Rabastan stormed out of the office like a petulant child. None of what he just said made the least bit of sense. Aberforth couldn't have died of a heart attack when he wasn't even in the Ministry! Assuming there was enough polyjuice potion for Dolores Umbridge to keep taking it for almost a week, which there wasn't, if she died of a heart attack even under the influence of the polyjuice potion, her body would revert back to her usual form in death.