In which type of AV block may a pacemaker be indicated even if the patient is asymptomatic?

A pacemaker may be indicated in Type II second-degree AV block, even when the patient is asymptomatic, because this type of AV block has a significant risk of progressing to complete heart block. In Type II second-degree AV block, there is intermittent failure of conduction of impulses from the atria to the ventricles without a preceding pattern of gradual lengthening, making it more unpredictable than Type I first-degree AV block, where each impulse consistently conducts with only a prolonged PR interval.

Asymptomatic patients with Type II second-degree AV block may still experience severe bradycardia or may suddenly have dropped beats, which can lead to syncope or other heart rhythm-related complications. Therefore, the placement of a pacemaker can preemptively address potential sudden changes in heart rhythm and maintain adequate heart rates.

In contrast, Type I first-degree AV block, which is characterized by a prolonged PR interval without dropped beats, typically does not require intervention as it often is not associated with significant morbidity or mortality. Complete heart block, or Type III, would traditionally require a pacemaker, but the question specifies that this scenario discusses asymptomatic patients and does not focus on the progression potential. Bundle branch block, although it can sometimes warrant a pacemaker if it is symptomatic