A mild heart attack affects a small part of the muscle or does little permanent damage, while a massive heart attack affects a large part of the muscle or causes a lot of damage. Both are due to blocked arteries, but the degree of blockage differs, according to Better Medicine.
A heart attack can be mild if blockage does not completely cut off the flow of blood to the heart or it does not last very long. It may also be mild because the blockage happens in a smaller artery, one only responsible for sending a small amount of blood to the muscle. A heart attack is typically massive if blockage occurs in a larger artery responsible for sending a large amount of blood to the muscle. An attack may also be considered massive if it lasts a long time, according to Better Medicine.
While a mild heart attack may only affect a small part of the muscle, it is still serious, states Better Medicine. It can cause life-altering damage, such as an irregular heartbeat, or lead to a second attack. A massive heart attack can result in permanent heart damage, cardiac arrest or death. Those who suffer a massive heart attack are also at risk for another.