What is the most common cause of cardiac arrests?

The most common cause of cardiac arrests is often attributed to ventricular fibrillation. This arrhythmia occurs when the heart's electrical signals become chaotic, leading to ineffective quivering of the ventricles rather than coordinated contractions. As a result, the heart fails to pump blood effectively, causing a sudden lack of blood flow to vital organs, including the brain.

While myocardial infarction is a significant precursor to ventricular fibrillation, leading to approximately 80% of cases of cardiac arrest, it is the chaotic rhythm itself—ventricular fibrillation—that is the direct cause of the loss of effective circulation. Therefore, identifying ventricular fibrillation as the primary mechanism allows swift and targeted intervention, such as defibrillation, which is critical for survival in these situations.

Heart valve disorders and atrial fibrillation, while important cardiovascular issues, do not lead as directly to cardiac arrest as ventricular fibrillation. Heart valve disorders often lead to chronic heart failure or conditions that can predispose to arrhythmias but are less commonly the acute cause of cardiac arrest. Atrial fibrillation can lead to blood clots and stroke but is not typically responsible for the immediate and severe loss of cardiac output experienced during cardiac arrest.