What is the most common cause of sudden cardiac arrest in adults?

The most common cause of sudden cardiac arrest in adults is a cardiac dysrhythmia. This refers to abnormal heart rhythms that can lead to the heart's failure to effectively pump blood. Often, this condition arises from underlying cardiovascular issues, most commonly myocardial infarction, which disrupts the normal electrical activity of the heart.

When a heart muscle is damaged by factors such as a myocardial infarction, it can lead to arrhythmias like ventricular fibrillation or ventricular tachycardia, which are both life-threatening conditions. In essence, while other factors like respiratory failure or accidental electrocution can lead to sudden cardiac arrest, the immediate physiological mechanism that typically triggers this critical event is a dysrhythmia. Thus, understanding the relationship between heart rhythms and cardiac arrest underscores the importance of rapid diagnosis and intervention in these emergencies.