Most people use the terms “heart attack” and “cardiac arrest” interchangeably, but they describe two distinct medical emergencies. While both conditions are life-threatening and demand immediate action, they differ fundamentally in their causes, mechanisms, and the required emergency response. Understanding the difference helps the public recognize symptoms accurately and provide the correct, life-saving aid until professional medical help arrives. The distinction lies in one being a plumbing problem and the other an electrical failure.
Understanding a Heart Attack
A heart attack, medically known as a myocardial infarction (MI), is primarily a problem with the circulatory system and blood flow to the heart muscle. This event occurs when a coronary artery, which supplies oxygen-rich blood to the heart tissue, becomes blocked, usually by a blood clot forming over ruptured plaque. The lack of blood flow starves a section of the heart muscle of oxygen, causing that tissue to sustain damage or die.
During a heart attack, the heart generally continues to beat, but its ability to pump blood efficiently is compromised due to the damaged area. Symptoms often develop gradually and can persist for several minutes or hours. The most common symptoms include a feeling of pressure, tightness, or squeezing chest pain, which may radiate to the arm, jaw, neck, or back.
Other symptoms include shortness of breath, sudden cold sweats, nausea, and lightheadedness. Women are more likely to experience atypical symptoms, such as unexplained fatigue, indigestion, or pain localized in the back or jaw, without the classic crushing chest pain. The degree of damage is directly related to how quickly the blockage is cleared and blood flow is restored.
Understanding Cardiac Arrest
Cardiac arrest, also called Sudden Cardiac Arrest (SCA), is an electrical malfunction where the heart abruptly stops beating effectively. This occurs when the heart’s electrical system malfunctions, leading to a disorganized rhythm called an arrhythmia, such as ventricular fibrillation. These chaotic electrical signals prevent the heart’s lower chambers from coordinating their contractions, causing the heart to quiver uselessly instead of pumping blood.
Because the heart is no longer pumping blood to the brain and other vital organs, the symptoms are immediate. A person experiencing cardiac arrest will collapse instantaneously, lose consciousness, and have no detectable pulse or breathing. Without immediate intervention, death or permanent brain damage can occur within minutes due to the lack of oxygenated blood supply.
When One Leads to the Other
While a heart attack is a circulation problem and cardiac arrest is an electrical problem, they are strongly linked, as one can directly cause the other. A heart attack is the most common cause of sudden cardiac arrest. The injury and tissue death (necrosis) resulting from the blocked artery can destabilize the heart’s electrical pathways.
This damaged, scarred tissue can interfere with normal electrical impulses, triggering a life-threatening arrhythmia like ventricular fibrillation that results in SCA. Cardiac arrest can also occur independently due to other conditions, such as severe heart failure, inherited heart disorders, electrocution, or major trauma.
Life-Saving Response: Key Differences in Treatment
The immediate actions required for these two emergencies are distinctly different because they target different underlying mechanisms. For a heart attack, the primary goal is to minimize damage by quickly restoring blood flow and obtaining definitive medical care. If a person is conscious and experiencing heart attack symptoms, the immediate response is to call emergency services.
While waiting for the ambulance, if the person is not allergic and has no contraindications, they may be advised to chew and swallow an aspirin tablet to help thin the blood and improve flow. The definitive treatment involves hospital procedures like percutaneous coronary intervention (angioplasty and stenting) or clot-dissolving medications to physically reopen the blocked artery.
In contrast, cardiac arrest requires immediate hands-on intervention because the heart has stopped pumping altogether. The response must focus on manually circulating blood and resetting the electrical rhythm. After calling emergency services, cardiopulmonary resuscitation (CPR) must begin immediately. CPR provides manual chest compressions, which act as a temporary pump to keep oxygenated blood flowing to the brain and vital organs.
The most effective treatment for ventricular fibrillation, the most common cause of SCA, is defibrillation. This involves using an Automated External Defibrillator (AED) to deliver an electrical shock to stop the chaotic rhythm, allowing the heart’s natural pacemaker to restart a normal beat. Survival rates for cardiac arrest decrease by about 10% for every minute treatment is delayed, making bystander CPR and early defibrillation paramount.