Cardiac Arrest: Symptoms, Types, Causes and Treatment

Cardiac arrest is a sudden, life-threatening event in which the heart suddenly stops beating effectively, leading to a loss of blood flow to the brain and other vital organs. Without immediate intervention, cardiac arrest is almost always fatal. Understanding the symptoms, types, causes, and treatments of cardiac arrest can help save lives and improve outcomes for survivors and their families.

Symptoms of Cardiac Arrest

Recognizing the warning signs of cardiac arrest is crucial, as early intervention can significantly improve survival and neurological outcomes. While cardiac arrest often occurs abruptly, research shows that many patients experience warning or prodromal symptoms minutes to weeks before the event. However, these symptoms are often ignored or misinterpreted, underscoring the importance of public awareness.

Symptom	Frequency/Description	Prognostic Value	Source
Chest Pain	Common, often typical or atypical	Linked to higher survival rates	1 2 3 4
Dyspnea	Shortness of breath	Frequent, especially in non-cardiac	3 4
Palpitations	Sensation of rapid or irregular heartbeat	Less common	1
Syncope	Fainting or sudden loss of consciousness	May precede arrest	1 3
Other	Nausea, vomiting, abdominal or back pain	Less specific	1 4

Table 1: Key Symptoms Associated with Cardiac Arrest

Early Warning Signs and Their Importance

Recent studies reveal that up to 51% of patients who experience sudden cardiac arrest (SCA) have warning symptoms within the preceding four weeks. The most common are chest pain and dyspnea, though palpitations, syncope, and less specific symptoms like nausea or back pain may also occur. These symptoms are often recurrent and can present hours, days, or even weeks before the arrest. However, most individuals either ignore these signs or fail to seek immediate medical care, missing a critical window for intervention 1 3 4.

Chest Pain and Dyspnea: The Most Telling Clues

• Chest pain is especially significant. Patients who experience chest pain before arrest are more likely to have a heart-related (cardiac) cause and a higher chance of survival, particularly if they call emergency services promptly 2 4.
• Dyspnea (shortness of breath) is another common symptom, especially in arrests due to non-cardiac causes (e.g., respiratory failure or pulmonary embolism). While frequent, dyspnea is associated with lower survival rates compared to chest pain, underscoring the need for rapid assessment 3 4.

Less Common Symptoms

Other symptoms such as palpitations, syncope (fainting), or non-specific complaints (nausea, abdominal pain) can also precede cardiac arrest. These may be less specific but should not be ignored, especially in patients with known risk factors for heart disease 1.

The Link Between Symptoms and Survival

The presence and timely recognition of warning symptoms can make a significant difference. Early activation of emergency medical services (EMS) in response to symptoms, especially chest pain, is associated with better survival and neurological outcomes 1 2 3 4. Public education about these warning signs remains a key strategy for improving outcomes.

Types of Cardiac Arrest

Cardiac arrest is not a single entity but encompasses several types, each with distinct clinical features, causes, and outcomes. Differentiating between these types helps guide treatment and informs prognosis.

Type	Description	Key Characteristics	Source
Out-of-Hospital	Occurs outside medical facilities	Often sudden, lower survival	3 4 7
In-Hospital	Occurs in healthcare settings (wards, ICU)	Older patients, more comorbid	7 8 10 11
Shockable	Arrest due to VT/VF (ventricular tachycardia/fib)	Better prognosis, treatable	7 8 10 11
Non-Shockable	Arrest due to asystole or PEA	Poorer prognosis	8 10 11

Table 2: Main Types of Cardiac Arrest

Out-of-Hospital vs. In-Hospital Cardiac Arrest

• Out-of-Hospital Cardiac Arrest (OHCA):

  • Occurs in the community, often without warning.
  • Survival rates are generally lower due to delays in starting CPR and defibrillation.
  • More likely to have a cardiac cause, but non-cardiac causes are also significant 3 7.

