When someone suddenly collapses in front of you, panic is often the first reaction. Many bystanders immediately assume it is a heart attack. While heart attacks are common and serious, not every sudden collapse is caused by one. In fact, another life-threatening emergency—Sudden Cardiac Arrest (SCA)—is frequently misunderstood and requires a very different response.
In an interview with HT Lifestyle, Bengaluru-based cardiothoracic and vascular surgeon Dr Chiran Babu A explains the critical differences between heart attacks and sudden cardiac arrest, how to identify warning signs, and what immediate steps can save a life.
Understanding the Core Difference
According to Dr Chiran Babu, the key difference lies in the underlying mechanism.
A heart attack is primarily a circulation problem. It occurs when blood flow to a part of the heart muscle is blocked, usually due to a clot in one of the coronary arteries. Although the heart muscle is damaged during a heart attack, the heart typically continues beating. Most patients remain conscious and may experience warning symptoms before the condition worsens.
Sudden cardiac arrest, on the other hand, is an electrical problem. It occurs when the heart’s electrical system malfunctions, leading to a dangerous abnormal rhythm known as arrhythmia. As a result, the heart suddenly stops pumping blood effectively. Blood flow to the brain and vital organs stops almost instantly, causing the person to collapse and lose consciousness within seconds.
Without immediate intervention, survival chances decrease rapidly with each passing minute.
Recognising the Symptoms
Signs of a Heart Attack
Dr Chiran Babu explains that heart attacks usually develop over minutes or even hours. Common warning signs include:
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Chest pain or pressure, often described as tightness or heaviness
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Pain radiating to the arm, jaw, neck, or back
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Sweating
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Nausea or vomiting
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Shortness of breath
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Lightheadedness
Importantly, many people experiencing a heart attack remain conscious and can communicate their discomfort or ask for help.
Signs of Sudden Cardiac Arrest
Sudden cardiac arrest is typically immediate and unexpected. A person may appear completely normal—walking, exercising, or talking—and then suddenly collapse.
Key signs include:
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Sudden collapse
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Loss of consciousness
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No pulse
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No normal breathing (or only gasping)
The person becomes unresponsive within seconds because blood flow to the brain has stopped.
“Timing is a major clue,” says Dr Chiran Babu. “Heart attacks often build up gradually. Sudden cardiac arrest is abrupt.”
Can a Heart Attack Lead to Cardiac Arrest?
Yes, it can. A severe heart attack can disrupt the heart’s electrical system and trigger sudden cardiac arrest. However, Dr Chiran Babu notes that many SCA cases occur without a heart attack.
Other causes of sudden cardiac arrest include:
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Hypertrophic obstructive cardiomyopathy (HOCM), a thickening of the heart muscle
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Inherited rhythm disorders
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Previous heart muscle damage
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Severe electrolyte imbalances
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Sometimes unknown causes
This distinction highlights why public awareness is essential. Not all cardiac emergencies present the same way.
Why Immediate Response Matters
The response required for a heart attack and sudden cardiac arrest is fundamentally different.
For a heart attack, the priority is urgent hospital care to restore blood flow to the heart. Treatment may involve medications or emergency procedures to open blocked arteries.
For sudden cardiac arrest, the situation is far more urgent. Immediate cardiopulmonary resuscitation (CPR) and early defibrillation are critical.
What To Do If Someone Collapses
Dr Chiran Babu advises the following steps if you witness a sudden collapse:
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Check responsiveness. Shake the person gently and shout.
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Call emergency services immediately.
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Check for normal breathing. If absent or abnormal, begin CPR.
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Start chest compressions at a steady, firm pace in the centre of the chest.
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Use an Automated External Defibrillator (AED) if available.
Early CPR helps maintain blood flow to the brain. Defibrillation—delivering an electric shock using an AED—can restore a normal heart rhythm in certain arrhythmias.
“When used within the first few minutes, AEDs can dramatically improve survival,” Dr Chiran Babu emphasises.
The Role of AEDs in Public Spaces
Automated External Defibrillators are increasingly available in public places such as airports, shopping malls, offices, gyms, and railway stations. These devices are designed for use by the general public and provide step-by-step voice instructions.
Many people hesitate to intervene because they fear doing something wrong. However, experts consistently stress that doing something is far better than doing nothing in cases of sudden cardiac arrest.
“Anyone can learn and provide CPR,” Dr Chiran Babu says. Basic life support training empowers ordinary citizens to act confidently during emergencies.
Building Public Awareness
Despite increasing cardiovascular disease rates, awareness about sudden cardiac arrest remains limited. Many people still equate every cardiac emergency with a heart attack.
Public education campaigns, CPR training in schools and workplaces, and wider AED installation can significantly improve survival rates. Quick action from bystanders often determines whether a person survives long enough to receive advanced medical care.
In urban centres like Bengaluru, where lifestyle-related heart conditions are rising, awareness becomes even more critical.
A Life-Saving Distinction
The difference between heart attack and sudden cardiac arrest is not just medical—it is lifesaving.
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Heart attack: circulation problem, usually gradual, person often conscious.
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Sudden cardiac arrest: electrical problem, immediate collapse, person unconscious and not breathing normally.
Recognising this difference ensures the right response at the right time.
“Not every collapse is a heart attack,” concludes Dr Chiran Babu. “Understanding sudden cardiac arrest and knowing how to respond can help save a life—possibly someone you love.”