Diastolic mitral regurgitation after dual chamber pacemaker.

First-degree Atrioventricular (AV) block can lead to symptoms of heart failure, due to AV dyssynchrony. We report a case of 40-year-old male with symptomatic 2:1 AV block with intermittent first-degree AV block who was implanted with dual chamber pacemaker with conduction system pacing (CSP). With conventional programming of managed ventricular pacing (MVP) and long AV delays, patient developed dyspnea due to diastolic mitral regurgitation because of AV dyssynchrony. Hence, AV delay optimization was done, and the patient became asymptomatic with atrial sensing and 100 % ventricular pacing. This report emphasizes the importance of AV delay optimization in CSP for symptomatic benefit.