Not quite; the way you phrased it could be read as the third pill preventing one in a hundred heart attacks that would have occurred, rather than might have occurred.
I.e: Pill One reduces the population rate by a third, from 3% to 2%. Pill Two does the same.
Pill Three does nothing for the 97% of the population that weren’t going to have heart attacks anyway, but reduces the unlucky 3% to an unlucky 2.97%.
