People are really helpless when struck by a heart attack, and if heart rate begins to beat improperly at someone usually they have about 10 seconds before lose consciousness.
Anyway there is a way to help yourself by coughing. It should be done energetically and continuously. Breathe in deeply and cough as hard as you can as you need to cough out some secretion.
Repeat the breathing in and coughing every two seconds continuously until some help is given to you by a medical person or the ambulance. If it happens for you to feel some improvement wait for a while and then you can stop with the coughing.
When taking deep breaths you intake more oxygen and by coughing it leads to pressure on the heart and maintain circulation and a normal heart beat. This way heart attack struck people can get to the hospital in time.
Source : houseandfamilytips.com