is stoppage of effective pumping of the heart. It could be due to ventricular asystole (no electrical activity) or fibrillation
(fast irregular ineffective activity). Heart attack
means a region of the heart is suddenly deprived of blood supply due to blockage of the artery supplying blood to the region. It is known as myocardial infarction
and can sometimes lead to cardiac arrest. But most cases of heart attack are not associated with cardiac arrest as the heart continues to pump blood by the work of the remaining heart muscle.