How does heart attack affect breathing rate?

yes, but it deserves to be precised.

During a heart attack, the heart is beating with an anarchic rate. This is the "Fibrillation" with the rapid, irregular, and unsynchronized contraction of the muscle fibers of the heart. A electric shock must be given rapidly in order to depolarize a critical mass of the heart muscle, terminate the arrhythmia, and allow normal sinuosidal rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart.

In case of heart attack

The "automated external defibrillators" (AEDs) can be used by everybody and allows to deliver this shock before the medical rescue's arrival. Simple to use , and efficient, they can save lives. In France, where the rescue delay is about 15 minutes (3 to 4 minutes in the US), those machines can be precious. Of course, first aid intervention gestures such as cardiopulmonary resuscitation (CPR) will be helpful. The good combination of them can increase the survival rate by 300-400 %.