Timing for intracoronary administration of bone marrow mononuclear cells after acute ST-elevation myocardial infarction: a pilot study

Introduction: Most studies on intracoronary bone marrow mononuclear cell transplantation for acute myocardial infarction involve treatment 3-7 days after primary percutaneous coronary intervention (PCI); however, the optimal timing is unknown. The present study assessed the therapeutic effect at different times after ST-elevation myocardial infarction. Methods: The present trial was not blinded. A total of 104 patients with a first ST-elevation myocardial infarction and a left ventricular ejection fraction below 50 %, who had PCI of the infarct-related artery, were randomly assigned to receive intracoronary infusion of bone marrow mononuclear cells within 24 hours (group A, n = 27), 3 to 7 days after PCI (group B, n = 26), or 7 to 30 days after PCI (group C, n = 26), or to the control group (n = 25), which received saline infusion performed immediately after emergency PCI. All patients in groups A, B and C received an injection of 15 ml cell suspension containing approximately 4.9 x 10(8) bone marrow mononuclear cells into the infarct-related artery after successful PCI. Results: Compared to control and group C patients, group A and B patients had a significantly higher absolute increase in left ventricular ejection fraction from baseline to 12 months (change: 3.4 +/- 5.7 % in control, 7.9 +/- 4.9 % in group A, 6.9 +/- 3.9 % in group B, 4.7 +/- 3.7 % in group C), a greater decrease in left ventricular end-systolic volumes (change: -6.4 +/- 15.9 ml in control, -20.5 +/- 13.3 ml in group A, -19.6 +/- 11.1 ml in group B, -9.4 +/- 16.3 ml in group C), and significantly greater myocardial perfusion (change from baseline: -4.7 +/- 5.7 % in control, -7.8 +/- 4.5 % in group A, -7.5 +/- 2.9 % in group B, -5.0 +/- 4.0 % in group C). Group A and B patients had similar beneficial effects on cardiac function (p = 0.163) and left ventricular geometry (left ventricular end-distolic volume: p = 0.685; left ventricular end-systolic volume: p = 0.622) assessed by echocardiography, whereas group C showed similar results to those of the control group. Group B showed more expensive care (p < 0.001) and longer hospital stays during the first month after emergency PCI (p < 0.001) than group A, with a similar improvement after repeat cardiac catheterization following emergency PCI. Conclusion: Cell therapy in acute myocardial infarction patients that is given within 24 hours is similar to 3-7 days after the primary PCI.