Sudden cardiac arrest (SCA) is a life-threatening emergency where the heart unexpectedly stops beating effectively, often due to an electrical malfunction. While the final event is sudden, studies show that many individuals experience warning signs in the hours, days, or even weeks leading up to the cardiac arrest. Recognizing these subtle, pre-event symptoms can be life-saving.
Early Warning Signs
The symptoms that precede a cardiac arrest are often related to an underlying heart condition, such as a heart attack (myocardial infarction) or an arrhythmia. Though a cardiac arrest is an electrical problem and a heart attack is a plumbing problem (a blockage of blood flow), a heart attack can often trigger a sudden cardiac arrest.
Key warning signs to watch for include:
- Chest Discomfort: This is the most common symptom, especially for men, and may feel like pressure, tightness, squeezing, or aching in the center of the chest. It may last more than a few minutes, or go away and come back.
- Shortness of Breath (Dyspnea): Experiencing sudden or unusual difficulty breathing, which may occur with or without chest discomfort. This is often reported by women.
- Palpitations: A feeling that the heart is racing, fluttering, skipping a beat, or pounding. This can signal an irregular heart rhythm (arrhythmia), which is the direct cause of most sudden cardiac arrests.
- Unexplained Fainting or Near-Fainting (Syncope or Pre-Syncope): Dizziness, lightheadedness, or sudden loss of consciousness, particularly during physical exertion. This is a critical warning sign and requires immediate medical attention.
- General Weakness and Fatigue: Unexplained, overwhelming tiredness that is not relieved by rest.
- Other Atypical Symptoms: These may include pain or discomfort in the arms (one or both, often the left), back, neck, jaw, or stomach. Nausea, vomiting, or breaking out in a cold sweat are also possible. Women are more likely to experience these non-traditional symptoms.
The Critical Difference: SCA vs. Heart Attack
It is crucial to understand the difference between a heart attack and sudden cardiac arrest (SCA) to know when to act:
| Feature | Sudden Cardiac Arrest (SCA) | Heart Attack (Myocardial Infarction) |
| Problem | Electrical (Heart stops beating) | Plumbing (Blood flow to the heart is blocked) |
| State | Unresponsive, no normal breathing, no pulse | Usually conscious, breathing, and has a pulse |
| Action | Call 911 immediately, start CPR, use an AED | Call 911 immediately, rest, take aspirin (if advised) |
The Sign that Cardiac Arrest is Happening
If a person has collapsed and you are observing the event, the definitive signs that they are currently in cardiac arrestare:
- Sudden Loss of Responsiveness: The person is unconscious and does not respond to tapping on the shoulders or a loud voice.
- No Normal Breathing: The person is not breathing, or is only making gasping, snorting, or gurgling sounds (often called agonal breaths, which are not normal breathing).
Immediate action is required: Call 911/emergency services and begin CPR (Cardiopulmonary Resuscitation) while retrieving an Automated External Defibrillator (AED). Immediate CPR can double or triple a person’s chance of survival.