Acute Response to Left Bundle Branch Area Pacing With SyncAV

This study measures the immediate heart response to a pacemaker programming technique called Left Bundle Branch Area Pacing (LBBAP) combined with a timing feature called SyncAV, which aims to make the heart beat in a more coordinated, natural way. **You may be eligible if...** - You are 18 or older and need a dual-chamber pacemaker or cardiac resynchronization device - You are scheduled to receive an Abbott brand pacemaker system - Your heart has a specific electrical pattern called left bundle branch block (LBBB) or a similar conduction delay - Your natural electrical signal takes 130 ms or longer to travel through your heart's lower chambers - Your heart's own electrical conduction from the top to bottom chambers is intact (PR interval ≤ 250 ms) **You may NOT be eligible if...** - Your resting heart rate is faster than 100 beats per minute - You have a second- or third-degree heart block (severe electrical conduction problem) - You have persistent abnormal heart rhythms (atrial tachycardia or atrial fibrillation) - You had a recent heart attack, ablation, or major cardiac event in the last 90 days - You are pregnant or nursing Talk to your doctor to see if this trial is right for you.