What is a common characteristic of PACs?

A common characteristic of premature atrial contractions (PACs) is that they are caused by a premature electrical discharge originating in the atrium of the heart. This discharge occurs before the next expected heartbeat, leading to an early contraction. PACs can occur in healthy individuals and are often benign. Their occurrence is usually influenced by factors such as stress, caffeine intake, or fatigue, making them a relatively common finding on an electrocardiogram (ECG).

In terms of the other options, PACs do not always indicate severe heart disease; they can occur in individuals with no underlying conditions. This makes the option suggesting that PACs always indicate severe heart disease incorrect. Furthermore, PACs do not specifically occur during bradycardia; they can happen at any heart rate and are more associated with normal sinus rhythm where occasional PACs may be detected. Lastly, while PACs can be associated with certain cardiac conditions, they are often benign and do not imply that they cannot be benign. Thus, recognizing that PACs result from premature atrial electrical activity is key to understanding their characteristics.