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.