Could bradycardia be a sign of apnea of prematurity?

Yes it can: The two often go together. The baby will have apnea-defined as 20 seconds or more of not breathing, which then in a neonate (baby <=28 days) will often lead to bradycardia, or low heart rate. Please have your baby seen by your pediatrician if this is going on, as prematurity is not the only cause of these symptoms. Sometimes medication is needed.