Cardiac Arrest vs Heart Attack: Explained for Singaporeans
A heart attack and sudden cardiac arrest are not the same emergency. Mix them up and you may fetch an AED for chest pain that does not need one, or worse, wait politely beside someone whose heart has already stopped pumping.
In Singapore, both situations start with the same number: 995. What you do next depends on whether the person is still awake and talking, or collapsed and not breathing normally.
What is a heart attack?
A heart attack (myocardial infarction) is usually a plumbing problem. A coronary artery that feeds the heart muscle becomes blocked, often by a clot on a ruptured plaque. Heart muscle starts to die from lack of blood flow.
The electrical system may still be coordinating a pulse. Many people stay conscious. They can speak, clutch their chest, sweat, feel sick, or insist they are “fine” and just need to sit down.
A heart attack is a medical emergency. Untreated, it can trigger cardiac arrest. The first-aid goal is rapid professional care, not defibrillation of a conscious person.
What is sudden cardiac arrest?
Sudden cardiac arrest is usually an electrical problem. The heart’s rhythm becomes chaotic or flat in a way that stops effective pumping. Blood flow to the brain cuts out within seconds.
The person collapses or is found unresponsive. They are not breathing normally. They may take occasional agonal gasps that look like breathing but are not. Without CPR and, when the rhythm is shockable, defibrillation, survival falls minute by minute.
An automated external defibrillator (AED) is built for this situation. It analyses rhythm through chest pads and delivers a shock only if the device decides one is indicated.
Heart attack vs cardiac arrest at a glance
| Heart attack | Sudden cardiac arrest | |
|---|---|---|
| Core problem | Blocked blood flow to heart muscle | Heart stops pumping effectively |
| Consciousness | Often awake, can talk | Unresponsive |
| Breathing | Usually present | Absent or abnormal (including gasping) |
| Typical first action | Call 995, keep them resting, follow dispatcher | Call 995, CPR if able, fetch AED |
| Role of a public AED | Not the priority while they are responsive | Critical when unresponsive with abnormal breathing |
| Can one lead to the other? | Yes: a heart attack can cause arrest | Arrest can also have other causes (arrhythmia, drowning, trauma, and more) |
If you remember only the consciousness and breathing row, you will choose the right path most of the time.
Heart attack symptoms to take seriously
Symptoms vary, and not everyone gets classic left-arm pain. Common warning signs include:
- Chest discomfort: pressure, squeezing, fullness, or pain in the centre or left side of the chest
- Pain or discomfort in one or both arms, the back, neck, jaw, or stomach
- Shortness of breath, with or without chest discomfort
- Cold sweat, nausea, light-headedness
- Unusual fatigue or a sense that something is badly wrong
Women, older adults, and people with diabetes may present with less “Hollywood” chest crushing and more breathlessness, nausea, or fatigue. Do not wait for a textbook picture.
In Singapore heat and humidity, people dismiss symptoms as indigestion, anxiety, or “just tired after the MRT.” If the pattern is new, severe, or worsening, call 995 rather than debating it in a Grab.
Cardiac arrest: what it looks like
Suspect cardiac arrest when the person:
- Does not respond to loud voice or a firm shoulder shake
- Is not breathing normally (no breaths, or only rare irregular gasps)
- Collapsed suddenly, or was found unresponsive
You do not need to find a pulse if you are unsure. Unresponsiveness plus abnormal breathing is enough to call 995 and start the arrest pathway.
Do not confuse a faint (brief loss of consciousness with quick recovery and normal breathing) with arrest. If they wake, breathe normally, and stay alert, keep them safe, call for help if the cause is unclear, and still involve 995 when chest pain, seizure, head injury, or another serious cause is possible.
What to do for a suspected heart attack
- Call 995 immediately. Say you suspect a heart attack. Give the exact building, floor, and landmark.
- Help the person rest in a comfortable position, often sitting upright if breathlessness is present and that feels easier for them.
- Loosen tight clothing around the neck and chest.
- Stay with them. Do not leave them alone to “get something from the car” unless you have no other option.
