Sudden Cardiac Arrest in Singapore: Causes, Warning Signs and Prevention

Sudden cardiac arrest (SCA) is the abrupt loss of heart function: the heart’s electrical system fails, the heart stops pumping, and the person collapses unconscious within seconds. Without immediate CPR and defibrillation, death follows within minutes. Thousands of out-of-hospital cardiac arrests occur in Singapore each year, and survival depends heavily on how quickly bystanders act. This page explains how cardiac arrest differs from a heart attack, what causes it, the warning signs that are often missed, what to do in an emergency, and how those at risk can be identified and protected. It is general information and not a substitute for advice from your own doctor.

What Is Sudden Cardiac Arrest?

Cardiac arrest is an electrical problem. The most common culprit rhythm is ventricular fibrillation (VF) – chaotic electrical activity that makes the heart’s pumping chambers quiver instead of contract. Circulation stops, the brain is starved of oxygen, and the person collapses, stops breathing normally and becomes unresponsive.

Cardiac arrest is not the same as a heart attack. A heart attack is a plumbing problem: a blocked coronary artery cuts off blood supply to part of the heart muscle. The person is usually conscious, often with chest pain. A cardiac arrest is an electrical problem in which the heart stops pumping altogether. The two are connected – a heart attack can trigger the electrical chaos that causes cardiac arrest – but they are different emergencies with different immediate treatments.

Warning Signs That Are Often Missed

Cardiac arrest can strike without any warning, but warning signs are frequently present in the days or weeks beforehand and are often dismissed:

• Fainting or blackouts, especially during exercise or emotional stress – the single most important red flag
• Chest pain or pressure on exertion
• Sudden palpitations followed by light-headedness or near-collapse
• Unexplained breathlessness out of proportion to activity
• Seizure-like episodes without a neurological diagnosis
• A family history of sudden, unexplained death under the age of 50, or of inherited heart conditions

Anyone with these features should be assessed rather than waiting to see if symptoms recur.

When to Seek Emergency Help: Call 995, Start CPR, Use an AED

If someone collapses, is unresponsive and is not breathing normally, treat it as cardiac arrest:

1. Call 995 immediately and put the phone on speaker – the SCDF operator will guide you through CPR.
2. Start chest compressions – push hard and fast in the centre of the chest, about 100 to 120 compressions per minute, and do not stop until help arrives. Hands-only CPR is far better than doing nothing.
3. Send someone for the nearest AED (automated external defibrillator – a portable device that analyses the rhythm and delivers a shock if needed). AEDs are deployed across Singapore in MRT stations, malls, community centres and HDB blocks, and are designed for untrained users: switch it on and follow the voice prompts.
4. The myResponder app, run by SCDF, alerts registered volunteers to nearby cardiac arrests and shows the nearest registered AEDs.

Every minute without CPR and defibrillation reduces the chance of survival – bystander action matters most.

Causes and Risk Factors

• Coronary artery disease – the leading cause in adults over 35. A heart attack, or scarring from an old one, can trigger VF. Cardiovascular disease accounted for 30.8% of deaths in Singapore in 2024 (MOH), and the same risk factors apply: hypertension, diabetes, high cholesterol and smoking.
• Weakened heart muscle (cardiomyopathy) – a heart with reduced pumping function after a heart attack, or from other causes, is more prone to dangerous ventricular rhythms.
• Hypertrophic cardiomyopathy – abnormal thickening of the heart muscle, a leading cause of sudden death in young athletes; hypertrophic cardiomyopathy often runs in families.
• Inherited electrical (channelopathy) syndromes – conditions such as Brugada syndrome and long QT syndrome affect the heart’s electrical channels in a structurally normal heart. Brugada syndrome is notably relevant in Southeast Asian populations and can cause arrest during sleep in otherwise healthy young men.
• Other causes – myocarditis (inflammation of the heart muscle), severe heart valve disease, electrolyte disturbances, drug toxicity, and a heavy blow to the chest at a precise moment in the heartbeat (commotio cordis).

How Sudden Cardiac Arrest Risk Is Assessed

• Electrocardiogram (ECG) – a resting electrocardiogram (ECG) can reveal the signatures of inherited syndromes, thickened heart muscle or previous damage.
• Echocardiogram – an echocardiogram (ultrasound scan of the heart) measures pumping strength and muscle thickness; a significantly weakened heart is the strongest single predictor of arrest risk.
• Treadmill (exercise stress) test and Holter monitoring – to provoke or capture exercise-related rhythm problems.
• Cardiac MRI and genetic testing – in selected cases, to characterise heart muscle disease and screen family members.
• Screening for young athletes and family members – young people doing competitive sport or NS training with symptoms or a family history, and first-degree relatives of anyone who died suddenly and unexpectedly, should consider structured heart screening with a cardiologist.

Treatment and Prevention Options

• Immediate treatment is defibrillation and advanced resuscitation, followed by intensive care and a full search for the cause.
• Implantable cardioverter-defibrillator (ICD) – for survivors of cardiac arrest, and for people at high risk (such as those with a significantly weakened heart muscle or certain inherited syndromes), an ICD continuously monitors the rhythm and automatically delivers a shock to stop a dangerous arrhythmia. See our cardiac pacemakers and devices service for what implantation involves.
• Treating the underlying disease – angioplasty and stenting or bypass surgery for coronary disease, medication for heart failure (drug classes such as beta-blockers and ACE inhibitors can reduce arrhythmic risk), and specific management plans for inherited conditions.
• Lifestyle and risk factor control – managing blood pressure, cholesterol, diabetes and smoking reduces the coronary disease that drives most cardiac arrests in older adults.

When to See a Cardiologist

See a cardiologist promptly if you have fainted during exertion, have palpitations with near-blackouts, or have a family history of sudden unexplained death or an inherited heart condition. Assessment is straightforward, and identifying a cause early allows preventive treatment before an emergency ever happens.

Frequently Asked Questions

Is sudden cardiac arrest the same as a heart attack?

No. A heart attack is a blocked artery cutting off blood supply to heart muscle – the person is usually conscious. Cardiac arrest is an electrical failure in which the heart stops pumping and the person collapses unconscious. A heart attack can lead to cardiac arrest, but they need different immediate responses.

Can you survive a sudden cardiac arrest?

Yes, if treatment starts fast. Survival depends on immediate CPR and early defibrillation – which is why calling 995, starting compressions and using the nearest AED without delay matter so much. Survivors are then investigated and usually protected with an ICD.

Who should be screened for sudden cardiac arrest risk?

Anyone who has fainted during exercise, has exertional chest pain or palpitations with near-collapse, or has a first-degree relative who died suddenly before 50. Young people entering competitive sport with symptoms or a family history should also consider screening.

Where can I find an AED in Singapore?

AEDs are installed in MRT stations, shopping malls, community centres, sports facilities and at many HDB blocks. The SCDF myResponder app maps registered AEDs near you and alerts trained volunteers to nearby arrests.

Can sudden cardiac arrest be prevented?

Often, yes. Controlling coronary risk factors, detecting inherited conditions through screening, treating a weakened heart muscle, and implanting an ICD in those at high risk can each lower the chance of an arrest, though no measure removes the risk entirely.