People often use these two terms interchangeably, but they’re not the same thing at all. A heart attack happens when a blood clot or plaque buildup blocks the flow of blood to part of the heart muscle. The heart usually keeps beating, and the person is often conscious  though they may feel chest pain, shortness of breath, sweating, nausea, or pain radiating into the arm or jaw. Cardiac arrest is a different beast entirely. It’s an electrical malfunction that causes the heart to stop pumping altogether, leading to sudden collapse, unconsciousness, no pulse, and breathing that’s either abnormal or absent. Here’s the connection worth remembering: a serious heart attack can sometimes trigger the rhythm disturbance that leads to cardiac arrest. Both are emergencies, no question. But cardiac arrest is the one where every second counts ,CPR and an AED, if one’s nearby, can be the difference between life and death.