• In-Hospital Cardiac Arrest (IHCA):

  • Occurs in patients already admitted to a hospital.
  • Patients are typically older, have more comorbidities, and the event is more likely to be witnessed.
  • Non-shockable rhythms (asystole, pulseless electrical activity) are more common.
  • Respiratory failure, infection, and heart failure are frequent causes, alongside cardiac causes 7 8 10 11.

Shockable vs. Non-Shockable Rhythms

• Shockable Rhythms:

  • Include ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT).
  • More likely in cardiac-origin arrests, especially those presenting with chest pain.
  • Respond well to early defibrillation, associated with better outcomes 7 8 10 11.

• Non-Shockable Rhythms:

  • Include asystole and pulseless electrical activity (PEA).
  • More common in older, hospitalized patients and those with non-cardiac causes (e.g., respiratory failure).
  • Associated with lower survival rates 8 10 11.

Special Subtypes

• EMS-Witnessed Arrests: Have higher survival rates, as intervention is immediate. Distinct prodromal symptoms are often noted, with chest pain and dyspnea being the most common 2 4.
• Refractory Cardiac Arrest: Cases that do not respond to standard resuscitation may require advanced interventions like extracorporeal membrane oxygenation (ECMO) 14.

Causes of Cardiac Arrest

The causes of cardiac arrest are diverse and vary depending on age, setting, and underlying health conditions. Understanding the root cause is essential for both acute management and prevention.

Cause	Frequency/Significance	Typical Setting	Source
Arrhythmias	Leading cause (VT/VF, asystole, PEA)	Both IHCA & OHCA	6 8 9 10
Acute Coronary Syndrome	Major cause, especially in OHCA	Community/hospital	8 9 10 11
Hypoxia	Common in IHCA (respiratory failure)	Hospitals, elderly	8 10 11 12
Heart Failure	Especially in advanced disease	Hospitals	9 8
Infection/Sepsis	Noted in many IHCA cases	Hospitals	8 10
Pulmonary Embolism	Less frequent but critical	Community/hospital	6 11
Electrolyte Disturbances	Hyper/hypokalemia, acidosis	Hospitals	9 16
Toxins, Tamponade, Trauma	Rare but important in certain cases	Hospitals/trauma centers	8 16

Table 3: Major Causes of Cardiac Arrest

Cardiac Causes

• Arrhythmias: The most frequent direct cause, including ventricular fibrillation (VF), pulseless ventricular tachycardia (VT), asystole, and pulseless electrical activity (PEA). VF/VT are more treatable, while asystole/PEA have a poorer prognosis 6 8 9 10.
• Acute Coronary Syndrome (ACS): Includes heart attacks (myocardial infarction) and acute coronary blockages, often precipitating sudden cardiac arrest, especially in out-of-hospital settings 8 9 10 11.

Non-Cardiac Causes

• Hypoxia: Respiratory failure leading to low blood oxygen is a leading cause in hospitals, especially in older or critically ill patients 8 10 11 12.
• Heart Failure: End-stage heart failure patients are at high risk, with cardiac arrest often precipitated by arrhythmias, electrolyte imbalances, or pump failure 9 8.
• Infection/Sepsis: Systemic infections can cause profound metabolic and circulatory disturbances leading to arrest 8 10.
• Pulmonary Embolism: A large blood clot in the lungs can obstruct blood flow and cause sudden cardiac arrest 6 11 16.
• Electrolyte Disturbances: Imbalances in potassium or other electrolytes can precipitate arrhythmias and cardiac arrest 9 16.
• Other Causes: Include drug overdoses, cardiac tamponade (fluid around the heart), trauma, and rare conditions like severe allergic reactions (anaphylaxis) 8 16.

The Challenge of Identifying the Cause

Accurately identifying the cause of cardiac arrest is often difficult, especially in the emergency setting. Studies show that while presumed causes are often correct, non-cardiac causes like pulmonary embolism or cerebral events are frequently overlooked. Correctly identifying the cause is linked with better survival and neurological outcomes 13.

