Despite the headlines, we do not know if this medicine would be useful, and most importantly safe, for people with heart failure. Studies in animals help scientists understand how medicines work. But they do not tell us if the results will translate to humans. The sheep had a pacemaker implanted, which made their heart beat artificially fast. This is not automatically the same thing as a human heart that's lost the ability to pump blood because of high blood pressure or a past heart attack.