Sudden cardiac arrest [1] and heart attacks are different:
A heart attack and SCA produce different symptoms in their victims.
Sudden Cardiac Arrest:
Heart attack:
Heart attack (or myocardial infarction): occurs when a blockage slows or stops blood flow to some part of the heart muscle. If the blockage is severe or if it is left untreated, that part of the heart muscle can die. Heart attacks do not necessarily cause cardiac arrest or sudden cardiac death, although those conditions could result.
Sudden cardiac arrest: usually the result of a congenital abnormality, but can result from a blow to the chest, a phenomenon called commotio cordis [2]
CPR may be an effective treatment for a heart attack until paramedics arrive
CPR is not effective for an SCA victim, for whom early defibrillation with an AED is essential, and the most important link in the Cardiac Chain of Survival [3]
Links:
[1] https://momsteam.com/node/371
[2] https://momsteam.com/node/301
[3] https://momsteam.com/health-safety/cardiac-safety/general/chain-of-survival-for-sudden-cardiac-arrest
[4] https://momsteam.com/health-safety/cardiac-safety/automatic-external-defibrillators-aeds/aeds-frequently-asked-questions
[5] https://momsteam.com/health-safety/cardiac-safety/general/cpr-and-aed-training
[6] https://momsteam.com/health-safety/cardiac-safety/news-studies/death-of-athlete-from-sudden-cardiac-arrest-hightlights-ne
[7] https://momsteam.com/health-safety/cardiac-safety/automatic-external-defibrillators-aeds/expert-consensus-aeds-ok-for-use