Treatment of Cardiac Arrest

Immediate and effective treatment of cardiac arrest is critical to survival. Advances in both basic and advanced life support have improved outcomes, but cardiac arrest remains a challenge requiring rapid, coordinated action.

Treatment	Description	Impact/Outcome	Source
CPR	Chest compressions + rescue breathing	Essential, improves survival	10 18
Defibrillation	Electric shock to restore rhythm	Key for shockable rhythms	10 18
Advanced Life Support	Medications, airway management, IV fluids	For refractory/non-shockable	10 18
Post-Arrest Care	ICU, targeted temperature management (TTM)	Improves neuro outcome	10 14 17 18
ECMO/E-CPR	Mechanical support for refractory cases	High survival in select cases	14
Treat Underlying Cause	PCI, treat PE, correct electrolytes, etc.	Essential for long-term survival	10 16 17

Table 4: Main Treatment Strategies in Cardiac Arrest

Immediate Actions: Basic and Advanced Life Support

• CPR (Cardiopulmonary Resuscitation): Early and effective chest compressions with minimal interruptions are the cornerstone of resuscitation. Immediate bystander CPR doubles or triples survival chances 10 18.
• Defibrillation: Rapid defibrillation is the only effective treatment for VF/VT. Automated external defibrillators (AEDs) have made defibrillation more accessible in communities 18.

Advanced Interventions

• Advanced Life Support (ALS): Includes airway management, intravenous medications (like epinephrine), and identification and correction of reversible causes (the "H's and T's": hypoxia, hypovolemia, hypo/hyperkalemia, hypothermia, toxins, thrombosis, trauma, tamponade, tension pneumothorax) 10 16 18.
• Extracorporeal Membrane Oxygenation (ECMO) and E-CPR: For patients with refractory cardiac arrest who do not respond to standard CPR and ALS, ECMO can provide artificial circulation and oxygenation, buying time to treat underlying causes like heart attack or pulmonary embolism. Early data show promising survival and neurological outcomes in select patients 14.

Post-Cardiac Arrest Care

• Targeted Temperature Management (TTM): Cooling the patient to 32-36°C for 24 hours after return of spontaneous circulation (ROSC) can help protect the brain and improve neurological outcomes 10 14.
• Treatment of the Underlying Cause: Immediate identification and management of the precipitating cause—such as coronary artery blockage (PCI), pulmonary embolism, or electrolyte disturbances—is essential for survival and prevention of recurrence 10 16 17.
• Specialty Center Care: Treatment at high-volume centers with organized post-arrest systems is linked to better long-term outcomes for survivors 15.

Prognosis and Recovery

• Neurological Outcome: Survival with good neurological function depends on prompt resuscitation, early defibrillation for shockable rhythms, and high-quality post-arrest care. Delayed recognition or prolonged arrest times reduce the chances of a full recovery 10 14 15.
• Long-Term Care: Survivors may face psychological challenges such as posttraumatic stress disorder (PTSD), which can impact long-term cardiovascular outcomes 5.

Conclusion

Cardiac arrest is a complex emergency with diverse symptoms, types, causes, and treatments. Early recognition and rapid intervention are critical for survival and optimal recovery.

Key Takeaways:

• Many cardiac arrest victims experience warning symptoms—especially chest pain and dyspnea—minutes to weeks before collapse. Recognizing and acting on these signs saves lives.
• Cardiac arrest occurs both out-of-hospital and in-hospital, with distinct characteristics and outcomes based on setting and underlying cause.
• Arrhythmias, acute coronary syndrome, and hypoxia are leading causes, but infections, electrolyte disturbances, and other conditions can also trigger arrest.
• Effective treatment hinges on immediate CPR, timely defibrillation for shockable rhythms, advanced life support, and aggressive post-arrest care including temperature management and treating the underlying cause.
• Survival and neurological recovery are optimized in settings with rapid intervention, accurate diagnosis, and coordinated post-arrest care.

By increasing public and professional awareness of cardiac arrest symptoms and ensuring rapid, evidence-based treatment, we can improve survival and quality of life for those affected by this critical event.