Sudden Cardiac Arrest: Understanding The Main Causes
Sudden cardiac arrest (SCA) is a life-threatening condition that occurs unexpectedly and requires immediate medical attention. While it can affect anyone, the majority of sudden cardiac arrest cases occur in individuals with underlying structural heart disease. In fact, approximately 80% of all SCA incidents are linked to coronary artery disease (CAD), making it the leading cause of sudden cardiac arrest.
Coronary Artery Disease And Previous Heart Attacks
Among patients with coronary artery disease, more than half have a history of myocardial infarction (heart attack). These individuals often experience a reduction in left ventricular ejection fraction, which refers to the heart's ability to pump blood efficiently. This decline in cardiac function significantly increases the risk of sudden cardiac arrest. Medical professionals consider this reduced ejection fraction as one of the most critical factors in predicting SCA occurrence.
The Role Of Ventricular Arrhythmias
In addition to structural heart issues, frequent and complex ventricular arrhythmias play a crucial role in predicting sudden cardiac arrest risk. These abnormal heart rhythms can serve as warning signs, particularly in patients who have previously suffered from a heart attack. Detecting and managing these arrhythmias early can be vital in preventing a full cardiac arrest episode.
Heart Conditions In Younger Individuals
While coronary artery disease dominates as a cause in older populations, heart diseases account for 5% to 15% of all sudden cardiac arrest cases overall and are the primary cause among individuals under 35 years old. In this younger demographic, specific cardiac conditions significantly increase the risk of SCA.
Common Causes In Younger Patients
- Hypertrophic obstructive cardiomyopathy: A condition where the heart muscle becomes abnormally thick, making it harder for blood to leave the heart.
- Arrhythmogenic right ventricular cardiomyopathy: A disorder that affects the heart's right ventricle and can lead to dangerous arrhythmias.
- Ion channelopathies: Such as Long QT syndrome, which disrupts the heart's electrical activity and can cause sudden, rapid heartbeats.
These conditions, while less common than coronary artery disease, are particularly dangerous because they often affect younger, seemingly healthy individuals. Many of these heart rhythm disorders can go undetected until a cardiac event occurs, highlighting the importance of early diagnosis and preventive care.