A critical analysis of clinical outcomes reported in stem cell trials for acute myocardial infarction: some thoughts for design of future trials.

The purpose of stem cell therapy for myocardial infarction is to improve clinical outcomes, and detailed information on clinical outcomes is critical to appropriate planning of phase III trials. We have examined data from select phase II trials using autologous bone-marrow-derived stem cells in patients with acute myocardial infarction. We have extracted available definitions and outcome data, and have generated standardized estimates of events to permit summary comparisons. Nine trials (1,040 patients) with results for 6 months to 5 years were evaluated. Adverse outcomes differed widely, and there was a general lack of details in the definitions of these outcomes. Heart-failure-related hospitalizations occurred in only 16 patients (1.5 %) and death occurred in only 43 patients (4.1 %). Ischemia-related outcomes outnumbered heart failure outcomes more than tenfold. Uniform criteria need to be developed to better define clinical outcomes of interest. Furthermore, a refocus from heart failure outcomes to ischemia-related outcomes seems appropriate.