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Dr. Nagesh H E

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Reviewed by

Dr. Nagesh H E

Consultant - Cardiology

Manipal Hospitals, Malleshwaram

Understanding Sudden Cardiac Death (SCD): Causes, Risk Factors, And Prevention

Reviewed by:

Dr. Nagesh H E

Posted On: Sep 29, 2023

blogs read 4 Min Read

Sudden Cardiac Death

Sudden Cardiac Death (SCD) claims hundreds of lives every year throughout the world. It is estimated that more than 7 million lives every year are lost to SCD, worldwide, with half of all cardiac deaths being attributed to SCDs. 

Anyone can suffer from SCD, regardless of age, exercise level, or medical history. Nearly 50% of individuals who experience sudden cardiac arrest (SCA) claim to have had no symptoms before passing out. We have lost many well-known personalities like Singer KK (53), Puneeth Rajkumar (46), and Sidharth Shukla (40) due to sudden cardiac arrest and death. 

What is Sudden Cardiac Death?

Sudden Cardiac Death (SCD) is a sudden, unexpected death from cardiac causes that happens quickly, often within an hour of symptom onset. It occurs in people with a known or unknown heart disease. Many individuals who encounter out-of-hospital cardiac arrest (OHCA) experience SCD as the first impression of cardiovascular disease in adults.

Sudden cardiac deaths most commonly occur between 6 am and noon, and again in the late afternoon. The incidence of SCD is higher on Mondays. Most people experience palpitations (rapid, irregular heartbeat), dizziness, or syncope (fainting) before they have a sudden cardiac arrest. But, about half of all people who have sudden cardiac arrests don’t report any warning signs.

Sudden cardiac arrest is characterised by:

  • Absence of breathing 

  • Loss of consciousness

  • Abrupt loss of heart function (cessation of heart contractions).

The condition usually results from a problem with the heart's electrical system (either Asystole, Ventricular fibrillation, or pulseless electrical activity). It interferes with the heart's pumping function and stops blood flow to the brain’s vital centres and body.

Other symptoms of sudden cardiac arrest and death include:

  • Palpitations

  • Dizziness

  • Near syncope 

Causes of Sudden Cardiac Arrest

Coronary Artery Disease:

Approximately 80% of all SCD cases are caused by coronary artery disease (CAD) i.e., ischemic heart disease. Cardiomyopathies (a disease of the heart muscles, making it difficult to pump blood to the rest of the body) and Inherited Channelopathies (defects in ion channels caused by genetic factors) are additional causes. 

The causes of coronary artery disease, myocardial infarction (or heart attack), and ischemic cardiomyopathy are:

  • Family history of premature coronary artery disease

  • Smoking

  • Dyslipidemia

  • Hypertension

  • Diabetes

  • Obesity

  • Sedentary lifestyle.

The risk of sudden cardiac death is at its highest in the first few months following a heart attack due to factors like - fatal tachyarrhythmias, re-infarction, or myocardial rupture. Non-ischemic SCD is frequently caused by fibrosis, overweight-related cardiomyopathy, and excessive alcohol usage.

Cardiac Channelopathies

Cardiac channelopathies are genetic abnormalities in heart cell proteins that control heart electrical activity and thus can cause heart rhythm disturbances. Nearly 30% of the victims of swimming-related drowning hosted a cardiac channel mutation. Sudden death in young athletes usually precipitated by intense physical activity may be due to a heterogeneous spectrum of cardiovascular disease, commonly known as Hypertrophic cardiomyopathy (HCM). 

Congenital Heart Disease

The primary cause of SCD in kids from birth to 13 years of age is the presence of congenital heart disease. When dealing with such children and asymptomatic adults with CHD, a major challenge for the cardiologist is risk ratifying the individual patients to the risk of SCD. Cardiac remodelling and fibrosis put these patients at increased risk. The American Heart Association suggests high school and university athletes get cardiovascular monitoring, including a medical examination and a review of the student or athlete's personal and family history.

Cardiomyopathy

Left ventricular dysfunction is a major independent predictor of total and sudden cardiac mortality in patients with ischemic and non-ischemic cardiomyopathy. 

