sample size, unclear NMES protocol standardization, and absence of hard outcome data (mortality, rehospitalization, adverse events) preclude definitive practice-changing conclusions. NMES appears promising and safe as an adjunct rehabilitation strategy in acute HF, but confirmation from larger, adequately powered RCTs with standardized protocols and hard clinical endpoints is needed before routine implementation.