No. Though people often mistake a cardiac arrest for a heart attack, they are not the same. A heart attack may cause cardiac arrest, but they are different conditions.
A heart attack is caused by a blockage of blood flow to a part of the heart muscle, usually by a blood clot. As a result, the heart muscles get damaged. A heart attack is a serious condition, and could even become fatal.
Cardiac arrest, on the other hand, is caused when the electrical system of the heart malfunctions. The heart stops beating properly, and its ability to pump blood suddenly stops.