To the Editor: The LateTIME trial findings1 suggest a lack of benefit from intracoronary delivery of bone marrow mononuclear cells (BMCs) 2 to 3 weeks after primary percutaneous coronary intervention (PCI) in patients with myocardial infarction (MI) and depressed left ventricular (LV) function. However, further clarification is needed to better appreciate the study conclusions.
While timing can affect efficacy of cardiac cell-based therapies, patient selection remains of paramount importance. It is unclear why patients with lesions in coronary arteries other than the left anterior descending (4 right coronary arteries and 1 left circumflex coronary artery, all in the intervention group) were included. Because the mean qualifying LV ejection fraction (LVEF) was 35% to 36%, could a mixed cardiomyopathy have explained the initial LV dysfunction and thus partly biased the efficacy findings in cell-treated patients? Moreover, was consideration given to including only patients with anterior wall MIs associated with severe but persistent LV dysfunction (ie, LVEF ≤35% at baseline and not just at screening), who would be more likely to benefit from BMC injection relative to a population with only moderate LV impairment? While more likely to induce recruitment delays, such a strategy might have resulted in greater benefit in the intervention group.