Cell-based therapies are a novel potential treatment for refractory angina and have been found to improve markers of angina. However, the effects on mortality and major adverse cardiac events (MACE) have not been definitively investigated.

To investigate the efficacy and safety of stem cell treatment compared with optimal medical treatment for refractory angina by conducting an updated meta-analysis, looking at clinical outcomes.

Methods and Results:
We performed a systematic review and meta-analysis of randomized controlled trials using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A comprehensive search was performed of PubMed, EMBASE (Excerpta Medica database), Cochrane, ClinicalTrials.gov, Google Scholar databases of randomized controlled trials, and scientific session abstracts. Studies were deemed eligible if they met the following criteria: (1) full-length publications in peer-reviewed journals; (2) evaluated cell therapy use in patients with no further revascularisation options while on optimal medical treatment; (3) patients had ongoing angina, Canadian Cardiovascular Society class II—IV; and (4) included a placebo/control arm. We calculated risk ratios for all-cause mortality, combined MACE events. We assessed heterogeneity using χ2 and I2 tests. We identified 1191 citations with 8 randomized controlled trials meeting inclusion criteria involving 526 patients. Outcomes pooled were MACE, mortality, and indices of angina (angina episodes, Canadian Cardiovascular Society angina class, exercise tolerance, and antianginal medications). Our analysis showed a decreased risk of both MACE (odds ratio, 0.41; CI, 0.25−0.70) and mortality (odds ratio, 0.24; 95% CI, 0.10−0.60) in cell-treated patients compared with patients on maximal medical therapy. This was supported by improvements in surrogate end points of anginal episodes, use of antianginal medications, Canadian Cardiovascular Society class, and exercise tolerance.

In addition to improvements in indices of angina, cell-based therapies improve cardiovascular outcomes (mortality/MACE) in patients with refractory angina. Given the premature termination of the phase III study, this supports the need for further definitive trials.