- Follow dispatcher instructions. If they become unresponsive and stop breathing normally, you have moved into cardiac arrest care: CPR and AED.
Do not drive them yourself if ambulance care is available. Do not give medication unless a clinician or the dispatcher specifically instructs you for that person. Aspirin and other drugs are not a bystander improvisation for every chest-pain episode.
A public AED does not treat a conscious heart attack. Keep the focus on 995 and monitoring. If arrest develops, switch pathways without delay.
What to do for suspected cardiac arrest
- Check scene safety, then confirm unresponsiveness and abnormal breathing.
- Call 995 (or point at one person: “You, call 995, speaker on”).
- Start CPR if trained, or as the dispatcher coaches you. Push hard and fast in the centre of the chest.
- Send someone for the nearest AED. Building security and customer service often know the cabinet. Learn likely spots near home and work on AEDLocator beforehand; in a live emergency prefer myResponder.
- Power on the AED, attach pads, stand clear, and continue as the device prompts. Full steps: how to use an AED.
- Keep going until professionals take over or the person shows clear signs of life.
Role assignment and handover tips: what to do before an ambulance arrives.
Why AEDs matter in sudden cardiac arrest (and not in every heart attack)
Defibrillation only helps certain electrical rhythms. In ventricular fibrillation and pulseless ventricular tachycardia, a timely shock can reset the heart so organised pumping has a chance to return. CPR buys time by circulating some oxygenated blood. Together they form the early links in the chain of survival.
A heart attack that has not progressed to arrest is a blocked artery problem. The person needs emergency medical care, possible clot-busting treatment or cath-lab intervention, and monitoring. Shocking a conscious person with a public AED is not the pathway those devices are for, and the AED will not advise a shock if analysis does not find a shockable arrest rhythm.
The practical takeaway for Singaporeans in malls, MRT stations, offices, and HDB estates:
- Responsive + chest symptoms: 995, rest, watch for deterioration.
- Unresponsive + abnormal breathing: 995, CPR, AED.
Public AEDs exist because bystanders reach the person before the ambulance. Every minute without effective CPR and defibrillation reduces the chance of a good outcome. That is why SCDF maintains a public-access registry, and why knowing the cabinet on your floor or at your usual station is useful preparation.
Access still depends on building hours. A listed device can sit behind locked doors at night. See why AED access depends on opening hours and where AEDs are commonly found.
Common mix-ups that delay care
“They are gasping, so they are fine.” Agonal gasps are a sign of arrest, not reassurance. Call 995 and start CPR as directed.
“I should wait for a doctor in the crowd.” Point at specific people for roles. Waiting for a stranger with a stethoscope while nobody compresses wastes the only minutes that matter.
“Chest pain means get the AED first.” For a talking, responsive person, prioritise 995 and rest. Fetch the AED if they collapse and stop breathing normally.
“Cardiac arrest only happens to people with known heart disease.” Arrest can strike with little warning. Heart attack is one pathway, not the only one.
“If I use an AED wrong I will make things worse.” Modern AEDs analyse before advising a shock. Follow the voice prompts. The larger failure mode is doing nothing.
Prepare before you need either pathway
Search AEDLocator for devices near home, work, and the MRT stops you use. Read floor text and hours. Walk past the cabinet once.
Take a community CPR and AED course so compressions and pad placement are muscle memory. These guides are educational, not certification.
Keep myResponder installed or bookmarked for live emergencies, and use this directory for planning. Data source notes: methodology.
FAQ: heart attack vs cardiac arrest in Singapore
Can a heart attack turn into cardiac arrest?
Yes. That is one reason chest-pain emergencies need 995 even when the person is still talking. If they later become unresponsive and stop breathing normally, start CPR and use an AED.
Should I use an AED on someone with chest pain who is awake?
No. Keep them resting, call 995, and monitor. Use the AED if they become unresponsive with abnormal or no breathing and the device is available.
What number do I call in Singapore?
Call 995 for SCDF emergency medical services. Stay on the line and follow instructions for either pathway.
How do I find a public AED nearby?
Search AEDLocator by building, postal code, mall, or planning area. For a live emergency, call 995 and prefer myResponder for the freshest official map.