Hi,ive been having chest pain/tightness for 2 weeks now,ive had 5/6 ecgs and somes bloods done all ok but the ecg thing is bugging me,everyone seems to have a different say on what it shows,i want to know do you have to have had or having a heart attack before it shows any abnormalities? or can it show if the heart isnt working due to a blockage or another problem,the resting ecg takes a minute or so and it worries me that its missed something serious.