Heart disease is one of the most prevalent diseases worldwide. According to World Heart Report 2023, more than half a billion people are affected by heart disease worldwide.

Sudden Cardiac Arrest (SCA) is one such condition where a sudden loss of all heart activity results in sudden collapse and loss of consciousness. 

Let’s understand the warning signs of SCA in people with an enlarged heart, the associated risk factors, and preventive measures in this article. 

Understanding Heart Enlargement (Cardiomegaly)

Cardiomegaly is a condition characterised by an abnormal increase in the size of the heart. It is not a disease in itself but the result of an underlying cause. 

The causes can be:

• High blood pressure: Increased pressure of blood against the internal walls of the blood vessel
• Valvular heart disease: Defective or impaired valves of the heart
• Cardiomyopathy: Diseased or impaired muscles of the heart 
• Coronary artery disease: Decreased lumen size of the vessels supplying blood to the heart due to various causes such as fat deposition. 
• Other potential causes, such as thyroid issues, congenital heart conditions, and long-term infections.

Connection Between Heart Enlargement and Sudden Cardiac Arrest (SCA)

Sudden Cardiac Arrest

Sudden Cardiac Arrest (SCA) is a sudden loss of heart function due to electrical disturbances, leading to loss of consciousness and lack of pulse. It is a daunting condition which may result in Sudden Cardiac Death (SCD). Recent studies show 50 to 100 sudden cardiac deaths per 100,000 people in the United States, Europe, and China.¹ 

Sudden Cardiac Arrest varies from a heart attack in its mechanism. While a heart attack occurs due to a blockage in the heart blood vessels, SCA occurs due to electrical malfunctioning of the heart and stopping suddenly. 

The risk of SCA in enlarged heart patients increases due to disruption in normal heart rhythm and reduced heart efficiency. An enlarged heart results from several malfunctions at the cellular level. These could be mechanical stress, circulating neurohormones, or oxidative stress. This leads to changes in the structural proteins of heart muscle cells and causes size enlargement (hypertrophy).²

Effects Of An Enlarged Heart

Due to the changes at the cellular level and the abnormal size of the heart, effects seen are:²

• Hyperdynamic contractility: increased strength in contraction of the chamber of the heart and rapid heart rate
• Poor relaxation: Inability of the heart chambers to relax between the heartbeats
• Increased energy consumption

Symptoms

Primary Warning Signs of Sudden Cardiac Arrest in People with Heart Enlargement

• Chest pain or discomfort especially due to physical exertion
• Shortness of breath during physical activities or when lying down
• Palpitations or racing heartbeats
• Dizziness
• Lightheadedness
• Unexplained tiredness
• Tendency to faint due to high stress or strenuous activity
• Family history of heart muscle diseases
• Medical history of hypertension or diabetes

Additional Concerning Symptoms That May Precede Sudden Cardiac Arrest

• Swelling in legs, ankles, or abdomen due to fluid retention from poor circulation
• Nausea or vomiting
• Persistent coughing sometimes with blood-tinged mucus
• Severe anxiety or feeling of impending doom
• Unexplained sweating or sudden cold sweats without physical exertion

Risk Factors for Sudden Cardiac Arrest in Enlarged Heart Patients

Lifestyle Factors

Unhealthy lifestyle practices such as smoking, excessive alcohol intake, and a sedentary lifestyle have a huge influence on health. 

Smoking

Some studies show that cigarette smoking leads to acute thrombosis (formation of clots in blood vessels), which increases the risk of sudden cardiac death.³

Alcohol Consumption

Alcohol misuse is another harmful habit. About 3 out of 20 cardiac arrest cases are linked to alcohol.⁴

Medical Conditions

Diabetes

SCA is a major cause of mortality in patients with diabetes. The risk of SCA increases by 2 to 4 times in people with type 2 diabetes.⁶ The insulin abnormalities caused by type 2 diabetes impact the development of diseases that affect small and large blood vessels, increasing the risk of SCA.⁶ Studies recommend 1-2 servings of fatty fish per week, smoking cessation, regular exercise, and treatment of high blood pressure and cholesterol to prevent SCA in diabetic patients.⁶

Obesity

Several epidemiological studies show an increased risk of SCA in obese patients, independent of other predisposing factors.⁷ A meta-analysis of 14 studies on about 406,079 people shows that every 5-unit increment in Body Mass Index (BMI) increased the risk of Sudden Cardiac Death (SCD) by 16%.⁸

