STAR-Heart Study: Stem Cells Associated With Improved Long-Term Hemodynamics and Reduced Mortality in Chronic Heart Failure

August 29, 2010 (Stockholm, Sweden) — The largest clinical trial so far of intracoronary autologous stem-cell transplantation in patients with chronic heart failure has shown that such treatment was associated with multiple hemodynamic and functional benefits as well as a reduction in mortality, benefits that were maintained out to five years of follow-up.

The STAR-heart study was presented today at the first clinical-trial hotline session here at the European Society of Cardiology (ESC) 2010 Congress. However, the same results were published in February this year in the European Journal of Heart Failure, leading some to question their inclusion as a “hotline” paper [1,2]. Presenter Dr Bodo-Eckehard Strauer (Heinrich-Heine University, Düsseldorf, Germany) explained to heartwire that the study was submitted to the journal with the intention of it being published “in parallel” with the ESC presentation, but the journal published it early.

The study involved 391 patients with chronic heart failure following an MI experienced three to eight years previously. Of these patients, 191 accepted the stem-cell treatment while the other 200, who did not agree to the intervention, acted as controls.

The therapy involved taking bone-marrow cells from the iliac crest and isolating mononuclear cells, which were cultivated, harvested, and then readministered via an intracoronary balloon catheter directly into the infarcted zone. Results at three months, 12 months, and five years after the bone-marrow-cell therapy showed significant improvement in left ventricular ejection fraction, cardiac index, exercise capacity, oxygen uptake, and left ventricular contractility. Controls, however, showed a deterioration in LV performance.

Mortality Benefit?

Of particular note, there appeared to be a significant decrease in long-term mortality in the stem-cell-treated patients. Within a median follow-up time of 4.6 years, seven patients died in the bone-marrow-cell-treated group, equivalent to an average mortality rate of 0.75% per year, whereas in the control group 32 patients died within a median follow-up time of 4.87 years, giving an average mortality rate of 3.68% per year.

Five-Year Results of the STAR-Heart Trial: Effect on Ejection Fraction

Group EF at baseline (%) EF at 5 y (%)
Stem cells 29.4 36.8
Controls 36.1 32.3

Strauer concluded: “Our study suggests that, when administered as an alternative or in addition to conventional therapy, bone-marrow-cell therapy can improve quality of life, increase ventricular performance, and increase survival. Intracoronary therapy has been shown to be effective in acute myocardial infarction, and the STAR-heart study now indicates its efficacy in chronic heart failure.”

When asked by heartwire why he thought this study was successful when some others have failed to show any improvement with stem-cell therapy, Strauer replied that this was probably due to the method of delivery of the cells. He explained that the cells were directly infused into the infarct-related artery via an angioplasty balloon catheter, and the balloon was inflated to prevent back-flow of the cells and extend the time for the cells to migrate into the infarct area. He added that the inflation of the balloon produced an ischemic provocation, which enhanced cell uptake by a preconditioning mechanism.

Designated discussant Dr Francisco Fernandez-Aviles (Hospital General Universitario Gregorio Marañón, Madrid, Spain) said the current results confirmed that stem cells can enhance the regenerative ability of the heart but that the mechanisms behind this concept remain poorly understood. He said that the dose of cells used in the study was not sufficient to benefit left ventricular function and geometry of the heart by transdifferentiation and suggested that the mechanism of the benefit might therefore be via a “scaffolding” effect or paracrine activation.

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