Abrupt heart rate fallings in a patient with biventricular pacing: latent risk for exacerbation of heart failure.

This case report describes abrupt heart rate fallings below the lower pacing rate limit in a patient with cardiac resynchronization therapy (CRT). Interrogated information including stored episodes or data regarding the lead did not show any device problems and only simultaneous intracardiac electrogram revealed the cause, T-wave oversensing during biventricular pacing. At this moment, CRT has become an established modality for patients with severe heart failure. However, bradycardia below the lower rate limit during biventricular pacing due to T-wave oversensing would exacerbate heart failure in patients with CRT. We should notice this latent risk and correct the malfunction immediately. ©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.