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart condition that causes abnormal heart rhythms and can lead to sudden death. It is most common in young people and athletes. In ARVC, the heart muscle is gradually replaced by fat and scar tissue. This can cause the heart to beat too fast or too slowly, and can also make it difficult for the heart to pump blood effectively. ARVC can run in families and is often caused by a gene mutation. But, not all people with ARVC have a family history. The incidence of atrial and ventricular arrhythmias (irregular heartbeat) increases with increasing age. QRS duration (Q wave, R wave, and S wave) in ECG is one of its important prognostic indicators.

Management of SCA

Initiating immediate care for sudden cardiac arrest is important to prevent SCD. It consists of immediate resuscitation followed, by acute & long-term therapy which depends on underlying aetiology. 

In the case of OHCA (Out-of-hospital cardiac arrest), cardiopulmonary resuscitation - CPR is the gold standard of emergency care if the patient is unable to breathe or the heart has stopped. CPR provides enough oxygen to the brain until a stable electrical rhythm can be established. Then, an automated external defibrillator can be used to reset the heart rhythm until the patient reaches a nearby hospital

In the hospital, therapeutic hypothermia (lowering the body temperature) can be induced to limit neurologic injury and reperfusion injuries. Therapeutic hypothermia is more effective for the management of ventricular tachycardia and ventricular fibrillation but can also be used in Pulseless electrical activity (PEA) and asystole. 

Anti-arrhythmic medicines such as beta-blockers, calcium channel blockers, and angiotensin-converting enzyme inhibitors (ACEi) are given to selected patients with SCA. 

Basic immediate Investigations that are done after successful resuscitation are:

  • ECG

  • Echocardiography

  • Serum electrolytes

  • Serum Calcium and magnesium levels

  • Blood sugar 

  • Holter monitoring 

  • Coronary angiography.

Surgical Intervention after a Sudden Cardiac Arrest

Some patients are advised to undergo surgery to address their heart issues. In some patients, an implanted cardioverter-defibrillator (ICD) device is implanted to improve irregular heartbeats. It is placed close to the collarbone. To clear the clogged artery and enhance the blood flow to the heart, a coronary angioplasty or coronary artery bypass surgery may be suggested. Other surgeries include radiofrequency catheter ablation and corrective heart surgery. 

Preventing Sudden Cardiac Arrest & Death

Keeping the heart healthy may help prevent SCA. You can do this by:

  • Adopting a healthy diet

  • Not smoking or using any form of tobacco

  • Maintaining blood pressure and cholesterol levels

  • Getting regular health screenings as directed by your cardiologist

  • Undergoing genetic testing if you are genetically predisposed to SCA due to diseases like QT syndrome.

It is important to understand that survival is always achievable with prompt and effective medical care. 

Whom to Consult and When?

Seek an appointment with one of the best heart doctors in Bangalore at a reputed tertiary care hospital in India equipped with state-of-the-art facilities, experienced cardiologists, and specialists. If you notice any of the symptoms, don’t waste time and consult a cardiologist immediately to rule out or diagnose heart diseases when they are highly treatable through therapies. 

Keep yourself informed, take proactive measures to maintain a healthy heart, and contribute to the battle against sudden cardiac death. 

To understand and keep your heart healthy, you can book an appointment with the best cardiologists at Manipal Hospitals, Malleshwaram, Bangalore.

Frequently Asked Questions (FAQs) on Sudden Cardiac Arrest

  1. Can diabetes increase the risk of SCD?

Yes, comorbidities such as hypertension, increased cholesterol, diabetes, and obesity can all increase the risk of SCD. 

  1. Who treats cases of sudden cardiac arrest?

Patients with SCA are treated by cardiologists or cardiac electrophysiologists. If any of your family members suffer from any cardiovascular diseases or have a risk of developing an SCA, you should meet the best cardiologists in Bangalore.

  1. Does SCD occur only in elderly people?

No. People of all ages, including teens and adults, can suffer from SCD. You should be aware that many celebrities lost their lives to SCD/heart attack in the recent past.

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