I would like to note that Heart Attack is the first song so far this rate to not get the "-" associated with the songs that received the most scores in the 0-5 range. Its position was due more to general apathy than real hatred.
The song was essentially panned by all the "casuals" who submitted ballots as well.
I can understand people giving it a bad score if they don't like this sound from 1D. But then how did WMYB, LWWY, etc. chart higher? It's so much better