system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between a major and a minor heart attack, and how is a heart attack classified?
gpt
Heart attacks are usually classified via EKG.
If there are certain changes from a usual, healthy EKG (ST-elevations in this case) it is classified as a STEMI, which in most cases is the major heart attack in comparison to the NSTEMI, which shows no changes in the EKG but only changes in heart enzymes in a patients bloodwork. 

Also, major heart attacks lead to malign arrhythmia more often which can result in loss of consciousness and sudden death, while minor heart attacks more often than not cause severe pain for the patient, but won't lead to loss of consciousness. 

Source: i'm a cath lab nurse.