State of the Art on the Evidence Base in Cardiac Regenerative Therapy: Overview of 41 Systematic Reviews

Objectives. To provide a comprehensive appraisal of the evidence from secondary research on cardiac regenerative therapy. Study Design and Setting. Overview of systematic reviews of controlled clinical trials concerning stem cell administration or mobilization in patients with cardiovascular disease. Results. After a systematic database search, we short-listed 41 reviews (660 patients). Twenty-two (54%) reviews focused on acute myocardial infarction (AMI), 19 (46%) on chronic ischemic heart disease (IHD) or heart failure (HF), 29 (71%) on bone marrow-derived stem-cells (BMSC), and 36 (88%) to randomized trials only. Substantial variability among reviews was found for validity (AMSTAR score: median 9 [minimum 3]; 1st quartile 9; 3rd quartile 10; maximum 11), effect estimates (change in ejection fraction from baseline to follow-up: 3.47% [0.02%; 2.90%; 4.22%; 6.11%]), and citations (Web of Science yearly citations: 4.1 [0; 2.2; 6.5; 68.9]). No significant association was found between these three features. However, reviews focusing on BMSC therapy had higher validity scores (P = 0.008) and showed more pronounced effect estimates (P = 0.002). Higher citations were associated with journal impact factor (P = 0.007), corresponding author from North America/Europe (P = 0.022), and inclusion of nonrandomized trials (P = 0.046). Conclusions. Substantial heterogeneity is apparent among these reviews in terms of quality and effect estimates.