Eighteen studies, with 999 participants in total, were included: 12 RCTs (830 participants) and 6 cohort studies (169 participants).
All cohort studies and 6 of the 12 RCTs failed to blind caregivers and participants; 3 of the 6 cohort studies and 2 of the 12 RCTs failed to blind outcome assessors. All studies had adequate loss to follow-up (less than 20%).
BMC transplantation was associated with a significant increase in LV ejection fraction (3.66%, 95% CI: 1.93, 5.40, p<0.001; I-squared 71%), a reduction in infarct scar size (5.49%, 95% CI: -9.10, -1.88, p=0.003; I-squared 66%) and a reduction in LV end-systolic volume (4.80 mL, 95% CI: -8.20, -1.41, p=0.006; I-squared 0%) compared with control. The reduction in LV end-diastolic volume was not statistically significant (1.92 mL, 95% CI: -6.31, 2.47, p=0.39; I-squared 0%).
No treatment-subgroup interaction was found in the subgroup analyses.
Except for 1 study reporting a higher incidence of in-stent restenosis in the BMC-treated group, the incidence of major local and systemic complications was comparable in the treatment and control groups.
The funnel plots were either uninterpretable or inconclusive.