Conclusion
In this study, we have demonstrated the impact of the appearance of VA
conduction due to LOC of RV lead and its potential risk for inducing
RRVAS in CRT device. RRVAS is rare but urgent in its adverse impact on
cardiac resynchronization therapy, which may predispose to exacerbated
heart failure. For patients with intact VA conduction, PVARP should be
programmed slightly longer than VA interval. Whereas, a regular
evaluation for LV- and RV-lead thresholds at different pacing rate are
also necessary to avoid tachycardia-dependent LOC on one or two
ventricular leads for the patients with intact VA conduction. A better
understanding of the underlying mechanism(s) for ECG changes needs
further investigation.
To our knowledge, this is the first case report of RRVAS in CRT device
triggered by a PAC without any prolongation in AV delay but following
the appearance of VA conduction due to loss of RV capture.