Heartbeat rate of only 80 and bad spotting at week 7 is it still possible that its not a miscarriage?

Actually a more scientific answer shows that low heart rates do show increased chances of miscarriage. The normal heartrate of a 7 week embryo is 135. Heart rates of less that 100 show increased chances of miscarriage. Not all end in miscarriage, but several do. Please see this study for more info. http://radiology.rsnajnls.org/cgi/content/full/236/2/643