To prevent SCA in obese patients, regular physical activity and diet optimisation are crucial while treatment options for weight loss include diet pills and bariatric surgery.⁷

Previous Heart Attacks 

A history of previous heart attacks increases the risk of sudden cardiac death. A family history of SCD in first-degree relatives shows a 20% increased risk of SCD.⁵ In such high-risk cases, an Implantable Cardioverter Defibrillator (ICD) is recommended to monitor the heart and treat irregular heartbeats.⁹

Electrolyte Imbalances

Electrolytes are essential minerals such as sodium, potassium, and calcium vital for body functioning. An imbalance in electrolyte levels can cause disturbance in the electrical and contractile functions of the heart and lead to arrhythmias, impaired circulation, and sudden cardiac arrest. 

Age and Gender

According to some studies, SCD occurs in asymptomatic children and adults younger than 35 years old. Typically, the risk of SCD decreases significantly with age and is uncommon in patients over 60 years old.⁵

Other Cardiac Conditions

Pre-existing arrhythmias, high blood pressure, and coronary artery disease increase the risk of SCA. However, timely diagnosis and treatment of coronary artery disease can increase the chances of survival after a sudden cardiac arrest by 50%.¹⁰

Preventive Measures and Monitoring for High-Risk Individuals

Regular Check-ups

Routine cardiac exams, such as ECG, echocardiograms, and stress tests are crucial in people at high risk or with existing heart diseases. These tests help detect early signs of heart disease, monitor heart functions, and prevent serious complications. 

Medications

Certain drugs such as Beta-blockers, ACE inhibitors, or anticoagulants can help manage symptoms and reduce SCA risk. However, it is crucial to always consult your healthcare provider before starting any medication. 

Lifestyle Modifications

• Follow a heart-healthy diet low in sodium and fats
• Do regular, moderately intense, and physician-approved exercise
• Avoid alcohol and smoking

Implantable Devices

Devices like implantable cardioverter-defibrillators (ICDs), also called a Shock Box, for individuals at high risk of SCA have become the first line of defence. It has proven survival benefits and also improves the quality of life in patients waiting for a suitable donor for a heart transplant.¹¹

Emergency Response to Sudden Cardiac Arrest

If you ever encounter an emergency, it is important to respond quickly and effectively. But do not panic! Below are the actions you can take:

Recognising Sudden Cardiac Arrest

Signs like sudden collapse, no pulse, and no breathing indicate sudden cardiac arrest. Make sure to check the pulse and breath of the collapsed person.

Immediate Actions

• Call emergency services
• Initiate CPR immediately if trained
• Use an automated external defibrillator (AED) if available

Importance of Quick Response

Immediate intervention increases the chances of survival for the collapsed person. Your quick thinking can save a life. 

Long-Term Management and Support for Patients with Enlarged Heart and High SCA Risk

Regular Cardiac Rehabilitation Programs

Cardiac rehabilitation programs are designed for people recovering from heart-related events such as heart attack, heart failure, heart surgery or other heart diseases. It provides physical, emotional, and mental support to improve quality of life. 

Family and Caregiver Education

Training family members in CPR and AED use for emergencies is crucial for managing cardiac emergencies. It increases the chances of survival, provides immediate response to the affected person, and instils confidence that they will be taken care of in case of emergency. 

Support Groups and Counseling

Coping with a heart condition can lead to feelings of anxiety, fear, and even depression. Support groups and counselling provide emotional support and management of anxiety related to heart conditions. Interacting with people with similar conditions gives the affected person a sense of relief and hope. 

Summary

Sudden Cardiac Arrest (SCA) is a sudden loss of heart function due to electrical disturbances, leading to loss of consciousness and lack of pulse. In patients with heart enlargement or cardiomegaly, the risk of SCA is higher. Primary warning signs include shortness of breath, chest pain or discomfort, palpitation, dizziness and a tendency to faint. Additional signs include swelling in the legs, nausea, vomiting, persistent coughing, and cold sweats. The factors which increase the risk of SCA are obesity, diabetes, smoking habits, alcohol consumption, and history of heart attack. It is important to recognize early warning signs and risk factors to provide immediate response to the affected person. Training in CPR and AED can help in saving a life during a cardiac emergency.